THURSDAY, Nov. 1, 2012 (HealthDay News) -- Vitamin D levels are known to decrease during the winter months, but for women with certain health problems, the drop may be even more significant, a new study finds.
For these women, extra measures may be required to maintain their levels of vitamin D, which is linked to a variety of health benefits, including strong bones, blood pressure regulation and cardiovascular health.
For the study, researchers from Vanderbilt University in Nashville, Tenn., assessed the winter and summer vitamin D levels of nearly 250 women with health conditions including osteoporosis, high blood pressure, arthritis, cancer and hypothyroidism.
Vitamin D levels of less than 20 nanograms per milliliter (ng/mL) are considered deficient, and levels of 20 to 29 ng/mL are deemed insufficient. Based on these parameters, 28 percent of the women had deficient levels of vitamin D in the winter and 33 percent had insufficient levels, compared with 5 percent and 38 percent, respectively, during the summer.
The study was scheduled for presentation Thursday at the annual meeting of the American Society for Clinical Pathology in Boston.
"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," Samir Aleryani, study senior author and assistant professor of pathology at Vanderbilt, said in a society news release.
"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," Aleryani advised.
Sunlight triggers vitamin D production by the body and it is normal for vitamin D levels to drop during the winter, especially among people who live in northern areas. Other sources of vitamin D include foods and supplements.
Dr. Matthew Krasowski, director of clinical laboratories at the University of Iowa, agreed that more attention needs to be paid to this issue.
"This research suggests the importance of increasing awareness about higher levels of vitamin D deficiency in certain groups of patients," Krasowski said in the news release.
"Health care providers and patients need to be aware of this issue," said Krasowski, who was not involved in the study.
The data and conclusions of research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.
The Harvard School of Public Health has more about vitamin D.