Thursday, October 21, 2010
Unique Relationship Observed Between Grain Intake and Visceral Adipose Tissue
People who consume several servings of whole grains per day while limiting daily intake of refined grains appear to have less of a type of fat tissue thought to play a key role in triggering cardiovascular disease and type 2 diabetes, a new study suggests. Researchers at the Jean Mayer USDA Human Nutrition Researcher Center on Aging (USDA HNRCA) at Tufts University observed lower volumes of Visceral Adipose Tissue (VAT) in people who chose to eat mostly whole grains instead of refined grains.
“VAT volume was approximately 10 % lower in adults who reported eating three or more daily servings of whole grains and who limited their intake of refined grains to less than one serving per day,” says first author Nicola McKeown, PhD, a scientist with the Nutritional Epidemiology Program at the USDA HNRCA. “For example, a slice of 100% whole wheat bread or a half cup of oatmeal constituted one serving of whole grains and a slice of white bread or a half cup of white rice represented a serving of refined grains.”
McKeown and colleagues, including senior author Caroline S. Fox, MD, MPH, medical officer at The Framingham Heart Study of the National Heart Lung and Blood Institute (NHLBI), examined diet questionnaires submitted by 2,834 men and women enrolled in The Framingham Heart Offspring and Third Generation study cohorts. The participants, ages 32 to 83, underwent multidetector-computed tomography (MDCT) scans, to determine VAT and subcutaneous adipose tissue (SAT) volumes.
Visceral fat surrounds the intra-abdominal organs while subcutaneous fat is found just beneath the skin. “Prior research suggests visceral fat is more closely tied to the development of metabolic syndrome, a cluster of risk factors including hypertension, unhealthy cholesterol levels and insulin resistance that can develop into cardiovascular disease or type 2 diabetes,” explains co-author Paul Jacques, DSc, director of the Nutritional Epidemiology Program at the USDA HNRCA and a professor at the Friedman School of Nutrition Science and Policy at Tufts. “Not surprisingly, when we compared the relationship of both visceral fat tissue and subcutaneous fat tissue to whole and refined grain intake, we saw a more striking association with visceral fat. The association persisted after we accounted for other lifestyle factors such as smoking, alcohol intake, fruit and vegetable intake, percentage of calories from fat and physical activity.”
Published online September 29 by The American Journal of Clinical Nutrition, the present study builds on prior research that associates greater whole grain intake with reduced risk of metabolic syndrome and insulin resistance. “However, because these studies are observational, future research that specifically investigates whole grain intake and body fat distribution in a larger, more diverse study population is needed to identify the mechanism that is driving this relationship,” Jacques adds.
Additionally, in the present study, the authors observed that participants who consumed, on average, three daily servings of whole grains but continued to eat many refined grains did not demonstrate lower VAT volume. “Whole grain consumption did not appear to improve VAT volume if refined grain intake exceeded four or more servings per day,” says McKeown, who is also an assistant professor at the Friedman School. “This result implies that it is important to make substitutions in the diet, rather than simply adding whole grain foods. For example, choosing to cook with brown rice instead of white or making a sandwich with whole grain bread instead of white bread.”
Tuesday, October 19, 2010
Despite Fewer Calories, Low-Carb Drink Provides Better Endurance in Cyclists, Reports Study in The Journal of Strength and Conditioning Research
Compared to a standard carbohydrate supplement, a low-carbohydrate beverage with added protein leads to longer endurance times in cyclists, reports the October issue of the The Journal of Strength and Conditioning Research, official research journal of the National Strength and Conditioning Association. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, and pharmacy.
Depending on exercise intensity, a low-carb beverage with a moderate amount of added protein can improve aerobic endurance—even though it contains half the carbohydrates and less than one-third the calories of standard sports drinks, according to a study by Lisa Ferguson-Stegall, M.S., and colleagues of The University of Texas at Austin.__Cyclists Go Longer on Low-Carb, Added-Protein Supplement_In the laboratory study, 15 trained endurance cyclists performed two long rides: three hours, followed by an intense ride—up to 85 percent of aerobic capacity (VO2 max)—until exhaustion. On one ride, the athletes were given a standard six percent carbohydrate supplement. On the other ride, they received a three percent carbohydrate supplement (containing a mix of carbohydrates) with 1.2 percent added protein. On each ride, the cyclists were given 275 mL of their assigned beverage every 20 minutes.
Overall, there was no significant difference in endurance times. Average time to exhaustion was 26 minutes with the standard supplement and 31 minutes with the low-carb plus protein supplement.
However, the difference became significant for athletes exercising at or below their ventilatory threshold (VT)—the point at which breathing starts to become increasingly difficult. For the eight cyclists in this group, average time to exhaustion was 45 minutes with the low-carb plus protein beverage, compared to 35 minutes with the standard carbohydrate drink.
Thus endurance improved by about 28 percent in cyclists exercising at or near their VT. For the seven athletes exercising above their VT, there was no significant difference in time to exhaustion—about 15 minutes with both supplements.
Studies have shown that carbohydrate-containing beverages increase endurance exercise performance, compared to water and placebo drinks. Supplements containing protein in addition to carbohydrates bring further performance benefits. "However, many athletes and recreational exercisers desire a lower carbohydrate, lower caloric content alternative when maintaining or reducing body weight...in addition to improving fitness and endurance," Ferguson-Stegall and coauthors write.
The new results suggest that a drink containing a lower amount of carbohydrate, plus a moderate amount of protein, leads to improved endurance performance in trained long-distance cyclists. The low-carb drink increases performance "despite containing 50 percent less total carbohydrate and 30 percent fewer calories relative to a higher carbohydrate beverage," according to the researchers.
The difference is significant only for athletes exercising at or below VT. The ability to exercise for long periods at or near VT is a "critical component of performance in long events such as marathons, longer cycling races, and long-distance triathlon," according to Ferguson-Stegall and colleagues. Thus the low-carb, added-protein supplement may be "more effective in extending endurance and delaying fatigue...around the exercise intensity at which prolonged endurance performance is crucial."
Use of folic acid supplements appears to lower blood levels of the amino acid homocysteine -- theorized to be a risk factor for heart and blood vessel disease -- but does not appear to be associated with reduced rates of cardiovascular events, cancer or death over a five-year period, according to a meta-analysis of previously published studies in the October 11 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
"Elevated plasma total homocysteine [an amino acid created by the body, usually as a byproduct of eating meat] has been suggested as a potentially modifiable risk factor for coronary heart disease, stroke and other occlusive vascular conditions," the authors write as background information in the article. High rates of cardiovascular disease in children with homocystinuria -- a rare genetic condition causing extreme elevations in homocysteine levels -- led researchers to hypothesize that moderate increases in blood homocysteine levels may increase cardiovascular disease risk in the general population.
Supplementation with B vitamins, and in particular folic acid, lowers blood homocysteine levels and reduces cardiovascular disease risk among individuals with homocystinuria. Several large clinical trials conducted in patients without the condition have been inconclusive. "Consequently, a collaboration between their investigators was established in 2004 to conduct a meta-analysis based on individual participant data from all large randomized trials of folic acid-based B-vitamin supplementation intended to lower plasma homocysteine levels for the prevention of cardiovascular disease," the authors write.
Robert Clarke, F.R.C.P., University of Oxford, England, and colleagues in the B-Vitamin Treatment Trialists' Collaboration report the results of the meta-analysis of all eight trials completed by the end of 2009. Of a total of 37,485 participants, 18,723 were assigned to take folic acid in doses ranging from 0.8 milligrams per day to 40 milligrams per day. The other 18,762 took placebo or an equivalently small dose of folic acid. Trials continued for a median (midpoint) of five years.
Among the 37,485 participants, 9,326 had a major vascular event during the treatment period, 3,010 developed cancer and 5,125 died. Overall, there was a 25 percent reduction in homocysteine levels associated with active folic acid supplementation. However, those who took folic acid were no less likely to have a major heart or blood vessel event than those who took placebo (4,670 or 24.9 percent of first events occurred in those taking folic acid, compared with 4,656 or 24.8 percent in the placebo group).
In addition, there was no significant difference between folic acid and placebo groups in the number of patients experiencing major coronary events (2,019 or 11.4 percent vs. 1,971 or 11.1 percent); stroke (747 or 4.2 percent vs. 781 or 4.4 percent); new cases of cancer (1,541 or 8.7 percent vs. 1,469 or 8.2 percent) or death (2,578 or 13.8 percent vs. 2.547 or 13.6 percent).
"The doses of folic acid used in all the trials included in this meta-analysis exceeded those required for near-maximal reduction in homocysteine levels," the authors write. "The randomized trials in the present meta-analysis found no evidence of benefit with treatment continued for more than five years. Although some benefit might emerge with even longer treatment and follow-up, the trial results give no reason to expect this (particularly because cardiovascular benefits tend to emerge within just a few years with other cardioprotective treatments, such as antihypertensives or statins)."
"One-third of adults in the United States and one-quarter of those in the United Kingdom report taking daily multivitamin supplements containing folic acid," they conclude. All doses in the trials were greater than those required in the United States, where foods are fortified with folic acid to prevent neural tube birth defects. "Although the lack of any other benefits is disappointing (albeit fairly definitive), the lack of any significant adverse effects on vascular events, cancer incidence, cancer mortality and overall mortality provides reassurance about the safety of population-wide folic acid fortification."
According to new research conducted at Oregon Health & Science University, yoga exercises may have the power to combat fibromyalgia -- a medical disorder characterized by chronic widespread pain. The research is being published in the November 10 online edition of the journal Pain and will appear online on Oct. 14.
"Previous research suggests that the most successful treatment for fibromyalgia involves a combination of medications, physical exercise and development of coping skills," said James Carson, Ph.D., a clinical health psychologist and an assistant professor of anesthesiology and perioperative medicine in the OHSU School of Medicine. "Here, we specifically focused on yoga to determine whether it should be considered as a prescribed treatment and the extent to which it can be successful."
In this study, researchers enrolled 53 female study subjects previously diagnosed with fibromyalgia. The women were randomly assigned to two research groups. The first group participated in an eight-week yoga program, which included gentle poses, meditation, breathing exercises and group discussions. The second group of women -- the control group -- received standard medication treatments for fibromyalgia.
Following completion of the yoga program, researchers assessed each study subject using questionnaires and physical tests. The results were then compared with testing results obtained prior to the yoga classes. The members of the control group underwent the same evaluations. In addition, each participant in the yoga group was urged to keep a daily diary to personally assess their condition throughout the entire program.
Comparison of the data for the two groups revealed that yoga appears to assist in combating a number of serious fibromyalgia symptoms, including pain, fatigue, stiffness, poor sleep, depression, poor memory, anxiety and poor balance. All of these improvements were shown to be not only statistically but also clinically significant, meaning the changes were large enough to have a practical impact on daily functioning. For example, pain was reduced in the yoga group by an average of 24 percent, fatigue by 30 percent and depression by 42 percent.
"One likely reason for the apparent success of this study therapy was the strong commitment shown by the study subjects. Attendance at the classes was good as was most participants' willingness to practice yoga while at home," added Carson. "Based on the results of this research, we strongly believe that further study of this potential therapy is warranted."
As an outcome of this study and Carson's previous research showing yoga can be helpful with cancer-related pain, next June the OHSU Department of Anesthesiology and Perioperative Medicine will be sponsoring a training course for U.S. and Canadian yoga teachers who want to build their skills for working with individuals who have chronic pain.
Fibromyalgia is a syndrome predominantly characterized by muscle pain and fatigue. It can cause sleep problems, fatigue and psychological stress. Other symptoms often include:
* Morning stiffness
* Tingling or numbness in the extremities
* Memory problems
Fibromyalgia affects between 11 million and 15 million Americans. The annual costs for health care for these patients have been estimated at $20 billion. The cause of fibromyalgia is currently unknown, but it is believed that genetics and physical/emotional stress may play a role.
Monday, October 18, 2010
A new study shows that vitamin B12 may protect against Alzheimer's disease, adding more evidence to the scientific debate about whether the vitamin is effective in reducing the risk of memory loss. The research will be published in the October 19, 2010, issue of Neurology®, the medical journal of the American Academy of Neurology.
"Our findings show the need for further research on the role of vitamin B12 as a marker for identifying people who are at increased risk of Alzheimer's disease," said study author Babak Hooshmand, MD, MSc, with Karolinska Institutet in Stockholm, Sweden. "Low levels of vitamin B12 are surprisingly common in the elderly. However, the few studies that have investigated the usefulness of vitamin B12 supplements to reduce the risk of memory loss have had mixed results."
For the seven-year study, researchers took blood samples from 271 Finnish people age 65 to 79 who did not have dementia at the start of the study. During that time, 17 people developed Alzheimer's disease. Blood samples were tested for levels for homocysteine, an amino acid associated with vitamin B12, and for levels of the active portion of the vitamin, called holotranscobalamin. Too much homocysteine in the blood has been linked to negative effects on the brain, such as stroke. However, higher levels of vitamin B12 can lower homocysteine.
The study found that for each micromolar increase in the concentration of homocysteine, the risk of Alzheimer's disease increased by 16 percent, whereas each picomolar increase in concentration of the active form of vitamin B12 reduced risk by two percent. The results stayed the same after taking into account other factors, such as age, gender, education, smoking status, blood pressure and body mass index. The addition of folate did not appear to raise or lower the risk of Alzheimer's disease.
"More research is needed to confirm these findings before vitamin B12 should be used solely as a supplement to help protect memory," said Hooshmand.
Post-menopausal breast cancer patients with hormone-sensitive cancers who consumed high amounts of soy isoflavones had a lower risk of recurrence, found a research study published in CMAJ (Canadian Medical Association Journal.
Soy isoflavones are similar to estrogen in chemical structure and may stimulate or inhibit estrogen-like action in tissues. Consumption of soy isoflavones, found in soybeans and soy products, has increased in recent years and there are concerns about the effect of soy consumption on women with estrogen and progesterone receptor positive breast cancer as tumour growth is dependent on estrogen.
The study, by researchers at the Cancer Hospital of Harbin Medical University, Harbin, China, involved 524 women who had surgery for breast cancer and were followed afterwards for between five to six years. Since little is known about the effects of soy isoflavones on breast cancer patients receiving adjuvant endocrine therapy, the researchers sought to understand its impact in these patients.
"Compared with postmenopausal patients in the lowest quartile of soy isoflavone intake (less than 15.2 mg/day), those in the highest quartile (more than 42.3 mg/day) had a significantly lower risk of recurrence," writes Dr. Qingyan Zhang with coauthors.
"The recurrence rate of estrogen- and progesterone- positive breast cancer was 12.9% lower among patients in the highest quartile of soy isoflavone intake than among those in the lowest quartile and was 18.7% lower for patients receiving anastrozole therapy in the highest quartile," they state.
However, there was no effect on overall survival in postmenopausal women and no association between soy intake and survival in premenopausal women.
The authors conclude that while this finding is potentially important regarding soy intake, large multicentre clinical trials are needed to provide more data.
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A systematic review of the medical literature supports the hypothesis that statins, cholesterol‐lowering drugs used to prevent cardiac problems, are associated with reduced risk of colon and rectal cancers. A comprehensive analysis by investigators at the University of Michigan at Ann Arbor, included 22 scientific studies with more than 2.5 million combined participants.
"Statin use was associated with a statistically significant reduction in colorectal cancer," explained Jewel Samadder, M.D., MSc. The relative risk was 0.88 (95% CI 0.84‐0.93; n=22) and represents a 12% reduction in the odds of colorectal cancer among statin users. This effect was largely consistent across study design with both case control and cohort studies showing a strong correlation. The length of statin use, both greater than 6 months and greater than 5 years of use was associated with reduction in colorectal cancer risk. Importantly, when the analysis was stratified for statin type, the most common category of statins, lipophilic (which includes atorvastatin or Lipitor), showed the greatest effect.
"Observational studies have suggested that long‐term use of statins is associated with reduced risk of several cancers, including breast, prostate, lung, pancreas and liver. Our findings suggest that randomized controlled trials designed to test the hypothesis that statins reduce the risk of colorectal cancer are warranted," added Dr. Samadder.
Saturday, October 16, 2010
Heart attack patients whose hearts have stopped beating and who receive cardiopulmonary resuscitation (CPR) from bystanders fare better if their resuscitators skip the rescue breaths and do only chest compression, according to a study led by researchers at Washington University School of Medicine in St. Louis.
The study, published online on Oct. 15 in The Lancet, determined that the chest compression-only method of CPR improved survival rates over standard CPR.
Standard CPR involves alternating chest compressions with rescue breaths.
“We looked at data from three studies,” says principal investigator Peter Nagele, MD. “Individually, the studies were ‘underpowered’ statistically and could not show a survival benefit. Basically, there were too few study subjects to determine whether one method of CPR improved survival more than another, but when we combined all three studies, there was a significant increase in survival when witnesses were told by 911 dispatchers to provide chest compression only.”
Nagele, an assistant professor of anesthesiology and chief of trauma anesthesiology at Barnes-Jewish Hospital in St. Louis, and his team combined the data from the three studies in a meta-analysis and were able to analyze survival rates in more than 3,700 cardiac arrest patients who received either standard CPR or chest compression only. Those smaller studies had suggested chest compression-only CPR may improve survival – one noted a 14 percent increased survival to hospital discharge, while a second reported a 24 percent improvement in 30-day survival – but because of relatively small numbers in those studies, it was impossible to conclusively determine which of the two CPR methods was actually better.
But analyzing all three studies, Nagele’s team determined that survival improved by 22 percent when bystanders called 911 and were advised by the dispatcher to do chest compression-only CPR.
“When a person goes into cardiac arrest because of a problem with the heart, that individual normally has plenty of oxygen in the body,” Nagele explains. “So rescue breaths aren’t as vital to survival as trying to keep blood flowing as regularly as possible. However, if cardiac arrest is secondary to trauma, drowning or a problem not directly related to heart function, then it is advisable to do standard CPR that includes rescue breaths. In those cases, getting oxygen into the system is crucial.”
The findings do not apply to children with cardiac arrest, Nagele stresses.
“It is very uncommon for kids to go into cardiac arrest due to a primary heart problem,” Nagele says. “If cardiac arrest does occur, it’s likely to be secondary to a severe asthma attack, an allergic reaction or something else unrelated to the heart. Under those circumstances, the body needs oxygen. I strongly recommend chest compression and rescue breaths in kids.”
Whether a bystander had previous training in CPR had no effect on patient survival in this study. When emergency dispatchers recommend only chest compression, it is relatively easy for a bystander to find the proper area of the chest, begin doing compressions and keep going until emergency medical technicians arrive, Nagele says.
Part of the reason earlier studies could not verify a statistical benefit from the chest-compression-only technique was that the patient survival rate hovers around 10 percent. Even with 1,000 or 2,000 patients in a study, the total number of survivors was small. Only by combining data from all three studies to generate larger numbers were the investigators able to confirm improved survival.
The research team, which included investigators from the Medical University of Vienna in Austria, determined that a 20 percent improvement in survival related to chest compression-only CPR in cardiac arrest patients in North America and the European Union could save as many as 5,000 to 10,000 lives each year.
The new study also found that the benefit occurred only when 911 dispatchers coached bystanders to use chest compression-only CPR. In several uncontrolled studies that simply asked bystanders whether they did only chest compressions or standard CPR, the investigators found no survival benefit with the chest compression-only technique.
Nagele says his findings suggest that if someone nearby has a heart attack, it’s important to first call 911, and then begin chest compressions. He says if it takes several minutes for help to arrive, it also may become necessary to begin rescue breaths, but for the first five to 10 minutes, chest compressions are more important.
“The heart doesn’t literally stop during cardiac arrest,” he says. “It gets super excited and electrically very active, and the only way to get it back into rhythm is with an electrical shock, a defibrillation. By doing chest compression-only CPR, a bystander is basically buying time until a paramedic with a defibrillator can jump-start the heart.”
Whether by coincudence or as a result of this study, the American Heart Association has announced that it is re-arranging the ABCs of cardiopulmonary resuscitation (CPR) in its 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, published in Circulation: Journal of the American Heart Association.
Recommending that chest compressions be the first step for lay and professional rescuers to revive victims of sudden cardiac arrest, the association said the A-B-Cs (Airway-Breathing-Compressions) of CPR should now be changed to C-A-B (Compressions-Airway-Breathing).
"For more than 40 years, CPR training has emphasized the ABCs of CPR, which instructed people to open a victim's airway by tilting their head back, pinching the nose and breathing into the victim's mouth, and only then giving chest compressions," said Michael Sayre, M.D., co-author of the guidelines and chairman of the American Heart Association's Emergency Cardiovascular Care (ECC) Committee. "This approach was causing significant delays in starting chest compressions, which are essential for keeping oxygen-rich blood circulating through the body. Changing the sequence from A-B-C to C-A-B for adults and children allows all rescuers to begin chest compressions right away."
In previous guidelines, the association recommended looking, listening and feeling for normal breathing before starting CPR. Now, compressions should be started immediately on anyone who is unresponsive and not breathing normally.
All victims in cardiac arrest need chest compressions. In the first few minutes of a cardiac arrest, victims will have oxygen remaining in their lungs and bloodstream, so starting CPR with chest compressions can pump that blood to the victim's brain and heart sooner. Research shows that rescuers who started CPR with opening the airway took 30 critical seconds longer to begin chest compressions than rescuers who began CPR with chest compressions.
The change in the CPR sequence applies to adults, children and infants, but excludes newborns.
Other recommendations, based mainly on research published since the last AHA resuscitation guidelines in 2005:
- During CPR, rescuers should give chest compressions a little faster, at a rate of at least 100 times a minute.
- Rescuers should push deeper on the chest, compressing at least two inches in adults and children and 1.5 inches in infants.
- Between each compression, rescuers should avoid leaning on the chest to allow it to return to its starting position.
- Rescuers should avoid stopping chest compressions and avoid excessive ventilation.
- All 9-1-1 centers should assertively provide instructions over the telephone to get chest compressions started when cardiac arrest is suspected.
"Sudden cardiac arrest claims hundreds of thousands of lives every year in the United States, and the American Heart Association's guidelines have been used to train millions of people in lifesaving techniques," said Ralph Sacco, M.D., president of the American Heart Association. "Despite our success, the research behind the guidelines is telling us that more people need to do CPR to treat victims of sudden cardiac arrest, and that the quality of CPR matters, whether it's given by a professional or non-professional rescuer."
Since 2008, the American Heart Association has recommended that untrained bystanders use Hands-Only CPR — CPR without breaths — for an adult victim who suddenly collapses. The steps to Hands-Only CPR are simple: call 9-1-1 and push hard and fast on the center of the chest until professional help or an AED arrives.
Key guidelines recommendations for healthcare professionals:
Effective teamwork techniques should be learned and practiced regularly.
Professional rescuers should use quantitative waveform capnography — the monitoring and measuring of carbon dioxide output — to confirm intubation and monitor CPR quality.
Therapeutic hypothermia, or cooling, should be part of an overall interdisciplinary system of care after resuscitation from cardiac arrest.
Atropine is no longer recommended for routine use in managing and treating pulseless electrical activity (PEA) or asystole.
Pediatric advanced life support (PALS) guidelines provide new information about resuscitating infants and children with certain congenital heart diseases and pulmonary hypertension, and emphasize organizing care around two-minute periods of uninterrupted CPR.
The CPR and ECC guidelines are science-based recommendations for treating cardiovascular emergencies — particularly sudden cardiac arrest in adults, children, infants and newborns. The American Heart Association established the first resuscitation guidelines in 1966.
The year 2010 marks the 50th anniversary of Kouwenhoven, Jude, and Knickerbocker's landmark study documenting cardiac arrest survival after chest compressions.
Forty-four healthy, overweight people between the ages of 50 and 75 took part in a diet study at the Antidiabetic Food Centre of Lund University.
For four weeks they ate foods which are presumed to reduce low-grade inflammation in the body, a condition which in turn triggers metabolic syndrome and thus obesity, type 2 diabetes and cardiovascular disease.
The test diet was high in antioxidants, low-GI foods (i.e. slow release carbohydrates), omega fatty acids, wholegrain products, probiotics and viscous dietary fibre. Examples of foods eaten were oily fish, barley, soy protein, blueberries, almonds, cinnamon, vinegar and whole grain bread.
The results of a diet study show that bad cholesterol was reduced by 33 per cent, blood lipids by 14 per cent, blood pressure by 8 per cent and a risk marker for blood clots by 26 per cent. A marker of inflammation in the body was also greatly reduced, while memory and cognitive function were improved.
Friday, October 15, 2010
No matter how you slice it, watermelon has a lot going for it –– sweet, low calorie, high fiber, nutrient rich –– and now, there's more. Evidence from a pilot study led by food scientists at The Florida State University suggests that watermelon can be an effective natural weapon against prehypertension, a precursor to cardiovascular disease.
It is the first investigation of its kind in humans. FSU Assistant Professor Arturo Figueroa and Professor Bahram H. Arjmandi found that when six grams of the amino acid L-citrulline/L-arginine from watermelon extract was administered daily for six weeks, there was improved arterial function and consequently lowered aortic blood pressure in all nine of their prehypertensive subjects (four men and five postmenopausal women, ages 51-57).
"We are the first to document improved aortic hemodynamics in prehypertensive but otherwise healthy middle-aged men and women receiving therapeutic doses of watermelon," Figueroa said. "These findings suggest that this 'functional food' has a vasodilatory effect, and one that may prevent prehypertension from progressing to full-blown hypertension, a major risk factor for heart attacks and strokes.
"Given the encouraging evidence generated by this preliminary study, we hope to continue the research and include a much larger group of participants in the next round," he said.
"Watermelon is the richest edible natural source of L-citrulline, which is closely related to L-arginine, the amino acid required for the formation of nitric oxide essential to the regulation of vascular tone and healthy blood pressure," Figueroa said.
Once in the body, the L-citrulline is converted into L-arginine. Simply consuming L-arginine as a dietary supplement isn't an option for many hypertensive adults, said Figueroa, because it can cause nausea, gastrointestinal tract discomfort, and diarrhea.
In contrast, watermelon is well tolerated. Participants in the Florida State pilot study reported no adverse effects. And, in addition to the vascular benefits of citrulline, watermelon provides abundant vitamin A, B6, C, fiber, potassium and lycopene, a powerful antioxidant. Watermelon may even help to reduce serum glucose levels, according to Arjmandi.
"Cardiovascular disease (CVD) continues to be the leading cause of death in the United States," Arjmandi said. "Generally, Americans have been more concerned about their blood cholesterol levels and dietary cholesterol intakes rather than their overall cardiovascular health risk factors leading to CVD, such as obesity and vascular dysfunction characterized by arterial stiffening and thickness –– issues that functional foods such as watermelon can help to mitigate.
"By functional foods," said Arjmandi, "we mean those foods scientifically shown to have health-promoting or disease-preventing properties, above and beyond the other intrinsically healthy nutrients they also supply."
Figueroa said oral L-citrulline supplementation might allow a reduced dosage of antihypertensive drugs necessary to control blood pressure.
"Even better, it may prevent the progression from prehypertension to hypertension in the first place," he said.
While watermelon or watermelon extract is the best natural source for L-citrulline, it is also available in the synthetic form in pills, which Figueroa used in a previous study of younger, male subjects. That investigation showed that four weeks of L-citrulline slowed or weakened the increase in aortic blood pressure in response to cold exposure. It was an important finding, said Figueroa, since there is a greater occurrence of myocardial infarction associated with hypertension during the cold winter months.
"Individuals with increased blood pressure and arterial stiffness –– especially those who are older and those with chronic diseases such as type 2 diabetes –– would benefit from L-citrulline in either the synthetic or natural (watermelon) form," Figueroa said. "The optimal dose appears to be four to six grams a day."
Approximately 60 percent of U.S. adults are prehypertensive or hypertensive. Prehypertension is characterized by systolic blood pressure readings of 120-139 millimeters of mercury (mm Hg) over diastolic pressure of 80-89 mm Hg. "Systolic" refers to the blood pressure when the heart is contracting. "Diastolic" reflects the blood pressure when the heart is in a period of relaxation and expansion.
Findings from Figueroa's latest pilot study at Florida State are described in the American Journal of Hypertension. A copy of the paper ("Effects of Watermelon Supplementation on Aortic Blood Pressure and Wave Reflection in Individuals With Prehypertension: A Pilot Study") can be accessed online.
The paper's lead author, Figueroa holds a medical degree, a doctoral degree in physiological sciences, and a master's degree in sports medicine. He has been a faculty member in the Florida State University Department of Nutrition, Food and Exercise Sciences since 2004. Figueroa's coauthor and colleague Arjmandi serves as chairman of the department, which is a part of Florida State's interdisciplinary College of Human Sciences. Arjmandi also is the author or coauthor of an extensive body of published research on the health benefits of prunes and other functional foods.
Thursday, October 14, 2010
The National Institute of Recreational Drinks (NIRD) has released a new study documenting the dramatic increase in cases of energy drink abuse. "A large majority of Americans are at risk. We are in the midst of an energy epidemic" claims the study.
The study required that 200 patients at the NIRD’s Wisconsin campus involved abstain from all energy drinks for 24 hours. The patients were then asked to write about their experiences in a clinical survey. Their feelings were comparable to those of drug and alcohol addicts seeking sobriety - describing their feelings when they have to abstain from using energy drinks in literally the same terms associated with drug and alcohol addictions: In withdrawal, frantically craving, very anxious, extremely antsy, miserable, jittery, crazy.
Not only did the patients feel an extreme lack of energy, they felt cut-off from the pleasures of life. The patients reported that they do not regularly drink juices, water, or other functional drinks. Instead they rely on energy drinks to stay productive, keep hydrated, and live life.
Data published today by the NIRD show that the disease of energy addiction now affects a staggering 210 million people worldwide, with 86% of all those affected in the 18-34 age group. Previous figures underestimated the scope of the problem, while even the most pessimistic predictions fell short of the current figure. The new data predict that the total number of people living with energy addiction will skyrocket to 380 million within twenty years if nothing is done.
The United States leads the global top ten in terms of the highest number of people with energy addiction with a current figure of 40.9 million, followed by China with 39.8 million. Behind them come Russia, Germany, Japan, Pakistan, Brazil, Mexico and Egypt.
Think Before You Drink leads a coalition of energy addiction representative organizations and other stakeholders demanding a United Nations Resolution on energy addiction to ensure that adequate attention is given to the new disease. Think Before You Drink is a New York-based watchdog group with an aggressively growing member associations growing wings in many countries. Their mission is to promote energy addiction care, prevention and a cure worldwide. Think Before You Drink leads the campaign for a UN Resolution on energy addiction.
Lenora Nunez, president of Think Before You Drink, spoke at a conference last Wednesday exclaiming, “massive use of energy drinks is an epidemic that rivals the 1980 cocaine crisis. Young adults are using at such extreme levels that before they’re even aware of it, the energy-user has developed a profound psychological and physical dependence.” She goes on to say that “what many users don’t realize until it’s too late is that when the effects of the stimulant drinks wear off, their energy level plummets and they immediately start looking for another stimulant drink, sending them spiraling downward into a cycle of dependence.”
In a trend Nunez calls “alarming,” recent studies have shown that the average age at which a child drinks his or her first energy drink is plummeting, while recreational use among young people is sharply on the rise. Nunez has been personally touched by this epidemic. She recalled with great emotion a vivid scene in which Nunez found her 15 year old niece, Marie, lying dazed and stammering on the floor next to twelve empty cans of energy drink. “She was just a child,” Nunez said before pausing to wipe her tears, “curious and full of life. Now doctors say she will have to take Monstrex, a prescription drug , to help wean her off the energy cravings.” Epidemiologists have been researching more effective ways help people cope with their energy addictions.
According to ULCA Medical Center addiction specialist Dr. Audra Hurst, “Energy drinks came into vogue in the late ’90s as a performance-enhancing beverage, consumed by young people seeking to prolong their enjoyment of such activities as skateboarding and mountain biking,” Hurst said. “But that was a far more innocent time. Today, we know a lot more about the costs of recreational energy drink use and what it can lead to.”
Hurst has been conducting research on the effects of energy drinks in lab rats. The rats who were injected with energy drinks showed a 34% increase in cognitive and motor skills over the rats who were injected with placebo. However, over a prolonged period of time, the percentage increase was less substantial. After the experiment was over, the lab rats who experienced energy drinks began to show withdrawal symptoms. They became very aggressive and combative towards each other. “It was like they were junkies. The rats would fight until they killed each other. When we separated the remaining rats they began to curl up in a ball and started to shiver.”
Nunez’s website, http://www.thinkdrink.org, has shifted its focus towards the education of parents whose children stand at risk to become energy-heads. Nunez wants “parents to become more involved in their children’s lives.” She also says, “Make sure to check what your kids are saying to each other. If they are using terms like B-party or Icarused than you can be sure they have been using stimulant drinks.” B-parties are parties where a group of people binge drink on energy drinks in order to get high off of the mass amounts of sugar, caffeine, and vitamin Bs found in the drinks. Getting Icarused, a nod to the popular Greek mythological figure who flew too close to the sun before falling to his death, is the slang term for getting high off of energy drinks.
Wednesday, October 13, 2010
Having a family history of breast cancer can lead some women to wonder if the risk is out of their control. However, a study of more than 85,000 postmenopausal women, published in BioMed Central's open access journal Breast Cancer Research, observed that regular physical activity, maintaining a healthy weight, and drinking less alcohol lowers breast cancer risk for those with and without a family history of the disease.
The University of Rochester Medical Center study is good news for women who have a close relative with breast cancer and fear that no matter what they do, it won't matter, said lead author Robert E. Gramling, M.D., D.Sc., associate professor of Family Medicine, and Community and Preventive Medicine at URMC.
"It's important to note that a family history of breast cancer can arise in part due to shared unhealthy behaviors that have been passed down for generations," Gramling said. "Untangling the degree to which genes, environments, and behaviors contribute to the disease is difficult. But our study shows that engaging in a healthy lifestyle can help women, even when familial predisposition is involved."
Gramling analyzed data from the Women's Health Initiative Observational Study that began in 1993. The data included women ages 50 to 79 who were divided into two groups; those who had a family history of later-onset breast cancer (after age 45) and those who did not. The amount of risk reduced by adhering to the three health behaviors was the same for women with and without a family history.
"Given the strong awareness of breast cancer and distress about inheritable risk", Gramling said, "it is essential that scientists understand the actions women can take to reduce their risk".
Investigators from the Slone Epidemiology Center at Boston University School of Medicine (BUSM) have reported that African American women who consume more vegetables are less likely to develop estrogen receptor-negative breast cancer than women with low vegetable intake. The study results, published in the American Journal of Epidemiology, were based on data from the Black Women's Health Study (BWHS), a large follow-up study of 59,000 African American women from across the U.S. conducted by investigators at the Slone Epidemiology Center since 1995.
The investigators followed 51,928 participants in the BWHS for 12 years, during which time 1,268 cases of breast cancer developed. Among cases on which hormone receptor status was obtained, 35 percent were estrogen receptor-negative/progesterone receptor-negative (ER-/PR-) breast cancers. The incidence of ER-/PR- breast cancer was 43 percent lower among women consuming at least two vegetables per day compared with women who ate fewer than four vegetables per week. African American women are more likely than white women to be diagnosed with estrogen receptor-negative tumors, which have a poorer prognosis than estrogen receptor-positive tumors.
According to the BUSM researchers, specific types of vegetables may play a greater role in reducing breast cancer risk. The investigators reported that high intake of cruciferous vegetables in particular may be associated with reduced risk of breast cancer overall. Cruciferous vegetables, which include broccoli, mustard and collard greens, and cabbage, are sources of glucosinolates, which may play a role in preventing the development of breast cancer through their effects on both estrogen metabolism and detoxification enzymes. The researchers also observed evidence suggesting that increased carrot consumption may be associated with lower risk of breast cancer. Carrots are rich sources of carotenoids, which may reduce cancer risk through their antioxidant properties.
New research suggests that walking at least six miles per week may protect brain size and in turn, preserve memory in old age, according to a study published in the October 13, 2010, online issue of Neurology®, the medical journal of the American Academy of Neurology.
"Brain size shrinks in late adulthood, which can cause memory problems. Our results should encourage well-designed trials of physical exercise in older adults as a promising approach for preventing dementia and Alzheimer's disease," said study author Kirk I. Erickson, PhD, with the University of Pittsburgh in Pittsburgh.
For the study, 299 dementia-free people recorded the number of blocks they walked in one week. Then nine years later, scientists took brain scans of the participants to measure their brain size. After four more years, the participants were tested to see if they had developed cognitive impairment or dementia.
The study found that people who walked at least 72 blocks per week, or roughly six to nine miles, had greater gray matter volume than people who didn't walk as much, when measured at the nine-year time point after their recorded activity. Walking more than 72 blocks did not appear to increase gray matter volume any further.
By four years later, 116 of the participants, or 40 percent, had developed cognitive impairment or dementia. The researchers found that those who walked the most cut their risk of developing memory problems in half.
"If regular exercise in midlife could improve brain health and improve thinking and memory in later life, it would be one more reason to make regular exercise in people of all ages a public health imperative," said Erickson.
Luteolin (LOOT-ee-oh-lin) is found in many plants, including carrots, peppers, celery, olive oil, peppermint, rosemary and chamomile.
The new study, which examined the effects of dietary luteolin in a mouse model of aging, appears in the Journal of Nutrition.
The researchers focused on microglial cells, specialized immune cells that reside in the brain and spinal cord. Infections stimulate microglia to produce signaling molecules, called cytokines, which spur a cascade of chemical changes in the brain. Some of these signaling molecules, the inflammatory cytokines, induce “sickness behavior”: the sleepiness, loss of appetite, memory deficits and depressive behaviors that often accompany illness.
Inflammation in the brain also appears to be a key contributor to age-related memory problems, said University of Illinois animal sciences professor Rodney Johnson, who led the new study. Johnson directs the Division of Nutritional Sciences at Illinois.
“We found previously that during normal aging, microglial cells become dysregulated and begin producing excessive levels of inflammatory cytokines,” he said.
“We think this contributes to cognitive aging and is a predisposing factor for the development of neurodegenerative diseases.”
Johnson has spent nearly a decade studying the anti-inflammatory properties of nutrients and various bioactive plant compounds, including luteolin. Previous studies – by Johnson’s lab and others – have shown that luteolin has anti-inflammatory effects in the body. This is the first study to suggest, however, that luteolin improves cognitive health by acting directly on the microglial cells to reduce their production of inflammatory cytokines in the brain.
The researchers showed that microglial cells that were exposed to a bacterial toxin produced inflammatory cytokines that could kill neurons. When the microglia were exposed to luteolin before they encountered the toxin, however, the neurons lived.
“The neurons survived because the luteolin inhibited the production of neurotoxic inflammatory mediators,” Johnson said.
Exposing only the neurons to luteolin before the experiment had no effect on their survival, the researchers found.
“This demonstrated that luteolin isn’t protecting the neurons directly,” he said. “It’s doing it by affecting the microglial cells.”
The researchers next turned their attention to the effects of luteolin on the brains and behavior of adult (3- to 6-month-old) and aged (2-year-old) mice. The mice were fed a control diet or a luteolin-supplemented diet for four weeks. The researchers assessed their spatial memory and measured levels of inflammatory markers in the hippocampus, a brain region that is important to memory and spatial awareness.
Normally, aged mice have higher levels of inflammatory molecules in the hippocampus and are more impaired on memory tests than younger adult mice. Aged mice on the luteolin-supplemented diet, however, did better on the learning and memory task than their peers, and the levels of inflammatory cytokines in their brains were more like those of the younger adult mice.
“When we provided the old mice luteolin in the diet it reduced inflammation in the brain and at the same time restored working memory to what was seen in young cohorts,” Johnson said.
Studies have shown that plant compounds such as luteolin can get into the brain, Johnson said.
“We believe dietary luteolin accesses the brain and inhibits or reduces activation of microglial cells and the inflammatory cytokines they produce. This anti-inflammatory effect is likely the mechanism which allows their working memory to be restored to what it was at an earlier age.”
“These data suggest that consuming a healthy diet has the potential to reduce age-associated inflammation in the brain, which can result in better cognitive health,” he said.
Monday, October 11, 2010
Most women, older men, and many other people don’t get enough calcium from food.
I am going to continue to take Vitamin D – see this study:
Forty-three percent of patients scheduled to undergo orthopaedic surgery have insufficient levels of vitamin D and two out of five of those patients had levels low enough to place them at risk for metabolic bone disease.
And this review Vitamin D: Many Benefits:
I am going to continue exercise vigorously:
Vigorous exercise of more than two hours per week reduces the risk of developing breast cancer...by 64 percent.
Boosting cardiovascular fitness improves sleep, vitality and mood for insomniacs.
I am going to continue to eat nuts:
Walnuts, walnut oil, improve reaction to stress:
This is the first study to show that walnuts and walnut oil reduce blood pressure during stress. Previous studies have shown that omega-3 fatty acids -- like the alpha linolenic acid found in walnuts and flax seeds -- can reduce low density lipoproteins (LDL) -- bad cholesterol. These foods may also reduce c-reactive protein and other markers of inflammation, which could also reduce risk of cardiovascular disease.
I’m NOT going to cut down on my sleep – I usually get 8 hours – but I think my intense physical exercise means the extra sleep is not harmful.
The best survival was observed among women who slept 5 to 6.5 hours. Women who slept less than five hours a night or more than 6.5 hours were less likely to be alive at the 14-year follow-up.
I wish I could show this to my insurance company, who is charging me extra for life insurance because I used to snore:
Researchers uncovered other interesting findings as well. For example, among older women, obstructive sleep apnea (pauses in breathing during sleep) did not predict increased mortality risk. “Although apneas may be associated with increased mortality risk among those under 60, it does not seem to carry a risk in the older age group.
I’m still glad I take a statin:
I’m going to keep up my moderate drinking, ( especially red wine – see this review) but probably not start drinking coffee:
Tea and decaffeinated coffee showed no relation with diabetes, but the regular moderate intake of both caffeinated coffee and alcohol appeared to reduce the risk of contracting late onset diabetes significantly.
My wife won’t let me increase my garlic consumption, a smuch as I’d like to.
Garlic has "significant" potential for preventing cardiomyopathy, a form of heart disease.
Out of season blueberries cost a fortune – I will miss them:
Blueberries may help fight atherosclerosis, also known as hardening of the arteries.
If I ever go on a diet, I will try to remember to drink milk
Regardless of Diet, Study Participants Who Consumed the Most Milk Lost the Most Weight
I’m trying to eat more bananas:
Potassium Lowers Blood Pressure
I will continue to take aspirin:
Even the lowest possible dose of aspirin (75 mg) can ward off bowel cancer, if taken regularly.
And eating broccoli:
Eating broccoli could guard against arthritis
I’m drinking more cranberry juice and taking cranberry supplements – I do get UT infections:
Cranberry juice really is effective for preventing urinary tract infections
And other good foods, while avoiding “bad’ foods – see this review.
Saturday, October 9, 2010
Turmeric—an herb commonly used in curry powders, mustards, and cheeses—may protect bones against osteoporosis, according to a recent laboratory study published in the Journal of Agricultural and Food Chemistry. Osteoporosis is a bone disease that can lead to an increased risk of fractures. The condition is common in postmenopausal women. This study, which used an animal (rat) model of post-menopausal osteoporosis, builds on previous laboratory research examining turmeric's anti-arthritic properties.
Funded in part by NCCAM, the study tested two turmeric extracts containing different amounts of curcuminoids—(components of the herb) in female rats whose ovaries had been surgically removed (ovariectomy—a procedure that causes changes associated with menopause, including bone loss). Researchers injected rats with enriched turmeric extract (94‑percent curcuminoids by weight) or non-enriched turmeric extract (41‑percent curcuminoids), at a dose of 60 mg/kg three times a week for 2 months. As controls, other rats received placebo injections after either ovariectomy or sham surgery. Tests showed that while non-enriched turmeric extract did not have bone-protective effects, curcuminoid-enriched turmeric extract prevented up to 50 percent of bone loss, and also preserved bone structure and connectivity. Other physiological changes associated with ovariectomy (weight gain and shrinking of the uterus) were unaffected—an indication that the bone-protective effects did not involve an estrogen-based chemical pathway.
The researchers concluded that turmeric may protect bones, but that the effect depends on the amount of curcuminoids present. If the protective effect does not involve estrogen-based pathways, turmeric may offer a safer alternative to menopausal hormone therapy or botanical phytoestrogens (compounds similar to the female hormone estrogen) for bone preservation in menopause. However, the researchers emphasized that clinical research is needed to evaluate the use of turmeric-derived curcuminoid products to guard against osteoporosis in humans.
- Wright LE, Frye JB, Timmermann BN, et al. Protection of trabecular bone in ovariectomized rats by turmeric (Curcuma longa L.) is dependent on extract composition. Journal of Agricultural and Food Chemistry. 2010;58(17):9498–9504.
Thursday, October 7, 2010
As they get older, men and women can develop weak and fragile bones, a condition called osteoporosis. Supplements of both vitamin D and calcium can reduce the risk of bone loss and fractures in elderly people. Talk with your healthcare provider about vitamin D and calcium as part of a plan to prevent or treat osteoporosis as you age.
Some studies have tried to find out whether getting more vitamin D can affect the chances of developing cancers of the colon, breast, prostate, pancreas, and other parts of the body. It's too early to say whether low levels of vitamin D affect one's risk of cancer.
Can vitamin D be harmful?
In healthy children and adults, vitamin D at doses up to 2,000 IU is safe. (In infants, up to 1,000 IU is safe.) When taken as a supplement at very high doses, vitamin D can cause nausea and vomiting, confusion, and serious heart problems. Vitamin D made in the body from sunlight does not rise to dangerous levels.
Does vitamin D interact with any medicines or dietary supplements?
Yes. For example, prednisone and some medicines taken to lose weight, lower cholesterol, or control epileptic seizures can raise the need for vitamin D.
Immune system and wound healing
Zinc supplements might help some people with sores and skin ulcers, but only if these people have low levels of zinc.
Children who live in developing countries often die from diarrhea. Zinc supplements might help these children get better more quickly. It is not clear if zinc supplements help children with diarrhea who get enough zinc, such as most children in the United States.
The common cold
Some scientists have tried to find out whether zinc lozenges help people with a cold feel better and recover more quickly. But these studies have had different results. At this time, it is not clear whether zinc lozenges can help treat the common cold.
Age-related macular degeneration (AMD)
People with AMD lose their vision over time. In one study, scientists gave older people with AMD a daily supplement with 80 mg zinc, vitamin C, vitamin E, beta-carotene, and copper for about 6 years. The people who took these supplements had a lower chance of getting advanced AMD and lost less of their vision. The same study showed that taking supplements containing only zinc also lowered the chance of getting advanced AMD in people with a high risk of this disease.
What foods provide calcium?
Many foods have some calcium. You can get enough calcium by eating a variety of foods including milk, cheese, and yogurt; vegetables like kale, broccoli, and Chinese cabbage; and canned sardines and salmon with soft bones that you eat.
Calcium is added to some breakfast cereals, fruit juices, soy and rice beverages, and tofu (check the product labels).
What kinds of calcium dietary supplements are available?
Many multivitamin-mineral supplements have calcium. You can also buy calcium alone or together with vitamin D. If your supplement has calcium carbonate, you should take it with food. Calcium citrate costs more but you can take it on an empty stomach, and people older than 50 can absorb it more easily.
To absorb the most calcium from a supplement, don’t take more than 500 mg at once. So, for example, if you take 1,000 mg of calcium a day, split the dose in two and take them at separate times.
Calcium pills can cause gas, bloating, or constipation. If these occur, take smaller amounts at different times of the day, take the pills with meals, or try a different brand.
Am I getting enough calcium?
Most women, older men, and many other people don’t get enough calcium from food. After menopause especially, women need calcium and vitamin D to help keep their bones strong. Calcium-rich foods and supplements can help women get enough calcium.
Other people who might not get enough calcium include (1) vegetarians who avoid dairy foods, (2) people who are lactose intolerant (drinking milk upsets their stomach), (3) people with eating disorders, and (4) women who exercise so much that they stop having a monthly period. These people might need to take calcium supplements.
What happens if I don't get enough calcium?
Usually nothing obvious happens in the short run if you don’t get enough calcium. But over many years, not getting the amount of calcium you need can weaken your bones and make them break more easily.
What are some effects of calcium on health?
Scientists are studying calcium to see how it affects health. Here are a few examples of what this research has shown.
As people get older, their bones can become weak and break easily (a condition called osteoporosis). Foods and supplements with both calcium and vitamin D can help keep bones healthy. Talk to your health care provider about how much calcium and vitamin D you need to prevent or treat osteoporosis.
High blood pressure
Getting recommended amounts of calcium may lower blood pressure. If your blood pressure is high, eat plenty of low-fat and fat-free dairy products, vegetables, and fruits.
Scientists are studying whether recommended amounts of calcium might lower the chance of getting cancer of the colon and rectum. It’s too early to tell whether calcium intakes affect the risk of cancer.
Most kidney stones are not caused by too much or too little calcium. To reduce the risk of kidney stones, it's more important to drink enough liquids.
Can more calcium help you lose weight or body fat? Maybe, but the best studies so far have not shown that calcium helps much.
Can calcium be harmful?
In healthy children and adults, up to 2,500 mg of calcium a day is safe. High amounts of calcium in the blood can harm the kidneys, but this is almost always caused by diseases like cancer or taking very high amounts of vitamin D—not from calcium in foods or dietary supplements.
Are there any interactions with calcium that I should know about?
Some medicines (like some laxatives, antibiotics, and drugs to treat osteoporosis or thyroid disease) lower the amount of calcium the body absorbs. Other medicines (antacids with aluminum or magnesium, and mineral-oil laxatives) lower the amount of calcium in the body.
Scientists are studying vitamin C to understand how it affects health. Here are several examples of what this research has shown.
Cancer prevention and treatment
People with high intakes of vitamin C from fruits and vegetables might have a lower risk of getting many types of cancer, such as lung, breast, and colon cancer. However, taking vitamin C supplements, with or without other antioxidants, doesn't seem to protect people from getting cancer.
It is not clear whether taking high doses of vitamin C is helpful as a treatment for cancer. Vitamin C's effects appear to depend on how it is administered to the patient. Oral doses of vitamin C can't raise blood levels of vitamin C nearly as high as intravenous doses given through injections. A few studies in animals and test tubes indicate that very high blood levels of vitamin C might shrink tumors. But more research is needed to determine whether high-dose intravenous vitamin C helps treat cancer in people.
Vitamin C dietary supplements and other antioxidants might interact with chemotherapy and radiation therapy for cancer. People being treated for cancer should talk with their oncologist before taking vitamin C or other antioxidant supplements, especially in high doses.
People who eat lots of fruits and vegetables seem to have a lower risk of cardiovascular disease. Researchers believe that the antioxidant content of these foods might be partly responsible for this association because oxidative damage is a major cause of cardiovascular disease. However, scientists aren't sure whether vitamin C itself, either from food or supplements, helps protect people from cardiovascular disease. It is also not clear whether vitamin C helps prevent cardiovascular disease from getting worse in people who already have it.
Age-related macular degeneration (AMD) and cataracts
AMD and cataracts are two of the leading causes of vision loss in older people. Researchers do not believe that vitamin C and other antioxidants affect the risk of getting AMD. However, research suggests that vitamin C combined with other nutrients might help keep early AMD from worsening into advanced AMD.
In a large study, older people with AMD who took a daily dietary supplement with 500 mg vitamin C, 80 mg zinc, 400 IU vitamin E, 15 mg beta-carotene, and 2 mg copper for about 6 years had a lower chance of developing advanced AMD. They also had less vision loss than those who did not take the dietary supplement.
More research is needed before doctors can recommend dietary supplements containing vitamin C for patients with AMD. However, people who have or are developing the disease might want to talk with their doctor about taking dietary supplements.
The relationship between vitamin C and cataract formation is unclear. Some studies show that people who get more vitamin C from foods have a lower risk of getting cataracts. But further research is needed to clarify this association and to determine whether vitamin C supplements affect the risk of getting cataracts.
The common cold
Although vitamin C has long been a popular remedy for the common cold, research shows that for most people, vitamin C supplements do not reduce the risk of getting the common cold. However, people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms when they do have a cold. Using vitamin C supplements after cold symptoms start does not appear to be helpful.
Forty-three percent of patients scheduled to undergo orthopaedic surgery have insufficient levels of vitamin D and two out of five of those patients had levels low enough to place them at risk for metabolic bone disease, according to a study published this month in the October 6th issue of the Journal of Bone and Joint Surgery (JBJS).
According to the National Institutes of Health (NIH), vitamin D helps the body absorb calcium and is essential for bone growth and bone remodeling. Without sufficient vitamin D, bones can become thin, brittle or misshapen. People can obtain vitamin D in three ways:
• by eating certain types of food (including fish, dairy products, eggs and mushrooms);
• receiving sun exposure; and
• taking supplements
"Given the importance of vitamin D in musculoskeletal health and its role in bone healing following orthopaedic procedures, low levels may negatively impact patient outcomes," said orthopaedic surgeon Joseph M. Lane, MD, study co-author and chief of the metabolic bone disease service at the Hospital for Special Surgery in New York.
All 723 patients in the study had been cleared by a specialist in internal medicine for elective surgery in one of the following orthopaedic service areas: Trauma, Foot and Ankle, Sports Medicine (only ACL and/or meniscal repair), Arthroplasty (only primary total hip and knee replacement), Hand (only distal radial or ulnar fracture) and Metabolic Bone Disease (only vertebral compression fracture).
The researchers found that, of the 723 patients studied:
• 411 (57 percent) had normal Vitamin D levels,
• 202 (28 percent) had insufficient levels; and
• 110 (15 percent) were vitamin D deficient.
"We found that nearly half of the patients who were considered 'healthy' enough for surgery had significantly low levels of vitamin D, placing them at risk for poor bone healing, osteomalacia (bone and muscle weakness) or even secondary hyperparathyroidism (increased secretion of the parathyroid hormone) in the most severe cases," said Dr. Lane, who is also a professor of orthopedic surgery at Weill Cornell Medical College in New York. "This was very disconcerting since vitamin D levels can be determined with a simple blood test and low levels can be easily treated with supplements in just a few weeks."
When results were broken down by orthopaedic service area, researchers uncovered a surprising finding: Despite having the youngest mean population (age 45 +/-14.9 years), the Sports Medicine group of patients had the second-highest rate of vitamin D insufficiency (52 percent) – exceeded only by patients in the Trauma group (66.1 percent). The remaining groups had insufficiency levels of 40 percent (Hand), 38 percent (Arthroplasty), 34 percent (Foot and Ankle) and 18.6 percent (Metabolic Bone Disease).
The researchers noted that their results are consistent with those of similar studies investigating the prevalence of vitamin D deficiency in the general population, including identification of risk factors including obesity and dark skin tone.
"This study should serve as a wake-up call to orthopedists that vitamin D deficiency is widespread, not necessarily tied to age, sex or background and screening for it should be part of routine pre-surgical care for adults," said Dr. Lane. "Meanwhile, patients who are planning to undergo any orthopaedic procedure can request a screening (specifically, a blood test called the 25 hydroxy Vitamin D test) or ask to be placed on a medically supervised Vitamin D supplement regimen prior to surgery."
Study specific details:
In a retrospective chart review, Dr. Lane and his colleagues measured Vitamin D levels of 723 patients who were scheduled for orthopaedic surgery between January 2007 and March 2008 and determined the prevalence of normal, insufficient and deficient levels according to the following parameters:
• Normal: equal to or greater than 32 nanograms per milliliter (ng/mL)
• Insufficient: less than 32 ng/mL
• Deficient: less than 20 ng/mL
How much Vitamin D does the skin make?
Our skin makes a lot of Vitamin D when we spend time in strong sunlight. With about 5-30 minutes of sunlight exposure of head, face, hands, arms, or legs), our skin can make about 1000 IUs of Vitamin D (Vitamin D is measured in units called "International Units," or IUs.) Vitamin D is therefore known as "the sunshine vitamin." However, as you age you can lose your ability to manufacture Vitamin D through sunlight.
How much Vitamin D is enough?
The American Academy of Orthopaedic Surgeons (AAOS) and recent research support that the body needs at least 1000 IU per day for good health — depending on age, weight, and growth. Indeed, many people need much more than 1000 IU to keep Vitamin D levels in a good range.
In general, babies (especially mothers who are breastfeeding) and small children should intake at least 400 IU of Vitamin D daily. Children over age 5, adolescents, and adults should get a minimum of 1000 IU of Vitamin D each day.
Tuesday, October 5, 2010
Vigorous exercise of more than two hours per week reduces the risk of developing breast cancer in postmenopausal African-American women by 64 percent, compared to women of the same race who do not exercise, according to researchers at Georgetown Lombardi Comprehensive Cancer Center.
Results were presented at the Third AACR Conference on The Science of Cancer Health Disparities, held Sept. 30 to Oct. 3, 2010.
"People often want to know what they can do to reduce their risk of disease, and we have found that just two or more hours of vigorous activity per week can made a difference in one's risk of developing breast cancer," said the lead researcher Vanessa Sheppard, Ph.D., a cancer control scientist and assistant professor in the department of oncology at the Lombardi Comprehensive Cancer Center.
In this study, more than two hours of aerobics, running or similar activity over the span of a week counted as vigorous activity.
"We also know from other studies that being physically active can have benefits in other diseases that occur at high rates in African-American women, such as diabetes and hypertension," Sheppard said. "Four out of five African-American women are either overweight or obese, and disease control is a particularly important issue for them."
Evidence showing exercise reduces breast cancer risk has been inconsistent, and there are few that look specifically at African-American women, Sheppard said. The issue is important, she added, because breast cancer has some important differences in this community. Whereas more white women are diagnosed with breast cancer, African-American women have a higher risk of developing premenopausal breast cancer than white women do, and comparatively more African-American women develop the most aggressive form of the disease, known as triple-negative breast cancer.
The researchers identified 97 recently diagnosed African-American breast cancer patients in the Washington, D.C., area and matched them with 102 African-American women without breast cancer. Participants filled out a questionnaire about exercise routines; the responses were analyzed and compared.
Women who exercised vigorously for more than two hours a week in the past year had a 64 percent reduced risk of breast cancer compared to women who did not exercise. Women who engaged in moderate exercise, like walking, had a 17 percent reduced risk, compared to women who were sedentary.
After evaluating those who were pre- and postmenopausal, they found that vigorous exercise only significantly benefitted postmenopausal women — they had a 62 percent reduction in risk.
"I was surprised that we did not find a significant effect in premenopausal women, but it may be because we need a larger sample," Sheppard said.
However, when the researchers examined the effect of total physical activity, which combined walking with vigorous activity of two or more hours per week, they saw significant gains for both premenopausal and postmenopausal women.
"We suggest that our findings, while promising, should be interpreted with caution. This is a pilot study and a larger, more rigorous study is needed to precisely quantify the effect of exercise on development of breast cancer. I think it is fair to conclude that if African American women exercise they can help take charge of their health," said Sheppard.
A diet rich in walnuts and walnut oil may prepare the body to deal better with stress, according to a team of Penn State researchers who looked at how these foods, which contain polyunsaturated fats, influence blood pressure at rest and under stress.
Previous studies have shown that omega-3 fatty acids -- like the alpha linolenic acid found in walnuts and flax seeds -- can reduce low density lipoproteins (LDL) -- bad cholesterol. These foods may also reduce c-reactive protein and other markers of inflammation.
"People who show an exaggerated biological response to stress are at higher risk of heart disease," said Sheila G. West, associate professor of biobehavioral health. "We wanted to find out if omega 3-fatty acids from plant sources would blunt cardiovascular responses to stress."
The researchers studied 22 healthy adults with elevated LDL cholesterol. All meals and snacks were provided during three diet periods of six weeks each.
IMAGE: This is a closeup of a walnut in its shell.
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The researchers found that including walnuts and walnut oil in the diet lowered both resting blood pressure and blood pressure responses to stress in the laboratory. Participants gave a speech or immersed their foot in cold water as a stressor. Adding flax seed oil to the walnut diet did not further lower blood pressure. They report their findings in the current issue of the Journal of the American College of Nutrition.
"This is the first study to show that walnuts and walnut oil reduce blood pressure during stress," said West. "This is important because we can't avoid all of the stressors in our daily lives. This study shows that a dietary change could help our bodies better respond to stress."
A subset of the participants also underwent a vascular ultrasound in order to measure artery dilation. Results showed that adding flax oil to the walnut diet significantly improved this test of vascular health. The flax plus walnuts diet also lowered c-reactive protein, indicating an anti-inflammatory effect. According to West, that could also reduce risk of cardiovascular disease.
The researchers used a randomized, crossover study design. Tests were conducted at the end of each six-week diet, and every participant consumed each of the three diets in random order, with a one-week break between. Diets included an "average" American diet – a diet without nuts that reflects what the typical person in the U.S. consumes each day. The second diet included 1.3 ounces of walnuts and a tablespoon of walnut oil substituted for some of the fat and protein in the average American diet. The third diet included walnuts, walnut oil and 1.5 tablespoons of flaxseed oil. The three diets were matched for calories and were specifically designed for each participant so that no weight loss or gain occurred. The walnuts, walnut oil, and flax oil were either mixed into the food in
IMAGE: The average portion of walnuts added to the diet was 1.3 ounces which is 9 whole walnuts or 18 walnut halves. The average portion of walnut oil was one teaspoon....
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such offerings as muffins or salad dressing or eaten as a snack. About 18 walnut halves or 9 walnuts make up the average serving used by the researchers.
After each diet, the participants underwent two stress tests. In the first test, they received a topic; and they were given two minutes to prepare a three-minute speech, which they presented while being videotaped. The second stressor was a standard physical test of stress consisting of submerging one foot in ice-cold water. Throughout these tests, the researchers took blood pressure readings from the participants.
Results showed that average diastolic blood pressure -- the "bottom number" or the pressure in the arteries when the heart is resting -- was significantly reduced during the diets containing walnuts and walnut oil.
Walnuts are a rich source of fiber, antioxidants, and unsaturated fatty acids, particularly alpha linolenic acid, an omega-3 fatty acid, and these compounds could be responsible for the beneficial effects on blood pressure. Flax oil is a more concentrated source of omega-3 fatty acids than walnut oil, but this study did not test whether flax oil alone could blunt cardiovascular responses to stress.
"These results are in agreement with several recent studies showing that walnuts can reduce cholesterol and blood pressure," noted West. "This work suggests that blood pressure is also reduced when a person is exposed to stress in their daily life."