Diabetes Research Centre, University of Leicester, Leicester General Hospital, Leicester, United Kingdom.
National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom.
J Nutr. 2021 Jul 1;151(7):1844-1853. doi: 10.1093/jn/nxab046.
Trimethylamine N-oxide (TMAO), a metabolite generated by the gut in response (in part) to meat consumption, is linked to poor cardiometabolic health.
We investigate the effect of an 8-week vegan diet, followed by a 4-week period of unrestricted diet, on glucose tolerance and plasma TMAO in human omnivores with obesity or dysglycemia.
This interventional single-group prospective trial involved 23 regular meat eaters with dysglycemia [glycated hemoglobin ≥ 5.7% and ≤8% (39-64 mmol/mol)], or obesity (ΒΜΙ ≥ 30 kg/m2) aged 57.8 ± 10.0 years. Participants [14 men (60.9%) and 9 women (39.1%)] were supported in following a vegan diet for 8 weeks, followed by 4 weeks of unrestricted diet. The primary outcomes (plasma TMAO and glucose) were assessed at baseline, during the vegan diet (weeks 1 and 8), and after the unrestricted diet period (week 12). TMAO was assessed after fasting and glucose was measured as a time-averaged total AUC using a 180-minute oral-glucose-tolerance test. Generalized estimating equation models with an exchangeable correlation structure were used to assess changes from baseline, adjusting for age, sex, ethnicity, and weight.
TMAO levels (marginal mean) were reduced after weeks 1 and 8 of a vegan diet compared to baseline, from 10.7 (97.5% CI, 6.61-17.3) μmol/L to 5.66 (97.5% CI, 4.56-7.02) μmol/L and 6.38 (97.5% CI, 5.25-7.74) μmol/L, respectively; however, levels rebounded at week 12 after resumption of an unrestricted diet (17.5 μmol/L; 97.5% CI, 7.98-38.4). Postprandial glucose levels (marginal means) were reduced after weeks 1 and 8 compared to baseline, from 8.07 (97.5% CI, 7.24-8.90) mmol/L to 7.14 (97.5% CI, 6.30-7.98) mmol/L and 7.34 (97.5% CI, 6.63-8.04) mmol/L, respectively. Results for glucose and TMAO were independent of weight loss. Improvements in the lipid profile and markers of renal function were observed at week 8.
These findings suggest that a vegan diet is an effective strategy for improving glucose tolerance and reducing plasma TMAO in individuals with dysglycemia or obesity. This study was registered at clinicaltrials.gov as NCT03315988.
三甲胺 N-氧化物（TMAO）是肠道响应（部分原因）肉类消费而产生的一种代谢物，与较差的心脏代谢健康有关。
我们研究了 8 周的纯素饮食，随后是 4 周的不受限制的饮食，对肥胖或糖代谢异常的杂食人类葡萄糖耐量和血浆 TMAO 的影响。
这项干预性单组前瞻性试验涉及 23 名经常吃肉的糖代谢异常者[糖化血红蛋白≥5.7%且≤8%（39-64mmol/mol）]或肥胖（BMI≥30kg/m2），年龄为 57.8±10.0 岁。参与者[14 名男性（60.9%）和 9 名女性（39.1%）]被支持遵循纯素饮食 8 周，然后进行 4 周的无限制饮食。主要结局（血浆 TMAO 和葡萄糖）在基线、纯素饮食期间（第 1 周和第 8 周）以及无限制饮食期后（第 12 周）进行评估。在禁食后评估 TMAO，通过 180 分钟口服葡萄糖耐量试验测量葡萄糖作为时间平均总 AUC。使用具有可交换相关性结构的广义估计方程模型来评估从基线开始的变化，调整年龄、性别、种族和体重。
与基线相比，纯素饮食第 1 周和第 8 周后 TMAO 水平（边缘均值）分别降低了 10.7（97.5%CI，6.61-17.3）μmol/L 至 5.66（97.5%CI，4.56-7.02）μmol/L 和 6.38（97.5%CI，5.25-7.74）μmol/L；然而，在恢复无限制饮食后第 12 周时，水平反弹至 17.5μmol/L（97.5%CI，7.98-38.4）。与基线相比，第 1 周和第 8 周后餐后血糖水平（边缘均值）分别降低了 8.07（97.5%CI，7.24-8.90）mmol/L 至 7.14（97.5%CI，6.30-7.98）mmol/L 和 7.34（97.5%CI，6.63-8.04）mmol/L。血糖和 TMAO 的结果独立于体重减轻。在第 8 周时观察到血脂谱和肾功能标志物的改善。
这些发现表明，纯素饮食是改善糖代谢异常和肥胖个体葡萄糖耐量和降低血浆 TMAO 的有效策略。本研究在 clinicaltrials.gov 上注册为 NCT03315988。
