Microbiota and Metabolite Modifications after Dietary Exclusion of Dairy Products and Reduced Consumption of Fermented Food in Young and Older Men

Abstract

The gut microbiota adapts to age-related changes in host physiology but is also affected by environmental stimuli, like diet. As a source of both pre- and probiotics, dairy and fermented foods modulate the gut microbiota composition, which makes them interesting food groups to use for the investigation of interactions between diet and ageing. Here we present the effects of excluding dairy products and limiting fermented food consumption for 19 days on gut microbiota composition and circulating metabolites of 28 healthy, young (YA) and older (OA) adult men. The intervention affected gut microbial composition in both groups, with significant increases in Akkermansia muciniphila and decreases in bacteria of the Clostridiales order. Lower fasting levels of glucose and insulin, as well as dairy-associated metabolites like lactose and pentadecanoic acid, were observed after the intervention, with no effect of age. The intervention also decreased HDL and LDL cholesterol levels. Dairy fat intake was positively associated with the HDL cholesterol changes but not with the LDL/HDL ratio. In conclusion, restricting the intake of dairy and fermented foods in men modified their gut microbiota and blood metabolites, while the impact of the dietary restrictions on these outcomes was more marked than the effect of age.

Postprandial Responses on Serum Metabolome to Milk and Yogurt Intake in Young and Older Men

“…In addition, the less efficient production of primary bile acids in the liver ( 35 ) and the modified gut microbiota composition during aging ( 57 ) could explain the lower levels of glycocholic acid observed in the OA group in the present study. However, our previous study with the same study individuals revealed that there were no significant differences in gut microbiota profile between the YA and the OA groups ( 26 ), suggesting the less efficient production of primary bile acids in the liver could be the major factor of the lower glycocholic acid levels in the OA group. Lipid metabolism was particularly influenced by age, presenting delayed t max of dodecanoic acid (C12:0), myristic acid (C14:0), and acylcarnitines in the OA group.…”

“…Not only the levels of these metabolites 24 h after the dairy challenge are still low, but their levels actually increased during the run-in period. The postprandial behavior of these lipids is complex as likely influenced by the fermentation of milk, processing by the gut microbiota and systemic metabolism ( 26 ). A more detailed discussion of these molecules would request that their molecular structure be precisely determined by high resolution GC-FID ( 26 ).…”

“…Telephone interview and medical check, including blood tests, were performed to screen the participants. The inclusion and exclusion criteria of the participants have been described elsewhere ( 26 ). Briefly, healthy lactose-tolerant individuals who consumed dairy products regularly (2–4 portion/d) were recruited.…”

“…A 3-week run-in period was conducted before a crossover intervention consisting in the acute and single ingestion of a milk or yogurt serving. During the run-in period, the participants were requested to do not consume dairy foods and to limit the consumption of fermented non-dairy as described by Kim et al ( 26 ) in order to maximize the postprandial metabolic signatures associated with the ingestion of milk or yogurt during the test day. On test day, the participants came to the research Center in the morning after an overnight fast and were randomly assigned to consume 600 ml of whole milk or yogurt.…”

Associations between dairy fat intake, milk-derived free fatty acids, and cardiometabolic risk in Dutch adults

“…In addition, several FFA groups were determined based on the sums of individual FFAs (Table S2). Immediately prior to analysis, plasma samples were thawed on ice and were prepared for analysis by adding 15 µL of the internal standard (C13, 7 µg/15 µL) to 100 µL of plasma, followed by methylation of FFAs with MeOH/HCl at 25 °C for 45 min using methods described previously [ 46 , 47 ]. A post-reaction treatment for neutralization was performed with 350 µL Na 2 CO 3 , and extraction was performed with 300 µL hexane.…”