Vitamin D deficiency is most common in the winter. Research suggests that over 50 percent of Americans are vitamin D deficient. The widespread use of sunscreens, reduced sun exposure, residence in northeastern US, and having more skin pigmentation, contributes to the high prevalence of vitamin D deficiency. Just ten to fifteen minutes of sun exposure daily can provide 2,000 to 5,000 IU of vitamin D. However, since sun exposure is not possible in the winter, experts recommend vitamin D supplementation during the winter.
One study found that many US teenagers have a vitamin D deficiency. Researchers from Children's Hospital in Boston conducted a study of 307 adolescents recruited at an annual physical examination. Findings revealed that 42 percent of participants were vitamin D deficient. "The prevalence was highest in African American teenagers and during winter, although the problem seems to be common across sex, season, and ethnicity," the study authors write.
Other studies report that vitamin D supplementation can lower the risk of breast, colon, ovarian and other cancers. Researchers at the University of California, San Diego analyzed breast cancer rates and vitamin D levels in 1,760 women. They found that women with the highest levels of vitamin D were 50 percent less likely to develop breast cancer, compared to those with the lowest levels. The researchers recommend increasing vitamin D intake through foods and supplements.
Another study published in the Journal of the National Cancer Institute, examined the association between vitamin D exposure and the risk of cancer in 47,800 men. They found that men with the highest levels of vitamin D (at least 1,500 IU daily) were 17 percent less likely to develop cancer and 29 percent less likely to die of the disease. The study authors recommend supplementing with at least 1500 IU of vitamin D daily.
REFERENCES:
1. Garland CF et al. Evidence of need for increased vitamin D fortification of food based on pooled analysis of studies of serum 25-hydroxyvitamin D and breast cancer. Abstract 4008, American Association of Cancer Research, April 4, 2006.
2. Knight JA et al. Potential reduction in breast cancer risk associated with Vitamin D. Abstract 4009, American Association of Cancer Research, April 4, 2006.
3. Giovannucci E et al. Prospective Study of Predictors of Vitamin D Status and Cancer Incidence and Mortality in Men. JNCI 2006 Apr5;98(7):451-459.
4. Gordon CM, et al. Prevalence of vitamin D deficiency among healthy adolescents. Arch Pediatr Adolesc Med. 2004 Jun;158(6):531-7.
Posted by Elaine Gavalas on December 11, 2006 03:35 PM
