Influence of vegetable protein sources on trace element and mineral bioavailability.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing evidence on phytate and mineral bioavailability without systematic search criteria.
PubMed 12949395 · doi:10.1093/jn/133.9.2973S
What was done
This paper reviewed literature on how phytic acid in vegetable protein sources and cereals affects the absorption and bioavailability of trace elements and minerals (iron, zinc, calcium, magnesium, manganese, and copper), focusing particularly on complementary feeding mixtures for infants and young children.
What was found
In adults, phytic acid inhibits the absorption of iron, zinc, calcium, and manganese, but not copper. In infants, phytic acid strongly inhibits iron absorption, has a modest effect on zinc absorption (potentially more important during recovery from infection), and has a minor effect on calcium and magnesium. Iron absorption from whole-grain cereal and legume porridge (phytic acid ~1 g/100 g) is reported as low as 2% to 3% in iron-deficient subjects. Decreasing phytic acid by 90% (~100 mg/100 g dried product) is estimated to increase iron absorption twofold, and complete degradation can increase it fivefold or more. Modest phytate reductions provide little benefit. The review suggests complete enzymatic degradation, maintaining a phytic acid-to-iron molar ratio <1 (preferably <0.5) in fortified foods, or reducing phytic acid to 20–30 mg/100 g dried product for satisfactory zinc absorption.
Why it matters
Because plant-based complementary foods often lead to widespread iron and zinc deficiencies in low-resource settings, this review highlights that minor reductions in phytate are ineffective and that substantial dephytinization or strict molar ratios are required.
Limits
The abstract describes a narrative review with no systematic search methodology, selection criteria, or study counts reported. Underlying primary sample sizes and trial designs are not provided. The abstract explicitly notes far fewer studies exist in infants than in adults.
Cited by
- supports Phytic acid found in grains inhibits and blocks the absorption of certain dietary minerals.