Is Vitamin D Toxic?

Recently a government agency known as The Institute of Medicine weighed in on the topic of vitamin D. After convening a 14 member panel of researchers to analyze over 1,000 published studies on vitamin D, the IOM made the following recommendations:

  • Infants should get no more than 400 IU of vitamin D daily
  • Adults should limit intake to 600 IU of vitamin D per day
  • Pregnant women should get 600 IU of vitamin D per day

What’s The Harm?

The New York Times, The Wallstreet Journal and other newspapers love controversy. They published headlines such as, “Can Too Much Vitamin D Be Hazardous to Your Health?” These articles suggested that more than the 600 IU of D may pose hazards even though the IOM themselves suggested that the safe upper limit of D is 4,000 IU (up from their previous 2,000 IU recommendation).

Many people confused the recommendation to take 600 IU as an indication that more was toxic. This is an inaccurate interpretation of the IOM recommendations. Remember, the 600 IU adult dose that was suggested is a recommended daily allowance, not a suggestion that higher doses may be toxic. In the IOM’s report, they suggest that a dose over 10,000 IU per day is toxic, even though they failed to provide proof of such toxicity.

What Harm?

According to the IOM, doses over 10,000 IU could cause damage to kidneys and other tissues, once again they came to this conclusion without providing reproducible proof of such side effects. It should be noted that the body will produce up to 10,000 IU of vitamin D from simple sun exposure, is the IOM suggesting that nature messed up?

I should point out that the IOM decided on its position regarding the safety of vitamin D based on the philosophy that because there is little evidence that higher doses of D are safe, we should assume it is toxic. Although I agree that we should exercise caution when taking high doses of anything, including vitamins, I feel that they should be more responsible with how they phrase such caution.

How Do We Know That It Is Safe?

First, let me point out that even the IOM, a notoriously conservative organization, suggests that doses up to 4,000 IU appear to be safe, meaning the research suggests that there is no toxicity at this dose. In other words, if you take up to 4,000 IU per day, you have absolutely nothing to worry about. The debate is whether or not doses above this 4,000 IU range are safe.

Personally, I typically do not recommend taking more than 4,000 IU per day unless we have blood tests that suggest that we need more. If, however, blood tests continue to be suboptimal on doses of D up to 4,000 IU, is the IOM suggesting that we not take more?

What Are We Missing?

Unfortunately, it appears that the IOM is not being forthcoming with all of the recommendations from the individual experts on the panel. In fact, some of the experts on the panel were staunch advocates for the safety and efficacy of higher dose vitamin D. Their reports, however, are being suppressed by the IOM. This means we can not read the recommendations of these experts, we are only provided access to the final paper of the IOM. The Vitamin D Council is in the process of filing, under the Freedom of Information Act, a lawsuit to have those reports made public. It makes you wonder what they are hiding.

What Should You Take Away from this Paper?

The purpose of today’s article was to defend the safety record of vitamin D, not to get into the mountains of research that support the use of vitamin D for the prevention of diseases such as heart disease, cancer, and brain dysfunction.

Based on this paper alone, we can establish the following:

  1. Vitamin D is extremely safe up to doses of 4,000 IU per day
  2. Vitamin D is probably safe up to doses of 10,000 IU, provided you are monitoring blood tests and keeping the blood levels within the optimal range of 50-80 ng/ml
  3. 400 IU per day is likely a sufficient dose for infants
  4. 600 IU is way too low for pregnant women and adults, even though the IOM suggests that it is sufficient
  5. Blood testing is recommended to assure that you are within the optimal range.
  6. The IOM provides no definitive evidence that higher doses of vitamin D are toxic; they are assuming toxicity based on a lack of evidence that doses higher than 4,000 IU per day are safe.

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