Not enough vitamin D in the diet could mean too much fat on adolescents

Too little vitamin D could be bad for more than your bones; it may also lead to fatter adolescents, researchers say.

A Medical College of Georgia study of more than 650 teens age 14-19 has found that those who reported higher vitamin D intakes had lower overall body fat and lower amounts of the fat in the abdomen, a type of fat known as visceral fat, which has been associated with health risks such as heart disease, stroke, diabetes and hypertension.

The group with the lowest vitamin D intake, black females, had higher percentages of both body fat and visceral fat, while black males had the lowest percentages of body and visceral fat, even though their vitamin D intake was below the recommended levels. Only one group – white males – was getting the recommended minimum intake of vitamin D.

“This study was a cross-section so, while it cannot prove that higher intake of vitamin D caused the lower body fat, we know there is a relationship that needs to be explored further," says Dr. Yanbin Dong, a molecular geneticist and cardiologist at the MCG Gerogia Prevention Institute.

Dr. Dong, who also co-directs the MCG Diabetes & Obesity Discovery Institute, and Inger Stallman-Jorgensen, a research dietician at the GPI, present their findings this week at the American Heart Association’s Joint 49th Conference on Cardiovascular Disease Epidemiology and Prevention and Nutrition, Physical Activity and Metabolism in Palm Harbor, Fla.

The pair will next study whether it is feasible for teens to take a daily vitamin D supplement in pill form. Those results will help them design a larger study to explore the relationship between vitamin D intake and body fat levels in teens.

“We already know that encouraging teens to get an adequate amount of vitamin D in their diets will help promote a healthy body as they grow and develop,” Ms. Stallman-Jorgensen says. “Now we need to do intervention studies where we give teens vitamin D supplements to determine if there is a cause and effect relationship between vitamin D intake and fat.”

The American Academy of Pediatrics recommends adolescents get at least 400 units of vitamin D per day – either from milk or sun exposure. There are typically 100 units in one 8-ounce glass of whole milk. The recommended daily dose from the sun would require at least 30 minutes of adequate exposure to direct sunlight two or three times a week at peak hours, between noon and 3 p.m.

Ms. Stallman-Jorgensen said there are many reasons teens don't get enough vitamin D, which has been linked to the prevention of diabetes, cancer and cardiovascular disease.

“As humans, our largest source of vitamin D should be the sun. But we don’t spend enough time outdoors to get enough sun exposure and when we do, we’re often covered up and wearing sunscreen," she said. "We can get vitamin D from certain foods, like fatty fish and liver, but it’s not in a lot of foods that we commonly consume. In this country, our milk is fortified with vitamin D. Unfortunately, teens just don’t drink enough milk to get their daily requirements.”

She points out that low sunlight during the winter months reduces the amount of vitamin D the skin produces, and that darker-skinned people obtain less vitamin D from the sun because the extra melanin in their skin filters out more sunlight.

Some people can't tolerate milk because they lack the enzyme that processes lactose, the natural sugar in milk, though "most people can handle it in small amounts,” Ms. Stallman says.

Cultural issues may also be at play, Ms. Stallman-Jorgensen says.

“Most teens want to drink sodas and sugary drinks. It’s not cool to drink milk – they think of it as more of a food for babies,” she said.

Potential study participants had their weekday and weekend diets tracked by researchers seven times during a three-month period. Those who provided at least four diet reports were included in the final group of 659.

Body fat percentages were measured by dual energy X-ray absorptiometry scans, which can measure total body composition. Visceral fat was measured in a subset of 432 teens.

Jennifer Hilliard
Medical College of Georgia

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Lack of Vitamin D Linked to Parkinson's Disease

A majority of Parkinson’s disease patients had insufficient levels of vitamin D in a new study from Emory University School of Medicine.

The fraction of Parkinson’s patients with vitamin D insufficiency, 55 percent, was significantly more than patients with Alzheimer’s disease (41 percent) or healthy elderly people (36 percent).

The results are published in the October issue of Archives of Neurology.

The finding adds to evidence that low vitamin D is associated with Parkinson’s, says first author Marian Evatt, MD, assistant professor of neurology at Emory.

Evatt is assistant director of the Movement Disorders Program at Wesley Woods Hospital. The senior author is endocrinologist Vin Tangpricha, MD, assistant professor of medicine at Emory and director of the Endocrine Clinical Research Unit.

Evatt says her team compared Parkinson’s patients to Alzheimer’s patients because they wanted to evaluate the possibility that neurodegenerative diseases in general lead to vitamin D insufficiency.

Most Americans get the majority of their vitamin D from exposure to sunlight or by dietary supplements; fortified foods such as milk and packaged cereals are a minor source. Only a few foods in nature contain substantial amounts of vitamin D, such as salmon and tuna.

The body’s ability to produce vitamin D using UV-B radiation from the sun decreases with age, making older individuals at increased risk of vitamin D deficiency.

“We found that vitamin D insufficiency may have a unique association with Parkinson’s, which is intriguing and warrants further investigation,” Evatt says.

The connection could come partly because patients with Parkinson’s have mobility problems and are seldom exposed to the sun, or because low vitamin D levels are in some way related to the genesis or progression of the disease.
She says her team saw their results as striking because their study group came from the Southeast, not a region with long gloomy winters, where vitamin D insufficiency is thought to be more of a problem.

In addition, the study found that the fraction of patients with the lowest levels of vitamin D, described as vitamin D deficiency, was higher (23 percent) in the Parkinson’s group than the Alzheimer’s group (16 percent) or the healthy group (10 percent).

The retrospective study examined 100 people in each group, who were recruited between 1992 and 2007. Every fifth Parkinson’s patient from Emory’s clinical neurology database was selected, then healthy controls and patients with Alzheimer’s disease were matched on age and state of residence.

Vitamin D insufficiency is frequently defined as less than 30 nanograms per milliliter of blood of the 25-hydroxy form (the major storage form) of the vitamin and deficiency as less than 20 nanograms per milliliter. However, most experts agree insufficiency warrants treatment and should not be ignored.

Doctors have known for decades that vitamin D plays a role in bone formation, Evatt says. More recently, scientists have been uncovering its effects elsewhere, including producing peptides that fight microbes in the skin, regulating blood pressure and insulin levels, and maintaining the nervous system. Low vitamin D levels also appear to increase the risk of several cancers and auto-immune diseases such as multiple sclerosis and diabetes.

Parkinson's disease affects nerve cells in several parts of the brain, particularly those that use the chemical messenger dopamine to control movement. The most common symptoms are tremor, stiffness and slowness of movement. These can be treated with oral replacement of dopamine.

Previous studies have shown that the part of the brain affected most by Parkinson’s, the substantia nigra, has high levels of the vitamin D receptor, which suggests vitamin D may be important for normal functions of these cells, Evatt says.

Emory clinicians are conducting further research to investigate whether vitamin D insufficiency is a cause or possibly a result of having Parkinson’s. In a pilot study, Parkinson’s patients are receiving either standard or larger doses of vitamin D, with an eye towards possibly reducing the severity of their condition.

The research was funded by the National Center for Research Resources, the National Institute of Aging and the National Institute of Environmental Health Sciences of the National Institutes of Health, and by an anonymous donor.

Reference:
Evatt M.L et al Prevalence of Vitamin D Insufficiency in Patients with Parkinson Disease and Alzheimer Disease. Arch. Neurol. Vol 65, p. 1348-1352 Oct 2008.

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Vitamin D Added to FDA Osteoporosis Risk-Reduction Health Claim

PRNewswire/ -- As a result of a 2004 petition from the Beverage Institute for Health & Wellness (hereafter the Institute) of The Coca-Cola Company (NYSE:KO) , the US Food and Drug Administration (FDA) announced today that it has amended its osteoporosis risk reduction health claim to reflect the importance of vitamin D, in combination with calcium, in promoting long-term bone health. The amended rule also includes a broader definition of the populations that could benefit from consuming calcium and vitamin D to include both men and women of all ages and races.

The amended labeling regulation explains that vitamin D is required for the normal absorption of calcium, and authorizes the health claim: "Adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis."

"Osteoporosis is a growing public health crisis, and all Americans, men and women alike, will benefit from knowing that vitamin D along with calcium can help delay or prevent the onset of this disease," said Robert P. Heaney MD, FACP, John A. Creighton University Professor and Professor of Medicine at Creighton University in Omaha, Nebraska. "Along with weight-bearing exercise, the most valuable intervention for maintaining bone health is an overall healthful diet that supplies adequate amounts of all nutrients such as vitamin D."

The US National Osteoporosis Foundation predicts that by 2010, about 12 million people over the age of 50 will have osteoporosis and another 40 million will have low bone mass. These numbers are expected to continue climbing. To help address this significant public health issue, the FDA developed this health claim for manufacturers to include on labels of appropriate foods and dietary supplements. The new labeling can help consumers identify products with adequate calcium and Vitamin D that can help to reduce their risk of osteoporosis.

Increasing Awareness and Consumption of Vitamin D

"We initiated this petition because we believe consumers will benefit from efforts to increase awareness of the link between calcium and vitamin D and bone health," said Dr. Rhona Applebaum, Vice President and Chief Scientific and Regulatory Officer for The Coca-Cola Company. "Revising the osteoporosis risk reduction health claim to include both vitamin D and calcium will help the food industry communicate the importance of these nutrients to consumers."

According to Carolyn E. Moore, PhD, RD, Principal Scientist with The Coca- Cola Company's Institute, studies sponsored by the Institute at the Boston University Medical Center and ENVIRON Health Sciences, demonstrated that many consumers are not getting enough Vitamin D from food and dietary supplements. The groups at greatest risk in the US include teenage girls, women, the elderly, and African-American and Mexican-American adults.

It was The Coca-Cola Company who sought approval to add vitamin D to calcium-fortified juices and juice drinks from the FDA, through research the Company sponsored at the Vitamin D and Bone Health Research Laboratory at Boston University Medical School. Results from this research demonstrated that vitamin D is readily absorbed by the body when added to skim milk and

orange juice. The FDA approved the addition of vitamin D to calcium-fortified juices in 2003.

The Importance of Vitamin D for Strong Bones

Vitamin D requirements of all age groups can be met under conditions of adequate exposure to sunlight. However, several factors can reduce the production of vitamin D from the skin including the use of sunscreens, increased skin pigmentation, normal aging, and insufficient exposure to sunlight.

The primary function of Vitamin D is to aid in the body's absorption of calcium, helping to form and maintain strong bones. Without Vitamin D, the body absorbs 10 - 15 percent of calcium consumed in the diet. With Vitamin D, the absorption level increases to 30 - 50 percent.

Emerging Research on Vitamin D

Vitamin D has been the subject of extensive basic and clinical research in the past several years, which has generated valuable insights about this vital nutrient.

-- In a recent study supported in part by the Institute, researchers from Boston University School of Medicine found that vitamin D2 (found naturally in plants) is equally as effective as vitamin D3 (produced as a result of sun exposure and found in some food sources such as cod liver oil and oily fish) in maintaining circulating blood levels of vitamin D.

-- With support from the National Institutes of Health and the Institute, the United States Department of Agriculture's Nutrient Data Laboratory is in the process of conducting an updated analysis of vitamin D content in a wide range of whole and processed foods, including, for the first time, specific forms of vitamin D, i.e., D2 and D3.

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Low Vitamin D Levels Pose Large Threat to Health

Researchers at Johns Hopkins are reporting what is believed to be the most conclusive evidence to date that inadequate levels of vitamin D, obtained from milk, fortified cereals and exposure to sunlight, lead to substantially increased risk of death.

In a study set to appear in the Archives of Internal Medicine online Aug. 11, the Johns Hopkins team analyzed a diverse sample of 13,000 initially healthy men and women participating in an ongoing national health survey and compared the risk of death between those with the lowest blood levels of vitamin D to those with higher amounts. An unhealthy deficiency, experts say, is considered blood levels of 17.8 nanograms per milliliter or lower.

Of the 1,800 study participants known to have died by Dec. 31, 2000, nearly 700 died from some form of heart disease, with 400 of these being deficient in vitamin D. This translates overall to an estimated 26 percent increased risk of any death, though the number of deaths from heart disease alone was not large enough to meet scientific criteria to resolve that it was due to low vitamin D levels.

Yet, researchers say it does highlight a trend, with other studies linking shortages of vitamin D to increased rates of breast cancer and depression in the elderly. And earlier published findings by the team, from the same national study, have established a possible tie-in, showing an 80 percent increased risk of peripheral artery disease from vitamin D deficits.

Researchers note that other studies in the last year or so in animals and humans have identified a connection between low levels of vitamin D and heart disease. But these studies, they say, were weakened by small sample numbers, lack of diversity in the population studied and other factors that limited scientists’ ability to generalize the findings to the public at large.

“Our results make it much more clear that all men and women concerned about their overall health should more closely monitor their blood levels of vitamin D, and make sure they have enough,” says study co-lead investigator Erin Michos, M.D., M.H.S.

“We think we have additional evidence to consider adding vitamin D deficiency as a distinct and separate risk factor for death from cardiovascular disease, putting it alongside much better known and understood risk factors, such as age, gender, family history, smoking, high blood cholesterol levels, high blood pressure, lack of exercise, obesity and diabetes,” says Michos. Vitamin D is well known to play an essential role in cell growth, in boosting the body’s immune system and in strengthening bones.

“Now that we know vitamin D deficiency is a risk factor, we can better assess how aggressively to treat people at risk of heart disease or those who are already ill and undergoing treatment,” says Michos, who adds that test screening for nutrient levels is relatively simple. It can, she says, be made part of routine blood work and done while monitoring other known risk factors, including blood pressure, glucose and lipid levels.

Heart disease remains the nation’s leading cause of death, killing more than a million Americans each year. Nearly 10 percent of those with the condition have not one identifiable, traditional risk factor, which the experts say is why a considerable extent of the disease goes unexplained.

Michos, an assistant professor at the Johns Hopkins University School of Medicine and its Heart and Vascular Institute, recommends that people boost their vitamin D levels by eating diets rich in such fish as sardines and mackerel, consuming fortified dairy products, taking cod-liver oil and vitamin supplements, and in warmer weather briefly exposing skin to the sun’s vitamin-D producing ultraviolet light.

Aware of the cancer risks linked to too much time spent in the sun, she says as little as 10 to 15 minutes of daily exposure to the sun can produce sufficient amounts of vitamin D to sustain health. The hormone-like nutrient controls blood levels of calcium and phosphorus, essential chemicals in the body.

If vitamin supplements are used, Michos says there is no evidence that more than 2,000 international units per day do any good. Study results show that heart disease death rates flattened out in participants with the highest vitamin D levels (above 50 nanograms per milliliter of blood), signaling a possible loss of the vitamin’s protective effects at too-high doses.

The U.S. Institute of Medicine suggests that an adequate daily intake of vitamin D is between 200 and 400 international units (or blood levels nearing 30 nanograms per milliliter). Previous results from the same nationwide survey showed that 41 percent of men and 53 percent of women are technically deficient in the nutrient, with vitamin D levels below 28 nanograms per milliliter.

Michal Melamed, M.D., M.H.S., study co-lead investigator who started the research as a clinical fellow at Johns Hopkins, says no one knows yet why or how vitamin D’s hormone-like properties may protect the heart, but she adds that there are plenty of leads in the better known links the vitamin has to problems with muscle overgrowth and high blood pressure, in addition to its control of inflammation, which scientists are showing plays a stronger role in all kinds of heart disease. But more research is needed to determine the nutrient’s precise biological action.

Researchers say their next steps are to test various high doses of vitamin D to find out if the nutritional supplementation results in fewer deaths and lower incidence of heart disease, including heart attack or moments of prolonged and severe chest pain.

The team also plans to investigate what biological triggers, such as obesity or hypertension, might offset or worsen the action of vitamin D on heart muscle, or whether vitamin D sets off some other reaction in the heart.

Melamed says that because vitamin D levels are known to fluctuate in direct proportion with daily physical activity, the growing epidemic of obesity and indoor sedentary lifestyles lend more urgency to act on the vitamin D factor.

Funding for this study was provided by the National Institutes of Health, the P.J. Schafer Cardiovascular Research Fund and the Paul Beeson Physician Faculty Scholars in Aging Program. Michos has received previous consulting fees from vitamin D therapeutics manufacturer Abbott Pharmaceuticals. The terms of these arrangements are being managed by the Johns Hopkins University in accordance with its conflict of interest policies.

Besides Michos and Melamed, other Hopkins researchers involved in this study, conducted solely at Hopkins, were Wendy Post, M.D.; and Brad Astor, Ph.D. Melamed is now an assistant professor at the Albert Einstein College of Medicine of Yeshiva University in New York City.

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