A daily dose of vitamin D may just be what people in northern climates need to get through the long winter, according to researchers at Loyola University Chicago Marcella Niehoff School of Nursing (MNSON). This nutrient lifts mood during cold weather months when days are short and more time is spent indoors.

"Vitamin D deficiency continues to be a problem despite the nutrient's widely reported health benefits," said Sue Penckofer, PhD, RN, professor, MNSON. "Chicago winters compound this issue when more people spend time away from sunlight, which is a natural source of vitamin D."

Diet alone may not be sufficient to manage vitamin D levels. A combination of adequate dietary intake of vitamin D, exposure to sunlight, and treatment with vitamin D2 or D3 supplements can decrease the risk of certain health concerns. The preferred range in the body is 30 -- 60 ng/mL of 25(OH) vitamin D.

Loyola faculty members plan to take vitamin D research a step further by evaluating whether weekly vitamin D supplements improve blood sugar control and mood in women with diabetes. Depression is associated with increased insulin resistance, so people with diabetes have a greater risk for the disease than those without depression. Women also tend to have greater rates of depression and poorer blood sugar control than men with diabetes.

"There is evidence to suggest that vitamin D supplementation may decrease insulin resistance," said Dr. Penckofer. "If we can stabilize insulin levels, we may be able to simply and cost effectively improve blood sugar control and reduce symptoms of depression for these women."

Loyola is currently enrolling women in this clinical trial. In order to enter the study, they must be 18 to 70 years of age, have stable type 2 diabetes, signs of depression and no other major medical illness. Eighty women with type 2 diabetes and signs of depression will be given a weekly dose of vitamin D (50,000 IU) for a period of six months. Study participants will be evaluated at three points during this time.

"Vitamin D has widespread benefits for our health and certain chronic diseases in particular," Dr. Penckofer said. "Our research may shed greater light on the role this nutrient plays in managing two conditions that impact millions of Americans. If proven to be successful, vitamin D may an important addition to care for diabetes and depression."