Effect of phytate removal on zinc absorption from soy formula

Abstract

Low zinc bioavailability from soy formula may be the result of the formula's phytate content. We assessed the effect of phytate removal from soy formula on Zn absorption using infant rhesus monkeys and suckling rat pups as animal models. Zn absorption in monkeys, as determined by whole-body counting, was 65% from human milk, 54% from monkey milk, 60% from whey-predominant formula, 46% from casein-predominant formula, and only 27% from conventional soy formula (0.621 mmol phytate/L). In contrast, Zn absorption from dephytinized soy formula (0.067 mmol phytate/L) was 45%. In suckling rats, Zn absorption from conventional soy formula was only 16% vs 47% from dephytinized soy formula. Phytate concentration in a variety of experimental soy formulas was inversely correlated to Zn absorption. These results suggest that the low bioavailability of Zn from soy formula is a function of its phytate concentration and can be overcome by the removal of phytate.

Iron Bioavailability Studied in Infants: The Influence of Phytic Acid and Ascorbic Acid in Infant Formulas Based on Soy Isolate

“…Zinc absorption was increased significantly when 90% dephytinized soy formula was compared with conventional soy formula in infant rhesus monkeys and in rat pups (24). However, when 60% dephytinized soy formula was fed to infants, there was no improvement in zinc absorption, although there was a significant reduction in the fecal excretion of endogenous zinc (25).…”

Behavioral consequences of developmental iron deficiency in infant rhesus monkeys

“…Also, monkey infants can be raised in primate nurseries where the amount and timing of iron in the diet can be precisely controlled through use of infant formulas. Infant monkeys have been used extensively as models for human infants to study absorption, growth and development with formulas of different nutritional content [11,13,35,51,58,41,42,43,33,40,54,57].…”

Absorption of Calcium, Magnesium, Phosphorus, Iron and Zinc in Growing Male Rats Fed Diets Containing either Phytate-free Soybean Protein or Soybean Protein Isolate or Casein.

“…The reason is because it was long difficult to remove phytic acid from soybean. To date, it has been confirmed that low-phytate or phy tate-free soybean protein isolate has positive effects on Ca (13,14), Zn (15) and Mn (16) absorption in hu mans. However, these studies were mainly done by a single dosing of low-phytate soybean together with ra diolabeled minerals, and by monitoring intestinal ab sorption and body retention of radiolabeled minerals.…”