The Challenging Chase for Nutrigenetic Predictors of Metabolic Responses to Dietary Interventions

Development of the metabolic syndrome (MetS) is influenced by genetic and environmental factors. It is of interest to identify genetic factors associated with changes in MetS in response to dietary interventions to maximize the individual benefits gained from preventive or therapeutic measures (i.e., personalized nutrition). In this issue of Diabetes Care , Qi et al. (1) examined the contributions of two genetic variants (rs1522813 and rs2943641) near the insulin receptor substrate 1 ( IRS1 ) gene and their interactions with dietary fat intake on the reversion of the MetS using the data of the Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST) study. The POUNDS LOST study was a 2-year population-based trial in which 811 overweight and obese adults (64% females) were randomly assigned to one of four diets (2). The percentage of calories derived from the macronutrients varied 20–40% for dietary fat, 15–25% for protein, and 35–65% for carbohydrates. A total of 645 subjects were defined as completers and they lost 4 kg on average with no significant differences among the four dietary groups. MetS was present in 32% of the participants at baseline and this prevalence was reduced to ∼20% at 2 years with no differences between diet groups. Participants changed their diets in the direction of the specified macronutrient goals, but these goals were not fully achieved. For instance, the reported fat intake at 2 years differed from the targets by almost 7 percentage points, with the differences being ∼7% higher for the 20% dietary fat diet group and ∼7% lower for the 40% fat diet group (2). For reasons not specified in the article, Qi et al. used 738 subjects for the current study, a number that apparently includes almost 100 noncompleters as defined in the …