Herbal medicine silymarin shown to help lower blood sugar in type II diabetes

Diabetes is a growing health problem. Giving antioxidants is recognised as one way of helping people with diabetes to control their blood sugar levels.

The herbal medicine extracted from seeds of the Milk Thistle, Silybum marianum (silymarin) is known to have antioxidant properties and research published this week in Phytotherapy Research shows that this extract can help people significantly lower the amount of sugar bound to haemoglobin in blood, as well as reducing fasting blood sugar levels.

Silymarin contains a number of active constituents called flavolignans which are also used to help protect the liver from poisoning.

“We don’t know the exact mechanism of action for this effect, but this work shows that silymarin could play an important role in treating type II diabetes,” says lead author Fallah Huseini, who works at the Institute of Medicinal Plants, which is based in Tehran, Iran.

The data came from a randomized double-blind clinical trial involving 51 people who had had type II diabetes for at least 2 years. One group of 25 patients received 200 mg of silymarin three times a day for 4 months, while the remaining 26 received a placebo treatment. All of the patients continued to use conventional oral hypoglycaemic treatment during the trial. Patients were examined at monthly intervals.

Compared with the beginning of the trial, the treatment group had a significant reduction in fasting blood glucose levels (p<0.001), and a reduction in glycosylated haemoglobin (p<0.001). Both of these measures rose significantly in the placebo group (p<0.0001). There were also non-significant decreases in blood lipids in the treatment group.

“The results are very encouraging, and we now need to do further large multi-centre studies,” says Huseini.

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Article adapted by MD Only Weblog from original press release.
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Huseini, H.F: The Efficacy of Silybum marianum (L.) Gaertn. (Silymarin) in the Treatment of Type II Diabetes: A Randomized, Double-blind, Placebo-controlled, Clinical Trial

Phytotherapy Research is an international journal for the publication of original medicinal plant research, focussing on pharmacology, toxicology and the clinical applications of herbs and natural products in medicine. Papers concerned with the effects of common food ingredients and standardised plant extracts, including commercial products, and mechanistic studies on isolated natural products are particularly welcome. Papers and communications range from case studies to full clinical trials, including studies of herb-drug interactions and other aspects of the safety of herbal medicines. Phytotherapy Research can be accessed online at: http://www.interscience.wiley.com/journal/ptr

John Wiley & Sons Ltd., with its headquarters in Chichester, England, is the largest subsidiary of John Wiley & Sons, Inc. Founded in 1807, John Wiley & Sons, Inc., provides must-have content and services to customers worldwide. Its core businesses include scientific, technical, and medical journals, encyclopaedias, books, and online products and services; professional and consumer books and subscription services; and educational materials for undergraduate and graduate students and lifelong learners. Wiley has publishing, marketing, and distribution centres in the United States, Canada, Europe, Asia, and Australia. The company is listed on the New York Stock Exchange under the symbols JWa and JWb. Wiley’s Internet site can be accessed at http://www.wileyeurope.com/
Contact: Polly Young
John Wiley & Sons, Inc.

Plant pigment in cherries helps lower sugar levels

Perhaps George Washington wouldn’t have chopped down his father’s cherry tree if he knew what chemists now know. They have identified a group of naturally occurring chemicals abundant in cherries that could help lower blood sugar levels in people with diabetes. In early laboratory studies using animal pancreatic cells, the chemicals, called anthocyanins, increased insulin production by 50 percent, according to a peer-reviewed study scheduled to appear in the Jan. 5 issue of the American Chemical Society’s Journal of Agricultural and Food Chemistry. ACS is the world’s largest scientific society.Anthocyanins are a class of plant pigments responsible for the color of many fruits, including cherries. They also are potent antioxidants, highly active chemicals that have been increasingly associated with a variety of health benefits, including protection against heart disease and cancer.

“It is possible that consumption of cherries and other fruits containing these compounds [anthocyanins] could have a significant impact on insulin levels in humans,” says study leader Muralee Nair, Ph.D., a natural products chemist at Michigan State University in East Lansing. “We’re excited with the laboratory results so far, but more studies are needed.” Michigan is the top cherry producing state in the nation.

Until human studies are done on cherry anthocyanins, those with diabetes should continue following their doctor’s treatment recommendations, including any medicine prescribed, and monitor their insulin carefully, the researcher says. The compounds show promise for both the prevention of type 2 (non-insulin-dependent) diabetes, the most common type, and for helping control glucose levels in those who already have diabetes, he adds.

While fresh cherries and fruits containing these anthocyanins are readily available, medicinal products may be the most efficient way to provide the beneficial compounds, according to Nair. It’s possible that anthocyanins eventually could be incorporated into new products, such as pills or specialty juices that people could take to help treat diabetes. Such disease-specific products may take several more years to develop, he notes.

Scientists in Nair’s laboratory have even developed a unique process, patented by the university, for removing sugar from fruit extracts that contain anthocyanins. This could lead to “sugar-free” medicinal products for people with diabetes.

The current study, partially funded by the U.S. Department of Agriculture, involved tart cherries (also known as sour cherries or pie cherries), a popular variety in the United States, and the Cornelian cherry, which is widely consumed in Europe. Nair and his associates, B. Jayaprakasam, Ph.D., L.K. Olson, Ph.D., and graduate student S. K. Vareed, tested several types of anthocyanins extracted from these cherries against mouse pancreatic-beta cells, which normally produce insulin, in the presence of high concentrations of glucose.

Insulin is the protein produced by the pancreas that helps regulate blood sugar (glucose) levels. Compared to cells that were not exposed to anthocyanins, exposed cells were associated with a 50 percent increase in insulin levels, the researchers say. The mechanism of action by which these anthocyanins boost insulin production is not known, Nair says.

Nair and his colleagues are currently feeding anthocyanins to a group of obese, diabetic mice to determine how the chemicals influence insulin levels in live subjects. Results of these tests are not yet available.

Although other fruits, including red grapes, strawberries and blueberries, also contain anthocyanins, cherries appear to be the most promising source of these compounds on the basis of serving size, according to the researcher. The compounds are found in both sweet and sour (tart) cherry varieties.

The potential benefits of cherries extend beyond diabetes. Previous studies by the researcher found that certain anthocyanins isolated from cherries have anti-inflammatory properties and may be useful in fighting arthritis. Nair’s colleagues have found that cherries also may help fight colon cancer.

But people with diabetes are encouraged to use caution when it comes to consuming maraschino cherries, the bright red candied version that adorns ice cream and cocktails, Nair points out. Many of the beneficial cherry pigments that were present in the fresh fruit have been removed during processing, replaced with food coloring, and extra sugar has been added.

The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 159,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.

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Article adapted by MD Only Weblog from original press release.
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Contact: Michael Bernstein
American Chemical Society

Are You Fueling Your Heart For Life or Death?

An age-related decline in heart function is a risk factor for heart disease in the elderly. While many factors contribute to a progressive age-related decline in heart function, alterations in the types of fuels the heart uses to produce energy also play important roles. Jason Dyck and his research team at the University of Alberta have been studying the types of fuels used by the heart in young and aged mice. The young healthy heart normally used a balance of fat and sugar to generate energy to allow the heart to beat and pump blood efficiently. However, as the heart ages the ability to use fat as an energy source deteriorates. This compromises heart function in the elderly. Interestingly, at a time when the heart is using less fat for energy, Dyck has shown that a protein that is responsible for transporting fat into the contractile cells of the heart actually increases. Based on this finding, Dyck proposed that the mismatch between fat uptake and fat use in the heart could lead to an accumulation of fat in the heart resulting in an age-related decrease in heart function.

Using a genetically engineered mouse that is deficient in a protein that is responsible for transporting fat into the cells of the heart, Dyck studied these mice as they aged. These genetically altered mice have no choice but to mainly use sugar as a fuel source because they lack the protein that allows them to use fat as a primary fuel source. In an exciting new finding, Dyck showed that old genetically modified mice did not accumulate fat in their hearts, as did ordinary mice. In addition, Dyck and his team showed that these old genetically altered mice out-performed ordinary old mice on a treadmill test, were completely protected from age-related decline in heart function, and in many ways their hearts looked and performed like hearts from a young mouse. His findings suggest that the protein responsible for transporting fat into the contractile cells of the heart may be a candidate for drug inhibition and that this drug could protect the heart from aging.

This research holds great promise for human beings. Dyck hopes it will lead to the development of medications that inhibit the uptake of fatty acids into the heart and prevent and/or reverse the effects of aging on the heart muscle.

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Article adapted by MD Only Weblog from original press release.
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Contact: Kris Connor
University of Alberta

This study appears in the October 22 edition of Circulation.

Boost brain power with chocolate

Eating chocolate could help to sharpen up the mind and give a short-term boost to cognitive skills, a University of Nottingham expert has found.

A study led by Professor Ian Macdonald found that consumption of a cocoa drink rich in flavanols — a key ingredient of dark chocolate — boosts blood flow to key areas of the brain for two to three hours.

Increased blood flow to these areas of the brain may help to increase performance in specific tasks and boost general alertness over a short period.

The findings, unveiled at one of the biggest scientific conferences in America, also raise the prospect of ingredients in chocolate being used to treat vascular impairment, including dementia and strokes, and thus for maintaining cardiovascular health.

The study also suggests that the cocoa flavanols found in chocolate could be useful in enhancing brain function for people fighting fatigue, sleep deprivation, and even the effects of ageing.

Ian Macdonald, professor of metabolic physiology at The University of Nottingham, used magnetic resonance imaging (MRI) to detect increased activity in specific areas of the brain in individuals who had consumed a single drink of flavanol-rich cocoa. The effect is linked to dilation of cerebral blood vessels, allowing more blood — and therefore more oxygen — to reach key areas of the brain.

Flavanols are not only found in chocolate with a high cocoa content — they are also present in other substances such as red wine, green tea and blueberries.

He presented his research at the annual meeting of the American Association for the Advancement of Science (AAAS), one of the biggest annual gatherings of scientists from all over the world. This year’s meeting takes place in San Francisco from February 15–19.

Professor Macdonald said: “Acute consumption of this particular flavanol-rich cocoa beverage was associated with increased grey matter flow for two to three hours.

“The demonstration of an effect of consuming this particular beverage on cerebral blood flow raises the possibility that certain food ingredients may be beneficial in increasing brain blood flow and enhancing brain function, in situations where individuals are cognitively impaired such as fatigue, sleep deprivation, or possibly ageing.”

He emphasised that the level of cocoa flavanol used in the study is not available commercially. The cocoa-rich flavanol beverage was specially formulated for the purpose of the study.

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Article adapted by MD Only Weblog from original press release.
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Contact: Ian Macdonald
University of Nottingham

Co-authors on the research were Dr Susan Francis, research associate Kay Head, and Professor Peter Morris, all from The University of Nottingham’s School of Physics and Astronomy.

Professor Macdonald is a member of the Food Standards Agency’s Scientific Advisory Committee on Nutrition, and is President-Elect of the UK Nutrition Society. His main research interests are concerned with the functional consequences of metabolic and nutritional disturbances in health and disease, with specific interests in obesity, diabetes, cardiovascular disease and exercise.

“Chocolate Lovers” Are Programed To Love Chocolate

For the first time, scientists have linked the all-too-human preference for a food — chocolate — to a specific, chemical signature that may be programmed into the metabolic system and is detectable by laboratory tests. The signature reads ‘chocolate lover’ in some people and indifference to the popular sweet in others, the researchers say.

The study by Swiss and British scientists breaks new ground in a rapidly emerging field that may eventually classify individuals on the basis of their metabolic type, or metabotype, which can ultimately be used to design healthier diets that are customized to an individual’s needs. The study is scheduled for publication in the Nov. 2 issue of American Chemical Society’s Journal of Proteome Research, a monthly publication.

Sunil Kochhar and colleagues studied 11 volunteers who classified themselves as ‘chocolate desiring’ and 11 volunteers who were ‘chocolate indifferent.’ In a controlled clinical study, each subject — all men — ate chocolate or placebo over a five day period while their blood and urine samples were analyzed. The ‘chocolate lovers’ had a hallmark metabolic profile that involved low levels of LDL-cholesterol (so-called ‘bad’ cholesterol) and marginally elevated levels of albumin, a beneficial protein, the scientists say.

The chocolate lovers expressed this profile even when they ate no chocolate, the researchers note. The activity of the gut microbes in the chocolate lovers was also distinctively different from the other subjects, they add.

“Our study shows that food preferences, including chocolate, might be programmed or imprinted into our metabolic system in such a way that the body becomes attuned to a particular diet,” says Kochhar, a scientist with Nestlé Research Center in Switzerland.

“We know that some people can eat a diet that is high in steak and carbs and generally remain healthy, while the same food in others is unhealthy,” he explains. “Knowing one’s metabolic profile could open-the-door to dietary or nutritional interventions that are customized to your type so that your metabolism can be nudged to a healthier status.”

Researchers have known for some time that metabolic status and food preferences can vary from person to person and even between different cultures. The recent growth of the new field of proteome research, which focuses on characterizing the structure and function of the complete set of proteins produced by our genes, has allowed scientists to gain a deeper understanding of the metabolic changes that occur when foods are digested, Kochhar says.

“There’s a lot of information in metabolism that can be used to improve health and this information is just now being explored and tapped,” the researcher says.

In the future, a test for determining one’s metabolic type could be performed as part of a blood or urine test during a regular visit to the doctor, Kochhar predicts. But a reliable test to measure one’s metabolic type may be five years away, as more research is still needed in this area, he notes.

Women were not included in the current study in order to avoid any metabolic variations linked to the menstrual cycle, which has been shown in studies by others to influence metabolic differences, Kochhar says. But the researchers plan to include women in future clinical trials on metabolic responses to chocolate to determine if there is a gender-specific response to the treat.

In addition to providing a better understanding of individual metabolic types, the current study could also lead to the discovery of additional biomarkers that can identify new health benefits linked to chocolate and other foods, says Kochhar, whose research was funded by Nestlé.

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Article adapted by MD Only Weblog from original press release.
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The American Chemical Society — the world’s largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

Contact: Michael Bernstein
American Chemical Society

Achieve Maximum Heart Health Eating Omega-3 Fatty Acids

While a heart-healthy diet has become synonymous with plenty of fruits and vegetables and little fat and cholesterol, there’s more to the story. Omega-3 fatty acids should be part of a heart-healthy diet, too, according to the August issue of Mayo Clinic Health Letter.

Omega-3 fatty acids are a form of polyunsaturated fat important to overall health. As it pertains to heart disease, their main benefit is their ability to reduce the risk of heart rhythm problems in certain groups of people, thus reducing the risk of sudden cardiac death. In addition, omega-3s may help reduce triglycerides, lower blood pressure slightly and reduce blood clotting.

The best source of omega-3s is fatty, cold water fish such as herring, mackerel, salmon and tuna. Plant oils, such as canola and flaxseed oils, also are sources of omega-3s.

For heart disease prevention, near-maximum benefit comes from eating two 3-ounce servings of cold water fish a week. More than that doesn’t appear to offer any additional preventive benefit.

Higher amounts of two kinds of omega-3, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), may benefit some people with established heart disease or high triglyceride levels and can have an anti-inflammatory effect for people with rheumatoid arthritis. In addition, DHA is being studied to see if it can slow the progression of Alzheimer’s disease.

For those who don’t eat fish, a fish oil supplement or an algae supplement can provide omega-3 fatty acids. However, supplements aren’t cheap, and the amount of DHA and EPA in supplements varies widely. Except for people who have established heart disease, the evidence of heart disease prevention is stronger when one eats fish instead of taking supplements. Supplements can pose risks, too. Taking more than 3 grams of fish oil a day may increase the risk of bleeding, worsen heart rhythm problems in those who have arrhythmias or cause other side effects.

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Article adapted by MD Only Weblog from original press release.
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Omega 3 Fatty Acid Anti-inflammatory Effects Linked To Lowering Of Prostaglandin

Omega 3 fatty acids in dietary fish oil are reported to have anti-inflammatory and anti-thrombogenic and anti-arrhythmic effects in humans, but the biochemical basis for these beneficial health effects is not well understood. Now a University of Michigan biochemist reports that fish oil significantly diminishes the production and effectiveness of various prostaglandins, naturally occurring hormone-like substances that can accentuate inflammation and thrombosis.

Dr. William L. Smith described his findings on April 4 at Experimental Biology 2006 in San Francisco. His presentation was part of the scientific program of the American Society for Biochemistry and Molecular Biology (ASBMB).

Dietary fish oil causes its prostaglandin-lowering effects through three different mechanisms, says Dr. Smith.

First, the much fewer prostaglandins are made from omega 3 fatty acids as compared to the other class of fatty acids in the body, the omega 6 family of fatty acids that originate in the diet from leafy vegetables and other plant sources.

Second, the omega 3 fatty acids compete with omega 6 fatty acids for the same binding site on the COX 1 enzyme that converts the omega 6 fatty acids to prostaglandin (which is why the COX 1 enzyme and its COX 2 cousin are the targets of anti-inflammatory drugs like ibuprofen). The more omega 3 fatty acids present to block the binding sites, the fewer omega 6 fatty acids are able to be converted to prostaglandin.

Third, although omega 3 fatty acids also are converted to prostaglandins, the prostaglandins formed from omega 3 are generally 2 to 50 times less active than those formed from the omega 6 fatty acids from dietary plants.

The biochemical basis of other benefits of dietary fish oil – for example, omega 3 fatty acids’ impact on neuronal development and visual acuity — are probably due to effects on biochemical pathways regulating nerve transmission. Understanding the different pathways through which omega 3 works to convert prostaglandin helps explain why the plant-based omega 6 fatty acids don’t simply provide the same benefits. Because of omega 3 fatty acids’ known benefits to health, especially cardiovascular health, Dr. Smith’s advice is simple: eat more fish.

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Article adapted by MD Only Weblog from original press release.
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Contact: Sarah Goodwin
Federation of American Societies for Experimental Biology

Diet rich in fatty acids could thwart diabetes onset

Omega-3 fatty acids have long been touted for their heart-healthy and brain-boosting benefits. Consider cod liver oil, fortified infant formula and enriched eggs.Now a study of nearly 1,800 children at risk for type 1 diabetes has found that increased consumption of dietary omega-3 fatty acids appears to reduce the risk of the body attacking its own insulin-producing cells, a precursor to this form of the disease, report researchers at the University of Colorado and the University of Florida.

The findings appear in the Sept. 26 issue of the Journal of the American Medical Association.

In the past few decades, there has been a dramatic rise in the incidence of type 1 diabetes, both in the United States and in Europe — a jump that coincides with changes in food manufacturing that have led to a decline in omega-3 fatty acids in the diet and an increase in the content of omega-6 fatty acids, said Dr. Michael Clare-Salzler, a professor and the Stetson chair in experimental pathology at the University of Florida College of Medicine.

“The foods we are eating now are qualitatively much different than those produced on a 1900s-era farm,” Clare-Salzler said. “When animals are commercially raised today, they are often fed grains rich in omega-6 fatty acids, fatty acids that can promote inflammation. In the old days, animals received a much more balanced intake of omega-3 and omega 6-fatty acids.”

The amount of omega-3 fatty acids found in food today has dropped 28-fold from 100 years ago, Clare-Salzler said. In contrast to the omega-6 variety, omega-3 fatty acids have potent anti-inflammatory effects.

“Animal studies have shown inflammation in the insulin-producing cells of the pancreas is an early event that leads to type 1 diabetes,” said Clare-Salzler, who also directs UF’s Center for Immunology and Transplantation. “From these studies in mice, it appears if you thwart inflammation you can prevent the disease from occurring. The human parallel in this study indicates that higher dietary intake of anti-inflammatory omega-3 fatty acids reduces the risk of developing an immune response to the insulin-producing cells.”

Scientists set out to study whether increased intake of omega-3 fatty acids would be associated with prevention of or delay in the emergence of autoantibodies in the blood that signal the immune system’s attack on insulin-producing cells. Children enrolled in the Denver-based Diabetes Autoimmunity Study in the Young, or DAISY, were all at increased risk for type 1 diabetes and were evaluated until they were, on average, 6 years old.

Their parents were asked annually to report what they ate, including how often they consumed canned tuna, dark-meat fish such as salmon, other fish, shrimp, lobster and scallops, and also what kind of fat was used in cooking. Blood samples also were taken to test study participants for the presence of autoantibodies, and Nancy J. Szabo, director of the Analytical Toxicology Core Laboratory at UF’s College of Veterinary Medicine, evaluated the fatty acid composition of red blood cell membranes isolated from blood samples taken from a subset of 244 children.

“Kids who had higher intakes of omega-3 fatty acids had a significant reduction in the risk of development of autoantibodies,” Clare-Salzler said, adding that the risk of developing the autoantibodies also went down as the concentration of omega-3 fatty acids rose in the red blood cells.

All fatty acids help bolster the structure and function of cell membranes, but omega-3 fatty acids strongly support the production of anti-inflammatory molecules than can quell an immune attack on insulin-producing cells, Clare-Salzler said.

The study’s lead author was Jill M. Norris, a professor of preventive medicine and biometrics at the University of Colorado at Denver’s School of Medicine. Funding came from the National Institutes of Health and the University of Colorado’s Diabetes Endocrine Research Center.

UF and University of Colorado researchers are continuing to explore links between diabetes and diet. Clare-Salzler and Peter Chase from the University of Colorado’s Barbara Davis Center for Childhood Diabetes are leading a National Institutes of Health-funded multicenter pilot trial, the Nutritional Intervention to Prevent Type 1 Diabetes, or NIP, to examine whether babies who receive dietary supplementation with the omega-3 fatty acid docosohexaenoic acid, or DHA, show fewer signs of inflammation. An expanded version of the trial will then determine whether DHA protects infants and children from the development of autoantibodies that lead to diabetes in comparison with babies who receive standard formula or diets with a much lower level of the omega-3 fatty acid.

If the trial confirms the hypothesis that dietary supplementation with DHA in infancy blocks early inflammatory events key to diabetes development, then, the authors write in JAMA, “dietary supplementation with omega-3 fatty acids could become a mainstay for early intervention to safely prevent the development of type 1 diabetes.”

“The compounds that are made from the omega-3s are natural, the body’s own protective mechanisms for overt inflammation,” said Dr. Charles Serhan, director of the Center for Experimental Therapeutics and Reperfusion Injury at Harvard Medical School. “What these results say is that you may now be able to add back through the diet these essential omega-3 fatty acids, and then they will be utilized by the body to generate its own set of protective molecules that help to instruct the immune cells in the local environment not to attack the insulin-producing islets cells in the pancreas … these are very powerful and potentially very important results.”

Source: Melanie Fridl Ross, ufcardiac@aol.com 

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Fight Diabetes With Low Doses of a Red Wine Ingredient

Even relatively low doses of resveratrol—a chemical found in the skins of red grapes and in red wine—can improve the sensitivity of mice to the hormone insulin, according to a report in the October issue of Cell Metabolism, a Cell Press publication. As insulin resistance is often characterized as the most critical factor contributing to the development of type 2 diabetes, the findings “provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.

The research group also confirmed that increased levels of an enzyme called SIRT1, which earlier studies had linked to longevity, DNA repair, and insulin secretion, improve insulin sensitivity in mice. Resveratrol is known to activate the SIRT1 enzyme.

The results suggest that “red wine might have some benefits for insulin sensitivity, but it needs to be confirmed by further investigation,” said Qiwei Zhai of the Chinese Academy of Sciences. Given the potential complications of drinking alcohol, “an even better option may be to find other natural foods enriched with resveratrol or foods supplemented with resveratrol,” he added, noting that the chemical is also an active ingredient in other plants, including one called Polygonum cuspidatum used in traditional Chinese and Japanese medicine.

Diabetes mellitus, the most common endocrine disorder, currently affects more than 170 million people worldwide and is expected to affect more than 353 million by the year 2030, Zhai said. Type 2 diabetes, which accounts for more than 90 percent of diabetes cases, is characterized by the resistance of body tissues to stimulation by the peptide hormone insulin. Insulin normally lowers blood glucose levels by facilitating the sugar’s uptake, mainly into skeletal muscle and fat tissue, and by inhibiting glucose production in the liver. Currently, alleviating insulin resistance is still one of the key avenues to treating type 2 diabetes.

Earlier studies had reported a connection between SIRT1 and the processes of glucose metabolism and insulin secretion. However, whether SIRT1 was directly involved in insulin sensitivity remained largely unknown, the researchers said.

Now, the researchers report that SIRT1 levels are reduced in insulin-resistant cells and tissues and that treatments that block the enzyme’s function lead to insulin resistance. Furthermore, increased SIRT1 activity improved insulin sensitivity. Similarly, resveratrol—at a dose of just 2.5 mg/kg/day—enhanced insulin sensitivity in cells. That low dose of resveratrol also reduced insulin resistance in animals fed a high-fat diet, the researchers showed.

“We found SIRT1 improves insulin sensitivity, especially under insulin-resistant conditions,” Zhai said. “Furthermore, we found that resveratrol, at a very low dose compared with many previous studies, improves insulin sensitivity via SIRT1.”

The findings suggest that those who drink red wine for the health-promoting benefits of resveratrol might “think about drinking less,” Zhai said. Previously, he noted, the effects of resveratrol seen in mice had implied that humans might need to drink about 120 liters of red wine each day to get enough resveratrol to enjoy the same benefit. “According to our findings, people might need to drink about three liters of red wine each day to get sufficient resveratrol—about 15 mg—for its biological effects.”

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Article adapted by MD Only Weblog from original press release.
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The researchers include Cheng Sun, Fang Zhang, Xinjian Ge, Tingting Yan, Xingmiao Chen, Xianglin Shi, and Qiwei Zhai of Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences in Shanghai.

This work was supported by grants from the National Natural Science Foundation of China (30400083 and 30570558), the Chinese Academy of Sciences (KSCX2-2-25, KSCX2-YW-N-034, and KSCX1-YW-02), the National Basic Research Program of China (973 Program, 2006CB503900 and 2007CB914501), the Science and Technology Commission of Shanghai Municipality (04 DZ14007), and the Program of Shanghai Subject Chief Scientist.

Sun et al.: “SIRT1 Improves Insulin Sensitivity under Insulin-Resistant Conditions by Repressing PTP1B.” Publishing in Cell Metabolism 6, 307–319, October 2007. DOI 10.1016/j.cmet.2007.08.014 http://www.cellmetabolism.org

Source: Nancy Wampler, nwampler@cell.com
Cell Press

Drinking Alcohol Shrinks Your Brain

Drinking Heavy Amounts of Alcohol Shrinks Your Brain

Drinking heavy amounts of alcohol over a long period of time may decrease brain volume, according to research presented at the American Academy of Neurology’s 59th Annual Meeting.

The study involved MRI scans of 1,839 people from the Framingham Offspring study, ages 34 to 88, who were classified as non-drinkers, former drinkers, low drinkers (one to seven drinks per week), moderate drinkers (eight to 14 drinks per week), or high drinkers (more than 14 drinks per week). MRI scans were performed and used to measure brain volume, which can be thought of as a measure of brain aging.

The study found the more alcohol people drink on a regular basis, the lower their brain volume.

“Research has shown that there is a beneficial effect of alcohol in reducing incidence of cardiovascular disease in people who consume low to moderate amounts of alcohol. However, this study found that greater alcohol consumption was negatively correlated with brain volume,” said study author Carol Ann Paul, MS, of Wellesley College in Wellesley, MA. This cross-sectional study found people who had more than 14 drinks per week had an average 1.6 percent reduction in the ratio of brain volume to skull size compared to people who didn’t drink. In other words, brain volume decreased .25 percent on average for every increase in drinking category (i.e. non-drinkers, former drinkers, low drinkers, moderate drinkers, or high drinkers).

In addition, Paul reported the inverse relationship between drinking and brain volume was slightly larger in women than in men. Also, drinking heavy amounts of alcohol seemed to have the biggest negative impact on brain volume for women in their 70s.

In looking at the longitudinal effects of drinking, people who had a 12-year history of heavy drinking had less brain volume than those who changed into the high drinking group during those 12 years. Researchers are following up on these findings to make sure these differences hold up.

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Article adapted by MD Only Weblog from original press release.
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Contacts: Robin Stinnett, rstinnett@aan.com.

Additional Supporting Research:

“Alcohol consumption and frontal lobe shrinkage: study of 1432 non-alcoholic subjects.”
M Kubota, S Nakazaki, S Hirai, N Saeki, A Yamaura, T Kusaka.
J Neurol Neurosurg Psychiatry 2001;71:104-106
Click here for Abstract.

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