A Systematic Review on Socioeconomic Differences in the Association between the Food Environment and Dietary Behaviors.

Little is known about socioeconomic differences in the association between the food environment and dietary behavior. We systematically reviewed four databases for original studies conducted in adolescents and adults. Food environments were defined as all objective and perceived aspects of the physical and economic food environment outside the home. The 43 included studies were diverse in the measures used to define the food environment, socioeconomic position (SEP) and dietary behavior, as well as in their results. Based on studies investigating the economic (n = 6) and school food environment (n = 4), somewhat consistent evidence suggests that low SEP individuals are more responsive to changes in food prices and benefit more from healthy options in the school food environment. Evidence for different effects of availability of foods and objectively measured access, proximity and quality of food stores on dietary behavior across SEP groups was inconsistent. In conclusion, there was no clear evidence for socioeconomic differences in the association between food environments and dietary behavior, although a limited number of studies focusing on economic and school food environments generally observed stronger associations in low SEP populations. (Prospero registration: CRD42017073587).

Differential effects of a 40-hour fast and bile acid supplementation on human GLP-1 and FGF19 responses.

Bile acids, glucagon-like peptide-1 (GLP-1), and fibroblast growth factor 19 (FGF19) play an important role in postprandial metabolism. In this study, we investigated the postprandial bile acid response in plasma and its relation to insulin, GLP-1, and FGF19. First, we investigated the postprandial response to 40-h fast. Then we administered glycine-conjugated deoxycholic acid (gDCA) with the meal. We performed two separate observational randomized crossover studies on healthy, lean men. In experiment 1: we tested 4-h mixed meal after an overnight fast and a 40-h fast. In experiment 2, we tested a 4-h mixed meal test with and without gDCA supplementation. Both studies measured postprandial glucose, insulin, bile acids, GLP-1, and FGF19. In experiment 1, 40 h of fasting induced insulin resistance and increased postprandial GLP-1 and FGF19 concentrations. After an overnight fast, we observed strong correlations between postprandial insulin and gDCA levels at specific time points. In experiment 2, administration of gDCA increased GLP-1 levels and lowered late postprandial glucose without effect on FGF19. Energy expenditure was not affected by gDCA administration. Unexpectedly, 40 h of fasting increased both GLP-1 and FGF19, where the former appeared bile acid independent and the latter bile acid dependent. Second, a single dose of gDCA increased postprandial GLP-1. Therefore, our data add complexity to the physiological regulation of the enterokines GLP-1 and FGF19 by bile acids.