MANGANESE ABSORPTION IN HUMANS - THE EFFECT OF PHYTIC ACID AND ASCORBIC-ACID IN SOY FORMULA

The absorption of manganese from soy formula was studied in adult volu nteers by extrinsic labeling of test meals with Mn-54, followed by who le-body retention measurements for approximate to 30 d after intake. E ight subjects participated twice in each of the two studies, acting as his or her own control. Soy formula containing the native content of phytic acid was compared with a similar dephytinized formula: geometri c mean manganese absorption increased 2.3-fold from 0.7% (range: 0.2-1 .1%) to 1.6% (range: 1.0-7.2%) (P < 0.01) with the dephytinized formul a. In addition, the effect of the ascorbic acid content of the phytic acid-containing formula was investigated. Manganese absorption was not influenced by an increase in the ascorbic acid from 625 mu mol/L (110 mg/L) to 1250 mu mol/L (220 mg/L): the geometric mean manganese absor ption was 0.6% (range: 0.3-1.0%) and 0.6% (range: 0.3-1.1%), respectiv ely. In conclusion, fractional manganese absorption was approximately doubled by the dephytinization of soy formula but was not influenced b y an increase in the ascorbic acid content of a soy formula containing the native amount of phytic acid.