U.S. Increases Recommendations for Vitamin D Intake but Misses the Mark

U.S. Increases Recommendations for Vitamin D Intake but Misses the Mark

As you probably know from news reports, the recommendations for individual consumption of vitamin D has now increased, as has the tolerable Upper Limit (UL) that indicates a higher intake level at which the vast majority of people will not suffer any unpleasant side effects. But these recommendations are controversial for being too conservative, and at the same time the report has been sensationalized in the popular media with an inappropriate emphasis on possible side effects of megadoses.

The Institute of Medicine (IOM), the health arm of the National Academy of Sciences, is an independent, nonprofit organization that works outside of government to provide unbiased and authoritative advice to decision makers and the public. Through more than three dozen sets of guidelines, known as Dietary Reference Intakes (DRIs), IOM provides estimates of the amounts of nutrients that individuals need to consume each day. Health care professionals and policy makers, including federal nutrition officials who develop nutrition programs as well as the food industry, rely on this guidance from the IOM. The reference numbers that you see on food and dietary supplement labels, such as Daily Values (DV), DRIs, and Recommended Daily Allowances (RDAs), are generated by IOM. (1) These values are also utilized by some foreign governments as authoritative references on which to base their own food and supplement regulations.

The good news is that, in a report issued by IOM on November 30, 2010, the RDA has now increased by 50% (from 400 IU to 600 IU) and the tolerable Upper Limit has now doubled (from 2,000 IU to 4,000 IU). Also, the RDA for adults over 71 years old has increased to 800 IU daily. (2) This means that the new recommendations are often higher than the 400 IU that is found in a typical multivitamin or calcium+D formula, thus requiring additional supplementation to meet the RDA. And the leeway for safe use at the upper end is now double what it was before, making such supplementation at higher levels still within a margin generally accepted as safe; at least up to 4,000 IU, though as usual that number is deliberately set low and has a large safety margin.

IOM’s report stating that most Americans have adequate circulating levels of vitamin D is somewhat controversial, as it utilizes a standard of 20 ng/mL (equivalent to a measure of 50 nmol/L) (3) that is not universally accepted as adequate for optimal health by many modern vitamin D researchers. While that amount may adequately support bone health, which was (as usual) the primary focus of the IOM committee, there are vitamin D receptors on many other human cells and this vitamin reportedly plays an important role in cardiovascular disease (4), immune health (5), prostate and breast health (7), blood sugar metabolism (6), cancer prevention (7,8) , and a host of natural processes. One recent report stated that, “The desirable serum 25 (OH) D levels is at least 100 nmol/L, a level that has generally been found to provide most of the health benefits of vitamin D.” (9) This recommendation is twice as high as the new RDA, evidencing the controversial nature of IOM’s RDA process.

However, the IOM committee admittedly based its recommendations solely on vitamin D’s effects on bone health after reviewing numerous studies on other benefits and concluding that more study is required to generate the level of evidence that IOM requires to set its recommendations. Committee chair Catharine Ross was quoted as saying, “Amounts higher than those specified in this report are not necessary to maintain bone health.” (10) As the amount of science in these other areas grows, so should the levels recommended for general health. But statements such as that by Dr. Ross that “people don't need more than the amounts established in this report” refer only to bone health and should not be construed as denying the fact that other benefits at higher levels of intake have been reported, though not as consistently as the IOM committee would need to accept them as conclusive enough to revise its recommended levels upward.

Based on current research, natural health advocates typically recommend levels 50-100% higher than the IOM report recommends in order for people to obtain the full protective benefits of vitamin D, and many physicians who test for this vitamin ask their patients to meet or exceed that higher level. This is perhaps the most controversial part of the report, and I predict that a barrage of higher numbers appearing in medical reports as protective will force another overdue round of RDA changes in perhaps another 10-15 years. In my opinion, the IOM is always behind the times in the area of nutrient recommendations, being by nature super cautious. We dared to hope, but nobody really expected the IOM panel to accept the evidence of recent published review studies in medical journals and raise both the RDA and UL to the recommended five times their previous levels, and frankly we were not surprised that they didn't. These special panels are typically very conservative and hesitant to make dramatic changes, and are comprised with well-qualified general nutrition experts but not with experts in the particular area in question who might push for acceptance of higher levels.

People have already been taking over 2,000 IU daily, the old tolerable Upper Limit, without apparent harm and will probably continue to take over the new 4,000 IU UL as well. Clinical science indicates that higher levels are still quite safe, at least up to 10,000 IU daily for most adults. In 2007 a review published in the American Journal of Clinical Nutrition applied the same risk assessment methodology used by the Food and Nutrition Board (FNB) to derive a proposed revision of the safe Tolerable Upper Intake Level (UL) for vitamin D. (11) Noting an absence of toxicity in trials conducted in healthy adults that used a vitamin D dose ≥250 µg/d (up to 10,000 IU of vitamin D3), a new UL of 10,000 IU was confidently proposed, but was apparently not accepted by the IOM. Nor was the recommendation for a new RDA to be raised to 2,000 IU.

In fact, the 10,000 IU daily UL proposal may have been conservatively low; so what does that make the revised tolerable UL of only 4,000 IU? According to a report in the journal Nutrition Reviews, "The input needed for efficacy, in addition to typical food and cutaneous [sunlight] inputs, will usually be 1000-2000 IU/day of supplemental cholecalciferol [vitamin D3]. Toxicity is associated only with excessive supplemental intake (usually well above 20,000 IU/day)." (12) [Italicized words added for clarity]

Dietary supplement manufacturers already were not allowed to make disease claims on dietary supplements without (always reluctant) FDA approval, so the IOM’s report that vitamin D has not been proven to prevent various diseases is not news for them. However, consumers will continue to be exposed to positive reports on the vitamin and most will understand that just because it has not yet been "proven" to prevent certain diseases doesn't mean that it doesn't, especially at levels higher than needed purely for bone health, nor does it suggest that there is no supporting evidence that it still may be an important preventative factor.

The government standard of proof in the dietary supplement area has been frequently criticized and the FDA in fact has lost several federal court cases, where courts have ordered the agency to comply with the law allowing such claims where substantial evidence already exists for some supplements’ role in disease prevention (for example, selenium and cancer). (13,14) Of course, almost never is anything "proven" in a scientific field; theories rule most scientific endeavors. But that should not suffice to allow the government to muzzle legitimate science nor to prevent the public from taking natural nutrients at levels that they may require due to their own individual biochemistry and relevant environmental factors. In this case, the new RDA and UL are simply baby steps in the right direction, but perhaps the full knowledge of vitamin D’s health benefits is still in its infancy.

REFERENCES:

1. http://www.iom.edu/About-IOM.aspx Accessed November 30, 2010
2. Dietary Reference Intakes for Calcium and Vitamin D. Food and Nutrition Board, Institute of Medicine, National Academies. Released: November 30, 2010
3. http://ods.od.nih.gov/factsheets/VitaminD-Consumer/ Accessed November 30, 2010
4. Wallis DE, Penckofer S, Sizemore GW. The "sunshine deficit" and cardiovascular disease. Circulation. 2008 Sep 30;118(14):1476-85. Review. Erratum in: Circulation. 2009 Jun 2;119(21):e550. PubMed PMID: 18824654.
5. Cannell JJ, Zasloff M, Garland CF, Scragg R, Giovannucci E. On the epidemiology of influenza. Virol J. 2008 Feb 25;5:29. Review. PubMed PMID: 18298852; PubMed Central PMCID: PMC2279112.
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7. Skinner HG, Michaud DS, Giovannucci E, Willett WC, Colditz GA, Fuchs CS. Vitamin D intake and the risk for pancreatic cancer in two cohort studies. Cancer Epidemiol Biomarkers Prev. 2006 Sep;15(9):1688-95. PubMed PMID: 16985031.
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9. Grant WB, Schwalfenberg GK, Genuis SJ, Whiting SJ. An estimate of the economic burden and premature deaths due to vitamin D deficiency in Canada. Mol Nutr Food Res. 2010 Aug;54(8):1172-81. PubMed PMID: 20352622.
10. http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=13050 Accessed November 30, 2010
11. Hathcock JN, Shao A, Vieth R, Heaney R. Risk assessment for vitamin D. Am J Clin Nutr. 2007 Jan;85(1):6-18. Review. PubMed PMID: 17209171.
12. Heaney RP. Vitamin D: criteria for safety and efficacy. Nutr Rev. 2008. Oct;66(10 Suppl 2):S178-81. Review. PubMed PMID: 18844846.
13. http://www.emord.com/FDA_Agrees_to_Allow_Selenium_Qualified_Health_Claims.html Accessed November 30, 2010
14. http://www.kelleydrye.com/publications/client_advisories/0576 Accessed November 30, 2010