Vitamins and Other Supplements: An Update

We are often asked about various vitamins and supplements and when important information becomes available, we try to make blog posts to update everyone.  We’ve also decided to summarize some of our thoughts about supplements and this is the result of that effort.  As always, the opinions expressed here are general recommendations and we always encourage a conversation with your physician before you make any changes to previously recommended treatments.

Multivitamins

There is general agreement among physicians that a well-balanced diet provides adequate vitamins and minerals required to maintain health and prevent diseases. Over half of Americans report that they regularly take dietary supplements in an effort to improve their health.  Unfortunately, no studies have documented any benefit from multivitamin supplementation in healthy adults and safety concerns have been raised.

Specific vitamins and supplements

We do not recommend routine supplementation with vitamins A, C, E, folic acid or beta-carotene.

Taking antioxidant vitamins (such as vitamin C and vitamin E) has been promoted as beneficial in prevention of colds, heart attack, stroke and cancer. Unfortunately, none of these illnesses are prevented by taking vitamins. And worse yet, evidence has accumulated that antioxidant vitamins can be harmful. 

A remarkable study from Norway published in the New England Journal of Medicine in 2006 rebuffed prior theories that heart attacks could be prevented by antioxidant vitamins and was among the first to raise concerns that these might actually increase heart attack and stroke risk. 

Supplemental beta-carotene, vitamin A and vitamin E may increase risk of death according to a recent JAMA review.  

A study published in the Proceedings of the National Academy of Sciences demonstrated that taking supplemental vitamin C and vitamin E eliminated one of the major benefits of exercise in healthy men (in this case, the body’s ability to respond to insulin). We described this study in detail in a prior post.

There is no evidence that vitamin E is effective in preventing Alzheimer’s disease or other types of dementia.

A recent review of 67 studies (involving over 230,000 participants) concluded that vitamin C (alone or in combination with other vitamins) did not lower mortality. The same review concluded that vitamin E supplementation (as well as supplementation with vitamin A and beta-carotene) may increase mortality significantly.  

A recent study published in the Archives of Internal Medicine also concluded that the “more is better” approach is not necessarily the best.  They concluded that for adult women, multivitamins, vitamin B₆, folic acid, iron, magnesium, zinc and copper all increased mortality in and that calcium supplementation decreased overall risk.

A study published in the Journal of the American Medical Association this month also concluded that men who took 400 IU of vitamin E were 17% more likely to develop prostate cancer over 7 years than were those who did not take vitamin E.  An earlier study concluded that vitamin E supplementation increased the risk of death in men.

Earlier studies in smokers found that beta-carotene supplements increased lung cancer risk and the trace mineral selenium has been linked to an increased risk of non-melanoma skin cancer in women and men.

The exceptions

Deficiencies of vitamins B₁₂ and D are linked to many health problems and when low levels are found in lab testing, we often recommend supplementation.  Also, most American adults should probably take a calcium supplement. 

It is very clear that vitamin D is important for bone health (to prevent osteoporosis). Recently, data have suggested that adequate vitamin D levels may also decrease the risk of falling, and prevent colon polyps and cancer and heart attack and may facilitate weight loss in those who are overweight. We’ve reviewed this data and while it’s unlikely that vitamin D is magic, it does seem to be important. Over-the-counter vitamin D supplementation is reasonable for average-risk patients who have a mild vitamin D insufficiency, but a much higher dose (prescription strength) supplement is probably more appropriate in patients at risk for osteoporosis or those with severe deficiency.

Low levels of vitamin B12 can cause anemia and damage to the brain and nerve cells. Symptoms of nerve damage may be present before anemia. They can include numbness or tingling in the fingers and toes, poor balance and coordination, forgetfulness, depression, confusion, difficulty thinking and concentrating, impaired judgment and poor control of impulses, a decreased ability to sense vibration, ringing in the ears (tinnitus), and dementia, a decline in mental abilities that is severe enough to interfere with daily life.

The Bottom Line

With the few exceptions above, vitamin supplements are unnecessary and potentially harmful.  A well-balanced diet coupled with daily exercise is the closest thing to a magic pill for good health.

Written by: Drs. Martin, Schrader and Yates

Triple That Vitamin D Intake, Panel Prescribes

A long-awaited report from the Institute of Medicine to be released Tuesday triples the recommended amount of vitamin D most Americans should take every day to 600 international units from 200 IUs set in 1997.

That's far lower than many doctors and major medical groups have been advocating—and it could dampen some of the enthusiasm that's been building for the sunshine vitamin in recent years.

Many doctors have added blood tests of vitamin D levels to annual physicals, and sales of vitamin D supplements have soared to $425 million last year from $40 million in 2001, according to the Nutrition Business Journal.

It's long been known that vitamin D is essential to maintaining strong bones. But hundreds of new studies have also linked low vitamin D levels to a higher risk of a slew of chronic health problems—heart disease, stroke, diabetes, prostate, breast and colon cancers, auto-immune diseases, infections, depression and cognitive decline. Studies have also suggested that many Americans are vitamin D deficient due to working and playing indoors and slathering on sunscreen.

The Institute of Medicine, an arm of the National Academy of Sciences that sets governmental nutrient levels, said there wasn't enough evidence to prove that low vitamin D causes such chronic diseases; it based its new recommendations on the levels needed to maintain strong bones alone.

"The evidence for bone health is compelling, consistent and gives strong evidence of cause and effect," said Patsy Brannon, a professor of nutritional sciences at Cornell University and member of the IOM panel. For the other health problems, she said, "there are relatively few randomized controlled trials, and even in the observational studies, the effects are inconsistent."

The new recommendations, which cover the U.S. and Canada, call for 600 IUs daily for infants through adults age 70 and 800 IUs after age 71. The IOM assumed that most people are getting minimal sun exposure, given rising concern over skin cancer and latitudes where the sun is too weak to create vitamin D on the skin much of the year. The panel also raised the acceptable upper limit of daily intake to 4,000 IUs for adults, from 2,000 previously.

Those levels do take into account vitamin D from food sources—but only a few, such as salmon and mackerel, contain much naturally. Milk fortified with vitamin D contains about 40 IUs per cup. Most Americans and Canadians need to get much of their vitamin D from supplements.

The IOM panel also issued new recommendations for daily calcium intake— ranging from 700 milligrams for children aged 1 to 3 up to 1,200 milligrams for women 51 and older. The main change from the 1997 recommendations was to lower the recommended level for men 50 to 70 to 1,000 from 1,200. The panel noted that teenage girls may not get enough calcium, and that postmenopausal women may get too much, running the risk of kidney stones.

The changes will impact the percentages of recommended daily allowances of vitamin D and calcium listed on food packages, as well as the composition of school-lunch menus and other federal nutrition programs.

The panel dismissed concerns that many Americans and Canadians are vitamin D deficient, noting that there is no scientifically validated level that's considered optimum. Even so, the panel concluded that for 97% of the population, a blood level of 20 nanograms of vitamin D per milliliter is sufficient.

Some vitamin D advocates took particular issue with that assumption. Several major medical groups, including the Endocrine Society and the International Osteoporsis Foundation, have concluded that a level of 30 ng/ml is necessary for optimal bone health.

"Randomized clinical trials have shown that in men and women 60 and older, you see fewer falls and fractures at the 30 ng/ml level," said Bess Dawson-Hughes, endocrinologist and director of the Bone Metabolism Laboratory at Tufts University. She also noted that while healthy people may reach that level taking 800 IUs per day, those who don't go outside, who use sunscreen religiously, have very dark skin or are taking some medications will need more.

Studies have also shown that at levels below 30 ng/ml, the body seeks calcium for everyday needs by leaching it from bones.

Dr. Brannon said the panel found such a wide range of blood levels considered optimal in various studies that it could not settle on a single threshold level. "I think the confusion is understandable. The committee is very concerned about the lack of evidence-based consensus guidelines for interpreting blood levels for vitamin D," said Dr. Brannon. "We strongly recommend that these be developed."

The panel was also concerned about what she called "emerging evidence of concern" about possible ill effects of too much vitamin D. Besides a risk of kidney and heart damage noted with vitamin D levels of 10,000 IUs per day, Dr. Brannon said the panel had seen higher death rates from pancreatic cancer, prostate cancer and other causes in men whose blood levels were above 50 ng/ml. The link is still tentative and may never be proven, she noted: "The difficulty is, you can't design a trial to look at adverse effects."

Other vitamin D advocates had guarded praise for the recommendations. "At least they recognized that there was a need to raise the daily intake level. That's a very important message," said Michael Holick, a professor of medicine at Boston University School of Medicine who testified before the committee in April.

He said that despite the paucity of randomized-controlled trials, the long list of chronic diseases associated with vitamin D does make sense, given that it is actually a hormone that affects virtually every organ in the human body and regulates as many as 2,000 genes.

For his part, Dr. Holick recommends that adults take 2,000 to 3,000 IUs per day—and notes that he had done studies giving subjects 50,000 IUs twice a month for six years and seen no harmful effects. "There is no downside to increasing your vitamin D intake, and there are more studies coming out almost on a weekly basis," he said.

One in particular may help settle whether vitamin D has long-term benefits beyond bone health: The National Institutes of Health has begun recruiting 20,000 men and women over age 60 for a nationwide clinical trial to study whether taking 2,000 IUs of vitamin D, or omega-3 fatty acids from fish oil, is any better than a placebo at lowering the risk of heart disease, cancer than other diseases.

In the meantime, some doctors say the IOM recommendations will not change their belief in testing patients' vitamin D levels and supplementing them as needed.

"I supplement patients who are deficient and they feel better. They come in and say, 'I've been much less achy and stiff or my mood's been better since I've been taking the vitamin D,' said Alan Pocinki, an internist in Washington D.C. Most of his patients are office workers, and 75% of them are below the 30 ng/ml level he considers necessary.

"Do we have the data to prove this conclusively? No. We don't have evidence for much of what we do in medicine, but if you wait for the evidence, you may be depriving your patients of beneficial treatments," Dr. Pocinki said.

By Melinda Beck, The Wall Street Journal

From Dr. Yates:  We've discussed this controversy.  Given the proven benefit of vitamin D in prevention of osteoporosis, as well as strong circumstantial evidence that vitamin D deficiency may increase the risk of heart disease, colon cancer and other common problems, we believe that testing vitamin D levels, and supplementing when necessary to maintain a level above 30 ng/ml is the most reasonable and prudent course.  Be sure to ask if you've any questions or concerns about your vitamin D level or supplement.

Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

Vitamin E Supplements to Prevent Stroke May Raise Stroke Risk, Study Says

Taking Vitamin E to Prevent Stroke May Be Harmful, Study Says

Taking vitamin E supplements doesn't reduce the risk of stroke, and may even be harmful, an analysis of previous research found.

The vitamin raised the risk of a severe type of stroke by 22 percent, while it lowered the risk of a milder kind by 10 percent, according to the study, published today in the British Medical Journal.

Exercise as well as medicines to lower blood pressure or cholesterol have a far greater effect on stroke prevention, the researchers, led by Markus Schuerks of Harvard Medical School, wrote in the study. 

About 13 percent of the U.S. population takes the supplement, they said. Previous studies of the vitamin's effectiveness have produced conflicting results, with some showing a protective effect and others seeing no effect and an increase in the risk of early death, the study said.

"Given the relatively small risk reduction of ischemic stroke and the generally more severe outcome of hemorrhagic stroke, indiscriminate widespread use of vitamin E should be cautioned against," the authors said.

The study pooled data from 9 previous trials involving a total of 118,756 patients, about half of whom took the supplement while the other half took a sugar pill. When the data were analyzed, the researchers found an increased risk of hemorrhagic stroke, and a smaller decrease in ischemic stroke.

The absolute risk is small, the study said. For every 1,250 subjects taking the supplement, one hemorrhagic stroke occurred, while one ischemic stroke was prevented for every 476 patients.

Oxygen Supply

Stroke occurs when a blood vessel carrying oxygen to the brain ruptures or is blocked by a blood clot or some other particle, cutting off the brain's supply of oxygen. Nerve cells then die, affecting the part of the body they control. These cells aren't replaced, leading to disability, according to the American Heart Association.

About 800,000 Americans suffer a stroke each year, and 137,000 of them die, according to the association.

Hemorrhagic stroke is caused when tissue is compressed by a hematoma, a collection of blood that has leaked out of a vessel. Ischemic stroke is seen when a loss of blood supply to part of the brain triggers a biochemical reaction that leads to cell death.

By Eva von Schaper, Bloomberg News

Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

Can a Caffeine-Packed Plant Give a Boost?

A highly caffeinated South American plant is increasingly being used to provide the pep in energy drinks, dietary supplements, food products and candy. Marketers say guarana-containing products boost energy, mood and cognitive function-and may even help with weight loss. Scientists say some science does back up those claims, but they warn guarana can overstimulate the heart in rare cases.

Guarana (pronounced gwa-rah-na) is a rain-forest vine with fruit that contains high levels of caffeine. Since 2008, nearly 500 products with guarana, including different sizes and flavors of the same product, have been introduced to U.S. stores, according to London market-research firm Datamonitor PLC. Products include energy drinks, beef jerky, chewing gum, mints and even lollipops.

Guarana products often claim to simply boost energy, and some say they enhance mental performance. Some are marketed as weight-loss aids. Several studies do link guarana to weight loss, but they tend to be small, short term and often involve products with other ingredients-overall, not yet conclusive, scientists say.

The claim that guarana improves energy and boosts mental function makes sense given that caffeine is known to do so, says Kevin A. Clauson, associate professor at Nova Southeastern University in Fort Lauderdale, Fla. A British study of 26 college students, published in the Journal of Psychopharmacology in 2007, found guarana tablets boosted scores on a battery of tests for memory, alertness and mood compared with the same students' performance on a different day after taking a placebo.

While many experts attribute guarana's effects solely to its caffeine content, the British study found the effects on cognition were larger than would be expected with caffeine alone, says senior author Andrew B. Scholey, now co-director of the National Institute of Complementary Medicine's collaborative center for neurocognition in Melbourne, Australia. The reason for this is unknown, but Dr. Scholey suspects that saponins, a class of nutrients found in guarana, may be adding to its positive effect by enhancing blood flow to the brain.

Many products don't list either the amount of guarana or the total caffeine content, so you could consume a product with too little guarana to have a meaningful effect-or so much that it gives you an unwanted buzz, scientists say.  Consumers can often find the information by going to company Web sites. Performance Enhancing Meat Snacks Inc., of Englewood, Colo., which sells Perky Jerky, a beef snack marinated in guarana extract, discloses on its Web site that a two-ounce packet of the jerky contains 120 milligrams of caffeine. In an interview, the company said the level varies from 45 to 58 milligrams an ounce. VE2 Energy Gum LLC, which includes guarana and added caffeine, discloses on its Web site that each tiny piece of VE2 gum has 35 milligrams of caffeine. (By comparison, a 12-ounce can of soda typically has 30 to 50 mg.; a 12-ounce cup of Starbucks's Pike Place Roast contains 260 milligrams.)

Dr. Clauson cautions that pregnant women should keep guarana consumption to a minimum, as high levels of caffeine may harm the fetus. Also, alcoholic drinks with guarana may fool people into thinking they are alert enough to drive, or engage in other dangerous activities, he says.

People with heart trouble should be cautious. Scientific literature links guarana to rare but severe heart-related side effects. According to a 2001 report in the Medical Journal of Australia, a woman with a heart condition called mitral valve prolapse died after ingesting most of a 55 milliliter guarana and ginseng energy drink. The caffeine levels of her blood were comparable to having had 15 to 20 cups of coffee, the report said. Whether or not they have an existing heart condition, people need to take into account their other sources of caffeine when taking guarana products, says Mahtab Jafari, an assistant professor of pharmacy at the University of California in Irvine. In the Journal of Herbal Pharmacology, Dr. Jafari reported the case of a California woman who suffered tachycardia, an abnormally fast heartbeat, after taking energy pills containing guarana in addition to a cup of coffee and two glasses of Pepsi a day for more than a month. The woman had no previous known heart condition, but the combination of ordinary caffeinated drinks and guarana tablets "really exposed the heart to a lot of stimulation," says Dr. Jafari. The women's tachycardia resolved after about a week after stopping the supplement, she adds.

The Food and Drug Administration is investigating the safety of caffeine, including caffeine from guarana, in alcoholic beverages. The Department of Agriculture says it allows a small amount of guarana in meat as a flavoring, not enough to create a stimulant effect. The agency says it is reviewing whether beef-jerky products with labels marketing a stimulant effect may violate this standard. The agency didn't specify which products are under review. Performance Enhancing Meat Snacks says it believes Perky Jerky complies with the law.

From: Laura Johannes, The Wall Street Journal
Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

Vitamin D May Influence Cognitive Dysfunction and Dementia

Vitamin D has been receiving a lot of attention recently, and now researchers report that inadequate vitamin D levels may be involved in cognitive dysfunction and dementia.

Two papers show in separate populations that low levels of vitamin D are associated with cognitive impairment and cerebrovascular disease, including stroke. A third study of only men finds no such association. The papers will appear in the January issue of Neurology.

"What should we make of these studies?" Joshua Miller, PhD, from the University of California in Sacramento, asked in an accompanying editorial. "First, it is evident that the prevalence of vitamin D deficiency is very high among older adults."

This in and of itself, he says, could warrant expanded screening for vitamin D deficiency and adding supplements. "Whether vitamin D supplements will maintain cognitive function in older adults remains an open question," he notes.

Dr. Miller does not rule out the possibility of reverse causation. "Cognitively impaired older adults may eat poorly or they may have reduced exposure to sunlight, which could lead to reduced vitamin D status."

Investigators led by Cédric Annweiler, MD, from Angers University Hospital in France, conducted a cross-sectional study exploring these questions. Their paper was released early online September 30. The researchers looked at more than 750 community-dwelling older women. Participants were from the French study known as Epidémiologie de l'Ostéoporose. The women were 75 years or older.

The researchers report that 17% of participants had vitamin D deficiency. This was defined as a serum 25-hydroxyvitamin D level of less than 10 ng/mL. Women with vitamin D deficiency had lower mean Short Portable Mental State Questionnaire scores (P < 0.001). They also had an odds ratio for cognitive impairment of about 2 after controlling for relevant confounders.

The authors conclude that inadequate vitamin D is associated with cognitive impairment in elderly women and that vitamin D supplements may improve or maintain cognitive function.

Two Studies, Similar Conclusion

The second report, by investigators led by Jennifer Buell, PhD, from Tufts University in Boston, Massachusetts, and released November 25, came to a similar conclusion. The researchers also conducted a cross-sectional study — this one of more than 300 men and women.

Participants were 65 years or older and were involved in the Nutrition and Memory in Elders study. They were evaluated for dementia and cerebrovascular disease and underwent magnetic resonance imaging to assess overall and regional brain volumes, white matter hyperintensity, and infarcts.

Investigators show that 14% of the study sample had inadequate vitamin D. Another 44% were classified as vitamin D insufficient (10 to 20 ng/mL).

Patients with low vitamin D levels had higher white matter hyperintensity volume and a higher prevalence of large vessel infarcts. Low vitamin D level was also linked with an odds ratio of about 2 for all-cause dementia, Alzheimer's disease, and stroke after controlling for relevant confounders.

The authors conclude that vitamin D deficiency is associated with an increased risk for dementia and cerebrovascular disease and that vitamin D may have vasculoprotective properties.

However, a third report, also released November 25, came to a different conclusion.

Third Study Questions Evidence

Investigators led by Yelena Slinin, MD, from the VA Medical Center and the University of Minnesota at Minneapolis, found little evidence linking vitamin D and cognitive impairment.

The researchers conducted a longitudinal assessment of more than 1600 community-dwelling men. Participants were 65 years or older and were involved in the Osteoporotic Fractures in Men Study.

Investigators assessed cognitive function using the modified Mini-Mental State Examination and the Trails B test.

At baseline, the odds ratios for cognitive impairment were between 1.6 and 1.8 in the lowest vitamin D quartile compared with the highest. However, these odds ratios did not reach statistical significance and were lower after controlling for race, ethnicity, and education.

Low vitamin D level was defined differently in this study at less than 20 ng/mL. In the other 2 studies, vitamin D deficiency was considered less than 10 ng/mL.

For incident cognitive impairment, the odds ratio for a significant decline in Mini-Mental State Examination score was 1.5 in the lowest quartile of vitamin D concentration compared with the highest quartile. The trend across the quartiles was significant. Yet again, control for confounding by race, ethnicity, and education slightly lowered the trend — enough to lose statistical significance.

The authors suggest that additional studies should be performed that include women and tests of other cognitive domains.

Editorialist Dr. Miller argues that this study is limited by a lack of women included in the work. He says it was also limited because the lowest quartile of vitamin D status consisted of all subjects with levels under 20 ng/mL. "Perhaps a reevaluation of the data comparing deficient subjects (<10 ng/mL) to nondeficient subjects would reveal significant associations," he notes.

Next Steps

"What are needed now are placebo-controlled intervention studies to determine if vitamin D supplements will protect against age-related cognitive decline." In the meantime, Dr. Miller says, neurologists, general practitioners, and geriatricians should be aware of the high prevalence of vitamin D deficiency in their patient populations and the possibility that supplementation could be beneficial.

Adequate vitamin D for patients aged 51 to 70 years are defined as 10 µg/day (400 IU). For people older than 70 years, 15 µg/day (600 IU) is suggested or enough to maintain a vitamin D level of about 30 ng/mL or more. These recommendations, he notes, are primarily for maintaining bone health and are evolving.

Dr. Miller suggests, "The appropriate intake amounts to support brain function in older adults remain to be determined."

Dr. Joshua Miller receives research support from the National Institutes of Health, the US Department of Defense, and the American Cancer Society. Dr. Slinin is a full-time employee of the US Department of Veterans Affairs. The other investigators have disclosed no relevant financial relationships.

From: Allison Gandey, Medscape Medical News

Reviewed / Posted by: Scott W Yates, MD, MBA, MS, FACP

Phys Ed: Can Vitamin D Improve Your Athletic Performance?

When scientists at the Australian Institute of Sport recently decided to check the Vitamin D status of some of that country’s elite female gymnasts, their findings were fairly alarming. Of the 18 gymnasts tested, 15 had levels that were “below current recommended guidelines for optimal bone health,” the study’s authors report. Six of these had Vitamin D levels that would qualify as medically deficient. Unlike other nutrients, Vitamin D can be obtained by exposure to ultraviolet radiation from sunlight, as well as through foods or supplements. Of course, female gymnasts are a unique and specialized bunch, not known for the quality or quantity of their diets, or for getting outside much.

But in another study presented at a conference earlier this year, researchers found that many of a group of distance runners also had poor Vitamin D status. Forty percent of the runners, who trained outdoors in sunny Baton Rouge, Louisiana, had insufficient Vitamin D. “It was something of a surprise,” says D. Enette Larson-Meyer, an assistant professor in the Department of Family and Consumer Sciences at the University of Wyoming and one of the authors of the study.

Vitamin D is an often overlooked element in athletic achievement, a “sleeper nutrient,” says John Anderson, a professor emeritus of nutrition at the University of North Carolina and one of the authors of a review article published online in May about Vitamin D and athletic performance. Vitamin D once was thought to be primarily involved in bone development. But a growing body of research suggests that it’s vital in multiple different bodily functions, including allowing body cells to utilize calcium (which is essential for cell metabolism), muscle fibers to develop and grow normally, and the immune system to function properly. “Almost every cell in the body has receptors” for Vitamin D, Anderson says. “It can up-regulate and down-regulate hundreds, maybe even thousands of genes,” Larson-Meyer says. “We’re only at the start of understanding how important it is.”

But many of us, it seems, no matter how active and scrupulous we are about health, don’t get enough Vitamin D. Nowadays, “many people aren’t going outside very much,” Johnson says, and most of us assiduously apply sunscreen and take other precautions when we do. The Baton Rouge runners, for instance, most likely “ran early in the morning or late in the day,” Larson-Meyer says, reducing their chances of heat stroke or sunburn, but also reducing their exposure to sunlight.

Meanwhile, dietary sources of Vitamin D are meager. Cod-liver oil provides a whopping dose. But a glass of fortified milk provides a fraction of what scientists now think we need per day. (A major study published online in the journal Pediatrics last month concluded that more than 60 percent of American children, or almost 51 million kids, have “insufficient” levels of Vitamin D and another 9 percent, or 7.6 million children, are clinically “deficient,” a serious condition. Cases of childhood rickets, a bone disease caused by lack of Vitamin D, have been rising in the U.S. in recent years.)

Although few studies have looked closely at the issue of Vitamin D and athletic performance, those that have are suggestive. A series of strange but evocative studies undertaken decades ago in Russia and Germany, for instance, hint that the Eastern Bloc nations may have depended in part on sunlamps and Vitamin D to produce their preternaturally well-muscled and world-beating athletes. In one of the studies, four Russian sprinters were doused with artificial, ultraviolet light. Another group wasn’t. Both trained identically for the 100-meter dash. The control group lowered their sprint times by 1.7 percent. The radiated runners, in comparison, improved by an impressive 7.4 percent.

More recently, when researchers tested the vertical jumping ability of a small group of adolescent athletes, Larson-Meyer says, “they found that those who had the lowest levels of Vitamin D tended not to jump as high,” intimating that too little of the nutrient may impair muscle power. Low levels might also contribute to sports injuries, in part because Vitamin D is so important for bone and muscle health. In a Creighton University study of female naval recruits, stress fractures were reduced significantly after the women started taking supplements of Vitamin D and calcium.

A number of recent studies also have shown that, among athletes who train outside year-round, maximal oxygen intake tends to be highest in late summer, Johnson says. The athletes, in other words, are fittest in August, when ultraviolet radiation from the sun is near its zenith. They often then experience an abrupt drop in maximal oxygen intake, beginning as early as September, even thought they continue to train just as hard. This decline coincides with the autumnal lengthening of the angle of sunlight. Less ultraviolet radiation reaches the earth and, apparently, sports performance suffers.

Concerned now about your Vitamin D status? You can learn your status with a simple blood test. An at-home version is available through the Web site of the Vitamin D Council. (Use of the tests is restricted in some states, including New York. See the website for details.) Be sure that any test checks the level of 25(OH)D in your blood. This level “should generally be above 50 nanograms per milliliter,” Larson-Meyer says.

If your levels are low, talk to your doctor about the best response. Sunlight is one easy, if controversial, fix. “Most dermatologists will still tell you that no amount of sun exposure is safe,” Johnson says.

But Larson-Meyer and other Vitamin D researchers aren’t so sure. “There’s no good, scientific evidence that five to thirty minutes of sunlight a few times a week is harmful,” she says.

Or try supplements. “1,000 IU a day and much more for people who are deficient” is probably close to ideal, Larson-Meyer says. This, by the way, is about double the current recommended daily allowance. Most experts anticipate that this allowance will be revised upward soon. Consult with your doctor before beginning supplements. Overdoses of Vitamin D are rare, but can occur.

Finally, stay tuned. “In the next few years, we’re going to be learning much more” about the role of vitamin D in bodily function and sports performance, Larson-Meyer says.

From The New York Times by Gretchen Reynolds

Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

The Evidence On Ginkgo Biloba and Memory

Medical research is finally starting to catch up with millions of Americans who have been taking vitamins and supplements for years. But people who swear by their pills to stay fit and sharp may not like the evidence that’s starting to accumulate.

The latest comes from a federally funded study of ginkgo biloba, a supplement widely used to improve memory and other cognitive functions. More than 3,000 people between the ages of 72 and 96 were randomly assigned to take a placebo or 120 mg of ginkgo twice a day. None of the patients had dementia when the study began, and they were followed for a median of just over six years. 

Those who took ginkgo fared no better than those who took placebo on a battery of tests that examined memory, language, attention and other measures of cognitive function. The results are published in this week’s JAMA; an earlier analysis of the same study also found that ginkgo didn’t reduce the risk of Alzheimer’s.

As this New York Times column noted earlier this year, several big studies in the past few years have suggested that certain vitamins pills and other supplements don’t improve key health outcomes.

“I’m puzzled why the public in general ignores the results of well-done trials,” one doc who has studied this stuff told the NYT. “The public’s belief in the benefits of vitamins and nutrients is not supported by the available scientific data.”

From: The Wall Street Journal

Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

Link Between Successful Weight Loss And Vitamin D Levels

Vitamin D levels in the body at the start of a low-calorie diet predict weight loss success, a new study found. The results, which suggest a possible role for vitamin D in weight loss, were presented at The Endocrine Society's 91st Annual Meeting in Washington, D.C.

"Vitamin D deficiency is associated with obesity, but it is not clear if inadequate vitamin D causes obesity or the other way around," said the study's lead author, Shalamar Sibley, MD, MPH, an assistant professor of medicine at the University of Minnesota.

In this study, the authors attempted to determine whether baseline vitamin D levels before calorie restriction affect subsequent weight loss. They measured circulating blood levels of vitamin D in 38 overweight men and women before and after the subjects followed a diet plan for 11 weeks consisting of 750 calories a day fewer than their estimated total needs. Subjects also had their fat distribution measured with DXA (bone densitometry) scans.

On average, subjects had vitamin D levels that many experts would consider to be in the insufficient range, according to Sibley. However, the authors found that baseline, or pre-diet, vitamin D levels predicted weight loss in a linear relationship. For every increase of 1 ng/mL in level of 25-hydroxycholecalciferol - the precursor form of vitamin D and a commonly used indicator of vitamin D status - subjects ended up losing almost a half pound (0.196 kg) more on their calorie-restricted diet. For each 1-ng/mL increase in the active or "hormonal" form of vitamin D (1,25-dihydroxycholecalciferol), subjects lost nearly one-quarter pound (0.107 kg) more.

Additionally, higher baseline vitamin D levels (both the precursor and active forms) predicted greater loss of abdominal fat.

"Our results suggest the possibility that the addition of vitamin D to a reduced-calorie diet will lead to better weight loss," Sibley said.

She cautioned, however, that more research is needed. "Our findings," she said, "need to be followed up by the right kind of controlled clinical trial to determine if there is a role for vitamin D supplementation in helping people lose weight when they attempt to cut back on what they eat."

The National Institutes of Health, the University of Minnesota, and the Pennock Family Endowment at the University of Minnesota funded this study.

Source: Aaron Lohr, The Endocrine Society

Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

Adequate Vitamin D Levels May Aid Weight Loss in Obese Patients

Adequate plasma levels of vitamin D, both the precursor and active
forms, may play a role in promotion of weight loss in obese patients,
perhaps through effects on adipose metabolism, according to research
reported Thursday at The Endocrine Society's annual meeting in
Washington, D.C.

While vitamin D deficiency is associated with obesity, "there are
limited data on the temporal relationship between vitamin D and weight
loss -- an important step in establishing a cause-effect link between
vitamin D deficiency and obesity," Dr. Shalamar Sibley from the
University of Minnesota in Minneapolis told the conference.

She and colleagues investigated the temporal relationship between
baseline vitamin D levels and subsequent weight loss success in 38
overweight and obese men and women.

They measured plasma vitamin D (25-hydroxyvitamin D and
1,25-dihydroxyvitamin D) concentrations before and after an 11-week
weight loss intervention consisting of a 750 calorie per day deficit
from estimated total daily calorie needs. They used dual-energy X-ray
absorptiometry and computed tomography to measure body composition and
fat distribution.

On average, vitamin D levels in study subjects were in the insufficient
range.

According to the investigators, in separate models adjusted for gender,
baseline (pre-diet) 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D
levels predicted subsequent weight loss success (p = 0.020 and p =
0.015, respectively) on a reduced calorie diet.

For each 1-ng/mL increase in level of 25-hydroxyvitamin D, obese
patients lost almost half a pound (0.196 kg) more on their
calorie-restricted diet. For each 1-ng/mL increase in
1,25-dihydroxyvitamin D, subjects lost nearly one-quarter pound (0.107
kg) more.

"Abdominal fat loss, in particular, tended to be related to baseline
vitamin D concentrations, with the effect being stronger with the active
form of vitamin D," Dr. Sibley reported. "Vitamin D status did not
predict lean body mass changes, so there was relative preservation of
lean tissue."

The researchers say studies are needed to confirm these findings and
define underlying mechanisms.

"If it is established," Dr. Sibley said, "that vitamin D does indeed
synergistically contribute to standard weight loss approaches, such as a
reduced calorie diet, then identification and treatment of inadequate
vitamin D status could ultimately have a large public health impact on
the obesity epidemic. Our findings suggest that vitamin D may play an
important role in promoting optimal weight management," she concluded.

From Reuters Health, by Megan Rauscher

Reviewed / Posted by: Scott W. Yates, MD, MBA, MS, FACP

More Bad News For Antioxidant Vitamins

Taking antioxidant vitamins (such as vitamin C and vitamin E) has been promoted as beneficial in prevention of colds, heart attack, stroke and cancer. Unfortunately, it appears that none of these illnesses are prevented by taking vitamins. And worse yet, evidence has accumulated that antioxidant vitamins can be harmful.

The most recent study, published in the Proceedings of the National Academy of Sciences demonstrated that taking supplemental vitamin C and vitamin E eliminated one of the major benefits of exercise in healthy men. The study included 40 healthy German men, half were previously sedentary and half not. In each of these two groups, half were given vitamin C and E supplements and half placebo. All underwent measurement of insulin sensitivity (the body’s ability to respond to insulin and control blood sugar – known to predict development of diabetes) before and after exercise training.

Insulin sensitivity improved in the men who were given placebo tablets but did not in those given vitamin supplements. The authors conclude (and we agree) that taking vitamin C and vitamin E prevent this beneficial impact of exercise.

A recent review of 67 studies (involving over 230,000 participants) concluded that vitamin C (alone or in combination with other vitamins) did not lower mortality. The same review concluded that vitamin E supplementation (as well as supplementation with vitamin A and beta-carotene) may to increase mortality significantly.

The recent German study describing the negative impact of vitamins C and E on the benefit of exercise joins a list of prior trials suggesting that in some patients these vitamins can increase risk of stroke and heart attack.

We do not recommend routine supplementation with vitamins A, C, E or beta-carotene.

Comments / Posted by Scott W. Yates, MD, MBA, MS, FACP