Nutrients nourish plants and animals to grow and live; anti-nutrients can block the absorption of nutrients.
Anti-nutritional factors such as trypsin inhibitor, phytic acid, and cyanogen are as important as any edible plant part’s nutritional content. They are generated in natural food substances by the normal metabolism of species.
Glucosinolates in cruciferous vegetables (broccoli, Brussel sprouts, cabbage)—can prevent iodine absorption, which may interfere with thyroid function and cause goiter.
Lectins in legumes (beans, peanuts, soybeans), whole grains can interfere with calcium, iron, phosphorus, and zinc absorption.
Phytates (phytic acid) in whole grains seeds, legumes, and nuts can decrease the absorption of iron, zinc, magnesium, and calcium.
Saponins in legumes, whole grains—can interfere with normal nutrient absorption.
Tannins in tea, coffee legumes—can decrease iron absorption.
Anti-nutrients may also exert health benefits. Phytates, for example, have been found to lower cholesterol, slow digestion, and prevent sharp rises in blood sugar. Many anti-nutrients have antioxidant and anticancer actions, so avoiding them entirely is not recommended.
Additional reading on nutrition and its impact on health: