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.

中文翻译：

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在老年女性中，包括动物源性食物在内的高蛋白饮食不会影响三甲胺-N-氧化物的血清水平和尿排泄

包括红肉和其他动物源性食物在内的饮食可能会增加蛋白水解发酵和微生物产生的三甲胺 (TMA) 以及随后的三甲胺-N-氧化物 (TMAO)，这是一种与心血管疾病和痴呆症风险增加相关的代谢物。假设与通常的饮食摄入量相比，维持能量高蛋白饮食 (HPD) 会增加蛋白水解发酵的产物，而辅助性益生元、益生菌和合生元补充剂可能会减轻这些影响。一个探索性目标是确定产生 TMA 的分类群 Emergencia timonensis 的相对丰度与血清和尿液 TMAO 之间的关联。在 5 个时间点（通常饮食摄入量、HPD 饮食、HPD + 益生元、HPD + 益生菌和 HPD + 合生元），分别通过液相色谱-串联质谱和 16S rRNA 基因扩增子测序分析测量了健康老年女性（n = 20）的尿液（24 小时）和血清代谢物以及粪便微生物群特征。HPD 会引起左旋肉碱、硫酸吲哚酚和苯乙酰谷氨酰胺的血清水平升高，但不会引起 TMAO 或对甲酚硫酸酯的升高。L-肉碱、硫酸吲哚酚、苯乙酰谷氨酰胺和 TMA 的尿液排泄随着 HPD 增加，但不增加 TMAO 或对甲酚硫酸盐。大多数参与者在基线时检测不到 E.timonensis 水平，在 HPD 干预期间只有 50%，这表明其他分类群是这些个体中 TMA 微生物产生的原因。含或不含益生元、益生菌或合生元的 HPD 饮食引起蛋白水解发酵产物的增加。