תזונה ותוספים A potential design flaw of randomized trials of vitamin supplements.

[Mike Bikov]

JAMA. 2011 Apr 6;305(13):1348-9.
A potential design flaw of randomized trials of vitamin supplements.

Morris MC, Tangney CC.

Section of Nutrition and Nutritional Epidemiology, Rush University Medical Center, Rush-Oak Park Professional Office Bldg, 610 S Maple, Ste 4700, Oak Park, IL 60304, USA. [email protected]


Randomised controlled trials (RCTs) of vitamin supplements are usually conducted on the basis of positive findings from prospective epidemiological studies and laboratory evidence of biological mechanisms. A common view is that the negative findings from the RCTs offer incontrovertible evidence that the nutrient is unrelated to disease and that the epidemiological studies are biased. An alternative explanation is that most RCTs of vitamin supplements are designed to test the hypothesis that supplementation, no matter the nutrient status, is protective. Vitamin treatment may not be effective in these trials because nutrient intake among the participants is already at optimum levels. Examples are specified from the field of dementia and investigations of 3 dietary components: vitamin E, B vitamins and docosahexaenoic acid.


PMID: 21467288 [PubMed - indexed for MEDLINE]

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