What the Institute of Medicine SHOULD have said 1. December 2010 William Davis (47) The news is full of comments, along with many attention-grabbing headlines, about the announcement from the Institute of Medicine that the new Recommended Daily Allowance (RDA) for vitamin D should be 600 units per day for adults. What surprised me was the certainty with which some of the more outspoken committee members expressed with their view that 1) the desirable serum 25-hydroxy vitamin D level was only 20 ng/ml, and 2) that most Americans already obtain a sufficient quantity of vitamin D. Here's what I believe the Institute of Medicine SHOULD have said:Multiple lines of evidence suggest that there is a plausible biological basis for vitamin D's effects on cancer, inflammatory responses, bone health, and metabolic responses including insulin responsiveness and blood glucose. However, the full extent and magnitude of these responses has not yet been fully characterized. Given the substantial observations reported in several large epidemiologic studies that show an inverse correlation between 25-hydroxy vitamin D levels and mortality, there is without question an association between vitamin D and mortality from cancer, cardiovascular disease, and all cause mortality. However, it has not been established that there are cause-effect relationships, as this cannot be established by epidemiologic study. While the adverse health effects of 25-hydroxy vitamin D levels of less than 30 ng/ml have been established, the evidence supporting achieving higher 25-hydroxy vitamin D levels remains insufficient, limited to epidemiologic observations on cancer incidence. However, should 25-hydroxy vitamin D levels of greater than 30 ng/ml be shown to be desirable for ideal health, then vitamin D deficiency has potential to be the most widespread deficiency of the modern age. Given the potential for vitamin D's impact on multiple facets of health, as suggested by preliminary epidemiologic and basic science data, we suggest that future research efforts be focused on establishing 1) the ideal level of 25-hydroxy vitamin D levels to achieve cancer-preventing, bone health-preserving or reversing, and cardiovascular health preventive benefits, 2) the racial and genetic (vitamin D receptor, VDR) variants that may account for varying effects in different populations, 3) whether vitamin D restoration has potential to exert not just health-preserving effects, but also treatment effects, specifically as adjunct to conventional cancer and osteoporosis therapies, and 4) how such vitamin D restoration is best achieved. Until the above crucial issues are clarified, we advise Americans that vitamin D is a necessary and important nutrient for multiple facets of health but, given current evidence, are unable to specify a level of vitamin D intake that is likely to be safe, effective, and fully beneficial for all Americans. Instead of a careful, science-minded conclusion that meets the painfully conservative demands of crafting broad public policy, the committee instead chose to dogmatically pull the discussion back to the 1990s, ignoring the flood of compelling evidence that suggests that vitamin D is among the most important public health issues of the age. Believe it or not, this new, though anemic, RDA represents progress: It's a (small) step farther down the road towards broader recognition and acceptance that higher intakes (or skin exposures) to achieve higher vitamin D levels are good for health. My view: Vitamin D remains among the most substantial, life-changing health issues of our age. Having restored 25-hydroxy vitamin D levels in over 1000 people, I have no doubt whatsoever that vitamin D achieves substantial benefits in health with virtually no downside, provided 25-hydroxy vitamin D levels are monitored.