In older women, a high-protein diet including animal-sourced foods did not impact serum levels and urinary excretion of trimethylamine-N-oxide.

Diets including red meat and other animal-sourced foods may increase proteolytic fermentation and microbial-generated trimethylamine (TMA) and, subsequently, trimethylamine-N-oxide (TMAO), a metabolite associated with increased risk of cardiovascular disease and dementia. It was hypothesized that compared to usual dietary intake, a maintenance-energy high-protein diet (HPD) would increase products of proteolytic fermentation, whereas adjunctive prebiotic, probiotic, and synbiotic supplementation may mitigate these effects. An exploratory aim was to determine the association of the relative abundance of the TMA-generating taxon, Emergencia timonensis, with serum and urinary TMAO. At 5 time points (usual dietary intake, HPD diet, HPD + prebiotic, HPD + probiotic, and HPD + synbiotic), urinary (24-hour) and serum metabolites and fecal microbiota profile of healthy older women (n = 20) were measured by liquid chromatography-tandem mass spectrometry and 16S rRNA gene amplicon sequencing analyses, respectively. The HPD induced increases in serum levels of l-carnitine, indoxyl sulfate, and phenylacetylglutamine but not TMAO or p-cresyl sulfate. Urinary excretion of l-carnitine, indoxyl sulfate, phenylacetylglutamine, and TMA increased with the HPD but not TMAO or p-cresyl sulfate. Most participants had undetectable levels of E.timonensis at baseline and only 50% during the HPD interventions, suggesting other taxa are responsible for the microbial generation of TMA in these individuals. An HPD diet with or without a prebiotic, probiotic, or synbiotic elicited an increase in products of proteolytic fermentation. The urinary l-carnitine response suggests that the additional dietary l-carnitine provided was primarily bioavailable, providing little substrate for microbial conversion to TMA and subsequent TMAO formation.

Calcium Supplementation Does Not Contribute to Constipation in Healthy Women.

PURPOSE: It is commonly suggested that calcium supplementation contributes to constipation; however, little research has explored the effects of calcium supplementation on gut motility. METHODS: In an 8-week, randomized, double-blind, crossover pilot study, healthy females (n = 27, aged 43.0 ± 10.6 years) received a split dose of 500 mg/d of elemental calcium from calcium carbonate or calcium phosphate each for 2 weeks, after a 2-week baseline and separated by a 2-week washout. Participants completed daily questionnaires of stool frequency, Bristol Stool Form Scale (BSFS), and supplement intake compliance. RESULTS: There were no differences among periods. Mean ± SE stool frequency averaged 1.3 ± 0.1 stools/d in each period. Participants reported 34%, 34%, 37%, and 29% of stools were indicative of slow transit or constipation (BSFS of 1 or 2) during baseline, calcium carbonate, calcium phosphate, and washout periods, respectively. Participants also reported from 6% to 10% of stools as fast transit or diarrhea (BSFS of 6 or 7) during the periods. CONCLUSION: This study suggests that neither calcium carbonate nor calcium phosphate, providing 500 mg/d of calcium, affects stool frequency or form. Although stool frequency was normal, the healthy females participating in the study experienced stools indicating slow (constipation) and fast (diarrhea) transit.