Kare about Health

Vitamin D has been getting lot of press lately. It seems that deficiency in this vitamin can cause more problems than just rickets. Vitamin D is one of the oldest hormones, having been produced by life forms for over 750 million years. Phytoplankton, zooplankton, and most plants and animals that are exposed to sunlight have the capacity to make vitamin D. In humans, vitamin D is critically important for the development, growth, and maintenance of a healthy body, from birth until death. To give you an idea of how the sun helps us in this regard, a light-skinned person will synthesize 20,000 IU of vitamin D in 20 minutes sunbathing on a tropical beach, at which point vitamin D synthesis shuts down for the day (it takes a dark-skinned person 6 to 10 times longer to make this amount). Also to give you an idea of how far off the Recommended Daily Allowances (RDAs) are; recommended doses are from 200-600 IU depending on age. Intake reference values for vitamin D and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of The National Academies (formerly National Academy of Sciences). In 2008, the American Academy of Pediatrics (AAP) issued recommended intakes for vitamin D that exceed those of FNB. The FNB established an expert committee in 2008 to review the DRIs for vitamin D (and calcium). The current DRIs for this nutrient were established in 1997, and since that time substantial new research has been published to justify a reevaluation of adequate vitamin D intakes for healthy populations. Determinations of DRIs are based on indicators of adequacy or hazard; dose-response curves; health outcomes; life-stage groups; and relations between intakes, biomarkers, and outcomes. For vitamin D, the FNB committee will focus on (1) effects of circulating concentrations of 25(OH)D on health outcomes, (2) effects of vitamin D intakes on circulating 25(OH)D and on health outcomes, and (3) levels of intake associated with adverse effects [21]. The FNB expects to issue its report, updating as appropriate the DRIs for vitamin D and calcium, by May 2010.

Very few foods in nature contain vitamin D. The flesh of fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. Small amounts of vitamin D are found in beef liver, cheese, and egg yolks. Vitamin D in these foods is primarily in the form of vitamin D3 (cholecalciferol) and its metabolite 25(OH)D3]. Some mushrooms provide vitamin D2 (ergocalciferol) in variable amounts. Mushrooms with enhanced levels of vitamin D2 from being exposed to ultraviolet light under controlled conditions are also available. Fortified foods provide most of the vitamin D in the American diet.

A growing body of evidence suggests that Vitamin D deficiency is involved in a multitude of diseases and syndromes. From Alzheimer’s to autoimmune diseases, cancer and even the flu, it seems there is a connection with Vitamin D levels. There is good evidence that Vitamin D deficiency is a causal factor in some 15 different common cancers. (NEJM 2007;357:266–81.)

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 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 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 seems to have receptors for Vitamin D. “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 diligent we are about health, don’t get enough Vitamin D. Nowadays, many people aren’t going outside very much, and most of us 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, as suggested above, 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 year 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 and evocative studies undertaken decades ago in Russia and Germany, for instance, suggest 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.

How much is safe?

So, maybe this is one area where supplements may be in order, but how much to take? “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

Most supplements are not adequate!

recommended daily allowance. Most experts anticipate that this allowance will be revised upward soon. “Well adults and adolescents should take 5,000 IU per day. Two months later have a 25-hydroxyvitamin D blood test, either through ZRT (see below*) or your doctor”, says John Jacob Cannell MD Executive Director, Vitamin D Council.

“National recommendations from the Food and Nutrition Board are 400 to 600 International Units (IU) a day,” Neil Binkley, MD, an Associate Professor in Geriatrics and Endocrinology at the University of Wisconsin said. “That’s simply not enough. Experts recommend somewhere between 1500 to 2600 IU daily. It’s considered a very safe vitamin. One would need daily doses of 40,000 IU or higher before seeing negative side effects.”

Vitamin D is essential for bone health, but Binkley discussed its role in improving muscle function. “One of the primary killers among older adults is falls,” Binkley said. “A sufficient amount of Vitamin D not only enhances bone strength but also improves muscle function thereby reducing the risk of fractures.”

Vitamin D receptors have been discovered in many tissues throughout the body. “There’s a lot that is unknown about vitamin D right now,” Dr. Binkley said. “But there is one certainty – its importance is widespread.” The ubiquitous effects of the “sunshine vitamin” are demonstrated by research studies associating lower circulating vitamin D levels with cancer, type 1 diabetes and cardiovascular disease.

No matter what the experts are saying, the current recommendation seems to be a far cry from what is ideal. Consult with your doctor before beginning supplements. Overdoses of Vitamin D are rare, but can occur.

Flu prevention?

Another side to this that has been getting not nearly enough press is that Vitamin D levels in the blood fall to their lowest point during flu seasons. Unable to be protected by the body’s own antibiotics (antimicrobial peptides) that this gene-expresser engineers, a person with a low vitamin D blood level is more vulnerable to contracting colds, influenza, and other respiratory infections, says Dr. Donald W. Miller, a cardiac surgeon and Professor of Surgery at the University of Washington in Seattle, and former head of cardiac surgery at the VA hospital in Seattle. (His web site is www.donaldmiller.com). There seems to be an interesting correlation between Vitamin D levels and immunity.Why is flu season when sunshine is at it’s lowest level in both hemispheres? Something that scientists are finally zooming in on.

Other things you can do to prevent the flu, according to Dr. Miller: “Avoid sugar. It suppresses immunity. Avoid Omega-6 vegetable oils (corn, safflower, sunflower, peanut, canola, and soybean oil). Americans consume 50 times more of these oils than are necessary for good health. In this amount they are powerful immune suppressants. Take a well-balanced multivitamin/mineral capsule on a daily basis. Eat garlic. Manage stress. Exercise. Get enough rest. And wash your hands. Viruses spread most often from touching contaminated objects, like doorknobs, phones, shared computer keyboards, and shaking hands.”  Hmmm… flu protection in a vitamin? So much safer and cheaper than flu shots, yes?

What can you do?

Get tested for your Vitamin D levels. The only blood test that can diagnose vitamin D deficiency is a 25-hydroxyvitamin D. Dr. Cannell, Dr. Miller, and others (including my MD colleagues at Canyon Ranch) agree that levels should be above 50 ng/ml year-round. Your doctor may try to tell you that anything above 30ng/ml is normal. But it seems that “normal” is not ideal. It can take 2-3 months for the right amount of supplementation to show up in the blood levels, so leave enough time before being re-tested.

* The Vitamin D Council has partnered with ZRT Labs to make a discounted take-home Vitamin D Test Kit that you can order on the Internet. A portion of the proceeds from the sale of each test will be donated to the Vitamin D Council by ZRT to help in their mission to end the worldwide epidemic of vitamin D deficiency. The tests will be available to order in either a quantity of one (1) or four (4). I checked the website today and the one-test kit was $65 and the 4-test kit $220. The 4 test kit is $10 less expensive per test. If you have insurance, you may just want to ask your doctor for a test. Make sure it tests for 25-hydroxyvitamin D.

So, the bottom-line (as I always like to give)… There seems to be balance and moderation in the amount of sunlight exposure (unprotected) that we need for our body to synthesize Vitamin D, and not to stimulate cancer cell growth. Gosh, that moderation thing just keeps showing up, over and over again!

How many of you have had your Vitamin D levels checked? Are (were) you deficient?  Do you care?

Sunshine and good health to all of you!

*** Remember… this is not meant to be a substitute for medical advice. Please discuss your individual situation with your doctor.