Phytate vs Minerals

Dietary Phytic Acid (Phytate) Compromising Mineral Bioavailability


1987 – Dr. L. Hallberg, University of Göteborg, Sweden

Wheat Fiber, Phytates and Iron Absorption

“The marked inhibitory effect of bran on iron absorption can almost completely be explained by its content of phytate.”

“As little as 5-10 mg of phytate phosphorus added to a wheat roll containing 3 mg of iron inhibited iron absorption by 50 percent. Ascorbic acid as well as meat strongly counteracted this inhibition.”

“Enzymatic dephytinization of bran almost fully removed its inhibiting effect.”


JAN 1989 – University of Göteborg, Sweden

Iron Absorption in Man: Ascorbic Acid and Dose-dependent Inhibition by Phytate

“The inhibition of Fe absorption was strongly related to the amount of phytate added; 2 mg inhibited absorption by 18%, 25 mg by 64%, and 250 mg by 82%.”

Summary statement: “The marked inhibition of Fe absorption by phytates and the significant counteracting effect of ascorbic acid have wide nutritional implications.”


MAR 1989 – University of Göteborg, Sweden

Iron Absorption: No Intestinal Adaptation to a High-Phytate Diet

“The present study examined the possibility that a high bran and phytate intake over a long period would induce changes in the intestines or its microflora leading to a reduction of the inhibitory effect of dietary phytates on iron absorption.”

Summary statement: “No intestinal adaptation to a high phytate intake could be observed. This finding has wide nutritional implications.”


SEP 1992 – American Journal of Clinical Nutrition

Soy Protein, Phytate, and Iron Absorption in Humans

The effect of reducing the phytate in soy-protein isolates on non-heme iron absorption was examined in 32 human subjects.

Summary statement: “…even after removal of virtually all the phytic acid, iron absorption from the soy-protein meal was still only half that of the egg white control. It is concluded that phytic acid is a major inhibitory factor of iron absorption in soy-protein isolates, but that other factors also contribute to the poor bioavailability of iron from these [soy] products.”


DEC 2002 – Chalmers University of Technology, Göteborg, Sweden

Bioavailability of Minerals in Legumes

“The mineral content of legumes is generally high, but the bioavailability is poor due to the presence of phytate, which is a main inhibitor of Fe and Zn absorption.”

“Furthermore, soy protein per se, has an inhibiting effect on Fe absorption.”

Summary statement: “Fe and Zn absorption have been shown to be low from legume-based diets. It has also been demonstrated that nutritional Fe deficiency reaches its greatest prevalence in populations subsisting on cereal and legume-based diets. However, in a balanced diet containing animal protein, a high intake of legumes is not considered a risk in terms of mineral supply.”


MAY 2003 – Nestle Research Center, Lausanne, Switzerland & Kansas University Medical Center, Kansas City, MO

Degradation of Phytic Acid in Cereal Porridges Improves Iron Absorption by Human Subjects

“Iron nutrition is particularly important during the weaning period, when the infant is growing rapidly and has a high demand for iron. In developing countries, the intake of absorbable iron by infants is often low, and iron deficiency anemia is common. A major consequence is retarded psychomotor and mental development, with possible long-term negative effects on school performance.”

“[T]he findings of the current studies confirm the very low iron absorption from cereal porridges and indicate that phytate degradation would be a useful means for improving iron absorption from cereal-based foods…”

Summary statement: “In conclusion, the magnitude of iron absorption from cereal-based porridges depends on the contents of the different components that enhance or inhibit iron uptake. Phytic acid, polyphenolic compounds, and milk are the major inhibitors, whereas ascorbic acid enhances iron absorption. In the absence of milk and polyphenols, phytic acid degradation greatly improves iron absorption from cereal-based foods and, in developing countries, dephytinization should be considered as a major strategy to improve iron nutrition during the weaning period.”


SEP 2003 – Institute of Food Science, Ruschlikon, Switzerland

Influence of Vegetable Protein Sources on Trace Element and Mineral Bioavailability

“Vegetable protein sources are often mixed with cereals for complimentary feeding. Both contain high levels of phytic acid, which can inhibit trace element and mineral absorption (in adults). There are far fewer studies in infants.”

“Because iron and zinc deficiencies are widespread in infants and young children in developing countries, the bioavailability of iron and zinc from complementary food is a major concern.”

“Iron absorption may be as low as 2-3% from porridge based on whole-grain cereals and legumes, even in iron-deficient subjects.”

“Decreasing phytic acid by 90% would be expected to increase absorption about twofold and complete degradation perhaps fivefold or more.”

Summary statement: “More modest reductions in phytic acid content may not usefully improve iron absorption. Complete enzymatic degradation of phytic acid is recommended.”


FEB 2004 – Swiss Federal Institute of Technology Zurich, Switzerland

Dephytinization of a Complementary Food Based on Wheat and Soy Increases Zinc, but not Copper, Apparent Absorption in Adults

“These results clearly demonstrate the beneficial effect of dephytinization of a complementary food on fractional absorption of zinc, but not copper in adults. The long-term nutritional benefits of dephytinization of complementary foods should be evaluated in young children.”

Summary statement:  “The usefulness of the newly developed technique to dephytinize cereal-based complementary foods by using phytase naturally occurring in whole-grain cereals should be explored in large-scale production, and the long-term nutritional benefits of dephytinization of foods consumed during early life should be evaluated in infants and young children.”


MAR 2007 – National Institute for Nutrition and Food Safety, Beijing, China

Phytate Intake and Molar Ratios of Phytate to Zinc, Iron and Calcium in the Diets of People in China

Study estimates the median daily intake of phytate in China at 1186 mg. [higher than in U.S.] 

Summary statement: “The dietary phytate intake of people in China was higher than those in Western developed countries and lower than those in developing countries. Phytate may impair the bioavailability of iron, calcium and zinc in the diets of people in China.”