Vitamin D: Higher Levels Needed for Better Health

More Vitamin D = Better Public Health

From a nutritionist's point of view, 2007 should be declared the Year of Vitamin D. Over the past year alone, there have been three major conferences on this topic and a multitude of research papers published. Now, a consensus among experts is emerging: We're not getting enough of this nutrient for optimal health.

What Does the Research Tell Us?

Many studies have linked higher intakes or blood levels of vitamin D with a lower risk of cancer. The evidence shows a protective effect against colon cancer, and suggests that vitamin D may also help reduce cancers of the breast and prostate. Vitamin D has been found to help prevent falls and preserve bone density in older people. In addition, researchers are exploring the role of vitamin D in such diverse conditions as MS and macular degeneration.

One recent and skillfully done study (1) looked at 18 clinical trials of vitamin D, each of which reported results for total mortality - an accurate measurement of poor health effects. "The results were remarkable" wrote Harvard's Dr. Edward Giovannucci in an accompanying editorial. Those who received vitamin D in these studies had a significant 7% reduction in death from any cause. Importantly, no "negative surprises" were seen from the doses given, which ranged from 300-2000 IU vitamin D daily.

More compelling evidence comes from a recent trial that supplemented postmenopausal women with 1,100 IU vitamin D plus calcium or calcium alone for 4 years (2). Women who received vitamin D had significantly fewer cancers of all types.

How Much Vitamin D Is Needed?

Experts from Tufts and Harvard put their heads together to tackle this question. They examined studies which looked at dental health, risk of falls, fractures and colon cancer, and that also reported blood levels of vitamin D. It was clear that blood levels associated with beneficial health outcomes began at 75 nmol/L. Calculations showed that at least 1000 IU vitamin D daily is needed to bring half the population into that healthy range (3). These findings led to a safety assessment of vitamin D (4), and eventually to vitamin D experts urging that the RDA be raised (5).

The "D" Dilemma: How Do We Get More?

Getting enough of this important vitamin can be challenging since very few foods contain significant amounts. The best sources are fatty fish such as mackerel, salmon, sardines and tuna, as well as fortified milk, which contains about 100 IU per glass. Diet alone, however, can't provide the amounts that researchers suggest we need to achieve.

Although vitamin D is produced when skin is exposed to sunlight, specifically ultraviolet B radiation (UVB), most people follow advice to apply UVB blocking sunscreen when outdoors. Making sufficient levels of the "sunshine vitamin" is even more difficult for Afro-Americans who need longer sun exposure to produce the same amount of "D" generated within lighter skin.

In fact the American Academy of Dermatology is concerned that reports about vitamin D's health benefits could lead to higher rates of skin cancer. People should avoid unprotected sun exposure, and take a multivitamin or drink a few glasses of vitamin D fortified milk every day, according to the Academy. But there's one glaring problem with that advice.

Sound Supplementation Can Bridge the Gap

"The amount of vitamin D in supplements isn't nearly enough," states Creighton University's Dr. Robert Heaney who has conducted nearly 2 decades of research on vitamin D.

The response of a forward-thinking, responsible supplement company might be to provide 800-1000 IU in supplements for adults. Along with a healthy diet and lifestyle that includes fish, whole foods, low-fat dairy, and regular exercise, supplementation based on good science can help improve public health.

References

1. Autier P, et al. Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials. Arch Intern Med 167:1730-7, 2007.
   
2. Lappe JM, et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. AJCN 85:1586-91, 2007.
   
3. Bischoff-Ferrari HA, et al. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. AJCN 84:18-28, 2006.
   
4. Hathcock JN, et al. Risk assessment for vitamin D. AJCN 85:6-18, 2007.
   
5. Veith R, et al. The urgent need to recommend an intake of vitamin D that is effective. AJCN 85:649-50, 2007.