Brain fatty acid levels linked to depression

A group of Israel researchers has discovered that rats with increased levels of the omega-6 fatty acid, arachidonic acid, show signs of depression.  There is also evidence that  a dietary deficiency in omega-3 fatty acids may be associated with depression.  The  ”phospholipid hypothesis” postulates decreased omega-3 fatty acid intake could be responsible for some types of depression.

The details of their findings appear in the Journal of Lipid Research  showing that omega-3 fatty acid concentration in the blood of depressed patients is lower than that in control patients.  Dr. Green in collaboration with Dr Gal Yadid of Bar-Ilan University, Ramat Gan used the Flinders Sensitive Line rats to investigate the link between omega-3 fatty acids and depression. They examined the brains of the depressed rats and compared them with brains from normal rats. Surprisingly, they found that the main difference between the two types of rats was in omega-6 fatty acid levels and not omega-3 fatty acid levels. Specifically, they discovered that brains from rats with depression had higher concentrations of arachidonic acid, a long-chain unsaturated metabolite of omega-6 fatty acid.

Arachidonic acid is found throughout the body and is essential for the proper functioning of almost every body organ, including the brain. It serves a wide variety of purposes, from being a purely structural element in phospholipids to being involved in signal transduction and being a substrate for a host of derivatives involved in second messenger function.

“The finding that in the depressive rats the omega-3 fatty acid levels were not decreased, but arachidonic acid was substantially increased as compared to controls is somewhat unexpected,” admits Dr. Green. “But the finding lends itself nicely to the theory that increased omega-3 fatty acid intake may shift the balance between the two fatty acid families in the brain, since it has been demonstrated in animal studies that increased omega-3 fatty acid intake may result in decreased brain arachidonic acid.”

Although far less attention has been paid to dietary requirements for omega-6 fatty acids, which can be found in most edible oils and meat, perhaps in the future depression may be controlled by increasing omega-3 fatty acid intake and decreasing omega-6 fatty acid intake.

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Contact: Nicole Kresge
American Society for Biochemistry and Molecular Biology 
The American Society for Biochemistry and Molecular Biology (ASBMB) is a nonprofit scientific and educational organization with over 11,000 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions, and industry.

The manuscript for the Journal of Lipid Research paper can be downloaded from clicking Here

Spices protect against the consequences of high blood sugar

Herbs and spices are rich in antioxidants, and a new University of Georgia study suggests they are also potent inhibitors of tissue damage and inflammation caused by high levels of blood sugar.

Researchers, whose results appear in the current issue of the Journal of Medicinal Food, tested extracts from 24 common herbs and spices. In addition to finding high levels of antioxidant-rich compounds known as phenols, they revealed a direct correlation between phenol content and the ability of the extracts to block the formation of compounds that contribute to damage caused by diabetes and aging.

“Because herbs and spices have a very low calorie content and are relatively inexpensive, they’re a great way to get a lot of antioxidant and anti-inflammatory power into your diet,” said study co-author James Hargrove, associate professor of foods and nutrition in the UGA College of Family and Consumer Sciences.

Hargrove explained that when blood sugar levels are high, a process known as protein glycation occurs in which the sugar bonds with proteins to eventually form what are known as advanced glycation end products, also known as AGE compounds. The acronym is fitting because these compounds activate the immune system, resulting in the inflammation and tissue damage associated with aging and diabetes.

The researchers found a strong and direct correlation between the phenol content of common herbs and spices and their ability to inhibit the formation of AGE compounds. Spices such as cloves and cinnamon had phenol levels that were 30 percent and 18 percent of dry weight, respectively, while herbs such as oregano and sage were eight and six percent phenol by dry weight, respectively. For comparison, blueberries – which are widely touted for their antioxidant capabilities – contain roughly five percent phenol by dry weight.

Study co-author Diane Hartle, associate professor in the UGA College of Pharmacy, said various phenols are absorbed differently by the body and have different mechanisms of action, so it’s likely that a variety of spices will provide maximum benefit.

“If you set up a good herb and spice cabinet and season your food liberally, you could double or even triple the medicinal value of your meal without increasing the caloric content,” she said.

She added that controlling blood sugar and the formation of AGE compounds can also decrease the risk of cardiovascular damage associated with diabetes and aging. She explained that high blood sugar accelerates heart disease partly because AGE compounds form in the blood and in the walls of blood vessels. The AGE compounds aggravate atherosclerosis, which produces cholesterol plaques.

The UGA researchers tested for the ability to block AGE compounds in a test tube, but animal studies conducted on the health benefits of spices lend support to their argument. Cinnamon and cinnamon extracts, for example, have been shown to lower blood sugar in mice. Interestingly, cinnamon lowers blood sugar by acting on several different levels, Hargrove said. It slows the emptying of the stomach to reduce sharp rises in blood sugar following meals and improves the effectiveness, or sensitivity, of insulin. It also enhances antioxidant defenses.

Hargrove said their findings suggest it’s likely that the herbs and spices they studied will provide similar benefits in animal tests. He points out that because humans have been consuming herbs and spices for thousands of years, they come without the risk of possible side effects that accompany medications.

“Culinary herbs and spices are all generally recognized as safe and have been time-tested in the diet,” he said. “Indeed, some of spices and herbals are now sold as food supplements because of their recognized health benefits.”

Study co-author Phillip Greenspan, associate professor in the College of Pharmacy, noted that most people don’t get their recommended five to nine servings of fruits and vegetables a day. Rather than seasoning their food with salt – which provides no beneficial phenols and has been linked to high blood pressure – he recommends that people use a variety of herbs and spices to help boost the nutritional quality of their meals.

“When you add herbs and spices to food, you definitely provide yourself with additional benefits besides taste,” Greenspan said.

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Contact: Sam Fahmy
University of Georgia

Arthritis sufferers get relief with Boswellia in 7 days

An enriched extract of the ‘Indian Frankincense’ herb Boswellia serrata has been proven to reduce the symptoms of osteoarthritis. Research published today in BioMed Central’s open access journal Arthritis Research & Therapy has shown that patients taking the herbal remedy showed significant improvement in as little as seven days.

Osteoarthritis is the most common form of arthritis; it commonly affects weight-bearing joints such as the knees and hips, along with the hands, wrists, feet and spine. The symptoms include pain, stiffness and limited movement. This randomised, double-blinded, placebo-controlled trial of 70 patients will be of great interest to sufferers, especially those who don’t get adequate relief from existing treatments.

The study was led by Siba Raychaudhuri, a faculty member of the University of California, Davis, in the United States. According to Raychaudhuri, “The high incidence of adverse affects associated with currently available medications has created great interest in the search for an effective and safe alternative treatment”. The extract the authors used was enriched with 30% AKBA (3-O-acetyl-11-keto-beta-boswellic acid), which is thought to be the most active ingredient in the plant. Raychaudhuri said, “AKBA has anti-inflammatory properties, and we have shown that B. serrata enriched with AKBA can be an effective treatment for osteoarthritis of the knee”. This is a proprietary product developed by Laila Nutraceuticals.

B. serrata has been used for thousands of years in the Indian system of traditional medicine known as ‘Ayurveda’. This study is the first to prove that an enriched extract of the plant can be used as a successful treatment.

The same authors have previously tested the safety of their remedy in animal experiments. They say that, “In this study, the compound was shown to have no major adverse effects in our osteoarthritis patients. It is safe for human consumption and even for long-term use”.

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Contact: Graeme Baldwin
BioMed Central 

 

References

1. A double blind, randomized, placebo controlled study of the efficacy and safety of 5-Loxin(R) for treatment of osteoarthritis of the knee Krishanu Sengupta, Krishnaraju V Alluri, Andey Rama Sathis, Simanchala Mishra, Trimurtulu Golakoti, Kadainti VS Sarma, Dipak Dey and Siba P Raychaudhuri Arthritis Research & Therapy (in press)

2. Arthritis Research & Therapy is an international, peer-reviewed online and print journal, publishing original research, reviews, commentaries and reports. Studies relate to the rationale and treatment of arthritis, autoimmune disease and diseases of bone and cartilage. The journal is edited by Prof Peter E Lipsky (USA) and Prof Sir Ravinder N Maini (UK) and has an Impact Factor of 4.04.

3. BioMed Central (http://www.biomedcentral.com/) is an independent online publishing house committed to providing immediate access without charge to the peer-reviewed biological and medical research it publishes. This commitment is based on the view that open access to research is essential to the rapid and efficient communication of science.

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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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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Contact: Michael Bernstein
American Chemical Society

Adding Vitamins C and E to diet improves effectiveness of insulin

Adding antioxidants to therapy improves drug’s ability to reduce blood sugar

Boosting insulin with vitamins C and E may improve the drug’s effectiveness for treating diabetes.

A UC Irvine College of Medicine study has found that the popular antioxidant supplements not only enhance insulin’s ability to reduce blood sugar, but also lower the risks of organ damage that can occur despite insulin treatments. The study appears in the January issue of Kidney International.

Dr. Nick Vaziri, professor of medicine, and his team found that untreated diabetes raised blood pressure and increased the production of damaging oxidizing agents called free radicals. The free radicals converted sugars and proteins into harmful chemicals, increasing the risks of tissue damage often seen in untreated diabetes.

Treating the rats with insulin alone improved high blood pressure somewhat and partially spared the sugars and proteins from the free radicals’ assault. But it also added a new problem, as the free radicals turned their attack on nitric oxide, a ubiquitous molecule that usually protects the body from free radicals. This new attack results in yet more toxic chemicals, with the potential to inflict damage to tissues.

Adding vitamins C and E to insulin, however, spared the sugars, proteins and nitric oxide from attack.

“Blood pressure was lowered to normal, and free radicals were not in sufficient numbers to degrade the sugars, proteins and nitric oxide,” Vaziri said. “We think this shows that a diet rich in antioxidants may help diabetics prevent the devastating cardiovascular, kidney, neurological and other damage that are common complications of diabetes.”

Diabetes affects nearly 17 million Americans. Insulin is the predominant treatment, but patients eventually develop complications, like various forms of heart disease and nerve, liver and kidney damage. Studies would still have to be tested in humans, but Vaziri believes that adding vitamins C and E to an insulin-dependent diabetic’s diet should help treat the disease and perhaps prevent future organ damage.

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Article adapted by MD Only Weblog from original press release.
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Contact: Andrew Porterfield
University of California – Irvine

Ginseng extract fights diabetes, lowers cholesterol and decreases weight

An extract from the ginseng berry shows real promise in treating diabetes and obesity, reports a research team from the University of Chicago’s Tang Center for Herbal Medicine Research. In the June issue of the journal Diabetes, they show that the extract completely normalized blood glucose levels, improved sensitivity to insulin, lowered cholesterol levels, and decreased weight by reducing appetite and increasing activity levels in mice bred to develop diabetes.For more than 2000 years, traditional Chinese medicine has used ginseng root to treat a variety of ailments. This study focused instead on substances found in the ginseng berry, which has very different concentrations of ginsenosides, the substances thought to be medically useful.

“Ginseng berry has a distinctive chemical profile and has not previously been used for therapy,” said Chun-Su Yuan, M.D., Ph.D., assistant professor of anesthesia and critical care at the University of Chicago and director of the study. “We were stunned by how different the berry is from the root and by how effective it is in correcting the multiple metabolic abnormalities associated with diabetes.”

Yuan’s team, which included researchers from the Tang Center, anesthesia, clinical pharmacology and medicine, studied the effects of the extract, made from the pulp of the berry. They also studied one particular substance known as ginsenoside Re, which is concentrated in ginseng berries but quite scarce in the root.

They tested the extract by injecting it once a day into mice with a gene defect that causes weight gain and type 2 diabetes. They found that —

• Daily injections of 150 mg/kg of the ginseng berry extract restored normal blood-sugar levels in diabetic mice. Blood-glusoce levels fell from 222 mg/dl (quite high for a mouse) to 137 mg/dl (normal) within 12 days. Treated mice also had better scores on a glucose tolerance test, which measures how quickly the mice could remove excess glucose from the blood.
• The extract caused diabetic mice, which were also obese, to lose more than 10 percent of their body weight in 12 days. Untreated mice gained five percent of their weight in 12 days. The treated mice ate 15 percent less and were 35 percent more active than untreated mice. Once the injections stopped, weight gain gradually resumed.
• The extract improved insulin secretion and insulin sensitivity, both of which were abnormal in mice with diabetes.
• Treated diabetic mice had 30 percent lower cholesterol levels than untreated diabetic mice (117mg/dl versus 169mg/dl).

The extract had no detectable effect on normal mice.

Tests using a ginsenoside Re alone found that it had all of the anti-diabetic but none of the obesity-fighting activities of the extract.

“This novel compound could serve as the basis for a whole new class of anti-diabetic medications,” said Yuan, who is also working to isolate other substances from the extract that contributed to the weight loss.

There is a pressing need for new and more effective drugs for both diabetes and obesity. Diabetes is the seventh leading killer in the U.S. Type 2 diabetes affects almost six percent of the U.S. population and 18.4 percent of those over 65. The cost of the disease is estimated at $105 billion each year.

The U.S. Surgeon General estimates that 61 percent of adults are overweight or obese. Obesity — wieghing more than 20 percent over your maximum recommended body weight — contributes to an estimated 300,000 deaths each year. The economic cost of obesity in the U.S. was about $117 billion in 2000. The rising rate of obesity also contributes to the growing prevalence of type 2 diabetes.

“Since this berry contains agents that are effective against both obesity and diabetes, the ginseng fruit has enormous promise as a source of new drugs,” said Yuan, who has worked with the University to apply for a patent on the development of ginsenoside Re as a diabetes medication.

“The next step is to isolate the other substances in the extract, find out whether they also effect glucose regulation or weight gain, learn how they work and determine the safe and effective dose.”

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Contact: John Easton
University of Chicago Medical Center

Additional authors of the study were Anoja Attele, Yun-Ping Zhou, Jing-Tian Xie, Ji An Wu, Liu Zhang, Lucy Dey, William Pugh and Paul Rue of the University of Chicago and Kenneth Polonsky, now at Washington University in St. Louis. The research was funded by the Tang Family Foundation and the National Institutes of Health.

Taking American Ginseng before meals reduces blood sugar

Researchers at St. Michael’s Hospital and the University of Toronto have found that taking American ginseng before a meal reduces blood sugar in people both with and without diabetes. The study appears in the April 9 issue of the Archives of Internal Medicine, a publication of the Journal of the American Medical Association (JAMA).

Dr. Vladimir Vuksan, lead investigator for the study, says that these findings may have important implications for the treatment and prevention of diabetes, a disease affecting approximately eight per cent of North American adults and continually rising. “Although preliminary, these findings are encouraging and indicate that American ginseng’s potential role in diabetes should be taken seriously and investigated further. Controlling after-meal blood sugar levels is recognized as a very important strategy in managing diabetes. It may also be important in the prevention of diabetes in those who have not yet developed the disease.”

Study participants, both diabetic (Type 2) and non-diabetic, consumed capsules containing three grams of ground Ontario-grown American ginseng either 40 minutes before or during a glucose test meal. Among participants with Type 2 diabetes, those who took the ginseng capsules experienced a 20 per cent reduction in blood sugar levels compared to when they took placebo capsules. Among non-diabetic participants, similar reductions were only seen when the ginseng capsules were taken before, not together, with the test meal, suggesting that the timing of administration may be important. (The trial was an acute clinical study and did not compare the diabetic participants to the non-diabetic participants.)

Although the results are encouraging, Vuksan, who associate director of the Risk Factor Modification Centre at St. Michael’s Hospital and assistant professor in the department of nutritional sciences at the University of Toronto, cautions that people should not use these findings as justification to start taking ginseng.

“This is an initial, short-term study that only indicates a need for more research. We don’t know what the effects of long-term consumption of ginseng will be. Because of poor standardization in the herbal industry, we also don’t know if these findings will hold true for all American ginseng products. Nor do we know whether taking different speciesof ginseng such as Chinese or Japanese will have the same outcome.”

In addition to implications for diabetes management, this study has considerable significance for broader research on herbals as potential medical treatments, an area that has generated a great deal of public controversy in recent years. “This study represents an important step in the evaluation of herbals,” says Vuksan. “A major criticism of the herbal field and past ginseng research has been the lack of scientific, placebo-controlled trials in humans. Our study applied traditional clinical trial standards to research on an alternative medical product.”

The use of herbals in North America has increased dramatically over the last decade and ginseng is one of the most widely-used herbs worldwide. There are several types, including American, Chinese, Japanese and Siberian. For the last 2000 years of Chinese traditional medicine, ginseng has been used as a tonic with supposed curative, restorative and aphrodisiac properties. Most of these claims have been based on anecdotal and other non-scientific observations. It is only recently that tests of ginseng have begun in humans, using rigorous scientific techniques.

Chai-Na-Ta, Langlay B.C., the world’s largest supplier of American ginseng, provided ginseng samples and, together with the Ontario Ministry of Agriculture, the funding for this study.

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Contact: Steven de Sousa
University of Toronto

Valuable Vitamin D report bridges gap in bone health benefits

A new evidence report on vitamin D and bone health reviews the current scientific evidence and identifies its strengths and weaknesses. This report is a valuable resource that examines a range of scientific perspectives related to vitamin D and bone health across the lifecycle.

“This independent, systematic review is timely because there are mixed messages and recommendations to consumers regarding the benefits and harms of vitamin D intake” said NIH Office of Dietary Supplements (ODS) Director, Paul M. Coates, Ph.D. He added, “The evidence report in combination with the conference presentations and discussions, newly available methodological tools, and newer information on the vitamin D status of the US population will provide an invaluable and very timely update for the research and public health communities of what we know and what we need to know for this key nutrient.”

Researchers have long known that vitamin D had an impact on bone health but there is uncertainty about how much vitamin D is needed to achieve optimal bone health and whether there are differences in the relationship of vitamin D status to bone health across age and life stage groups. This report highlights the fact that the largest amount of evidence for bone health benefits is in postmenopausal women and older men (the majority over 60 years of age) taking vitamin D supplements. This report also confirms that vitamin D from ultraviolet-B (sunlight) exposure, fortified foods, or dietary supplements are all effective in raising the level of circulating vitamin D. Of concern, there were only sparse data on other subgroups cited as being at high risk for the consequences of low vitamin D, such as dark-skinned individuals and pregnant and lactating women.

The report found it difficult to define specific blood levels of markers for vitamin D status that indicate optimal levels for bone health. One reason for this is that current methods, which measure serum-25-hydroxy vitamin D as the marker for vitamin D status, yield highly inconsistent results. As part of its broader vitamin D initiative, ODS is working with laboratory testing facilities to standardize the quantification of vitamin D status.

The report investigators were not able to separate the impact of vitamin D from that of calcium, as most trials studied the effect of vitamin D plus calcium. The combination of vitamin D3 (daily dose 700 to 800 IU) and calcium (daily dose 500 to1200 mg) decreased the risk of falls, fractures and bone loss in the elderly (ages ranged from 62 to 85 years). The current recommended intake is 400 IU/day for people 51-70 years of age, and 600 IU/day for people over 70 years of age. Based on the combined data of two trials, the decreased risk of fractures was seen primarily in the subgroup of elderly women (average age 85 years) living in nursing homes.

Vitamin D intake above current recommended levels was not reported to be associated with an increased risk of harms. However, most trials using higher doses of vitamin D were not adequately designed to assess potential harms.

“The vitamin D and bone health evidence report provides valuable insights because it is based on an independent and rigorous examination of the totality of evidence across all age groups and during pregnancy and lactation,” said Agency for Healthcare Research and Quality (AHRQ) Director Carolyn Clancy, M.D. “It Is important that health care decisions are made using a review of all available evidence and not solely on the results of individual study reports.”

This report served as the framework for a conference, Vitamin D and Health in the 21st Century: An Update. The ODS-sponsored report was produced by the University of Ottawa Evidence-based Practice Center, and is available at:
http://www.ahrq.gov/clinic/tp/vitadtp.htm.

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Contact:
Lisa Ahramjian
National Institute of Health

The mission of ODS is to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results, and educating the public to foster an enhanced quality of life and health for the U.S. population.

Magnesium shown to reverse memory loss

Magnesium helps build bones, make proteins, release energy stored in muscles and regulate body temperature. In the cover story of the Dec. 2 issue of Neuron, MIT researchers report a possible new role for magnesium: helping maintain memory function in middle age and beyond.

The adult daily nutritional requirement for magnesium, a trace mineral found in foods such as dark green, leafy vegetables, is around 400 mg a day. But studies show that as many as half of all Americans do not consume enough magnesium. Magnesium deficits have been tied to allergies, asthma, attention deficit disorder, anxiety, heart disease, muscle cramps and other conditions.

Associate Professor Guosong Liu and postdoctoral associate Inna Slutsky at MIT’s Picower Center for Learning and Memory found that magnesium helps regulate a key brain receptor important for learning and memory. Their work provides evidence that a magnesium deficit may lead to decreased memory and learning ability, while an abundance of magnesium may improve cognitive function.

“Our study shows maintaining proper magnesium in the cerebrospinal fluid is essential for maintaining the plasticity of synapses,” the authors wrote. “Since it is estimated that the majority of American adults consume less than the estimated average requirement of magnesium, it is possible that such a deficit may have detrimental effectsSresulting in potential declines in memory function.”

Plasticity, or the ability to change, is key to the brain’s ability to learn and remember. Synapses, the connections among brain cells, undergo physical changes in response to brain activity. While the mechanisms underlying these changes remain elusive, it is known that synapses are less plastic in the aging or diseased brain. Loss of plasticity in the hippocampus, where short-term memories are stored, causes the forgetfulness common in older people.

“The important issue is how the plasticity of synapses is regulated physiologically,” said Liu, who has appointments in MIT’s Department of Biology and Department of Brain and Cognitive Sciences. Working with Slutsky, graduate student Safa Sadeghpour and technician Bing Li, Liu identified a key principle that predicts which chemicals can enhance plasticity.

This finding is akin to the difference between hearing music on an old radio or a high-fidelity stereo. Synapses, like speakers, have a level of background noise that can get in the way of transmitting their signal from one neuron to another. Just as our ears become more sensitive to nuances in music played on a top-of-the-line music system, synapses become more plastic when background noise is reduced.

Armed with this new understanding, the researchers then identified magnesium’s importance in synaptic function.

Magnesium is the gatekeeper for the NMDA receptor, which receives signals from an important excitatory neurotransmitter involved in synaptic plasticity. Magnesium helps the receptor open up for meaningful input and shut down to background noise. “As predicted by our theory, increasing the concentration of magnesium and reducing the background level of noise led to the largest increases of plasticity ever reported in scientific literature,” Liu said.

The researchers have identified and are now studying several families of drugs that may restore learning and memory in animals. Most important, Liu said, “This new theory may help create strategies to prevent aging-induced loss of synaptic plasticity.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Sean Wagner
MIT News Office
Massachusetts Institute of Technology
Room 11-400
77 Massachusetts Avenue
Cambridge, MA 02139-4307
Phone: 617-253-2700
http://web.mit.edu/newsoffice/www

This work was supported by the RIKEN-MIT Neuroscience Center and the National Institutes of Health.

A version of this article appeared in MIT Tech Talk (download PDF).