Phytate

Phytate refers to the negatively charged forms and salts of phytic acid, also called myo-inositol hexakisphosphate or InsP6. The molecule consists of an inositol ring carrying six phosphate groups, which give it a strong negative charge under physiological conditions. In plants, phytate is an important storage form of phosphorus and is concentrated particularly in seeds, including cereal grains and legumes .^1,2

Because of its multiple phosphate groups, phytate can bind positively charged mineral ions. In the gastrointestinal tract, it can form complexes with minerals such as iron, zinc, calcium, and magnesium. Some of these complexes are poorly soluble or less available for intestinal uptake. Dietary phytate can therefore reduce mineral bioavailability, with its effects on nonheme iron and zinc absorption particularly well established .^1,2

Phytate can be broken down by enzymes called phytases, which progressively remove phosphate groups and produce lower inositol phosphates. Humans have limited capacity to digest intact phytate in the small intestine, although phytases present in foods or produced by microorganisms can contribute to its degradation. Food-processing methods that activate phytase, including fermentation and germination, can therefore reduce phytate content .^1,2

Phytate and phytic acid are closely related but chemically distinct terms. Phytic acid refers to the protonated acid, whereas phytate refers to its ionized forms and salts. In nutrition literature, however, “phytate” is often used more broadly for the naturally occurring forms of phytic acid and its salts in foods .^1,2