Thursday August 8, 2013
I never ceased to be amazed at how important medical issues are presented in the media (at least most of the time). The current hubbub about vitamin D is no exception.
There is NO question vitamin D is important in building strong bones in kids and helping (along with calcium, exercise and good fortune) prevent osteoporosis, particularly in post - menopausal females.
Lately, however, there has been an onslaught of talk about vitamin D and coronary heart disease (CHD). This talk has been MOST misleading. My goodness, even the Journal of the American Medical Assn. is now guilty, as this week they allowed authors of an article to write "low circulating concentrations ...of vit D...consistently associated with clinical and subclinical ...CHD" This is true in only the most tangential way.
The facts of the matter are these: THERE IS NO PROOF (a key word here, eh?!?) WHATSOEVER LOW VIT D LEVELS CAUSE CHD!!!!!!!!!!!! NONE.....ZERO....NADA
There have been retrospective analyses SUGGESTING there might be a link between low vit D levels and CHD incidence. However, the ONLY way to prove something observed in a retrospective analysis is to test that theorem in randomized, clinically - controlled trials. The good news is there are five such trials currently either underway or enrolling patients. We will see if PROOF of a causal association emerges from these trials.
You say, Tim, why are you so fired up over all of this? Why don't you just tell folks to take plenty of vit D in the interim, in case there IS a causal assn. between low vit D levels and CHD.
Well, vit D in excess dosage MAY damage the liver, manifesting itself in a chemical hepatitis sort of picture, which could cause significant changes in how other drugs one might be taking are metbolized. I see a couple cases of abnormal liver function tests from vit D each year.
Anyone can likely get away with 1,000 - 2,000 U of vit D daily without any problems. Some folks, most females with osteopenia or osteoporosis need more. I cannot imagine anyone needing 5,000 U or more daily.
The ONLY way to prove a causal assn. between various risk factors, substances or anything else and later events is with a randomized, controlled prospective (NOT retrospective analysis)clinical trial, with the results published in a scientific journal after prior peer review. The vitamin D cheerleaders have cleared NONE of those hurdles.
When the results of VITAL (Vitamin D and Moega-3 Trial) are published, you'll read about it here...after I read about it in The New England Journal, Annals of Int Medicine, Circulation, JAMA or some other peer - reviewed scientific journal.