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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Is vitamin D a modifiable factor in some cases of seasonal affective disorder?

Dear Dr. Cannell:

In 2003, my husband and I moved to the Olympic Peninsula in western Washington State, an area famous for cloudy, wet winters. I have always suffered from seasonal affective disorder (SAD), but it became worse once we moved.

In 2007, I began taking vitamin D (1400 I.U. per day from October to May) due to research that showed that vitamin D may reduce the risk of breast cancer. To my surprise, I did not get SAD that winter. I now take vitamin D as an antidepressant as soon as the days get shorter. I increase the amount whenever I start to feel a touch of depression. By February, I am taking 6,000 I.U. per day. Loving those rainy days!

Susan, Washington

Dear Susan:

Last year, four researchers from various institutions supported your personal experience in one of my favorite journals, Medical Hypotheses. (Without Medical Hypotheses, I would never have had my vitamin D and autism theory published in 2007).

Stewart AE, Roecklein KA, Tanner S, Kimlin MG. Possible contributions of skin pigmentation and vitamin D in a polyfactorial model of seasonal affective disorder. Med Hypotheses. 2014 Nov;83(5):517-25.

As these researchers make clear, SAD is complex, with many factors contributing to it. Although not everyone with SAD is helped by vitamin D, some are. I recommend that anyone who is affected by SAD, to try supplementing with vitamin D. However, I would suggest supplementing with 10,000 IU/day in the fall and winter and full body sunbathing in the spring and summer.

There are 3 randomized controlled trials of vitamin D in treating SAD; two trials show no treatment effect and one does, but the doses were no where near 10,000 IU every day. Not all patients were vitamin D deficient at the start of the studies. Also, pre and post treatment vitamin D blood levels were not obtained to assure compliance and adequate doses.

I am happy to hear that vitamin D supplementation has helped

John Cannell, MD

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

One Response to Is vitamin D a modifiable factor in some cases of seasonal affective disorder?

  1. Rebecca Oshiro says:

    I moved to Seattle 5 years ago from Southern California and used to dread the winters. I discovered that if I take enough vitamin D to maintain a 25(OH)D level of 60 ng/mL I, too, can love those rainy days.