Doctor In Your House: Does vitamin D really work?

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Vitamin D reminds many doctors of the tonics sold in the 1800s; lots of hype with very little evidence. However, the scientific community is beginning to change as the results of new studies come to light.

What is the latest major study regarding vitamin D?

The Whitehall Study was a prospective trial just published in the European Heart Journal in July of 2013.

Scientists examined associations of plasma concentrations of vitamin D and the death rate in elderly British men. Higher levels of vitamin D resulted in a 20-25 percent reduction in mortality from vascular and nonvascular cause of death.

Supplementation with vitamin D may be helpful but cause and effect is not yet proven concerning overall mortality.

Does vitamin D prevent cancer?

Trials are controversial but some of them show reductions in cancers of the breast, colon, prostate and pancreas with higher levels of vitamin D. Once cancer developed, vitamin D did not seem to help.

Does vitamin D reduce heart disease and diabetes?

A meta-analysis of 11 prospective studies involving 60,000 participants provided the largest and most comprehensive assessment thus far of the association between circulating vitamin D levels and type 2 diabetes. It suggested a strong association between higher serum vitamin D concentration and a lower incidence of type 2 diabetes.

Similarly, in another meta-analysis, limited data suggested that vitamin D supplements at moderate to high doses may reduce the risk of cardiovascular disease but most studies that used lower doses found no effect on heart disease.

Can Multiple Sclerosis (MS) be prevented and treated by consuming vitamin D?

Evidence continues to accumulate supporting a protective role for vitamin D in MS risk and prevention. An American study of more than 187,000 women followed up for 1-2 decades reported promising results with women taking at least 400 IU of supplemental vitamin D daily. The risk of developing MS was decreased by over 40 percent. In another trial using doses up to 40,000 units daily of vitamin D3 for 28 weeks followed by 10,000 units daily for 12 weeks, there were no significant side effects, and there seemed to be significantly less progression of disability in the treatment group.

What about vitamin D and fracture reduction?

In many trials, taking vitamin D at doses of 700-1000 units daily resulted in less hip fractures and less falls. In some of the trials, calcium was added. After a hip fracture, 35 percent of patients die within a year so the prevention of falls is quite important.

Is there any other important data regarding vitamin D?

In one recent trial, Prozac plus vitamin D was more effective than Prozac alone in treating depression.

Taking vitamin D during pregnancy might prevent low birth weights.

Vitamin D did not reduce the incidence of upper respiratory infections.

What is the recommended dose of vitamin D?

Although it is recommended that 600 to 800 units daily should meet the requirements to optimize bone health, higher vitamin D intakes (1000-2000 IU) are needed to reach and maintain vitamin D levels in the normal range (greater than 30 ng/ml). I personally take 2000 units of vitamin D3 daily but recommend you check with your doctor.

Doctor's Summary: Vitamin D may be helpful in preventing and treating a large number of chronic diseases. An efficacious strategy to prevent vitamin D deficiency is to obtain some sensible sun exposure, consume foods that contain vitamin D, and take a vitamin D supplement.


Evan Lipkis, MD, is a physician, author and lecturer based in Glenview, Illinois. The advice contained in this column is for informational purposes only. Readers should consult with their physician to evaluate any illness or medical condition. Contact Dr. Lipkis through his website at