The Institute of Medicine’s conservative position on vitamin D is understandable given the history of hyped vitamin supplements (vitamin A, beta carotene, folic acid, vitamin C, vitamin E) that turned out worthless or worse.
The Institute of Medicine raised their vitamin D recommendations based on a blood level target of 20 (ng/ml) to prevent bone softening disorders such as rickets. Although the Institite’s target of 20 may “prevent the overt skeletal deformities associated with rickets, there is now,” according to a review last year, “overwhelming and compelling data suggesting that the human body requires a blood level of above 30 ng/mL for maximum health.” Dr. Holick bases this assertion on data like this, a graph not of rickets risk, but of colon cancer risk versus vitamin D levels suggesting that the Institute of Medicine’s 20 is good, but 30 or more may be even better if you’re considering vitamin D from the cancer prevention angle instead of just strictly skeletal health.
There are similar graphs for breast cancer risk, multiple sclerosis and other conditions linked to vitamin D status. Instead of going through each lets just jump straight to total mortality. What blood level of vitamin D will enable us to, on average, live longest? Here’s the graph, and as you can see, it’s kind of a U shaped curve.
Not having enough in our bloodstream is associated with higher mortality; but looks like we can have too much as well. So what’s the sweet spot in the middle, the lowest mortality risk? This is the Institute of Medicine recommendation, 20 ng/ml (which translates to the 50 nanomoles per liter you see here). Here’s 30 (75) and this is 40 (100).
So for longevity, around 30 would seem the best target. So one strategy to arrive at a vitamin D recommendation would be to figure out how much sun and/or supplements we might need take to get our levels to 30.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by veganmontreal.
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Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. This is the third video in a nine day series on vitamin D. Be sure to check out yesterday's video-of-the-day Evolutionary argument for optimal vitamin D level.
For some context, please check out my associated blog posts: Vitamin D: Shedding Some Light on the New Recommendations, Acai to Zucchini: antioxidant food rankings, Eating To Extend Our Lifespan, and Vitamin D from Mushrooms, Sun, or Supplements?