Kirschner Sarah K, Engelen Mariëlle Pkj, Haas Paula, Bischoff Stephan C, Deutz Nicolaas Ep
Center for Translational Research in Aging & Longevity, Texas A&M University, College Station, TX, United States.
Institute of Nutritional Medicine, University of Hohenheim, Stuttgart, Germany.
Am J Clin Nutr. 2025 Jun;121(6):1224-1235. doi: 10.1016/j.ajcnut.2025.04.018. Epub 2025 Apr 22.
Beneficial short-chain fatty acids (SCFAs) are produced through intestinal microbial fiber fermentation. Using stable tracer methodology and compartmental modeling, we observed lower SCFA production in older (OAs) than in young adults (YAs) in both an accessible [that is, systemic circulation; whole-body production] and inaccessible [potentially representing intestine absorbing microbially produced SCFAs (U)] pool.
We now investigated whether fiber supplementation increases SCFA production in OAs and whether concentrations reflect production rate changes.
In this randomized, placebo-controlled, double-blind crossover study, 21 YAs (20-29 y) and 40 OAs (59-87 y) adults were supplemented with inulin or placebo (maltodextrin) for 7 d (final intake: 30 g/d). Before and after interventions, participants collected stool and received an intravenous pulse containing [U-C]-labeled SCFAs followed by blood draws. We measured plasma tracer enrichments, plasma and fecal concentrations by gas chromatography-mass spectrometry and performed compartmental analysis. Data are mean (95% confidence interval).
Inulin evoked a 44% increase in butyrate production (μmol/min) in the inaccessible pool {YA: 28-44 [+16.2 (4.3, 28.1); P = 0.038], OA: 14-20 [+6.1 (2.2, 9.9); P = 0.011]} and were not different between YAs and OAs. In addition, a 34% increase in propionate production in YA only. We found a 50%-60% increase in fecal acetate, propionate, and butyrate and a 34% increase in plasma butyrate in OA, whereas in YA only 34% increase in fecal acetate. Plasma but not fecal concentrations correlated positively with SCFA production in the inaccessible pool (R = 0.20-0.45; P < 0.001).
OAs have a lower SCFA production. Inulin intake increases SCFA production. Tracer pulse approach detects SCFA metabolism changes more sensitively than plasma or fecal concentration measurements (NCT04459156).
有益的短链脂肪酸（SCFAs）通过肠道微生物对纤维的发酵产生。使用稳定示踪方法和房室模型，我们观察到在可及池（即体循环；全身产生）和不可及池（可能代表肠道吸收微生物产生的SCFAs（U））中，老年人（OAs）的SCFA产生量均低于年轻人（YAs）。
我们现在研究纤维补充是否会增加OAs的SCFA产生量，以及浓度是否反映产生速率的变化。
在这项随机、安慰剂对照、双盲交叉研究中，21名年轻成年人（20 - 29岁）和40名老年人（59 - 87岁）补充菊粉或安慰剂（麦芽糊精）7天（最终摄入量：30克/天）。干预前后，参与者收集粪便，并接受静脉注射含有[U - C]标记的SCFAs的脉冲，随后进行采血。我们通过气相色谱 - 质谱法测量血浆示踪剂富集、血浆和粪便浓度，并进行房室分析。数据为均值（95%置信区间）。
菊粉使不可及池中丁酸盐产生量（微摩尔/分钟）增加了44% {年轻成年人：28 - 44 [+16.2（4.3，28.1）；P = 0.038]，老年人：14 - 20 [+6.1（2.2，9.9）；P = 0.011]}，年轻成年人与老年人之间无差异。此外，仅年轻成年人中丙酸盐产生量增加了34%。我们发现老年人粪便中乙酸盐、丙酸盐和丁酸盐增加了50% - 60%，血浆丁酸盐增加了34%，而年轻成年人中仅粪便乙酸盐增加了34%。血浆浓度而非粪便浓度与不可及池中SCFA产生量呈正相关（R = 0.20 - 0.45；P < 0.001）。
老年人的SCFA产生量较低。摄入菊粉会增加SCFA产生量。示踪脉冲法比血浆或粪便浓度测量更能灵敏地检测SCFA代谢变化（NCT04459156）。
