Seasonal Affective Disorder (SAD) and Vitamin D

If you suffer from SAD, the end of daylight savings time is always bad news. SAD is characterized by symptoms of depression that flare up in the winter months when daylight hours decrease. It is far more prevalent up north, but I have seen it even here in Houston.

Since lack of sunlight obviously has something to do with SAD, treatment often involves daily exposure to bright white fluorescent light. However, this approach often doesn’t help and so many doctors just prescribe antidepressants.

An interesting theory is that it is not the lack of sunlight that causes depression, but the resulting vitamin D deficiency. Several studies appear to support this view.

In one study, 37 patients with marginal blood levels of vitamin D were given either 600 or 4,000 IU per day of vitamin D3 for three months, December through February. After this period, all patients reported improved wellbeing, with the higher-dose group faring significantly better (Nutr J 2004 Jul 19; 3 (1): 8).

In an older study, 15 patients with SAD were randomly assigned to receive vitamin D or daily light therapy. In this study only the group receiving vitamin D recovered (J Nutr Health Aging 1999; 3 (1): 5-7).

Last January I wrote about the many benefits of vitamin D (click on “Vitamin D” on the topics list of the Newsletters page on my website to view the full article). This vitamin plays important roles in calcium and bone metabolism, immunity, and protection from critical illness. If you suspect you are prone to SAD, that may be one more good reason to have your blood levels of vitamin D tested. The correct test to measure your vitamin D levels is one called “25-hydroxy vitamin D.” It is also important to ignore the lab’s reference ranges because they are based on the average of a vitamin D-deficient population. Instead, a good range is between 35 and 50 ng/ml.

If your levels are low, consider supplementing with vitamin D3, the most natural and safest form of this vitamin. Supplements in the range of 4,000 to 6,000 IU per day are safe for adults and probably necessary to reestablish adequacy if you are deficient. However, if you take high doses, it is important to monitor your blood levels of vitamin D through periodic testing and regular communication with your healthcare professional. Excessively high levels of Vitamin D can have toxic effects that could include kidney stones. Once an adequate level has been established, long-term maintenance intake of 1,000 IU per day has been shown to be safe (Am J Clin Nutr 2001; 73: 288-94).

Comments are closed.