A review of phytate, iron, zinc, and calcium concentrations in plant-based complementary foods used in low-income countries and implications for bioavailability.
Level 5 - mechanism / opinion, no new human data
Narrative review of food composition and chemical molar ratio data without direct human clinical trials.
PubMed 20715598 · doi:10.1177/15648265100312S206
What was done
The authors reviewed concentrations of phytate (hexa- and penta-inositol phosphate), iron, zinc, and calcium, as well as phytate:mineral molar ratios, across 26 indigenous and 27 commercially processed plant-based complementary foods sold in low-income countries.
What was found
Phytate concentrations were highest in unrefined cereals and legumes (~600 mg/100 g dry weight), followed by refined cereals (~100 mg/100 g dry weight), and starchy roots and tubers (< 20 mg/100 g dry weight), with mineral concentrations following the same trend. Sixty-two percent (16/26) of indigenous foods and 37% (10/27) of processed foods had at least two phytate:mineral molar ratios exceeding recommended thresholds for adequate absorption (phytate:iron < 1, phytate:zinc < 18, phytate:calcium < 0.17). Desirable molar ratios were met by 25% of foods for iron, 70% for zinc, and 57% for calcium, primarily in products fortified with minerals or enriched with animal-source foods.
Why it matters
Plant-based infant foods in developing settings frequently fail to meet infant mineral requirements due to phytate inhibition. The findings show that dephytinization alone is generally insufficient to meet WHO targets and must be paired with mineral fortification or animal-source food enrichment.
Limits
The review relies on published chemical composition and theoretical molar ratios rather than direct in vivo human absorption or clinical status measurements. Search strategy, selection criteria, and comprehensive statistical variance among food samples were not reported in the abstract.
Cited by
- supports Phytic acid found in grains inhibits and blocks the absorption of certain dietary minerals.