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How do phytic acid and oxalic acid affect mineral absorption?

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Illustration of a vegan food pyramid divided into four sections: whole grains at the base, followed by vegetables, then fruit, and legumes at the top, with recommended daily servings and images of representative foods in each group. — vegetarianism A vegan food pyramid, which excludes meat and animal products.

Phytic acid and oxalic acid act as antinutrients that can reduce the bioavailability of minerals in the human diet, particularly in plant-based foods.

Phytic acid: Found primarily in cereal grains and legumes, phytic acid interferes with mineral absorption by forming complexes with certain minerals. This process renders the minerals insoluble and, consequently, indigestible to the body.1
Oxalic acid: This compound binds to minerals, most notably calcium, preventing their absorption. A clear example is spinach, which contains high levels of oxalic acid; as a result, only a small percentage of the calcium present in the vegetable is actually absorbed by the body.1

In general, minerals are better absorbed from animal-derived foods than from plant foods, as the latter often contain fiber and these specific substances that inhibit the body's ability to utilize essential minerals.1