On Wednesday, Nov 30, the Institute of Medicine’s Food and Nutrition Board issued a report saying in essence that supplemental vitamin D over 800 IUs was unnecessary and could even be harmful (more on this in a minute).
Should you ignore this report? Yes. And I’ll tell you why.
The committee looked only at the amount of vitamin D known to be needed for strong bones. That’s like evaluating an iPhone based solely on its built-in calculator. Vitamin D is important for bones, of course, but that’s only one tiny thing that this miraculous nutrient does.
Vitamin D expert William Grant, PhD, puts it this way:
“The health benefits of vitamin D extend to at least 100 types of disease, with the strongest evidence for many types of cancer (breast, colon, ovarian, pancreatic, prostate, and rectal), cardiovascular disease, diabetes types 1 and 2, respiratory infections such as type A influenza and pneumonia, other infections such as sepsis, and autoimmune diseases such as multiple sclerosis.”
There is a massive amount of research showing that low levels of vitamin D increase the risk for with every disease mentioned by Dr. Grant (above). What’s more, when people are low in vitamin D levels it affects their mood, ability to lose weight, physical performance, immune system function and even their chances of dying. (A 2008 study found that low levels of vitamin D increased the risk for death from any cause- called the mortality risk—by a whopping 26% compared to those who had “optimal” levels in their blood.)
Which brings us to the question of “optimal” levels, and the related question of toxicity.
Dietitians and doctors are mired in a culture that looks at vitamin needs solely in terms of what’s needed to prevent deficiency diseases. The “recommended daily allowance” for vitamin C is the amount you need to prevent scurvy; the recommended daily allowance for vitamin B1 (thiamine) is the amount you need to prevent beriberi.
I call this “minimum wage nutrition” and consider it utterly irrelevant to those interested in optimal health and well-being.
So what is the optimal level of vitamin D anyway? Well—not surprisingly– there’s some dispute about this. The above-quoted expert, Dr. William Grant, says it should be “at least 40-60 ng/mL”. According to Dr. Grant’s research(1) raising serum vitamin 25(OH)D levels to 40 ng/mL could reduce mortality rates by 15% in the United States, corresponding to a 2-year increase in life expectancy.
The vitamin D council thinks 50 ng/ml is the minimum acceptable level, and that optimal levels are between 50 ng/ml and 80 ng/ml.* (This is in line with what most experts I know believe to be ideal– many of them use 70 ng/ml or 80 ng/ ml as the optimal goal.)
It’s impossible to get anywhere near that number without supplements. And there’s virtually no chance of achieving it with the paltry 600 IUs a day recommended by the FNB.
The Food and Nutrition Board admits that 97% of Americans have a vitamin D level that falls within the range of 20 ng/ ml to 30 ng/ ml. A supplement of 600 IUs per day will increase vitamin D blood levels by a measily 6 ng/ ml. Someone with an “average” vitamin D level of 25 ng/ml would need to take at least 2000 IUs a day to bring it up to 45 ng/ ml, and according to the Vitamin D council—which is way more on top of this than the government’s Food and Nutrition Board—45 ng/ml doesn’t begin to cut it. Most people who know what they’re talking about are looking for optimal levels of 60-80.
According to vitamin D expert Zoltan Roma, MD, MSc, author of “Vitamin D: The Sunshine Vitamin”, “Research now indicates that the correct figure for the minimum daily requirement is 4,000 IUs”, adding that “it will probably take another decade before the government nutritional authorities acknowledge this fact and recommend higher vitamin D intakes for the population”.
Which brings us to the issue of toxicity.
The FNB also reported that vitamin D toxicity might occur at an intake of 10,000 IU/day (250 micrograms/day), although they could produce no reproducible evidence that 10,000 IU/day has ever caused toxicity in humans and only one poorly conducted study indicating 20,000 IU/day may cause mild elevations in serum calcium, but not clinical toxicity.
In an excellent review of all the literature on vitamin D, Reinhold Vieth, PhD, professor in the Departments of Nutritional Sciences, Laboratory Medicine and Pathobiology of the University of Toronto, had this to say:
“Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D.” He added: “If there is published evidence of toxicity in adults from an intake of 250 ug (10,000 IU) per day, and that is verified by the 25(OH)D concentration, I have yet to find it.”
Vieth reports human toxicity probably begins to occur after chronic daily consumption of approximately 40,000 IUs a day (about 100 of the typical 400 IU capsules). Dr. Rona says that “real toxicity begins at 40,000 IUs a day after only many weeks of use”. Let’s remember that the body itself will easily make 10,000 IUs a day in a few hours in the sun. As one cynic commenting on the new report put it, “I guess they think God doesn’t know what she’s doing”.
It’s very sad that this report- which has been horribly reported by the mainstream media with headlines like “vitamin D can be dangerous” will probably scare off many people who would benefit enormously from taking supplements of this important nutrient.
I recommend that people take at least 1000IUs, preferably 2000IUs of Vitamin D daily.
*Remember that there are two ways to measure vitamin D in the blood; don’t confuse the measurements. In the US we usually use ng/ml, but the international measure is nmol/ mL. So if someone tells you their level is “50” be sure to ask which measurement they’re using. (A measurement of 50 ng/ml is equal to 124.8 nmol/L.)
1) Grant, WB, “In defense of the sun: An estimate of changes in mortality rates in the United States if mean serum 25-hydroxyvitamin D levels were raised to 45 ng/mL by solar ultraviolet-B radiance”, Dermato-Endocrinology, 2009; 1(4): 207-14