In 2008, the NHMRC commissioned the Dieticians Association of Australia to undertake systematic literature reviews to support the revision of the Dietary Guidelines for Australians. The primary aim was to undertake a series of systematic reviews of the national and international literature from the year 2002 on the food-diet-health-disease inter-relationship for different population subgroups. One of the 29 sections in the report (pp 613-678) covered the evidence for the risks and benefits of alcohol drinking. This critique is only of the alcohol section.
The systematic reviews were primarily conducted using the methods described in the NHMRC publication “How to use the evidence: assessment and application of scientific evidence”, and have resulted in body of evidence statements. Databases searched were CINAHL, PREMEDLINE, MEDLINE, EBM REVIEWS, DARE, COCHRANE, PUBMED, PSYCHINFO, ERIC and SCIENCE DIRECT. All reviewers were dieticians. The search considered only evidence published from 2002, to provide an update on literature published since the last edition of the Dietary Guidelines for Australians. The searches were mostly carried out to April 2009, so more recent publications are generally not included unless specifically requested by the NHMRC.
The report noted that when examining diet-health relationships, there is a notable dearth of evidence from Level I and Level II studies, and much of the scientific evidence is observational, especially from prospective cohort studies. It is rarely possible to conduct blinded intervention studies with whole foods or diets, and very few trials are conducted for long enough periods to assess long term health outcomes. Therefore in the review authors’ view, Level III prospective cohort studies often provide more important evidence for the development of dietary guidelines than Level I evidence summarising small short-term randomised controlled trials.
The review did not use cross-sectional epidemiological studies because of their low rating in the NHMRC evidence hierarchy (Level IV evidence) and because correlation cannot be used as evidence of causation. Only studies that provided total alcohol intake in grams, or enabled its calculation, were included. > > > > Read More
