Getting enough vitamin D in the winter can be a real problem. Although medical experts throw about a number of different figures, it is thought that as much as 70% of the adult population is deficient in vitamin D. No big deal, you might be thinking — as soon as the sun gets stronger, you’ll boost your vitamin-D levels back to normal.
While this is definitely true, being deficient in vitamin D all winter is not going to be good for you. You need vitamin D to help your body absorb calcium. You also need this vitamin to build strong bones, reduce inflammation, regulate blood pressure and secrete insulin — already a long list of important functions! But the role of the vitamin in your continued good health doesn’t stop there. It’s also important for immune function and cell growth. Having low levels of vitamin D could definitely put you at higher risk for a number of health conditions, including flu, autoimmune diseases, cancer (read this article to learn more) and heart disease.
A recent clinical trial investigated vitamin D’s role in another important area — mental health. Noting that vitamin-D deficiency and mood disorders are both common among the elderly, a research team evaluated the association between vitamin-D intake and mental-health-related quality of life. This study was an analysis of the Iowa Women’s Health Study, a prospective study of cancer risk factors among post-menopausal women in Iowa that began in 1986. Additional survey data were collected from study participants in 1987, 1989, 1992, 1997 and 2004.
The researchers measured mental-health-related symptoms by measuring quality of life (QOL) scores. They found that low vitamin-D intake was associated with poorer QOL scores compared to women with a higher intake (i.e. more than 400 international units [IU]/day). The researchers concluded that women who consumed less than 400 IU/day of vitamin D had significantly lower mental-health-related QOL compared to those who consumed more than 400 IU/day.
Your vitamin-D levels in the winter depend in large part on the sun. You’re more likely to be vitamin-D deficient in the winter because the sun doesn’t provide sufficient ultraviolet light for your body to synthesize the vitamin in most of the U.S. and Canada. You have to rely entirely on your stores of vitamin D and what you consume through your diet. Get your doctor’s advice — you may need to supplement to keep your levels up.