Samir Aleryani, PhD
Women with health conditions ranging from arthritis to diabetes are significantly more likely to be deficient in all-important vitamin D in the winter than in the summer, suggests research presented at the 2012 American Society for Clinical Pathology (ASCP) Annual Meeting in Boston, which began on October 31 and continues through November 3.
Physicians have long been aware that almost everyone’s vitamin D levels drop in the winter—particularly if they live in the northern part of the country—but new research suggests that vitamin D inadequacy is associated with specific health conditions, suggesting that extra intervention may be required to maintain optimum vitamin D levels.
Researchers at Vanderbilt University Medical Center, Nashville, Tenn. evaluated the seasonal vitamin D levels of 244 women with a health condition (including osteoporosis, high blood pressure, arthritis, hypothyroidism, and cancer) who visited the medical center between September 2008 and December 2009. Vitamin D levels of less than 20 ng/mL are considered deficient, and levels of 20-29 ng/mL are insufficient. In the winter, 28% of the women had deficient levels and 33% had insufficient levels of vitamin D. In the summer, only 5% of the women had deficient levels and 38% had insufficient levels of vitamin D.
“We found that these women have a severe drop off in vitamin D levels in the winter, which is a real concern for women who already are coping with significant health conditions,” says Samir Aleryani, PhD, senior author of the study and assistant professor of pathology at Vanderbilt. “Women with these health conditions need to be much more proactive, and should talk to their doctors regarding the best supplements to take to ensure adequate levels of vitamin D.”
Linked to a variety of health benefits, ranging from strong bones to the regulation of blood pressure to the improvement of cardiovascular health, vitamin D is produced by the body when it is exposed to the sun’s ultraviolet B (UVB) rays. However, vitamin D production in the skin is most effective with sun exposure during peak sunlight hours (10 am to 3 pm). People working indoors during the day produce little vitamin D in their skin and mainly get it from foods and supplements. In the mid- and northern part of the country, essentially no vitamin D is produced in skin—even with direct sunlight exposure—in the months from November to March, due to the sun’s weaker intensity.
“Vitamin D receptors are now believed to play major roles in health via their presence in virtually every cell in the body,” says Fahd A. Al Qureshah, lead author of the study and a molecular and cellular biology student in the department of biological sciences at Vanderbilt.
Next, the research team may evaluate vitamin D levels in other at-risk groups, for example, patients who spend longer periods in the hospital and those who are obese and less likely to take many trips outside of the home.
“This research suggests the importance of increasing awareness about higher levels of vitamin D deficiency in certain groups of patients,” says Matthew Krasowski, MD, ASCP member, and director of clinical laboratories at the University of Iowa, Iowa City, Iowa. “Health care providers and patients need to be aware of this issue.”