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JPEN J Parenter Enteral Nutr. 2012 Mar;36(2):159-68. doi: 10.1177/0148607111416485. Epub 2012 Jan 24.

Do dietary supplements have beneficial health effects in industrialized nations: what is the evidence?

Author information

1
Department of Medicine and the Nutrition Study Group, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA. marikpe@evms.edu

Abstract

BACKGROUND:

Dietary supplements are regularly used by at least half of the American population, yet the health benefits of these agents are unclear.

OBJECTIVE:

A systematic review to determine the benefits and risks of dietary supplements in Westernized societies.

DATA SOURCES:

MEDLINE, Embase, Cochrane Register of Controlled Trials and citation review of relevant articles.

STUDY SELECTION:

Randomized, placebo-controlled clinical trials in non-pregnant Westernized adults that evaluated clinical outcomes of nutritional supplements.

DATA EXTRACTION:

Data were abstracted on study design, study size, study setting, patient population, dietary intervention and clinical outcomes. The outcome of each study was classified as non-beneficial, beneficial or harmful according to whether the end-point(s) of interest reached statistical significance.

DATA SYNTHESIS:

Sixty-three studies met the criteria for our systematic review. No benefit was recorded in 45 studies, with 10 of these showing a trend towards harm and with two showing a trend towards benefit. Four studies reported harm with increased cancer deaths (n=2) and increased fractures (n=2). Two studies reported both a harmful as well as a beneficial outcome. A beneficial outcome was reported in 12 studies; 6 which studied vitamin D and three which investigated omega-3 fatty acids. While a benefit was reported in one study each which investigated Vitamin E, folic acid and Ginkgo biloba this benefit was not confirmed by larger and more adequately powered studies.

CONCLUSIONS:

With the possible exceptions of Vitamin D and omega-3 fatty acids there is no data to support the widespread use of dietary supplements in Westernized populations; indeed, many of these supplements may be harmful.

PMID:
22275325
DOI:
10.1177/0148607111416485
[Indexed for MEDLINE]

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