Monday, August 22, 2016
The millions of people who consume green tea all over the world benefit from the catechins it contains. Catechins are a class of chemical compounds with anti-oxidant and anti-inflammatory properties, among other healthy ingredients. Researchers at the University of São Paulo's Public Health School (FSP-USP) have discovered that guarana (Paullinia cupana) is a worthy competitor, at least as far as catechins are concerned: the seeds of the tropical shrub, used in fizzy drinks that are among the most popular in Brazil, as well as in over-the-counter supplements, contain more than ten times the amount of catechins found in green tea.
A clinical trial with healthy human volunteers has demonstrated that guarana is a rich source of catechins, which, when properly absorbed, reduce the oxidative stress associated with the development of neurodegenerative and cardiovascular disorders, as well as diabetes, cancer, inflammation and premature aging due to cell death, among other conditions harmful to health and wellbeing.
"Guarana has always been seen above all as a stimulant, especially by the international scientific community, because of its high caffeine content. We also found few Brazilian scientific studies that seek to identify other biological effects of guarana," said Lina Yonekura, the principal investigator for this research and currently an assistant professor at Kagawa University's School of Agriculture in Japan. "This pioneering assessment of the absorption and biological effects of its catechins in human volunteers should foster interest in guarana as a functional food on the part of scientists, the market, and society in general."
The paper with the results of the study is featured on the cover of the latest issue of Food & Function, published by the Royal Society of Chemistry in the United Kingdom as one of the "Hot Articles in Food & Function 2016.
The month-long study was conducted in two stages. After selecting volunteers who were healthy but slightly overweight and with a moderately elevated risk of cardiovascular disease, the researchers measured baseline parameters on the first day and evaluated the same items again on day 15 after a the implementation of a controlled diet.
The participants were then asked to take guarana at home every morning before breakfast for the next fortnight. They were given bottles containing guarana seed powder and instructed to prepare a daily drink with the contents of one bottle (3 g of guarana powder) in 300 mL of water.
This procedure ensured that each participant acted as his or her own control. The researchers compared the same volunteers' blood tests at different times to avoid the influence of variability between individuals. The acute effect of guarana was measured one hour after the participants drank the solution on day 1 and day 15. The prolonged effect was assessed after overnight fasting on the same days.
The researchers assessed the extent to which guarana affected oxidative stress markers during the two-week intervention period. They also performed a detailed study to evaluate the subjects' absorption of catechins and their metabolites, as they had found no information in the scientific literature on the bioavailability of these compounds in guarana.
The oxidative stress markers included oxidation of low-density lipoprotein (LDL), popularly known as bad cholesterol. LDL is essential to an organism's proper functioning because it is the main particle that carries cholesterol to cells. Cholesterol is a structural component of all cell membranes and is used to manufacture steroid hormones (estrogen and testosterone). When oxidized, however, LDL causes atherosclerosis and increases the risk of cardiovascular disease. The tests performed by Yonekura's team showed an increase in oxidation resistance of the LDL in the blood samples taken from the volunteers after they drank guarana.
They also performed a comet assay, also called single cell gel electrophoresis (SCGE), a technique for quantifying and analyzing DNA damage in individual cells due to various factors, including oxidative stress. In this case, lymphocyte DNA in blood samples taken one hour after guarana intake was less damaged than expected when submitted to an oxidizing environment, indicating the presence of anti-oxidant substances or enhanced performance of the lymphocytes' enzymatic anti-oxidant system.
"All these markers depend on the presence of catechins in the bloodstream," Yonekura said. "The improvement in the parameters we assessed was associated with a rise in the concentration of plasma catechins after guarana intake, showing that guarana was indeed responsible for this effect."
Moreover, she went on, the guarana catechins strengthened the cells' native anti-oxidant enzymes, especially glutathione peroxidase, catalase, and superoxide dismutase, which combine to convert superoxide into peroxide and finally into water, protecting cells from the oxidative damage caused by their own metabolism of outside factors.
The tests showed increased glutathione peroxidase and catalase activity both shortly after guarana ingestion and on the following day.
"These results are exciting, suggesting that the bioavailability of guarana catechins is equal to or greater than that of green tea, cocoa and chocolate catechins," Yonekura said. "In fact, their bioavailability was sufficient to have a positive effect on plasma anti-oxidant activity, protect erythrocyte DNA, reduce plasma lipid oxidation, and increase anti-oxidant enzyme activity. We hope the results lead to heightened interest in guarana as the species is native to the Amazon, and Brazil is practically the only country that produces it on a commercial scale."
Oranges and other citrus fruits are good for you -- they contain plenty of vitamins and substances, such as antioxidants, that can help keep you healthy. Now a group of researchers reports that these fruits also help prevent harmful effects of obesity in mice fed a Western-style, high-fat diet.
The researchers are presenting their work today at the 252nd National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features more than 9,000 presentations on a wide range of science topics.
"Our results indicate that in the future we can use citrus flavanones, a class of antioxidants, to prevent or delay chronic diseases caused by obesity in humans," says Paula S. Ferreira, a graduate student with the research team.
More than one-third of all adults in the U.S. are obese, according to the U.S. Centers for Disease Control and Prevention. Being obese increases the risk of developing heart disease, liver disease and diabetes, most likely because of oxidative stress and inflammation, Ferreira says. When humans consume a high-fat diet, they accumulate fat in their bodies. Fat cells produce excessive reactive oxygen species, which can damage cells in a process called oxidative stress. The body can usually fight off the molecules with antioxidants. But obese patients have very enlarged fat cells, which can lead to even higher levels of reactive oxygen species that overwhelm the body's ability to counteract them.
Citrus fruits contain large amounts of antioxidants, a class of which are called flavanones. Previous studies linked citrus flavanones to lowering oxidative stress in vitro and in animal models. These researchers wanted to observe the effects of citrus flavanones for the first time on mice with no genetic modifications and that were fed a high-fat diet.
The team, at Universidade Estadual Paulista (UNESP) in Brazil, conducted an experiment with 50 mice, treating them with flavanones found in oranges, limes and lemons. The flavanones they focused on were hesperidin, eriocitrin and eriodictyol. For one month, researchers gave groups either a standard diet, a high-fat diet, a high-fat diet plus hesperidin, a high-fat diet plus eriocitrin or a high-fat diet plus eriodictyol.
The high-fat diet without the flavanones increased the levels of cell-damage markers called thiobarbituric acid reactive substances (TBARS) by 80 percent in the blood and 57 percent in the liver compared to mice on a standard diet. But hesperidin, eriocitrin and eriodictyol decreased the TBARS levels in the liver by 50 percent, 57 percent and 64 percent, respectively, compared with mice fed a high-fat diet but not given flavanones. Eriocitrin and eriodictyol also reduced TBARS levels in the blood by 48 percent and 47 percent, respectively, in these mice. In addition, mice treated with hesperidin and eriodictyol had reduced fat accumulation and damage in the liver.
"Our studies did not show any weight loss due to the citrus flavanones," says Thais B. Cesar, Ph.D., who leads the team. "However, even without helping the mice lose weight, they made them healthier with lower oxidative stress, less liver damage, lower blood lipids and lower blood glucose."
Ferreira adds, "This study also suggests that consuming citrus fruits probably could have beneficial effects for people who are not obese, but have diets rich in fats, putting them at risk of developing cardiovascular disease, insulin resistance and abdominal obesity."
For older adults, having more or closer family members in one's social network decreases his or her likelihood of death, but having a larger or closer group of friends does not, finds a new study that will be presented at the 111th Annual Meeting of the American Sociological Association (ASA).
"We found that older individuals who had more family in their network, as well as older people who were closer with their family were less likely to die," said James Iveniuk, the lead author of the study and a post-doctoral researcher at the University of Toronto's Dalla Lana School of Public Health. "No such associations were observed for number of or closeness to friends."
Titled, "Social Relationships and Mortality in Older Adulthood," the study used nationally representative data from the 2005/2006 and 2010/2011 survey waves of the National Social Life, Health, and Aging Project (NSHAP), to investigate which aspects of social networks are most important for postponing mortality. Mortality of wave one respondents, who were 57 to 85-years old, was assessed at wave two.
In the first wave, these older adults were asked to list up to five of their closest confidants, describe in detail the nature of each relationship, and indicate how close they felt to each person. Excluding spouses, the average number of close confidants named was 2.91, and most older adults perceived high levels of support from their social contacts. Additionally, most respondents were married, in good physical health, and reported not being very lonely.
Iveniuk and co-author L. Philip Schumm, a senior biostatician at the University of Chicago, found that older adults who reported feeling "extremely close" on average to the non-spousal family members they listed as among their closest confidants had about a six percent risk of mortality within the next five years, compared to approximately a 14 percent risk of mortality among those who reported feeling "not very close" to the family members they listed.
Furthermore, the study found that respondents who listed more non-spousal family members in their network -- irrespective of closeness -- had lower odds of death compared to those who listed fewer family members. "Regardless of the emotional content of a connection, simply having a social relationship with another person may have benefits for longevity," Iveniuk said.
Iveniuk said he was surprised that feeling closer to one's family members and having more relatives as confidants decreased the risk of death for older adults, but that the same was not true of relationships with friends.
"Because you can choose your friends, you might, therefore, expect that relationships with friends would be more important for mortality, since you might be better able to customize your friend network to meet your specific needs," Iveniuk said. "But that account isn't supported by the data -- it is the people who in some sense you cannot choose, and who also have little choice about choosing you, who seem to provide the greatest benefit to longevity."
Besides comparing friendships to relationships with family members, the study examined the characteristics of social networks in general and their association with mortality. The four factors most consistently associated with reduced mortality risk were being married, larger network size, greater participation in social organizations, and feeling closer to one's confidants, which all mattered to about the same degree. Factors found to be less important included time with confidants, access to social support, and feelings of loneliness.
"I expected the association between participation in social organizations and mortality to diminish in size considerably once we controlled for other aspects of peoples' social worlds, but that didn't happen," Iveniuk said.
Interestingly, marriage was found to have positive effects on longevity, regardless of marital quality. "We observed no association between measures of support from the spouse and mortality, indicating that the presence of a marital bond may be more important for longevity than certain aspects of the bond itself," Iveniuk said.
Generally, Iveniuk said his findings underscore the substantial importance of familial relationships for longevity. "Going back to the very first sociological theorists, many different thinkers have noted that there is some kind of special significance that people attribute to family ties, leading people to stay close to and support people who wouldn't necessarily be individuals that they would associate with if they had the choice," Iveniuk said.
Women between the ages of 50 and 74 may benefit from more or less frequent mammography screening than is generally recommended, depending on breast density and risk. For average-risk women with lower breast density, which comprises a large proportion of the population, triennial screening offers about the same or better balance of benefits and harms as biennial screening and is also cost-effective. Higher-risk women with dense breasts may fare better with annual screening. Findings from a collaborative modeling study are published in Annals of Internal Medicine.
Accepted clinical guidelines recommend biennial mammography screening for women aged 50 to 74. These recommendations also advocate shared decision making regarding screening frequency that takes into consideration an individual woman's preferences, risk level, and breast density. However, there is limited data available to guide clinicians and women in making these decisions.
Researchers from the Cancer Intervention and Surveillance Modeling Network, collaborating with the Breast Cancer Surveillance Consortium (BCSC), used three well-established models to evaluate outcomes using various screening intervals for digital mammography among subgroups of women based on age, risk, and breast density. The outcomes were projected for women 50 or older who were deciding whether to initiate (or continue) biennial screening until age 74 or to have annual or triennial screening.
The models showed that average-risk women with lower breast density could safely and effectively extend their screening interval to once every three years, which could reduce false-positives, biopsies, and overdiagnosis with minimal effect on breast cancer deaths averted. Women at higher risk for breast cancer and with dense breasts would reap greater benefit from annual screening. The authors suggest that these findings could be useful for guiding shared decision making and tailoring screening intervals.
Supplementing with soluble corn fiber at two critical times in a woman's life - adolescence and post-menopause - can help build and retain calcium in bone, according to new research from Purdue University.
"We are looking deeper in the gut to build healthy bone in girls and help older women retain strong bones during an age when they are susceptible to fractures," said Connie Weaver, distinguished professor and head of nutrition science. "Soluble corn fiber, a prebiotic, helps the body better utilize calcium during both adolescence and post-menopause. The gut microbiome is the new frontier in health."
The post-menopause findings are published in the American Journal of Clinical Nutrition, and the adolescent findings are published in Journal of Nutrition. The studies are funded by Tate & Lyle Ingredients America LLC. Weaver serves on the scientific advisory board for Pharmative LLC.
A prebiotic fiber passes through the gut for the microbes in the lower gut to digest. Here is where Weaver found that soluble corn fiber is broken down into short chain fatty acids to aid in bone health.
In the post-menopausal study, calcium retention was measured in 14 women by using an isotope to measure the excretion of 41Ca to measure bone loss. The women consumed 0 grams, 10 grams or 20 grams of this nondigestible carbohydrate each day for 50 days. Bone calcium retention was improved by 4.8 percent and 7 percent for those who consumed 10 grams and 20 grams, respectively. These amounts of soluble corn fiber would be found in supplement form.
"If projected out for a year, this would equal and counter the average rate of bone loss in a post-menopausal woman," said Weaver, an expert in mineral bioavailability, calcium metabolism, botanicals and bone health.
The calcium 41 technology, an isotope measure to trace calcium deposits through accelerator mass spectrometry in the Purdue Rare Isotope Measurement Laboratory (PRIME Lab), can measure atomic quantities. In the adolescent study, 44Ca and 43Ca were used.
Thirty-one girls either consumed 0 grams, 10 grams or 20 grams of soluble corn fiber carbohydrate each day for three weeks while maintaining their regular diets. Both 10 grams and 20 grams led to improved calcium absorption by 12 percent for female adolescents, which would build 1.8 percent more skeleton a year.
In both studies, gastrointestinal symptoms were minimal and the same for the control groups, as well as in those who consumed soluble corn fiber.
"Most studies looking at benefits from soluble corn fiber are trying to solve digestion problems, and we are the first to determine that this relationship of feeding certain kind of fiber can alter the gut microbiome in ways that can enhance health," Weaver said. "We found this prebiotic can help healthy people use minerals better to support bone health."
Calcium is considered a shortfall nutrient, and few people meet the recommended intake of 1,300 milligrams of calcium for healthy bone mass.
"The finding doesn't mean we should diminish our recommendation to drink milk and follow a well-balanced diet. This is a strategy to better utilize your minerals for those not consuming the whole recommendation of dairy," Weaver said. "Calcium alone suppresses bone loss, but it doesn't enhance bone formation. These fibers enhance bone formation, so they are doing something more than enhancing calcium absorption."
Weaver's team is looking into the mechanisms of how soluble corn fiber boosts calcium absorption and retention, as well as if the prebiotic fiber benefits the body in other ways.
Thursday, August 18, 2016
A study by researchers at UCLA's Semel Institute for Neuroscience and Human Behavior has found that a healthy diet, regular physical activity and a normal body mass index can reduce the incidence of protein build-ups that are associated with the onset of Alzheimer's disease.
In the study, 44 adults ranging in age from 40 to 85 (mean age: 62.6) with mild memory changes but no dementia underwent an experimental type of PET scan to measure the level of plaque and tangles in the brain. Researchers also collected information on participants' body mass index, levels of physical activity, diet and other lifestyle factors. Plaque, deposits of a toxic protein called beta-amyloid in the spaces between nerve cells in the brain; and tangles, knotted threads of the tau protein found within brain cells, are considered the key indicators of Alzheimer's.
The study found that each one of several lifestyle factors -- a healthy body mass index, physical activity and a Mediterranean diet -- were linked to lower levels of plaques and tangles on the brain scans. (The Mediterranean diet is rich in fruits, vegetables, legumes, cereals and fish and low in meat and dairy, and characterized by a high ratio of monounsaturated to saturated fats, and mild to moderate alcohol consumption.)
"The fact that we could detect this influence of lifestyle at a molecular level before the beginning of serious memory problems surprised us," said Dr. David Merrill, the lead author of the study, which appears in the September issue of the American Journal of Geriatric Psychiatry.
Earlier studies have linked a healthy lifestyle to delays in the onset of Alzheimer's. However, the new study is the first to demonstrate how lifestyle factors directly influence abnormal proteins in people with subtle memory loss who have not yet been diagnosed with dementia, Merrill said. Healthy lifestyle factors also have been shown to be related to reduced shrinking of the brain and lower rates of atrophy in people with Alzheimer's.
Older age is the No. 1 non-modifiable risk factor for Alzheimer's disease, which affects an estimated 5.2 million people in the United States and results in more than $200 billion in health care costs annually.
"The study reinforces the importance of living a healthy life to prevent Alzheimer's, even before the development of clinically significant dementia," Merrill said. "This work lends key insight not only into the ability of patients to prevent Alzheimer's disease, but also physicians' ability to detect and image these changes."
The next step in the research will be to combine imaging with intervention studies of diet, exercise and other modifiable lifestyle factors, such as stress and cognitive health, Merrill said.
Merrill sees patients with cognitive problems, particularly memory loss, at the UCLA Psychiatry Cognitive Health Clinic and Research Program.
According to a new study, calcium supplements may be associated with an increased risk of dementia in older women who have had a stroke or other signs of cerebrovascular disease. The research is published in the August 17, 2016, online issue of Neurology®, the medical journal of the American Academy of Neurology.
Cerebrovascular disease is a group of disorders that affect blood flow in the brain. These diseases, including stroke, are the fifth leading cause of death in the United States and increase the risk of developing dementia.
"Osteoporosis is a common problem in the elderly. Because calcium deficiency contributes to osteoporosis, daily calcium intake of 1000 to 1200 mg is recommended. Getting this recommended amount through diet alone can be difficult, so calcium supplements are widely used," said study author Silke Kern, MD, PhD with the University of Gothenburg in Sweden. "Recently, however, the use of supplements and their effect on health has been questioned."
The study involved 700 dementia-free women between the ages of 70 and 92 who were followed for five years. Participants took a variety of tests at the beginning and end of the study, including tests of memory and thinking skills. A CT brain scan was performed in 447 participants at the start of the study.
Scientists also looked at the use of calcium supplements in the participants and whether they were diagnosed with dementia over the course of the study. A total of 98 women were taking calcium supplements at the start of the study and 54 women had already experienced a stroke. During the study, 54 more women had strokes, and 59 women developed dementia. Among the women who had CT scans, 71 percent had lesions on their brains' white matter, which is a marker for cerebrovascular disease.
The study found that the women who were treated with calcium supplements were twice as likely to develop dementia than women who did not take supplements. But when the researchers further analyzed the data, they found that the increased risk was only among women with cerebrovascular disease. Women with a history of stroke who took supplements had a nearly seven times increased risk of developing dementia than women with a history of stroke who did not take calcium supplements. Women with white matter lesions who took supplements were three times as likely to develop dementia as women who had white matter lesions and did not take supplements. Women without a history of stroke or women without white matter lesions had no increased risk when taking calcium supplements.
Overall, 14 out of 98 women who took supplements developed dementia, or 14 percent, compared to 45 out of 602 women who did not take supplements, or 8 percent. A total of six out of 15 women with a history of stroke who took supplements developed dementia, compared to 12 out of 93 women with a history of stroke who did not take supplements. Among the women with no history of stroke, 18 out of 83 who took supplements developed dementia, compared to 33 out of the 509 who did not take supplements.
"It is important to note that our study is observational, so we cannot assume that calcium supplements cause dementia," said Kern. The author also noted that the study was small and results cannot be generalized to the overall population, and additional studies are needed to confirm the findings.
Kern noted that calcium from food affects the body differently than calcium from supplements and appears to be safe or even protective against vascular problems.