The glycemic response of humans to the ingestion of foods is a key parameter in food and medical sciences as it provides information on both the quality of the ingested foods and the health status of patients. On the other hand, hundreds of metabolites in blood react to food intake. Thus, in addition to glucose, the postprandial metabolome must contain specific, yet undiscovered, markers of food intake as well as markers of the genotypic and phenotypic status of humans. This paper explores these questions by analyzing the postprandial metabolomes derived from three human intervention studies. The first study investigates how the postprandial serum metabolome responds to increasing caloric doses of a high-fat meal. This analysis highlights saturation at higher caloric doses as well as global differences in the response of normal weight and obese subjects. The second and third study compare the postprandial serum and urine metabolome of healthy subjects having ingested milk, yoghurt, cheese, and a soy drink. The results highlight the ability of metabolomics to differentiate foods based on the postprandial response of specific metabolites as well as on metabolite signatures. Interestingly, a dichotomic response to milk ingestion is observed in blood and urine for galactonate and galactitol, two metabolites derived from lactose. These metabolites associate with the lactase-persistence genotype of the subjects. A dichotomic response is also observed in serum for the Lewis a antigen suggesting that genetic polymorphisms related to the metabolism of oligosaccharides interact with the intestinal microbiome to modulate the production of this trisaccharide