EFFECT OF DIETARY PHYTIC ACID ON ZINC-ABSORPTION IN THE HEALTHY ELDERLY, AS ASSESSED BY SERUM CONCENTRATION CURVE TESTS

Zn absorption was investigated in healthy elderly subjects aged 71-78 years and in young subjects aged 23-43 years using serum concentration curve (SCC) tests. Both groups had similar Zn and protein status. The increase in serum Zn was monitored for 180 min after ingestion of 200 mi of soya milk enriched with 50 mg of Zn. Three levels of phytic aci d were used: 0 g/200 mi (totally dephytinized soya milk), 0.13 g/200 m i (half dephytinized), and 0.26 g/200 mi (natural phytic acid content) . In a first study the effect of 0 v; 0.26 g/200 mi phytic acid was co mpared in 10 elderly and 10 young subjects, each subject receiving bot h treatments. In a second study soya milks with 0 and 0.13 g/200 mi we re tested in nine elderly and ten young subjects, again receiving both treatments. Mean areas under the curve of the SCC tests conducted wit h the 0 g/200 mi soya milk were found to be the same in both studies. Phytic acid strongly depressed Zn absorption in both studies (P less t han or equal to 0.05), but to a greater extent at the 0.26 g/200 mi le vel. No difference was found between the groups of young and elderly s ubjects. Therefore, no significant effect of aging on Zn absorption, a s evaluated by the SCC test, or on the inhibitory effect of phytic aci d was detected.