Not so sunny: Vitamin D does not protect against depression, study finds

BOSTON — The theory that vitamin D levels in the body factor into one’s depressive feelings has existed for decades. Consequently, countless people take supplements every day in hopes of staving off the blues. Now, a rather depressing new study shows that vitamin D offers no protection or benefits in the battle against depression.

Researchers from Massachusetts General Hospital say that a regimen of vitamin D supplements provides absolutely no mental health benefits among a group of middle-aged and older adults.

“There was no significant benefit from the supplement for this purpose. It did not prevent depression or improve mood,” says lead study author Dr. Olivia I. Okereke.

Supplements versus placebo

This was no small research project; more than 18,000 men and women over 50 took part in this study. Half of the participants adhered to a strict routine of vitamin D3 (cholecalciferol) supplements for an average of five years. The other half of participants were given a placebo each day for the same period.

Of course, this isn’t the first study to investigate the relationship between vitamin D and depression. Moreover, many prior studies on this topic conclude that low levels of vitamin D in the blood can raise one’s risk of feeling down in the dumps. However, none of those studies are able to establish causation.

“One scientific issue is that you actually need a very large number of study participants to tell whether or not a treatment is helping to prevent development of depression,” Okereke explains. “With nearly 20,000 people, our study was statistically powered to address this issue.”

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At the beginning of the tracking period, all 18,353 participants showed no signs of depression. This provided a good starting point to see if the vitamin D supplements could make a significant difference among the experimental group and the placebo group.

Vitamin D is great — just not for depression

Once everything was said and done, the study’s authors say their findings left little room for debate. Researchers see no significant differences in either risk of depression or risk of experiencing depression-centric symptoms among all 18,000+ randomized participants. Over time, neither group showed much difference regarding their daily moods either.

Still, regardless of what vitamin D can or can’t do for depression, it’s still quite important for bodily health.

“It’s not time to throw out your vitamin D yet though, at least not without your doctor’s advice,” Okereke notes.

“Vitamin D is known to be essential for bone and metabolic health, but randomized trials have cast doubt on many of the other presumed benefits,” adds senior study author JoAnn Manson, MD, DrPH, from Brigham and Women’s Hospital.

The study is published in JAMA.

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