What are phytates? How they affect iron and zinc absorption
Phytates, phosphorus's storage form in beans and grains, chelate iron, zinc and calcium and measurably cut how much a vegetarian diet absorbs, but soaking, sprouting and fermenting the same foods strip out most of it, and clinical trials also credit phytate with cutting kidney stones and slowing bone loss.
Vegan Brief·Evidence last reviewed August 22, 2026
This is a summary of the cited evidence, not medical advice.
Vegetarian iron absorption~5–12% vs. 14–18% on mixed diets
Fermentation phytate reduction28–96%, up to 85.6% in one trial
World zinc deficiency~17%, tied partly to dietary phytate
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The short version
Phytate is the form phosphorus takes in seeds, beans and grains, and it has a second job besides storing phosphorus: it grabs onto minerals before the gut can absorb them.
Primary source 01 / 10
Phytates, the storage form of phosphorus in plants, bind some minerals such as zinc in the intestine and form an insoluble complex that inhibits zinc absorption
NIH's iron fact sheet puts a number on the difference a phytate-heavy, meat-free diet makes.
Primary source 02 / 10
The bioavailability of iron is approximately 14% to 18% from mixed diets that include substantial amounts of meat, seafood, and vitamin C (ascorbic acid, which enhances the bioavailability of nonheme iron) and 5% to 12% from vegetarian diets
None of this is fixed. NIH points straight at the kitchen fix for people on plant-heavy diets.
Primary source 05 / 10
People who follow vegetarian or vegan diets might benefit from using certain food preparation techniques that reduce the binding of zinc by phytates and increase its bioavailability, such as soaking beans, grains, and seeds in water for several hours before cooking them
A 2023 review pulled together the clinical-trial literature on phytate and found the antinutrient label only tells half the story.
Primary source 08 / 10
phytate can have beneficial health effects such as antioxidant, anticancer potential and reduction of pathological calcifications in blood vessels and organs; but also, negative effects by reducing the absorption of minerals important for maintaining the homeostasis of the human body
Two of the clinical findings it cites are the same compound working directly against two conditions this shelf covers elsewhere: bone loss and kidney stones.
Primary source 09 / 10
phytate consumption by postmenopausal women reduced their risks of hip and major osteoporotic fractures
Phytate genuinely lowers how much iron, zinc and calcium a meal delivers, and that effect is well documented enough to explain part of the gap between vegetarian and mixed-diet mineral absorption. It is also genuinely reducible: soaking, sprouting and fermenting beans and grains, the ordinary preparation steps behind sourdough bread, tempeh and properly cooked lentils, remove much of it before it reaches the table. And in the same body of clinical research, the compound shows up as a measured protective factor against bone loss and kidney stones rather than only as an obstacle. That combination, real cost and real, preparable benefit, is what earns a Mixed grade instead of a flat warning.
Iron on a vegan diet: what the NIH fact sheet saysPlants have iron, just the kind your body absorbs less easily. The government fact sheet quantifies exactly how much less, and what raises the odds in your favor.
Zinc on a vegan dietPlants have zinc; phytates make you absorb less of it. The fix is more intake plus a few kitchen tricks that free the zinc up.
Oxalates in plant foodsSpinach can carry more than a thousand milligrams of oxalate per 100 grams, and the compound does bind calcium and iron and feed kidney stones in people prone to them, but boiling leaches much of it out and cutting dietary calcium to fight stones backfires.
Do phytates reduce iron and zinc absorption on a vegan diet?
Yes, measurably. NIH's fact sheets put vegetarian iron absorption at roughly 5 to 12% versus 14 to 18% on a mixed diet, and name phytate directly as a reason zinc absorbs less efficiently from beans, nuts and whole grains than from animal foods.
Does soaking or sprouting beans actually remove phytate?
Yes. A 2024 trial on maize found phytate reduction ranging from 28 to 96% depending on the method, with a combination of soaking, germination and fermentation cutting phytate by up to 85.6% in one test.
Are phytates only bad for you?
No. A 2023 review of clinical trials found phytate also has measured benefits, including reduced risk of hip and osteoporotic fractures in postmenopausal women and inhibition of the crystal formation behind some kidney stones.
The primary sources
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