The newest entry on the snake oil scene would seem to be vitamin D. I've lost track of all that this vitamin is supposedly good for -- everything from building strong bones to protecting us from strokes and heart failure to reducing our risk of cancer and on to helping us regulate our immune system and control inflammation, our blood pressure, and even our blood glucose. Recently, some people are even recommending it for respiratory problems ranging from the common cold to the H1N1 (swine) flu virus.
If even half of this is true, vitamin D must be the biggest health discovery since aspirin. But so far we have only a few generally accepted uses of vitamin D.
We've known since the early 1920s that vitamin D cures rickets and other diseases that soften our bones, including osteomalacia and osteoporosis. The U.S. Food and Drug Administration in 1994 approved a vitamin D preparation to treat psoriasis.
We just don't have enough evidence yet that vitamin D might cure or treat any of the other conditions. This is because most of the evidence comes from in vitro, animal, and epidemiological studies, rather than from the randomized clinical trials that would be definitive.
The American medical establishment is awfully conservative. Your doctor is especially careful to follow the received wisdom, because if you would get worse from any treatment that the medical authorities don't recommend and you sued, he or she would have a good chance of losing big time.
Think of all the pain and suffering the a single misguided treatment can cause. For example, doctors routinely prescribed hormone therapy to treat menopausal symptoms and to protect long-term health. Then, in 2002 a large clinical trial unearthed its health risks. It this case, the American medical establishment wasn't even conservative enough.
Think too of all of the people with diabetes whose lives may have been cut short because the American medical establishment demonized fat on the basis of little or no evidence. In this case, the establishment wasn't conservative enough originally but now is so conservative that it won't budge.
But just because we don't have enough scientific support for a low-carb (and therefore a high-fat) diet or for increasing the amount of vitamin D we get doesn't mean that each of us should stick to the accepted recommendations.
Those recommendations are for 200 to 600 IU of vitamin D per day, depending on how old you are. Even an official U.S. government site says, however, that they "were established in 1997, and since that time substantial new research has been published to justify a reevaluation of adequate vitamin D intakes."
That reevaluation is certain to come some day. But should we wait for it?
I'm not waiting. I want to be in the best possible health now, not when I'm 100 years old.
Still, I know that everything has a therapeutic level and a toxic level. The "tolerable upper intake level" for adults of vitamin D is 2,000 IU per day.
However, "several nutrition scientists recently challenged these ULs [Upper Intake Levels], first published in 1997," this government site says. "They point to newer clinical trials conducted in healthy adults and conclude that the data support a UL as high as 10,000 IU/day. Although vitamin D supplements above recommended levels given in clinical trials have not shown harm, most trials were not adequately designed to assess harm. Evidence is not sufficient to determine the potential risks of excess vitamin D in infants, children, and women of reproductive age."
For several years I have indeed been taking 10,000 IU of vitamin D every day. As I read the evidence this level is safe. I know that I've never had a cold in all the years that I've taken this much vitamin D.
Still, 5,000 IU per day is probably enough. In any case, you will have to decide for yourself. I can't make any medical recommendations and the government recognizes that its official recommendations are out of date.
Very few foods contain much vitamin D. Only cod liver oil and sockeye salmon have more than 400 IUs per serving. Our choices boil down to sunshine or vitamin D supplements. Especially now as winter grows close and we get much less sunshine we need to reconsider how much vitamin D we are getting.