Antinutrients Explained: Oxalates, Phytates, Lectins, and Whether to Worry

Antinutrients are naturally occurring plant compounds that can interfere with nutrient absorption or digestion. The main ones are oxalates, phytates, and lectins.

In a varied diet they rarely cause problems, and the same plants deliver fiber and micronutrients that outweigh the downside.^[1]

Oxalate binds calcium and, in susceptible people, contributes to kidney stones. It concentrates in a short list of foods:

Pairing oxalate rich foods with a calcium source at the same meal can lower the amount of oxalate your gut absorbs, since calcium binds to oxalate in the intestine before it reaches the kidneys.^[5] This is one reason low calcium diets are linked to a higher risk of kidney stones, not a lower risk.^[6] Cooking methods also matter, since oxalate levels can vary a lot even within the same food, as seen in spinach grown and prepared different ways.^[4]

Phytate binds minerals such as iron and zinc, lowering their absorption from a meal. It is highest in whole grains, legumes, nuts, and seeds.

Soaking, sprouting, and fermenting reduce it.^[2]

Fermentation may work even better than simple soaking for freeing up minerals from legumes.

One study on chickpea protein isolate found that both bacterial and yeast fermentation cut phytate content substantially compared to the unfermented isolate, while also boosting protein digestibility.^[7] Yeast fermentation performed especially well, suggesting the type of microbe used can change how much benefit you get.^[7]

Lectins in raw legumes can cause digestive upset, but ordinary cooking deactivates the vast majority; properly cooked beans are safe and nutritious.^[3]

For most people antinutrients are not a reason to avoid nutrient-dense plants. Soak and cook legumes and grains, vary your diet, and only stone-formers need to watch oxalate closely.

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