Antinutritional factors

Substances that erode the nutritional value of foods by cutting nutrient content, bioavailability, digestibility or utilisation. The roster includes enzyme inhibitors — proteinase and amylase inhibitors abundant in legumes and cereals; phytates and phytic acid, which lock up iron, zinc and calcium; tannins and related polyphenols that complex proteins; and goitrogenic or haemagglutinating compounds. Traditional processing exists largely to tame them: soaking, germination, fermentation and thorough cooking each neutralise particular factors. Plant breeders also select low-antinutrient varieties, balancing nutritional gain against the pest resistance some of these compounds provide.