THE IMPORTANCE OF DIETARY POLYAMINES IN CELL REGENERATION AND GROWTH

The polyamines putrescine, spermidine and spermine are essential for c ell renewal and, therefore, are needed to keep the body healthy. It wa s previously believed that polyamines are synthesized by every cell in the body when required. However, in the present paper evidence is pro vided to show that, as in the case of the essential amino acids, the d iet can supply sufficient amounts of polyamines to support cell renewa l and growth. Systematic analysis of different foods was carried out a nd from the data obtained, the average daily polyamine consumption of British adults was calculated to be in the range 35-500 mu mol/person per d. The major sources of putrescine were fruit, cheese and non-gree n vegetables. All foods contributed similar amounts of spermidine to t he diet, although levels were generally higher in green vegetables. Me at was the richest source of spermine. However, only a part of the pol yamines supplied by the diet is available for use by the body. Based o n experiments with rats it was established that polyamines were readil y taken up from the gut lumen, probably by passive diffusion, and were partly metabolized during the process of absorption. More than 80% of the putrescine was converted to other polyamines and non-polyamine me tabolites, mostly to amino acids. The enzyme responsible for controlli ng the bioavailability of putrescine was diamine oxidase (EC 1.4.3.6). For spermidine and spermine, however, about 70-80% of the intragastri cally intubated dose remained in the original form. Considering the li mitations on bioavailability (metabolism and conversion), the amounts of polyamines supplied by the average daily diet in Britain should sat isfy metabolic requirements.