How Much Vitamin D is enough?

Posted on December 28, 2010 by Joel Fuhrman, M.D.

A few weeks ago, the Institute of Medicine (IOM) surprised many of us when it announced its new dietary reference intake (DRI) for vitamin D. The consensus of the scientific community was that the previous DRI of 400 IU was insufficient, and that supplementation with at least 1000 IU would be necessary for most people to achieve vitamin D sufficiency. The IOM disagreed.
The IOM’s new recommendations:– Recommended intake: 600 IU per day (for children and adults under age 70)- Tolerable upper limit (amount not to be exceeded in one day): 4000 IU (raised from 2000 IU)- Sufficient blood 25(OH)D level: 20 ng/ml

There has been a great deal of research in recent years on vitamin D’s role in a variety of human diseases. Low vitamin D status has been associated with cardiovascular disease, certain cancers, cognitive decline, depression, diabetes, pregnancy complications, autoimmune diseases, and even a 78% increase in all-cause mortality risk (<17.8 ng/ml 25(OH)D compared to >32.1 ng/ml). [1] However, because there are not yet enough randomized controlled trials to clearly and conclusively confirm the benefits of vitamin D supplementation for conditions unrelated to bone health [2], the IOM did not find the existing evidence for non-skeletal conditions sufficient enough to raise the daily recommendations any higher than 600 IU. The 600 IU figure is based solely on bone health – they did not take into account whether a greater quantity of vitamin D might be necessary to prevent non-skeletal diseases, even though there are vitamin D receptors in almost every cell of the human body.

Many experts are weighing in on – and disagreeing with – the IOM’s report, and there is general agreement among the experts on these points:

• The increase of the tolerable upper limit to 4000 IU is a positive change.
• The IOM’s definition of 20 ng/ml as a sufficient 25(OH)D is potentially low, and this could be dangerous for some people
• The lack of randomized controlled trials does not mean that we should ignore the epidemiological evidence showing vitamin D’s importance for preventing non-skeletal diseases.

Compare my recommendations to those of the IOM:

Recommendations:	25(OH)D	Vitamin D supplementation (adults)
Institute of Medicine	>20 ng/ml	600 IU
Dr. Fuhrman	35-55 ng/ml	2000 IU*

*adjust supplementation according to 25(OH)D level