Monday, June 03, 2013

Should You Take Vitamin D?

There are pros and cons. A deficiency of vitamin D leads to osteomalacia or rickets. Too much can lead to kidney stones. And the source for vitamin D used in most supplements is solvent-treated, irradiated sheeps' wool fat, not the kind of wholesome nutrient our ancestors were likely to have ingested. Still, should most of us be taking a vitamin D supplement? Not even endocrinologists who want to agree, cant:

To [Vitamin] D or Not to D? That Is the Question, Medscape, April 2013

Two experts in the field of vitamin D debated the subject at the 2013 European Congress on Endocrinology.

Dr. Chantal Mathieu from Catholic University in Belgium says we would all benefit from taking a vitamin D supplement.
"There are correlations in large observational studies "indicating that if you are vitamin-D deficient you get more cancer, especially colon cancer, you get more cardiovascular diseases, your immune system doesn't function properly, and overall you have a higher risk of dying."

"It's too expensive to go around and measure vitamin-D levels in everybody. My argument would be to stop measuring levels in everybody. It's nonsense. There is a very easy way to prevent all of this, and that is to give small doses of vitamin D to the whole population."

Dr. Mark Cooper from University Hospital in Birmingham, UK says only a small segment would benefit from taking vitamin D, and there may be more harm than good in supplementing everyone:
"I am an investigator in randomized clinical trials of vitamin D, and I have nothing personally against [it], and I use it in my patients. But I tend to give it to people who actually need it, and that doesn't really include most of us,"

And Dr. Cooper — who noted that there is a huge sector of the scientific community that is "evangelical" in its pro–vitamin-D stance — warned that physicians have been here before, with many other nutrients that subsequently, in large intervention trials, turned out to have a null effect or even be harmful. In fact, there is already evidence of risks with supplements of vitamin D from randomized clinical trials, with no evidence of benefit, he argued.

"Vitamin D — we all need more? Most of us don't, and more could actually do more harm than good."
Cooper said that more telling gold standard randomized clinical trials don't support the hypotheses generated by the observational studies that Mathieu cited. The RECORD trial, which looked at vitamin-D supplementation in 5000 women showed:
"... Absolutely nothing, [at least] to falls and fractures. ... The Women's Health Initiative, with 36 000 people [taking vitamin D] combined with calcium, didn't show any effect whatsoever. It did show, however, that [vitamin D plus calcium] caused kidney stones, a 17% increase, which is not medically insignificant."

He went on to list a number of other, recent randomized clinical trials with vitamin D, for conditions such as cognition, muscle strength, cancer, osteoarthritis, TB, etc. "Different doses of vitamin D, different groups, all well-designed, all in major journals, and all negative." He added that at least one in 20 of these studies "should be positive" just by chance, "but we haven't seen that yet.""

So, everyone doesn't need to take vitamin D; taking it is not benign, it can cause kidney stones; and even if it's warranted, small doses are best:
"But the key, [Mathieu] said, is to use smaller doses of vitamin D than have previously been recommended. The US Endocrine Society guidance, for example, advises supplementation with up to 2000 IU per day, but this is overzealous, she said. "A more reasonable dose is 600 to 800 IU per day," she noted, adding that she is an author on a new guidance, soon to be published in the Journal of Clinical Endocrinology and Metabolism, which will state that 2000 IU per day "is not warranted.""
One thing Mathieu and Cooper agreed on:
"They also agreed on one way people can obtain more vitamin D: by going out in the sun for 30 minutes per day."
Photo by Ingrid Brandt.

1 comment:

caulfieldkid said...

So if I remember correctly, higher impact exercise (like running) strengthens bones. If you do that outside in the sun ...

It's not a solution for everybody, but I bet it is for a lot of folks.