A report published in the Times on November 29, 2010 (http://www.nytimes.com/2010/11/30/health/30vitamin.html?_r=2&hp) has created some alarm amongst people taking vitamin D supplements. The NY Times report alluded to the deliberations of a 14 person expert committed assembled by the Institute of Medicine in the US. This group has been meeting regularly since March 2009, attempting to frame Dietary Reference Intakes (DRIs) for vitamin D and calcium, that is they were looking at coming up with the Estimated Average Requirement, which is the amount estimated to satisfy the needs of 50% of people in the American population. The report was released on November 30, 2010. A press release from the IOM states that “Most Americans and Canadians up to age 70 need no more than 600 international units (IUs) of vitamin D per day to maintain health…”. They suggested an upper safe limit of supplementation as 4,000IU per day. The report also noted that all North Americans are receiving enough calcium and vitamin D.
Most people reading this report would be very surprised about these findings. Haven’t we been reading paper after paper about the worldwide epidemic of vitamin D deficiency due to sun avoidance? But the findings can be explained partly by the purpose of the committee, which was to update longstanding and out of date dietary reference values for vitamin D and calcium. DRIs were introduced in 1997 to broaden existing guidelines known as Recommended Dietary Allowances (RDAs) that were used in the US, Canada and Australia to provide nutrition advice with a substantial margin of safety. The RDA was essentially the minimum intake required to meet the requirements of 97-98% of healthy individuals. Additionally, the findings can be partly explained by such committees’ requirements for absolutely proven evidence, much like the Cochrane Collaboration. Most people reading the reviews in the Cochrane Database are struck by the fact that it is almost impossible to prove anything in medicine, and that most of their reviews come out with the conclusion that there is not enough evidence on a particular topic to make definite recommendations, and that more research is needed. The IOM committee for example, made the recommendation that there is evidence that vitamin D was helpful in bone health, but had not been proven to be helpful in any other condition. If we had taken the same approach when Doll and Hill’s groundbreaking epidemiological study came out in 1950 about cigarette smoking causing lung cancer, we would have lost thousands more lives to lung cancer while we waited for definitive proof.
The truth is, as we have long said on this website and in the books ‘Taking Control of Multiple Sclerosis’ and ‘Overcoming Multiple Sclerosis’, there is compelling evidence that vitamin D deficiency increases the risk of developing MS, and that vitamin D supplementation reduces that risk and very likely reduces the risk of progression of the disease. Most of the evidence supporting these contentions is outlined on this site and in the books; a lot of it appears in the What’s New section, and is very recent, certainly appearing after this committee began preparing its report. For instance, the Southern Tasmanian Longitudinal Cohort Study showed that for every 10nmol/L increase in blood vitamin D level, there was a 12% decrease in the risk of relapse. Further, this was a clear dose-response curve, and extrapolating their data to a zero risk suggested that a level of around 150nmol/L was the minimum protective level. There is much supporting data around this issue on this site and in the books that readers can look into for themselves.
The problems with the IOM report are that this was not their brief, to examine what supplement amount would be best for people with serious illness, just to look at an average requirement for healthy people. And this was just an average amount needed for maintenance, not even for the prevention of serious illness, let alone its treatment. New data are appearing all the time on the potential of vitamin D to prevent a variety of cancers in addition to heart disease, depression, hypertension, diabetes, and so on, as well as osteoporosis. The IOM focused completely on bone health. But as we have long said here, higher doses and higher blood levels of vitamin D are required for management of autoimmune illness than for maintenance of bone health.
To look a little more closely at what the IOM said, their recommendations about not taking large doses of calcium were actually sensible, and we have been arguing this for some time, based on good evidence. Enough said. But with vitamin D, firstly they demanded too high a standard of proof that vitamin D is helpful in conditions other than bone disease, like MS, and secondly they raised the old spectre of toxicity, saying “The onus is on the people who propose extra calcium and vitamin D to show it is safe..” Well, we have very responsibly advised people not to take calcium supplements, as they suggest, because the evidence shows that calcium supplementation is not safe.
But as far as vitamin D goes, the IOM report did not show supplementation is dangerous, they just demanded proof that higher doses are safe. Of course, proving something is safe is much harder than proving something is dangerous. Just one case report of someone coming to harm from taking 10,000IU a day of vitamin D a day would be considered proof that it is dangerous. But, clearly, they were unable to provide that proof, as that hasn’t been reported. Indeed, Hatchcock et al’s 2007 review paper noted that the estimated blood level associated with hypercalcemia, the major toxic side effect was 600nmol/L, and that the safe Tolerable Upper Intake Level of vitamin D was 10,000IU per day. That paper is downloadable above right for those wanting to see the evidence first hand. The IOM’s report conveniently ignores the fact that people in sunny countries often have levels around 200nmol/L without taking supplements, a level that would require at least 10,000IU of vitamin D a day if one was achieving this with supplements. It also ignores the reality that just by standing out in the sun with bathers on in Melbourne at midday today for 10 minutes, you would make 15,000IU of vitamin D. Why would the upper limit of safe intake be 4,000IU, as suggested by the IOM?
It is important for people with MS trying to do the best for their health not to be deterred by such reports. The approach at OMS is to make recommendations based on a distillation of the best and most recently available evidence that will allow people with MS to immediately and safely apply new research to their condition, without having to wait for years for scientists and expert groups to catch up. In this case, it is about balancing risks: the risk of what will happen to people with a serious progressive neurological disorder like MS waiting until such groups decide that vitamin D supplementation is proven beyond doubt to prevent and improve the outcome from MS far outweighs the remote potential risk of toxicity from supplementation at the doses we recommend. To date, such side effects have been reported only in people taking 40,000IU a day or more. We reiterate, people with MS should check their vitamin D levels annually aiming for a blood level of vitamin D that is high-normal, around 150nmol/L or more, but not above the top of the normal range which is about 225nmol/L depending on the laboratory (even though this allows for a margin of safety probably up to about 500nmol/L). This can be achieved with regular low dose sun exposure plus vitamin D supplements; if sun exposure is low or not possible, this may require supplementation with doses up to 10,000IU a day.