Nutrition and Food Science Area, Faculty of Pharmacy, University of Valencia, Avda. Vicent Andrés Estellés s/n, 46100, Burjassot, Valencia, Spain.
Department of Statistics and Operations Research, University of Valencia, C/ Dr. Moliner 50, 46100, Burjassot, Valencia, Spain.
Clin Nutr. 2019 Aug;38(4):1549-1560. doi: 10.1016/j.clnu.2018.08.012. Epub 2018 Sep 7.
Cholesterol microbial transformation has been widely studied using in vitro fermentation assays, but less information is available on the biotransformation of plant sterols (PS). The excretion percentage of animal sterols (AS) (67-73%) is considerably greater than that of PS (27-33%) in feces from healthy humans following a Western diet. However, a lower content of AS in feces from subjects following a vegetarian, vegan or low-fat animal diet has been seen when compared to omnivorous subjects. Although only one human study has reported fecal sterol excretion after the consumption of PS-enriched food (8.6 g PS/day), it was found that the target group showed an increase in the excretion of cholesterol and a 57% decrease in its metabolites compared to the control group.
Evaluation of the impact of a PS-enriched milk based fruit beverage intake on fecal sterol excretion and the microbial conversion of sterols in postmenopausal women with mild hypercholesterolemia.
Forty postmenopausal women participated in a randomized, double-blind, crossover study with two beverages, with a PS-enriched (2 g PS/day) or without. The women were divided in two groups: 20 women consumed the PS-enriched beverage and the other 20 women consumed a placebo (without PS) beverage for 6 weeks. After a four-week washout period, the type of beverage was exchanged and consumed for another 6 weeks. Feces were collected at the start (0 and 10 weeks) and end of each intervention period (6 and 16 weeks), and fecal sterols were determined by capillary gas chromatography with mass spectrometry.
The intake of the PS-enriched beverage modified the fecal sterol excretion profile. A significant increase mainly in PS and their metabolites versus the placebo intervention period was observed. Although the same effect was not observed in the case of AS, a tendency towards increased cholesterol and decreased coprostanol (the main metabolite of cholesterol) was recorded after PS-enriched beverage intake versus placebo. Furthermore, the PS-enriched beverage also modified the microbial conversion of sterols. In this context, an important decrease in the conversion percentage of cholesterol in 16 women (between 11% and 50%) and of sitosterol in 24 women (between 15% and 61%) was observed.
The results obtained suggest that the microbiota could preferably use PS as a substrate, when present in a greater proportion compared with cholesterol. Besides, a lower sitosterol and cholesterol conversion trend would mean that intake of the PS-enriched beverage could modulate the metabolic activity of the gut microbiota. Therefore, further studies on the impact of PS-enriched foods upon gut microbiota modulation are needed. Clinical Trial Registry Number: NCT02065024 listed on the NIH website: ClinicalTrials.gov. Clinical Trial Registry Name: Food Matrix and Genetic Variability as Determinants of Bioavailability and Biological Effects of Beta-cryptoxanthin and Phytosterols (foodmagenpol). The full trial protocol is available upon request to the corresponding author.
胆固醇微生物转化已广泛应用于体外发酵研究，但关于植物甾醇（PS）生物转化的信息较少。在西方饮食下，健康人群粪便中动物甾醇（AS）（67-73%）的排泄量明显大于 PS（27-33%）。然而，与杂食人群相比，素食、纯素或低脂动物饮食人群粪便中的 AS 含量较低。尽管只有一项人类研究报告了富含 PS 的食物摄入后的粪便甾醇排泄情况（每天 8.6 克 PS），但研究发现，目标组的胆固醇排泄增加，其代谢物减少 57%。
评估富含 PS 的牛奶基水果饮料摄入对轻度高胆固醇血症绝经后妇女粪便甾醇排泄和甾醇微生物转化的影响。
40 名绝经后妇女参加了一项随机、双盲、交叉研究，分为两组，分别饮用富含 PS（每天 2 克 PS）或不含 PS 的饮料。将妇女分为两组：20 名妇女饮用富含 PS 的饮料，另 20 名妇女饮用不含 PS 的安慰剂（不含 PS）饮料 6 周。在 4 周洗脱期后，交换饮料类型并再饮用 6 周。在每个干预期的开始（0 和 10 周）和结束时（6 和 16 周）收集粪便，并通过毛细管气相色谱-质谱法测定粪便甾醇。
富含 PS 的饮料摄入改变了粪便甾醇的排泄模式。与安慰剂干预期相比，主要是 PS 及其代谢物的排泄显著增加。虽然在 AS 方面没有观察到相同的效果，但在富含 PS 的饮料摄入后，胆固醇和粪甾醇（胆固醇的主要代谢物）的含量呈下降趋势。此外，富含 PS 的饮料还改变了甾醇的微生物转化。在这种情况下，16 名妇女（11%至 50%）和 24 名妇女（15%至 61%）的胆固醇转化率和豆甾醇转化率分别显著下降。
研究结果表明，当 PS 与胆固醇相比以更大的比例存在时，微生物群可能更优先地将其作为底物使用。此外，甾醇和胆固醇转化率呈下降趋势，这意味着富含 PS 的饮料摄入可能会调节肠道微生物群的代谢活性。因此，需要进一步研究富含 PS 的食物对肠道微生物群调节的影响。临床试验注册号：NCT02065024 在美国国立卫生研究院网站上注册：ClinicalTrials.gov。临床试验名称：食物基质和遗传变异作为 β-隐黄质和植物甾醇生物利用度和生物学效应的决定因素（foodmagenpol）。完整的试验方案可应要求提供给相应的作者。
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