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- Lönnerdal B, Jayawickrama L, Lien EL
- Am J Clin Nutr 1999 Mar 69:3 490-6
- Abstract
- BACKGROUND: Although soy formulas have been designed to meet
the nutrient requirements of human infants, they also contain
phytate, which may negatively affect trace element absorption.
OBJECTIVE: We evaluated the effect of removing phytate on zinc
and copper absorption and status in infant rhesus monkeys and
suckling rat pups and evaluated differences between intact and
partially hydrolyzed soy protein. DESIGN: In monkeys, regular
and low-phytate soy formulas were fed exclusively for 4 mo and
whole-body absorption and retention of 65Zn, 67Cu, 59Fe, 54Mn,
and 47Ca were determined at different time points with a whole-body
counter. Subsequently, zinc and copper absorption from several
human infant formulas and the effect of phytate concentration
were evaluated in suckling rat pups by using 65Zn and 64Cu. Finally,
infant rhesus monkeys were fed low-phytate formulas with intact
or hydrolyzed soy protein for 4 mo and plasma zinc and copper
were measured monthly. RESULTS: In the first monkey study, zinc
absorption at 1 mo was higher from low-phytate soy formula (36%)
than from regular soy formula (22%), whereas there was no significant
difference between groups in the absorption of other minerals.
Plasma copper was significantly lower in monkeys fed low-phytate
soy formula from 2 to 4 mo. In rat pups, zinc absorption was significantly
higher from low-phytate soy formula (78%) than from regular soy
formula (51%) and hydrolysis of the protein had no significant
effect. Phytate content or protein hydrolysis did not significantly
affect copper absorption. In the second monkey study, plasma copper
concentrations were highest in monkeys fed the low-phytate, hydrolyzed-protein
soy formula. CONCLUSION: Reducing the phytate content and partially
hydrolyzing the protein in soy formula had a beneficial effect
on zinc and copper absorption and status in infant rhesus monkeys.
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