Does Vitamin D Help Beat Seasonal Affective Disorder?

Here's a question:Does a lack of vitamin D, in turn caused by a lack of sunlight, lead to seasonal affective disorder? And if so, can vitamin D supplements reduce the winter blahs? The Boston Globe attempts to answer the question, and the best they can say is "maybe." The Globe reports that the link between vitamin D and SAD is still speculative, and light, not vitamin D, is the
only SAD therapy supported by a large body of evidence. The paper reports that specialized cells in the retina have been shown to respond to long-term light
exposure and communicate directly with the brain, which may be why
light affects our mood. Vitamin D is produced in the skin in response
to ultraviolet radiation from the sun; light boxes used for SAD
treatment do not produce these UV rays. The Globe quotes Elizabeth Bertone-Johnson, a vitamin D specialist at University of
Massachusetts Amherst, who tells us that incomplete evidence doesn’t mean that
people should discount vitamin D supplements. “The majority of the
population in New England is going to be deficient in the winter
months,’’ she says, adding that studies have linked the vitamin to prevention of
colon and breast cancers, osteoporosis, heart disease, and multiple
sclerosis, she says, and taking 1000 or 2000 IU per day as a supplement
could benefit health on many fronts.

Read more in the Boston Globe.