Women with health issues such as arthritis and diabetes are much more likely to have inadequate levels of vitamin D during the winter than in the summer, according to new research introduced at the 2012 American Society for Clinical Pathology (ASCP) Annual Meeting.

Medical professionals have long known that all people’s vitamin D levels drop in the wintertime, especially in the northern part of the country. This new study points out that vitamin D deficiency is connected with certain health issues, and that extra action may be needed to keep vitamin D levels steady.

A team of researchers from Vanderbilt University examined the seasonal vitamin D levels of 244 women with different health issues such as arthritis, hypothyroidism, cancer, high blood pressure, and osteoporosis, who came to the medical center during the period of September 2008 and December 2009.

Levels of vitamin D less than 20ng/mL are regarded as deficient, and levels of 20-29 ng/mL are insufficient. During the winter, 28 percent of the women had deficient levels and 33 percent had insufficient levels of vitamin D. During the summer, just 5 percent of the women had deficient levels, while 38 percent had insufficient levels of vitamin D.

Low levels of vitamin D have been linked with high blood pressure, diabetes, hypothyroidism, arthritis, and cancer.

A previous study suggests that in postmenopausal women, low levels of vitamin D can be linked with gaining weight, while regular levels of vitamin D were not.

Samir Aleryani, PhD, senior author of the study and assistant professor of pathology at Vanderbilt University Medical Center in Nashville, Tenn says:

“The good news is that we found women who were taking supplements in winter were able to significantly elevate their vitamin D levels compared to those who didn’t take supplements. The take home message is that 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.”

Vitamin D is associated with many health benefits such as strong bones, regulation of blood pressure, and the improvement of cardiovascular health.

a Recently, it has been seen that high levels of vitamin D in women under the age of 75 are associated with a decreased risk of macular degeneration, the loss of one’s central vision and a main cause of partial-blindness in people over the age of 50.

Vitamin D is produced when the body is exposed to ultraviolet B (UVB) rays from the sun. The production of vitamin D is most prevalent with sun exposure during peak sunlight hours (10AM-3PM).

People who work indoors everyday do not make much vitamin D in their skin and generally obtain it from supplements and food. Due to the sun’s weaker intensity during the winter months (November to March), hardly any vitamin D is produced in the skin, even with direct sunlight exposure, in the mid and northern part of the US.

Fahd A. Al Qureshah, lead author of the study and a molecular and cellular biology student in the department of biological sciences at Vanderbilt explains, “Vitamin D receptors are now believed to play major roles in health via their presence in virtually every cell in the body.”

The team of investigators may plan to examine vitamin D levels in other at-risk groups, such as patients who are in the hospital for long stays and those that are obese and less likely to make trips outside of their home.

Matthew Krasowski, MD, ASCP member and director of clinical laboratories at the University of Iowa in Iowa City, Iowa, concludes, “This research suggests the importance of increasing awareness about higher levels of vitamin D deficiency in certain groups of patients. Healthcare providers and patients need to be aware of this issue.”

Written by Kelly Fitzgerald