Age-Dependent Serum Volatilomics of Milk and Yogurt Intake: A Randomized Crossover Study in Healthy Young and Older Men

Nutritional biomarkers of dairy intake can be affected
by both
food transformation and the metabolic status of the consumer. To assess
these effects, this study investigated the serum volatilome of 14
young (YA) and 14 older (OA) adult men undergoing a 3 week restriction
of dairy and fermented foods followed by a randomized crossover acute
intake of milk and yogurt. 3,5-Dimethyl-octan-2-one was identified
as a potential marker of dairy product intake as its response after
both milk and yogurt intake was significantly increased during the
postprandial phase but significantly decreased in fasting serum samples
of the OA group after the restriction phase. The postprandial response
of two metabolites was significantly different for the two dairy products
while 19 metabolites were modulated by age. Remarkably, the response
of all age-dependent metabolites was higher in the OA than in the
YA group after milk or yogurt intake, whereas at the end of the restriction
phase, their fasting concentrations were lower in the OA than in the
YA group. Among these, p-cresol, a specific marker
of colonic protein fermentation, had a significant response in the
OA but not the YA group, which may suggest impaired intestinal processing
of dietary proteins in the OA group.