E391 - Phytic acid

At a glance

• E-number: E391; common names: phytic acid, myo-inositol hexakisphosphate (IP6).
• What it does: binds metal ions like iron and copper (a “chelating” or “sequestering” agent), which can influence color, flavor, and stability in foods.
• Where it occurs: naturally present in the bran/germ of cereals, pulses, nuts, and seeds.
• Nutrition note: phytic acid can reduce the absorption of minerals such as iron and zinc when eaten in the same meal.
• Labeling: when used as an additive, it may appear as “phytic acid,” “phytate,” or “E391,” but this is uncommon in everyday foods.

Why is Phytic acid added to food?

Phytic acid binds metal ions (for example, iron and copper) very strongly. In recipes and manufactured foods, this “metal-grabbing” action can help control reactions that cause off-flavors, browning, or discoloration, so it may be used as a chelating/sequestering aid in certain formulations.¹

What foods contain Phytic acid?

• Natural sources: whole and unrefined plant foods. It is abundant in the bran of grains, beans, lentils, peanuts, and other nuts and seeds.² These foods are nutritious, but the phytate they contain can inhibit iron absorption from the same meal.²
• Zinc is affected too: diets high in unrefined cereals and legumes can reduce zinc absorption because of phytate.³
• As an additive: you will only occasionally see “phytic acid,” “phytate,” or “E391” on ingredient lists; most exposure in typical diets comes from the natural phytate present in plant foods.

What can replace Phytic acid?

Depending on the job:

• For chelating/sequestering metal ions: citric acid or calcium disodium ethylenediaminetetraacetate (EDTA) are commonly used alternatives.
• For antioxidant support or color/flavor protection: ascorbic acid can help in many foods.
• For binding minerals in processed meats and seafoods: polyphosphates are often used.

How is Phytic acid made?

In nature, plants make phytic acid by adding phosphate groups to myo‑inositol, then store it in seeds and bran as their main phosphorus reserve.⁴ That is why whole grains, legumes, nuts, and seeds naturally contain the highest amounts.⁴

Is Phytic acid safe to eat?

Phytic acid is a normal part of many plant foods and is safe for most people as part of a balanced diet. The main nutritional concern is not toxicity but reduced mineral absorption—especially nonheme iron (the form in plants). Vitamin C (for example, from fruit or citric acid-rich foods) and animal protein can counter this iron inhibition when eaten in the same meal.² Phytate can also lower zinc absorption, particularly in diets that rely heavily on unrefined cereals and legumes without enhancers of absorption.³

Does Phytic acid have any benefits?

• Technological: as a strong chelating agent, it can help manage metal-catalyzed reactions that lead to rancidity or discoloration in some formulations.¹
• Botanical: in plants, it safely stores phosphorus and minerals for the seed, which explains its natural presence in many staple foods.⁴
• Nutrition context: foods that contain phytic acid (whole grains, legumes, nuts, seeds) also provide fiber, protein, and micronutrients; overall diet quality matters more than the presence of a single compound.

Who should avoid Phytic acid?

• People with iron deficiency or at high risk of it may want to limit high-phytate side dishes during iron-rich meals, or pair those meals with vitamin C sources to improve iron absorption.⁵
• People at risk of zinc deficiency (for example, those eating diets very high in unrefined cereals/legumes with few enhancers) should be mindful of phytate’s effect on zinc absorption.⁶ If you have a diagnosed deficiency, a clinician or dietitian can tailor meal timing and preparation to your needs.

Myths & facts

• Myth: “Phytic acid is a toxin.” Fact: it is a natural plant compound found in many healthy foods.
• Myth: “You must cut out all phytate.” Fact: most people do fine including whole grains and legumes; the focus should be on overall diet and smart pairing to support mineral absorption.
• Myth: “Phytic acid always causes deficiencies.” Fact: risk depends on the whole diet; vitamin C, leavening/fermentation, and food choices can offset its effects on iron and zinc.

Phytic acid in branded foods

You will seldom see E391 on everyday labels. If present, it may appear as “phytic acid,” “phytate,” or a specific salt such as “sodium phytate.” Check ingredient lists on specialized beverages, supplements, or fortified products where metal chelation or color stabilization might be desired.

References

Footnotes

1. Phytic acid — PubChem, National Library of Medicine (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/Phytic-acid ↩ ↩²

2. Iron Fact Sheet for Health Professionals — NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/ ↩ ↩² ↩³

3. Zinc Fact Sheet for Health Professionals — NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/ ↩ ↩²

4. Phosphorus Fact Sheet for Health Professionals — NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Phosphorus-HealthProfessional/ ↩ ↩² ↩³

5. Scientific Opinion on Dietary Reference Values for iron — European Food Safety Authority (EFSA). https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2015.4254 ↩

6. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (Zinc chapter) — Institute of Medicine via NCBI Bookshelf (NIH). https://www.ncbi.nlm.nih.gov/books/NBK222318/ ↩