Wednesday, May 22, 2013
Widely-used fish oil supplements modestly increase amounts of a hormone that is associated with lower risk of diabetes and heart disease, according to a study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM).
Fish oil supplements, also called omega 3 fatty acid capsules, raise levels of adiponectin in the bloodstream. Adiponectin is an important hormone that has beneficial effects on metabolic processes like glucose regulation and the modulation of inflammation. In long-term human studies, higher levels of adiponectin are associated with lower risks of type 2 diabetes and coronary heart disease.
"While prior animal studies found fish oil increased circulating adiponectin, whether similar effects apply in humans is not established," said the study's lead author, Jason Wu, PhD, of the Harvard School of Public Health. "By reviewing evidence from existing randomized clinical trials, we found that fish oil supplementation caused modest increases in adiponectin in the blood of humans."
The meta-analysis reviewed and analyzed results from 14 randomized, placebo-controlled clinical trials. In total, 682 subjects were treated with fish oil, and 641 were given placebos – most commonly olive and sunflower oils. In those taking fish oil, adiponectin levels increased by 0.37 ug/mL. The results also suggested the effect of fish oil on adiponectin differed substantially across the trials, suggesting that fish oil supplementation may have stronger influence on adiponectin in some populations and weaker effects in others.
This is the first study to pool data from previous trials to suggest that fish oil consumption increases adiponectin in humans. The findings quantify the potential impact of fish oil on adiponectin level, and highlight the need to further investigate populations that may particularly benefit from fish oil supplementation.
"Although higher levels of adiponectin in the bloodstream have been linked to lower risk of diabetes and coronary heart disease, whether fish oil influences glucose metabolism and development of type 2 diabetes remains unclear," said Wu. "However, results from our study suggest that higher intake of fish oil may moderately increase blood level of adiponectin, and these results support potential benefits of fish oil consumption on glucose control and fat cell metabolism."
Despite the uncertainty about the effectiveness of fish oil on cardiovascular and metabolic diseases, about 37 percent of adults and 31 percent of children nationwide use omega-3 supplements, according to the 2007 National Health Interview Survey from the National Institutes of Health's National Center for Complementary and Alternative Medicine (NCCAM).
The omega 3 fatty acids in fish oil have long been thought to protect against cardiovascular disease—so much so that the American Heart Association currently recommends eating at least two servings of fish a week, particularly fatty varieties rich in omega 3s. However, the mechanism behind this protective effect still remains a mystery.
In a new study, scientists led by Jason R. Carter of Michigan Technological University shed light on this phenomenon by providing evidence that fish oil might specifically counteract the detrimental effects of mental stress on the heart. Their findings show that volunteers who took fish oil supplements for several weeks had a blunted response to mental stress in several measurements of cardiovascular health, including heart rate and muscle sympathetic nerve activity (MSNA), part of the "fight or flight" response, compared to volunteers who took olive oil instead. The results may explain why taking fish oil could be beneficial to the heart and might eventually help doctors prevent heart disease in select populations.
The article is entitled "Fish Oil and Neurovascular Reactivity to Mental Stress in Humans." It appears in the May edition of the American Journal of Physiology – Regulatory, Integrative, and Comparative Physiology, published by the American Physiological Society. It is available online at http://bit.ly/10j0CSS
Carter and his colleagues worked with 67 adult volunteers. At the beginning of the study, each volunteer underwent a battery of tests to assess cardiovascular function, including heart rate, blood pressure, MSNA, and blood flow through the forearm and calf. These tests were performed first when the volunteers were at rest, and then again while they were performing a mental arithmetic test while the investigator encouraged them to hurry, a situation designed to induce acute mental stress. The study subjects were then nearly equally assigned to take either 9 grams of fish oil per day or 9 grams of olive oil, a placebo that hasn't been shown to have the same beneficial cardiovascular effects as fish oil. None of the volunteers were aware of which supplement they were taking. After 8 weeks of this intervention, the study subjects underwent the same tests again.
The researchers found that test results didn't change between the two groups of study subjects when they were at rest. However, results for the volunteers who took fish oil and those who received the placebo differed significantly for some of the tests during the mental stress. Those in the fish oil group showed blunted heart rate reactivity while they were stressed compared to those who took olive oil. Similarly, the total MSNA reactivity to mental stress was also blunted in the fish oil group.
Importance of the Findings
These results show that fish oil could have a protective effect on cardiovascular function during mental stress, a finding that adds a piece to the puzzle on why taking fish oil helps the heart stay healthy, the authors suggest. Future studies might focus on the effects of taking fish oil for longer time periods and examining this effect on older populations or people with cardiovascular disease.
"Overall," the study authors say, "the data support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans and suggest important physiological interactions between fish oil and psychological stress that may contribute to disease etiology."
Calcium-rich diet and supplements provide similar benefits
Taking a calcium supplement of up to 1,000 mg per day can help women live longer, according to a study whose lead author was Lisa Langsetmo, a Ph.D. Research Associate at McGill University, and whose senior author was Prof. David Goltzman, Division of Endocrinology and Metabolism in the Department of Medicine of the Faculty of Medicine and researcher in the Musculoskeletal Disorders axis at the Research Institute of the McGill University Health Centre (RI-MUHC).Their findings are published in the Journal of Clinical Endocrinology & Metabolism (JCEM).
Calcium, an essential nutrient for bone health, is commonly found in dairy products as well as vitamins. Although calcium is an essential nutrient for bone health, past studies have linked calcium supplements to heart disease risk. The researchers, located at universities across the country, analyzed data from the large-scale Canadian Multicentre Osteoporosis Study (CaMos) seeking to determine whether calcium and vitamin D intake were associated with overall increased risk of death.
"We found that daily use of calcium supplements in women was associated with a lower risk of death, irrespective of cause," said the study's lead author, Prof. Goltzman, Director, Calcium Research Laboratory at McGill. "The benefit was seen for women who took doses of up to 1,000 mg per day, regardless of whether the supplement contained vitamin D."
The longitudinal study of participants living in or near 9 cities across Canada monitored the health of 9,033 Canadians between 1995 and 2007. During that period, 1,160 participants died. Although the data showed women who took calcium supplements had a lower mortality risk, there was no statistical benefit for men. The study found no conclusive evidence that vitamin D had an impact on mortality.
"Higher amounts of calcium were potentially linked to longer lifespans in women, regardless of the source of the calcium," says Goltzman. "In other words, the same benefits were seen when the calcium came from dairy foods, non-dairy foods or supplements."
Tuesday, May 21, 2013
Widely available in pharmacies and health stores, phosphatidylserine is a natural food supplement produced from beef, oysters, and soy. Proven to improve cognition and slow memory loss, it's a popular treatment for older people experiencing memory impairment. Now a team headed by Prof. Gil Ast and Dr. Ron Bochner of Tel Aviv University's Department of Human Molecular Genetics has discovered that the same supplement improves the functioning of genes involved in degenerative brain disorders, including Parkinson's disease and Familial Dysautonomia (FD).
In FD, a rare genetic disorder that impacts the nervous system and appears almost exclusively in the Ashkenazi Jewish population, a genetic mutation prevents the brain from manufacturing healthy IKAP proteins — which likely have a hand in cell migration and aiding connections between nerves — leading to the early degeneration of neurons. When the supplement was applied to cells taken from FD patients, the gene function improved and an elevation in the level of IKAP protein was observed, reports Prof. Ast. These results were replicated in a second experiment which involved administering the supplement orally to mouse populations with FD.
The findings, which have been published in the journal Human Molecular Genetics, are very encouraging, says Prof. Ast. "That we see such an effect on the brain — the most important organ in relation to this disease — shows that the supplement can pass through the blood-brain barrier even when administered orally, and accumulate in sufficient amounts in the brain."
Slowing the death of nerve cells
Already approved for use as a supplement by the FDA, phosphatidylserine contains a molecule essential for transmitting signals between nerve cells in the brain. Prof. Ast and his fellow researchers decided to test whether the same chemical, which is naturally synthesized in the body and known to boost memory capability, could impact the genetic mutation which leads to FD.
Researchers applied a supplement derived from oysters, provided by the Israeli company Enzymotec, to cells collected from FD patients. Noticing a robust effect on the gene, including a jump in the production of healthy IKAP proteins, they then tested the same supplement on mouse models of FD, engineered with the same genetic mutation that causes the disease in humans.
The mice received the supplement orally, every two days for a period of three months. Researchers then conducted extensive genetic testing to assess the results of the treatment. "We found a significant increase of the protein in all the tissues of the body," reports Prof. Ast, including an eight-fold increase in the liver and 1.5-fold increase in the brain. "While the food supplement does not manufacture new nerve cells, it probably delays the death of existing ones," he adds.
Therapeutic potential for Parkinson's
That the supplement is able to improve conditions in the brain, even when given orally, is a significant finding, notes Prof. Ast. Most medications enter the body through the blood stream, but are incapable of breaking through the barrier between the blood and the brain.
In addition, the researchers say the supplement's positive effects extend beyond the production of IKAP. Not only did phosphatidylserine impact the gene associated with FD, but it also altered the level of a total of 2400 other genes — hundreds of which have been connected to Parkinson's disease in previous studies.
The researchers believe that the supplement may have a beneficial impact on a number of degenerative diseases of the brain, concludes Prof. Ast, including a major potential for the development of new medications which would help tens of millions of people worldwide suffering from these devastating diseases.
A Mediterranean diet with added extra virgin olive oil or mixed nuts seems to improve the brain power of older people better than advising them to follow a low-fat diet, indicates research published online in the Journal of Neurology Neurosurgery and Psychiatry.
The authors from the University of Navarra in Spain base their findings on 522 men and women aged between 55 and 80 without cardiovascular disease but at high vascular risk because of underlying disease/conditions.
These included either type 2 diabetes or three of the following: high blood pressure; an unfavourable blood fat profile; overweight; a family history of early cardiovascular disease; and being a smoker.
Participants, who were all taking part in the PREDIMED trial looking at how best to ward off cardiovascular disease, were randomly allocated to a Mediterranean diet with added olive oil or mixed nuts or a control group receiving advice to follow the low-fat diet typically recommended to prevent heart attack and stroke
A Mediterranean diet is characterised by the use of virgin olive oil as the main culinary fat; high consumption of fruits, nuts, vegetables and pulses; moderate to high consumption of fish and seafood; low consumption of dairy products and red meat; and moderate intake of red wine.
Participants had regular check-ups with their family doctor and quarterly checks on their compliance with their prescribed diet.
After an average of 6.5 years, they were tested for signs of cognitive decline using a Mini Mental State Exam and a clock drawing test, which assess higher brain functions, including orientation, memory, language, visuospatial and visuoconstrution abilities and executive functions such as working memory, attention span, and abstract thinking.
At the end of the study period, 60 participants had developed mild cognitive impairment: 18 on the olive oil supplemented Mediterranean diet; 19 on the diet with added mixed nuts; and 23 on the control group.
A further 35 people developed dementia: 12 on the added olive oil diet; six on the added nut diet; and 17 on the low fat diet.
The average scores on both tests were significantly higher for those following either of the Mediterranean diets compared with those on the low fat option.
These findings held true irrespective of other influential factors, including age, family history of cognitive impairment or dementia, the presence of ApoE protein--associated with Alzheimer's disease--educational attainment, exercise levels, vascular risk factors; energy intake and depression.
The authors acknowledge that their sample size was relatively small, and that because the study involved a group at high vascular risk, it doesn't necessarily follow that their findings are applicable to the general population.
But they say, theirs is the first long term trial to look at the impact of the Mediterranean diet on brain power, and that it adds to the increasing body of evidence suggesting that a high quality dietary pattern seems to protect cognitive function in the ageing brain.
Monday, May 20, 2013
Regular consumption of coffee is associated with a reduced risk of primary sclerosing cholangitis (PSC), an autoimmune liver disease, Mayo Clinic research shows. The findings were being presented at the Digestive Disease Week 2013 conference in Orlando, Fla.
PSC is an inflammatory disease of the bile ducts that results in inflammation and subsequent fibrosis that can lead to cirrhosis of the liver, liver failure and biliary cancer.
"While rare, PSC has extremely detrimental effects," says study author Craig Lammert, M.D., a Mayo Clinic gastroenterologist. "We're always looking for ways to mitigate risk, and our first-time finding points to a novel environmental factor that also might help us to determine the cause of this and other devastating autoimmune diseases."
The study examined a large group of U.S. patients with PSC and primary biliary cirrhosis (PBC) and a group of healthy patients. Data showed that coffee consumption was associated with reduced risk of PSC, but not PBC. PSC patients were much likelier not to consume coffee than healthy patients were. The PSC patients also spent nearly 20 percent less of their time regularly drinking coffee than the control.
At a time when the spotlight is focused on obesity more than ever, new research suggests that frequency of candy consumption is not associated with weight or certain adverse health risks. According to a recent data analysis published in the April 30th issue of Nutrition Journal, adults who consume candy at least every other day are no more likely to be overweight nor have greater risk factors for cardiovascular disease (CVD) than moderate consumers (about once a week) or even less frequent candy eaters (less than 3 times per month).1
Almost all adults (96%) reported eating candy, but there is variability in frequency and quantity consumed at a given time. Previous research has shown that candy consumers are not more likely to be overweight or have greater risk factors for chronic disease than non-consumers of candy. 2 This research showed that even the consumers who reported eating the most candy on a given day were not more likely to be at risk for increased weight or disease. Such findings were surprising and required further investigation which this new study set out to do, delving into the role of usual frequency of candy consumption and health/weight outcomes.
This study found that frequency of candy consumption was not associated with the risk of obesity, using objective measures such as BMI, waist circumference and skinfold thickness. Additionally, frequency of candy consumption was not associated with markers of cardiovascular disease risk including blood pressure, LDL- and HDL-cholesterol, triglycerides and insulin resistance. Frequency of candy consumption was based on analyses of food frequency questionnaires and data from the 2003-2006 National Health and Nutrition Examination Survey (NHANES) – the most recent data set in which these food frequency questionnaires were available – of more than 5,000 U.S. adults ages 19 and older.
"We did not find an association between frequency of candy intake and BMI or cardiovascular risk factors among adults," notes lead author Mary M. Murphy, MS, RD of Exponent®, Inc., Center for Chemical Regulation & Food Safety.
The study certainly doesn't provide evidence that candy can be consumed without limits. However, these results suggest that most people are treating themselves to candy without increasing their risk of obesity or cardiovascular disease. More research is needed to further understand the role candy plays in life and the best tips for candy lovers to include their favorite treats as a part of a happy healthy lifestyle.
Candy's Contribution to Total Calories, Sugar and Saturated Fat is small
According to the National Cancer Institute's analysis of NHANES 05-06 data (same timeframe as this study), candy contributed an estimated 44 calories per day, or only about 2% of the total caloric intake of an average adult.3
In addition, candy accounted for slightly more than one teaspoon of added sugars (approximately 5 g) or 20 kcal in the diets of adults on a daily basis,4 which corresponds to a fraction of the 100-150 calorie upper limit of added sugars recommended by the American Heart Association.5 By comparison the top three dietary sources of added sugars for adults – sugary drinks, grain-based desserts, and sweetened fruit drinks – account for approximately 60% of the total added sugars intake.
Furthermore, data from the National Cancer Institute's analysis of NHANES 05-06 indicate that candy accounted for only 3.1% of the total saturated fat intake by the US population aged 2 years, or slightly less than 1 g based on a total saturated fat intake of 27.8 g/day.
"There is a place for little pleasures, such as candy, in life. A little treat in moderation can have a positive impact on mood and satisfaction, and as emerging research suggests, minimal impact on diet and health risk," said Laura Shumow, MHS, Director of Scientific and Regulatory Affairs, National Confectioners Association.