Topical Area: Aging and Chronic Disease
Objectives : Qualitatively, nutrition science and policy experts recognize that variation in muscle food categories (CAT) and descriptions (DESCR) hinder effective translation of research into policy. The purpose of this systematic review was to quantitatively describe CAT and DESCR patterns in nutrition-related chronic disease literature.
Methods : We identified 3,427 articles in PubMed, Cochrane, and CINHAL up to March 2018. Inclusion criteria were: 1) observational (OBS) or randomized controlled trial (RCT) designs, 2) muscle food consumption as an independent variable, 3) primary prevention of cardiovascular disease, obesity, type 2 diabetes, or cancer as a dependent variable, 4) population 19+ years, and 5) females not pregnant/lactating. We considered a CAT as the phrase researchers used to refer to a muscle food group and DESCR as the explanation of a CAT. Table 1 describes our empirical scoring scale. We used generalized linear mixed models to assess effect of publication date, one-way ANOVAs to assess differences between study designs and chronic disease types, and binary logit models to estimate probabilities of DESCR factors.
Results : We identified 1,019 CAT and 833 DESCR from 369 articles. Mean CAT specificity for RCT and OBS was 2 and 3 points, respectively (out of 7; Table 1), with no differences among chronic disease types. Specificity of OBS CAT was higher in more recent publications but RCT CAT became less specific in the 2000s compared to previous years. RCT CAT were 5x more likely to include species, 6x more likely to include leanness, but 5x less likely to include processing degree compared to OBS CAT. Among all CAT, 76% and 82% included a DESCR for OBS and RCT, respectively. Researchers described processed meat, red meat, and total meat categories more commonly than poultry or fish categories. Of processed meat DESCR provided by researchers, 31% included a common term used in publicly available regulatory definitions.
Conclusions : Muscle food categories and descriptions are substantively different within and between observational and experimental studies and do not match definitions used by regulatory agencies. A practical muscle food classification system is warranted to improve interpretation of evidence regarding muscle food consumption and chronic disease.
Funding Sources : The Beef Checkoff
National Cancer Institute
Doctoral student, Department of Animal Science
Colorado State University
Texas Tech University
Colorado State University
Center on Aging and the Life Course