Polyamines in human and rat milk and in infant formulas.

Polyamines are ubiquitous compounds known to be involved in cell proliferation and differentiation in many tissues. Enteral administration of these compounds has been shown to produce effects in suckling and adult animals. Using HPLC techniques, we verified the presence of putrescine, spermidine, and spermine in human milk and quantitated their concentration in samples collected from the first week up to 4 mo of lactation. Mean values of these compounds ranged (per liter) from 0 to 615 nmol putrescine, from 73 to 3512 nmol spermidine, and from 722 to 4458 nmol spermine. Polyamine concentrations in infant formulas were dependent on the protein source, the particular polyamine, and the protein concentration of the formula. Concentrations of these three compounds in rat milk over the first 3 wk of lactation were higher than in human milk, with spermidine being the polyamine most elevated compared with human milk (almost 20-fold higher). An artificial formula used for the rearing of suckling rats contained trace to immeasurable amounts of polyamines. Our study identifies milk as one vehicle for polyamine delivery to the intestinal mucosa of suckling animals.