A systematic review and meta-analysis determined the effect of restaurant menu labeling on calories and nutrients chosen in laboratory and away-from-home settings in U.S. adults. Cochrane-based criteria adherent, peer-reviewed study designs conducted and published in the English language from 1950 to 2014 were collected in 2015, analyzed in 2016, and used to evaluate the effect of nutrition labeling on calories and nutrients ordered or consumed. Before and after menu labeling outcomes were used to determine weighted mean differences in calories, saturated fat, total fat, carbohydrate, and sodium ordered/consumed which were pooled across studies using random effects modeling. Stratified analysis for laboratory and away-from-home settings were also completed. Menu labeling resulted in no significant change in reported calories ordered/consumed in studies with full criteria adherence, nor the 14 studies analyzed with ≤1 unmet criteria, nor for change in total ordered carbohydrate, fat, and saturated fat (three studies) or ordered or consumed sodium (four studies). A significant reduction of 115.2 calories ordered/consumed in laboratory settings was determined when analyses were stratified by study setting. Menu labeling away-from-home did not result in change in quantity or quality, specifically for carbohydrates, total fat, saturated fat, or sodium, of calories consumed among U.S. adults.

Dietary approaches, particularly those including fiber supplementation, can be used to promote health benefits by shaping the gut microbial communities. Whereas community diversity measures, such as richness and evenness, are often used in microbial ecology to make sense of these complex and vast microbial ecosystems, it is less clear how these concepts apply when dietary fiber supplementation is given. In this perspective, we summarize and demonstrate how factors including experimental approach, number of bacteria sharing a dietary fiber, and initial relative abundances of bacteria that use a fiber can significantly affect diversity outcomes in fiber fermentation studies. We also show that a reduction in alpha diversity is possible, and perhaps expected, for most approaches that use fermentable fibers to beneficially shape the gut microbial community while still achieving health-related improvements.

The modern diet delivers nearly equal amounts of carbohydrates and protein into the colon representing an important protein increase compared to past higher fiber diets.

Insoluble dietary fibers are typically known to be poorly fermented in the large intestine. However, their value may be high as evidence shows that important butyrogenic bacteria preferentially utilize insoluble substrates to support their energy needs. The objective of this study was to increase fermentability of an insoluble bran fiber (pearl millet) while keeping it mostly insoluble to promote bacteria in the community that rely on fermentable insoluble dietary fibers. Following pretests with different processing methods, a combination of microwave and enzymatic treatments were applied to isolated pearl millet fiber to increase its accessibility of gut bacteria. In vitro human fecal fermentation was conducted and analyses were made for short chain fatty acids and microbiota changes. Combined microwave and enzymatic processing increased the amount of insoluble fiber fermented in vitro from 36 to 59% of total dietary fiber, with a minor increase in soluble fiber (8%). Microwave/enzymatic processing doubled butyrate production and almost tripled acetate production at 6 h fermentation compared to the native millet fiber. 16S rRNA gene sequencing showed that the processing promoted a significant increase in Firmicutes/Bacteroidetes ratio compared to the native fiber with relative abundance increases in Blautia and Copprococcus genera and a decrease in Bacteroidetes. Overall, these data show that processing techniques can be used to increase the value of insoluble fiber, presumably by increasing accessibility of the fiber to degrading bacteria, and to support Firmicutes that preferentially compete on insoluble fibers.