Once again, the pace of new health related research reports is overwhelming. Here are updates on alcohol (so distressing that my wife, who has made an effort to have a drink a day, is going on the wagon), tea ( so encouraging I am going to try to drink even more green tea), vitamins and minerals (D and calcium encouraging, E baffling), diet, exercise and apples (all encouraging):
Million women study shows even moderate alcohol consumption associated with increased cancer risk
Low to moderate alcohol consumption among women is associated with a statistically significant increase in cancer risk and may account for nearly 13 percent of the cancers of the breast, liver, rectum, and upper aero-digestive tract combined, according to a report in the February 24 online issue of the Journal of the National Cancer Institute.
With the exception of breast cancer, little has been known about the impact of low to moderate alcohol consumption on cancer risk in women.
To determine the impact of alcohol on overall and site-specific cancer risk, Naomi Allen, D.Phil., of the University of Oxford, U.K., and colleagues examined the association of alcohol consumption and cancer incidence in the Million Women Study, which included 1,280,296 middle-aged women in the United Kingdom. Participants were recruited to the study between 1996 and 2001. Researchers identified cancer cases through the National Health Service Central Registries.
Women in the study who drank alcohol consumed, on average, one drink per day, which is typical in most high-income countries such as the U.K. and the U.S. Very few drank three or more drinks per day. With an average follow-up time of more than 7 years, 68,775 women were diagnosed with cancer.
The risk of any type of cancer increased with increasing alcohol consumption, as did the risk of some specific types of cancer, including cancer of the breast, rectum, and liver. Women who also smoked had an increased risk of cancers of the oral cavity and pharynx, esophagus, and larynx. The type of alcohol consumed--wine versus spirits or other types--did not alter the association between alcohol consumption and cancer risk.
Each additional alcoholic drink regularly consumed per day was associated with 11 additional breast cancers per 1000 women up to age 75; one additional cancer of the oral cavity and pharynx; one additional cancer of the rectum; and an increase of 0.7 each for esophageal, laryngeal, and liver cancers. For these cancers combined, there was an excess of about 15 cancers per 1000 women per drink per day. (The background incidence for these cancers was estimated to be 118 per 1000 women in developed countries.)
"Although the magnitude of the excess abso¬lute risk associated with one additional drink per day may appear small for some cancer sites, the high prevalence of moderate alco¬hol drinking among women in many populations means that the proportion of cancers attributable to alcohol is an important public health issue," the authors write.
In an accompanying editorial, Michael Lauer M.D., and Paul Sorlie, Ph.D., of the National Heart, Lung, and Blood Institute, in Bethesda, M.D., emphasize that these new results derived from such a large study population should give readers pause. Although previous epidemiological studies have suggested that there is a cardiovascular benefit associated with moderate alcohol consumption, the excess cancer risk identified in the current study may outweigh that benefit. "From a standpoint of cancer risk, the message of this report could not be clearer. There is no level of alcohol consumption that can be considered safe," the editorialists write.
Green, black tea can reduce stroke risk
Drinking at least three cups of green or black tea a day can significantly reduce the risk of stroke, a new UCLA study has found. And the more you drink, the better your odds of staving off a stroke.
The study results, published in the online edition of Stroke: Journal of the American Heart Association, were presented Feb. 19 at the American Heart Association's annual International Stroke Conference in San Diego, Calif.
The UCLA researchers conducted an evidence-based review of all human observational studies on stroke and tea consumption found in the PubMed and Web of Science archives. They found nine studies describing 4,378 strokes among nearly 195,000 individuals, according to lead author Lenore Arab, a professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA.
"What we saw was that there was a consistency of effect of appreciable magnitude," said Arab, who is also a professor of biological chemistry. "By drinking three cups of tea a day, the risk of a stroke was reduced by 21 percent. It didn't matter if it was green or black tea."
And extrapolating from the data, the effect appears to be linear, Arab said. For instance, if one drinks three cups a day, the risk falls by 21 percent; follow that with another three cups and the risk drops another 21 percent.
This effect was found in tea made from the plant Camellia sinensis, not from herbal teas.
There are very few known ways to reduce the risk of stroke, Arab said. And developing medications for stroke victims is particularly challenging, given that the drug has to get to the stroke-damaged site quickly because damage occurs so fast. Arab said that by the time a stroke victim gets medical care, it's nearly too late to impede the damage.
"That's why these findings are so exciting," she said. "If we can find a way to prevent the stroke, or prevent the damage, that is simple and not toxic, that would be a great advance."
Though no one is certain which compounds in tea are responsible for this effect, researchers have speculated that the antioxidant epigallocatechin gallate (EGCG) or the amino acid theanine may be what helps. Antioxidants are believed to help prevent coronary artery disease.
"And we do know that theanine is nearly 100-percent absorbed," Arab said. "It gets across the blood-brain barrier and it looks a lot like a molecule that's very similar to glutamate, and glutamate release is associated with stroke.
"It could be that theanine and glutamate compete for the glutamate receptor in the brain," she added.
Although a randomized clinical trial is needed to confirm this effect, the findings suggest that drinking three cups of green or black tea a day could help prevent an ischemic stroke.
Multivitamins Have No Impact on Risk of Cancer Or Heart Disease in Postmenopausal Women
The largest study of its kind concludes that long-term multivitamin use has no impact on the risk of common cancers, cardiovascular disease or overall mortality in postmenopausal women. The results of the Women’s Health Initiative study, led by researchers at Fred Hutchinson Cancer Research Center, were published in the Feb. 9 issue of the Archives of Internal Medicine.
“Dietary supplements are used by more than half of all Americans, who spend more than $20 billion on these products each year. However, scientific data are lacking on the long-term health benefits of supplements,” said lead author Marian L. Neuhouser, Ph.D., an associate member of the Public Health Sciences Division at the Hutchinson Center.
The study focused the effects of multivitamins because they are the most commonly used supplement. “To our surprise, we found that multivitamins did not lower the risk of the most common cancers and also had no impact on heart disease,” she said.
The study assessed multivitamin use among nearly 162,000 women enrolled in the Women’s Health Initiative, one of the largest U.S. prevention studies of its kind designed to address the most common causes of death, disability and impaired quality of life in postmenopausal women. The women were followed for about eight years.
Nearly half of the study participants – 41.5 percent – reported using multivitamins on a regular basis. Multivitamin users were more likely to be white, live in the western United States, have a lower body-mass index, be more physically active and have a college degree or higher as compared to non-users. Multivitamin users also were more likely to drink alcohol and less likely to smoke than non-users, and they reported eating more fruits and vegetables and consuming less fat than non-users.
During the eight-year study period, 9,619 cases of breast, colorectal, endometrial, renal, bladder, stomach, lung or ovarian cancer were reported, as well as 8,751 cardiovascular events and 9,865 deaths. The study found no significant differences in risk of cancer, heart disease or death between the multivitamin users and non-users.
These findings are consistent with most previously published results regarding the lack of health benefits of multivitamins, Neuhouser said, but this study provides definitive evidence. “The Women’s Health Initiative is one of the largest studies ever done on diet and health. Thus, because we have such a large and diverse sample size, including women from 40 sites across the nation, our results can be generalized to a healthy population.” Since the study did not include men, Neuhouser cautions that the results may not apply to them.
So what advice do Neuhouser and colleagues offer to women who want to make sure they’re getting optimal nutrition? “Get nutrients from food,” she said. “Whole foods are better than dietary supplements. Getting a wide variety of fruits, vegetables and whole grains is particularly important.”
Vitamin E may decrease and increase mortality of male smokers with high dietary vitamin C intake
Six-year vitamin E supplementation decreased mortality by 41% in elderly male smokers who had high dietary vitamin C intake, but increased mortality by 19% in middle-aged smokers who had high vitamin C intake, according to a study published in the American Journal of Epidemiology.
Large-scale controlled trials have not found any overall effects of vitamin E supplementation on the mortality of participants. Nevertheless, the effect of vitamin E on respiratory infections has significantly diverged between different population groups suggesting that the effects of vitamin E may not be uniform over all the population.
Dr. Harri Hemila, and Professor Jaakko Kaprio, of the University of Helsinki, Finland, studied whether the effect of vitamin E supplementation on mortality might diverge between different population groups. They analyzed the data of the large randomized trial (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) which was conducted in Finland between 1985-1993 and included male smokers aged 50-69 years. There were 3571 deaths in 29,133 participants during the 6-year supplementation of 50 mg/day of vitamin E.
Although vitamin E had no overall effect on mortality, its effect was modified by age and dietary vitamin C intake. Vitamin E had no effect on participants who had low dietary vitamin C intake, less than 90 mg/day. However, in those who had high vitamin C intake, over 90 mg/day, the effect of vitamin E diverged so that it increased mortality in young participants (50-62 years), but decreased mortality in old participants (66-69 years).
The US nutritional recommendations, issued by the prestigious Institute of Medicine, consider that vitamin E is safe in doses up to 1000 mg/day. This new study gives further evidence indicating that in some population groups vitamin E may be harmful in a substantially lower dose, 50 mg/day.
The researchers concluded that "in people younger than 65 years, taking vitamin E supplements should be strongly discouraged, until clear evidence emerges that some population groups of younger or middle-aged people benefit". They also concluded that the effect of vitamin E on elderly people should be further investigated.
Vitamin B and folic acid may reduce risk of age-related vision loss
Taking a combination of vitamins B6 and B12 and folic acid appears to decrease the risk of age-related macular degeneration in women, according to a report in the February 23 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Age-related macular degeneration (AMD) is a leading cause of vision loss in older Americans, according to background information in the article. Treatment options exist for those with severe cases of the disease, but the only known prevention method is to avoid smoking. Recent studies have drawn a connection between AMD and blood levels of homocysteine, an amino acid. High levels of homocysteine are associated with dysfunction of the blood vessel lining, whereas treatment with vitamin B6, vitamin B12 and folic acid appears to reduce homocysteine levels and may reverse this blood vessel dysfunction.
William G. Christen, Sc.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues conducted a randomized, double-blind clinical trial involving 5,442 women age 40 and older who already had heart disease or at least three risk factors. Of these, 5,205 did not have AMD at the beginning of the study. In April 1998, these women were randomly assigned to take a placebo or a combination of folic acid (2.5 milligrams per day), pyridoxine hydrochloride (vitamin B6, 50 milligrams per day) and cyanocobalamin (vitamin B12, 1 milligram per day). Participants continued the therapy through July 2005 and were tracked for the development of AMD through November 2005.
Over an average of 7.3 years of treatment and follow-up, 137 new cases of AMD were documented, including 70 cases that were visually significant (resulting in a visual acuity of 20/30 or worse). Of these, 55 AMD cases, 26 visually significant, occurred in the 2,607 women in the active treatment group, whereas 82 of the 2,598 women in the placebo group developed AMD, 44 cases of which were visually significant. Women taking the supplements had a 34 percent lower risk of any AMD and a 41 percent lower risk of visually significant AMD. "The beneficial effect of treatment began to emerge at approximately two years of follow-up and persisted throughout the trial," the authors write.
"The trial findings reported herein are the strongest evidence to date in support of a possible beneficial effect of folic acid and B vitamin supplements in AMD prevention," the authors write. Because they apply to the early stages of disease development, they appear to represent the first identified way—other than not smoking—to reduce the risk of AMD in individuals at an average risk. "From a public health perspective, this is particularly important because persons with early AMD are at increased risk of developing advanced AMD, the leading cause of severe, irreversible vision loss in older Americans."
Beyond lowering homocysteine levels, potential mechanisms for the effectiveness of B vitamins and folic acid in preventing AMD include antioxidant effects and improved function of blood vessels in the eye, they note.
Calcium associated with lower risk of cancer in women
Women with higher intake of calcium appear to have a lower risk of cancer overall, and both men and women with high calcium intakes have lower risks of colorectal cancer and other cancers of the digestive system, according to a report in the February 23 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Calcium is known to benefit bone health, according to background information in the article. Because of this, the Institute of Medicine recommends 1,200 milligrams of calcium for adults age 50 and older, and the 2005 dietary guidelines for Americans recommend 3 cups per day of low-fat or fat-free dairy products. Studies of dairy products, calcium intake and cancer have revealed different results for different cancer sites.
Yikyung Park, Sc.D., of the National Cancer Institute, Bethesda, Md., and colleagues analyzed data from 293,907 men and 198,903 women who participated in the National Institutes of Health-AARP Diet and Health Study. Participants took a food frequency questionnaire when they enrolled in the study between 1995 and 1996, reporting how much and how often they consumed dairy and a wide variety of other foods and whether they took supplements. Their records were then linked with state cancer registries to identify new cases of cancer through 2003.
Over an average of 7 years of follow-up, 36,965 cancer cases were identified in men and 16,605 in women. Calcium intake was not associated with total cancer in men but was in women—the risk decreased in women with intake of up to 1,300 milligrams per day, after which no further risk reduction was observed.
"In both men and women, dairy food and calcium intakes were inversely associated with cancers of the digestive system," the authors write. The one-fifth of men who consumed the most calcium through food and supplements (about 1,530 milligrams per day) had a 16 percent lower risk of these types of cancer than the one-fifth who consumed the least (526 milligrams per day). For women, those in the top one-fifth of calcium consumption (1,881 milligrams per day) had a 23 percent lower risk than those in the bottom one-fifth (494 milligrams per day). The decreased risk was particularly pronounced for colorectal cancer. Calcium and dairy food intake was not associated with prostate cancer, breast cancer or cancer in any other anatomical system besides the digestive system.
"Dairy food, which is relatively high in potentially anticarcinogenic nutrients such as calcium, vitamin D and conjugated linoleic acid, has been postulated to protect against the development of colorectal and breast cancer," the authors write. Calcium has been shown to reduce abnormal growth and induce normal turnover among cells in the gastrointestinal tract and breast. In addition, it binds to bile and fatty acids, potentially reducing damage to the mucous membrane in the large intestine.
"In conclusion, our findings suggest that calcium intake consistent with current recommendations is associated with a lower risk of total cancer in women and cancers of the digestive system, especially colorectal cancer, in both men and women," the authors write.
Multivitamins Have No Impact on Risk of Cancer Or Heart Disease in Postmenopausal Women
The largest study of its kind concludes that long-term multivitamin use has no impact on the risk of common cancers, cardiovascular disease or overall mortality in postmenopausal women. The results of the Women’s Health Initiative study, led by researchers at Fred Hutchinson Cancer Research Center, were published in the Feb. 9 issue of the Archives of Internal Medicine.
“Dietary supplements are used by more than half of all Americans, who spend more than $20 billion on these products each year. However, scientific data are lacking on the long-term health benefits of supplements,” said lead author Marian L. Neuhouser, Ph.D., an associate member of the Public Health Sciences Division at the Hutchinson Center.
The study focused the effects of multivitamins because they are the most commonly used supplement. “To our surprise, we found that multivitamins did not lower the risk of the most common cancers and also had no impact on heart disease,” she said.
The study assessed multivitamin use among nearly 162,000 women enrolled in the Women’s Health Initiative, one of the largest U.S. prevention studies of its kind designed to address the most common causes of death, disability and impaired quality of life in postmenopausal women. The women were followed for about eight years.
Nearly half of the study participants – 41.5 percent – reported using multivitamins on a regular basis. Multivitamin users were more likely to be white, live in the western United States, have a lower body-mass index, be more physically active and have a college degree or higher as compared to non-users. Multivitamin users also were more likely to drink alcohol and less likely to smoke than non-users, and they reported eating more fruits and vegetables and consuming less fat than non-users.
During the eight-year study period, 9,619 cases of breast, colorectal, endometrial, renal, bladder, stomach, lung or ovarian cancer were reported, as well as 8,751 cardiovascular events and 9,865 deaths. The study found no significant differences in risk of cancer, heart disease or death between the multivitamin users and non-users.
These findings are consistent with most previously published results regarding the lack of health benefits of multivitamins, Neuhouser said, but this study provides definitive evidence. “The Women’s Health Initiative is one of the largest studies ever done on diet and health. Thus, because we have such a large and diverse sample size, including women from 40 sites across the nation, our results can be generalized to a healthy population.” Since the study did not include men, Neuhouser cautions that the results may not apply to them.
So what advice do Neuhouser and colleagues offer to women who want to make sure they’re getting optimal nutrition? “Get nutrients from food,” she said. “Whole foods are better than dietary supplements. Getting a wide variety of fruits, vegetables and whole grains is particularly important.”
Vitamin E may decrease and increase mortality of male smokers with high dietary vitamin C intake
Six-year vitamin E supplementation decreased mortality by 41% in elderly male smokers who had high dietary vitamin C intake, but increased mortality by 19% in middle-aged smokers who had high vitamin C intake, according to a study published in the American Journal of Epidemiology.
Large-scale controlled trials have not found any overall effects of vitamin E supplementation on the mortality of participants. Nevertheless, the effect of vitamin E on respiratory infections has significantly diverged between different population groups suggesting that the effects of vitamin E may not be uniform over all the population.
Dr. Harri Hemila, and Professor Jaakko Kaprio, of the University of Helsinki, Finland, studied whether the effect of vitamin E supplementation on mortality might diverge between different population groups. They analyzed the data of the large randomized trial (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) which was conducted in Finland between 1985-1993 and included male smokers aged 50-69 years. There were 3571 deaths in 29,133 participants during the 6-year supplementation of 50 mg/day of vitamin E.
Although vitamin E had no overall effect on mortality, its effect was modified by age and dietary vitamin C intake. Vitamin E had no effect on participants who had low dietary vitamin C intake, less than 90 mg/day. However, in those who had high vitamin C intake, over 90 mg/day, the effect of vitamin E diverged so that it increased mortality in young participants (50-62 years), but decreased mortality in old participants (66-69 years).
The US nutritional recommendations, issued by the prestigious Institute of Medicine, consider that vitamin E is safe in doses up to 1000 mg/day. This new study gives further evidence indicating that in some population groups vitamin E may be harmful in a substantially lower dose, 50 mg/day.
The researchers concluded that "in people younger than 65 years, taking vitamin E supplements should be strongly discouraged, until clear evidence emerges that some population groups of younger or middle-aged people benefit". They also concluded that the effect of vitamin E on elderly people should be further investigated.
Vitamin B and folic acid may reduce risk of age-related vision loss
Taking a combination of vitamins B6 and B12 and folic acid appears to decrease the risk of age-related macular degeneration in women, according to a report in the February 23 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Age-related macular degeneration (AMD) is a leading cause of vision loss in older Americans, according to background information in the article. Treatment options exist for those with severe cases of the disease, but the only known prevention method is to avoid smoking. Recent studies have drawn a connection between AMD and blood levels of homocysteine, an amino acid. High levels of homocysteine are associated with dysfunction of the blood vessel lining, whereas treatment with vitamin B6, vitamin B12 and folic acid appears to reduce homocysteine levels and may reverse this blood vessel dysfunction.
William G. Christen, Sc.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues conducted a randomized, double-blind clinical trial involving 5,442 women age 40 and older who already had heart disease or at least three risk factors. Of these, 5,205 did not have AMD at the beginning of the study. In April 1998, these women were randomly assigned to take a placebo or a combination of folic acid (2.5 milligrams per day), pyridoxine hydrochloride (vitamin B6, 50 milligrams per day) and cyanocobalamin (vitamin B12, 1 milligram per day). Participants continued the therapy through July 2005 and were tracked for the development of AMD through November 2005.
Over an average of 7.3 years of treatment and follow-up, 137 new cases of AMD were documented, including 70 cases that were visually significant (resulting in a visual acuity of 20/30 or worse). Of these, 55 AMD cases, 26 visually significant, occurred in the 2,607 women in the active treatment group, whereas 82 of the 2,598 women in the placebo group developed AMD, 44 cases of which were visually significant. Women taking the supplements had a 34 percent lower risk of any AMD and a 41 percent lower risk of visually significant AMD. "The beneficial effect of treatment began to emerge at approximately two years of follow-up and persisted throughout the trial," the authors write.
"The trial findings reported herein are the strongest evidence to date in support of a possible beneficial effect of folic acid and B vitamin supplements in AMD prevention," the authors write. Because they apply to the early stages of disease development, they appear to represent the first identified way—other than not smoking—to reduce the risk of AMD in individuals at an average risk. "From a public health perspective, this is particularly important because persons with early AMD are at increased risk of developing advanced AMD, the leading cause of severe, irreversible vision loss in older Americans."
Beyond lowering homocysteine levels, potential mechanisms for the effectiveness of B vitamins and folic acid in preventing AMD include antioxidant effects and improved function of blood vessels in the eye, they note.
Calcium associated with lower risk of cancer in women
Women with higher intake of calcium appear to have a lower risk of cancer overall, and both men and women with high calcium intakes have lower risks of colorectal cancer and other cancers of the digestive system, according to a report in the February 23 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Calcium is known to benefit bone health, according to background information in the article. Because of this, the Institute of Medicine recommends 1,200 milligrams of calcium for adults age 50 and older, and the 2005 dietary guidelines for Americans recommend 3 cups per day of low-fat or fat-free dairy products. Studies of dairy products, calcium intake and cancer have revealed different results for different cancer sites.
Yikyung Park, Sc.D., of the National Cancer Institute, Bethesda, Md., and colleagues analyzed data from 293,907 men and 198,903 women who participated in the National Institutes of Health-AARP Diet and Health Study. Participants took a food frequency questionnaire when they enrolled in the study between 1995 and 1996, reporting how much and how often they consumed dairy and a wide variety of other foods and whether they took supplements. Their records were then linked with state cancer registries to identify new cases of cancer through 2003.
Over an average of 7 years of follow-up, 36,965 cancer cases were identified in men and 16,605 in women. Calcium intake was not associated with total cancer in men but was in women—the risk decreased in women with intake of up to 1,300 milligrams per day, after which no further risk reduction was observed.
"In both men and women, dairy food and calcium intakes were inversely associated with cancers of the digestive system," the authors write. The one-fifth of men who consumed the most calcium through food and supplements (about 1,530 milligrams per day) had a 16 percent lower risk of these types of cancer than the one-fifth who consumed the least (526 milligrams per day). For women, those in the top one-fifth of calcium consumption (1,881 milligrams per day) had a 23 percent lower risk than those in the bottom one-fifth (494 milligrams per day). The decreased risk was particularly pronounced for colorectal cancer. Calcium and dairy food intake was not associated with prostate cancer, breast cancer or cancer in any other anatomical system besides the digestive system.
"Dairy food, which is relatively high in potentially anticarcinogenic nutrients such as calcium, vitamin D and conjugated linoleic acid, has been postulated to protect against the development of colorectal and breast cancer," the authors write. Calcium has been shown to reduce abnormal growth and induce normal turnover among cells in the gastrointestinal tract and breast. In addition, it binds to bile and fatty acids, potentially reducing damage to the mucous membrane in the large intestine.
"In conclusion, our findings suggest that calcium intake consistent with current recommendations is associated with a lower risk of total cancer in women and cancers of the digestive system, especially colorectal cancer, in both men and women," the authors write.
It's no fish tale: Omega-3 fatty acids prevent medical complications of obesity
New article in the FASEB Journal shows how omega-3 fatty acids protect against liver damage and insulin resistance
According to a recent study published online in The FASEB Journal (http://www.fasebj.org), diets rich in omega-3 fatty acids protect the liver from damage caused by obesity and the insulin resistance it provokes. This research should give doctors and nutritionists valuable information when recommending and formulating weight-loss diets and help explain why some obese patients are more likely to suffer some complications associated with obesity. Omega-3 fatty acids can be found in canola oil and fish.
"Our study shows for the first time that lipids called protectins and resolvins derived from omega-3 fatty acids can actually reduce the instance of liver complications, such as hepatic steatosis and insulin resistance, in obese people," stated Joan Claria, a professor from the University of Barcelona and one of the researchers involved in the work.
The scientists found that two types of lipids in omega-3 fatty acids—protectins and resolvins—were the cause of the protective effect. To reach this conclusion, they studied four groups of mice with an altered gene making them obese and diabetic. One group was given an omega-3-enriched diet and the second group was given a control diet. The third group was given docosahexaenoic acid, and the fourth received only the lipid resolvin. After five weeks, blood serum and liver samples from the test mice were examined. The mice given the omega-3-rich diet exhibited less hepatic inflammation and improved insulin tolerance. This was due to the formation of protectins and resolvins from omega-3 fatty acids.
"Doctors are always looking for simple and easy ways to counter the harmful effects of obesity, and the great thing about this study is that the information can be used at dinner tonight," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "It's not unlikely that eating lots more fish or a simple switch to canola oil will make a difference."
People who exercise lower their risk of colon cancer
An ambitious new study has added considerable weight to the claim that exercise can lower the risk for colon cancer. Researchers at Washington University School of Medicine in St. Louis and Harvard University combined and analyzed several decades worth of data from past studies on how exercise affects colon cancer risk. They found that people who exercised the most were 24 percent less likely to develop the disease than those who exercised the least.
"What's really compelling is that we see the association between exercise and lower colon cancer risk regardless of how physical activity was measured in the studies," says lead study author Kathleen Y. Wolin, Sc.D., a cancer prevention and control expert with the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University. "That indicates that this is a robust association and gives all the more evidence that physical activity is truly protective against colon cancer."
Colorectal cancer is the third most common type of cancer. Each year more than 100,000 people in the United States are diagnosed with colon cancer and about 40,000 are diagnosed with rectal cancer. The study suggests that if the American population became significantly more physically active, up to 24 percent, or more than 24,000, fewer cases of colon cancer would occur each year.
Wolin's report was published Feb. 10, 2009 through advance online publication in the British Journal of Cancer. In the study, she and her colleagues gathered the results from all relevant studies published in English on the effect of physical activity on colon cancer risk.
They eliminated from consideration any studies that combined both colon and rectal cancer because exercise has not been shown to affect rectal cancer risk — including such studies would have led to an underestimation of the effect of exercise on colon cancer risk. In all, they analyzed 52 studies going back as far as 1984, making their analysis the most comprehensive to date.
They found that the protective effect of exercise held for all types of physical activity, whether that activity was recreational, such as jogging, biking or swimming, or job related, such as walking, lifting or digging.
"The beneficial effect of exercise holds across all sorts of activities," says Wolin, also assistant professor of surgery. "And it holds for both men and women. There is an ever-growing body of evidence that the behavior choices we make affect our cancer risk. Physical activity is at the top of the list of ways that you can reduce your risk of colon cancer."
The difference between people who were the most physically active and those who were the least varied from study to study in Wolin's analysis. As an example, in a 2007 study by Wolin and colleagues, women who walked the most realized a 23 percent reduction in their risk of colon cancer. Those highly active women walked briskly for five to six hours each week. By comparison, the women in that study who walked the least walked only a half hour each week.
Exercise improves quality of life in postmenopausal women
Exercise appears to improve quality of life in postmenopausal women regardless of whether they lose weight, according to a report in the February 9 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Physical inactivity is a risk factor for various chronic conditions including diabetes mellitus, heart disease, stroke and several types of cancers, according to background information in the article. Regular physical activity is often reported to improve mood, reduce stress and increase energy levels, all of which are measurements of quality of life. However, these claims are largely derived from studies composed of participants with serious illnesses and have not been confirmed in healthy populations.
Corby K. Martin, Ph.D., of the Pennington Biomedical Research Center and Louisiana State University System, Baton Rouge and colleagues studied the effect of 50 percent, 100 percent and 150 percent of current public health physical activity recommendations on quality of life in 430 sedentary postmenopausal women (average age 57.4). Participants were randomly assigned to a non-exercise control group (n=92) or one of three exercise groups: exercise energy expenditure of 4 kilocalories per kilogram (2.2 pounds) of body weight per week (4-KKW) (n=147), 8-KKW (n=96) or 12-KKW (n=95). A short health survey was used to measure physical and mental aspects of quality of life at the beginning of the study and six months later.
“Adherence to exercise was 95.4 percent, 88.1 percent and 93.7 percent for the 4-, 8- and 12-KKW groups, respectively, and each group spent 73.9, 138.3 and 183.6 minutes per week exercising,” the authors write. The average weight loss in the control, 4-KKW, 8-KKW and 12-KKW groups was 0.94 kilograms (2.07 pounds), 1.34 kilograms (2.95 pounds), 1.86 kilograms (4.10 pounds) and 1.34 kilograms (2.95 pounds), respectively.
“A dose-response effect of exercise on quality of life was noted for all aspects of quality of life except bodily pain,” they note. “In addition, the 4-KKW group had significantly improved general health perception, vitality and mental health compared with the control group. All three exercise groups had significantly improved social functioning compared with the control group.”
“Our results indicate that improved quality of life can be added to the list of exercise benefits and that these improvements are dose dependent and independent of weight loss, at least among people similar to this study’s sample,” the authors conclude. “The exercise doses are easily obtainable and were well tolerated by sedentary women, resulting in confidence that the exercise doses used in this study can be achieved by women in the community.”
Vigorous Exercise May Help Prevent Vision Loss
There's another reason to dust off those running shoes. Vigorous exercise may help prevent vision loss, according to a pair of studies from the U.S. Department of Energy's Lawrence Berkeley National Laboratory. The studies tracked approximately 31,000 runners for more than seven years, and found that running reduced the risk of both cataracts and age-related macular degeneration.
The research, which is among the first to suggest that vigorous exercise may help prevent vision loss, offers hope for people seeking to fend off the onset of eye disease.
"In addition to obtaining regular eye exams, people can take a more active role in preserving their vision," says Paul Williams, an epidemiologist in Berkeley Lab's Life Sciences Division who conducted the research. "The studies suggest that people can perhaps lessen their risk for these diseases by taking part in a fitness regimen that includes vigorous exercise."
A cataract, which is a cloudy opacity of the eye lens, is the leading cause of blindness. More than one-half of people in the U.S. over the age of 65 suffer from some form of cataracts. Age-related macular degeneration, which is damage to the retina, is the leading cause of irreversible vision loss in older white Americans, affecting 28 percent of people aged 75 and older.
The diseases have several known risk factors, such as sunlight exposure and diabetes in the case of cataracts, but few interventions. Now, it appears that vigorous cardiovascular exercise may be one way to derail the diseases.
To conduct the research, Williams analyzed data collected in the National Runners' Health Study, which he established in 1991 to determine the health benefits of running.
In this case, he followed approximately 29,000 male runners and 12,000 female runners for more than seven years. Of these people, 733 men reported being diagnosed with cataracts on a questionnaire filled out at the end of the study. Too few women reported cataracts to track.
Men who ran more than 5.7 miles per day had a 35 percent lower risk of developing cataracts than men who ran less than 1.4 miles per day. The study also analyzed men's 10-kilometer race performances, which is a good indicator of overall fitness. The fittest men boasted one-half the risk of developing cataracts compared to the least-fit men.
A second study found that running appeared to reduce the risk of age-related macular degeneration. In the study, 152 men and women reported being diagnosed with the disease. Compared to people who ran less than 1.2 miles per day, people who averaged between 1.2 and 2.4 miles per day had a 19 percent lower risk for the disease, and people who ran more than 2.4 miles per day had between 42 percent and 54 percent lower risk of the disease.
"These findings are compelling because of the large size of the study, and the fact that we are looking at something that is fairly well defined: vigorous exercise, as opposed to more moderate exercise," says Williams.
Most of the runners in the study exceeded the current public health recommendations for physical activity, which is at least 30 minutes of moderate-intensity activities such as brisk walking five days a week, or smaller doses of more vigorous exercise such as running. It is unclear whether people might also lower their risk for cataracts and age-related macular degeneration by walking.
"We know there are important health benefits to walking, including lowering heart disease risk," says Williams. "It is quite likely that the studies' results might apply to a lesser extent to smaller doses of more moderate exercise."
Williams also adds that further research is needed to explore why there is a link between vigorous exercise and a decreased risk for eye disease.
"We know some of the physiological benefits of exercise, and we know about the physiological background of these diseases, so we need to better understand where there's an overlap," says Williams.
High-Fat Diets Inflame Fat Tissue Around Blood Vessels, Contribute to Heart Disease
A study by researchers at the University of Cincinnati shows that high-fat diets, even if consumed for a short amount of time, can inflame fat tissue surrounding blood vessels, possibly contributing to cardiovascular disease.
These findings will be published in the Feb. 20 edition of the American Heart Association journal Circulation Research.
Neal Weintraub, MD, and colleagues examined adipose tissue—or fat—surrounding the coronary arteries of humans. The researchers found these fat cells to be highly inflamed, suggesting that they could trigger inflammation of the blood vessels, an important component of atherosclerosis.
They also found that the inflammation of fat tissues around the arteries of mice is increased by feeding the animals a high-fat diet for just two weeks.
“This is independent of weight gain or blood lipids—cholesterol levels,” says Weintraub, senior author of the study and chair of the cardiovascular diseases division at UC.
Weintraub says that high fat diets contribute to atherosclerosis—or the hardening of arteries—in a number of ways.
“Elevated blood lipids—or cholesterol levels—can worsen with the intake of high fat diets, and this is known to contribute to atherosclerosis,” he says. “However, many patients who consume high fat diets do not exhibit abnormal lipid profiles but still develop atherosclerosis nonetheless.
“These new findings suggest a direct link between poor dietary habits and inflammation of blood vessels, mediated by the fat cells surrounding the blood vessel wall.”
Weintraub adds that the diet fed to the mouse models was not unlike the diets consumed by many Americans.
“It produced striking abnormalities of the fat tissue surrounding blood vessels in a very short period of time,” he says. “This is a warning to those who say there isn’t a problem because their weight and cholesterol levels are under control. Lipid profiles don’t hold all the answers.
“Bad dietary habits can lead to a number of problems, and this suggests that a high fat diet is detrimental in ways we didn’t previously understand.”
Weintraub says there is no real way to measure the effects of poor dietary habits on fat tissue surrounding blood vessels.
“We don’t know why these cells are so responsive to high-fat diets,” he says. “We must now conduct further experiments to answer these types of questions.”
An apple a day can keep the breast-cancer away
Six studies published in the past year by a Cornell researcher add to growing evidence that an apple a day -- as well as daily helpings of other fruits and vegetables -- can help keep the breast-cancer doctor away.
In one of his recent papers, published in the Journal of Agricultural and Food Chemistry (57:1), Rui Hai Liu, Cornell associate professor of food science and a member of Cornell's Institute for Comparative and Environmental Toxicology, reports that fresh apple extracts significantly inhibited the size of mammary tumors in rats -- and the more extracts they were given, the greater the inhibition.
"We not only observed that the treated animals had fewer tumors, but the tumors were smaller, less malignant and grew more slowly compared with the tumors in the untreated rats," said Liu, pointing out that the study confirmed the findings of his preliminary study in rats published in 2007.
In his latest study, for example, he found that a type of adenocarcinoma -- a highly malignant tumor and the main cause of death of breast-cancer patients, as well as of animals with mammary cancer -- was evident in 81 percent of tumors in the control animals. However, it developed in only 57 percent, 50 percent and 23 percent of the rats fed low, middle and high doses of apple extracts (the equivalent of one, three and six apples a day in humans), respectively, during the 24-week study.
"That reflects potent anti-proliferative [rapid decrease] activity," said Liu.
The studies highlight the important role of phytochemicals, known as phenolics or flavonoids, found in apples and other fruits and vegetables. Of the top 25 fruits consumed in the United States, Liu reported in the same journal (56:18) that apples provide 33 percent of the phenolics that Americans consume annually._In a study of apple peel published in the same journal (56:21), Liu reported on a variety of new phenolic compounds that he discovered that also have "potent antioxidant and anti-proliferative activities" on tumors. And in yet another study in the same journal (56:24), he reported on his discovery of the specific modulation effects that apple extracts have on cell cycle machinery. Recently, Liu's group also reported the finding that apple phytochemicals inhibit an important inflammation pathway (NFkB) in human breast cancer cells.
Breast cancer is the most frequently diagnosed invasive cancer and the second leading cause of cancer deaths in women in the United States, said Liu._"These studies add to the growing evidence that increased consumption of fruits and vegetables, including apples, would provide consumers with more phenolics, which are proving to have important health benefits. I would encourage consumers to eat more and a wide variety of fruits and vegetables daily."
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