Human milk, despite a much lower protein content, is as effective as cow milk on insulin stimulation under iso-lactose conditions. The causes for such a similar potency are unknown. This effect could be due to incretin and amino-acid responses, and/or to milk-protein interactions.In this study the investigators will address the above question(s) by testing, in young healthy volunteers, the effects of natural cow and human milk, as well as of the manipulation of the casein and whey protein content in cow milk, on insulin, C-peptide, GLP-1 and GIP secretion, as well as on circulating amino acids.

Objective: To determine plasma glucose, insulin, C-peptide, glucagon-like polypeptide-1 (GLP-1), glucose-inhibitory-polypeptide (GIP) and amino-acid responses, following administration of human and cow milk, either natural or with experimentally-modified casein and whey-protein content(s).

Design. Young healthy volunteers of both sexes will receive iso-lactose loads (0.36 g lactose / kg body weight) of: natural cow milk; natural human milk; and of cow milk with modified casein and whey protein contents. Blood samples will be frequently collected over 4 hours. Plasma glucose, amino acids, insulin and incretin concentrations will be measured.

Inclusion Criteria:

• Age 20-35 yrs
• Both sexes
• Healthy
• In post-absorptive state
• Hemoglobin Hb1c values within normal values.
• Previous regular, moderate physical activity
• Stable body weight and regular dietary habits.

Exclusion Criteria:

• Familial or personal history of diabetes.
• Altered fasting glucose and/ or impaired glucose tolerance.
• Any metabolic, hormonal, hepatic, renal, and cardiovascular disease.
• Current drug treatments