Antinutrient

Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients.^[1] Nutrition studies focus on antinutrients commonly found in food sources and beverages. Antinutrients may take the form of drugs, chemicals that naturally occur in food sources, proteins, or overconsumption of nutrients themselves. Antinutrients may act by binding to vitamins and minerals, preventing their uptake, or inhibiting enzymes.

Throughout history, humans have bred crops to reduce antinutrients, and cooking processes have developed to remove them from raw food materials and increase nutrient bioavailability, notably in staple foods such as cassava.

Mechanisms

Preventing mineral uptake

Phytic acid has a strong binding affinity to minerals such as calcium, magnesium, iron, copper, and zinc. This results in precipitation, making the minerals unavailable for absorption in the intestines.^[2][3] Phytic acids are common in the hulls of nuts, seeds, and grains and of great importance in agriculture, animal nutrition, and in eutrophication, due to the mineral chelation and bound phosphates released into the environment. Without the need to use milling to reduce phytate (including nutrient),^[4] the amount of phytic acid is commonly reduced in animal feeds by adding histidine acid phosphate type of phytases to them.^[5]

Oxalic acid and oxalates are present in many plants and in significant amounts particularly in rhubarb, tea, spinach, parsley, and purslane. Oxalates bind to calcium and prevent its absorption in the human body.^[6]

Protease inhibitors are substances that inhibit the actions of trypsin, pepsin, and other proteases in the gut, preventing the digestion and subsequent absorption of protein. For example, Bowman–Birk trypsin inhibitor is found in soybeans.^[7] Some trypsin inhibitors and lectins are found in legumes and interfere with digestion.^[8]

Amylase inhibitors prevent the action of enzymes that break the glycosidic bonds of starches and other complex carbohydrates, preventing the release of simple sugars and absorption by the body. Like lipase inhibitors, they have been used as a diet aid and obesity treatment. They are present in many types of beans; commercially available amylase inhibitors are extracted from white kidney beans.^[10]

Other

Excessive intake of required nutrients can also result in them having an anti-nutrient action. Excessive intake of

Avidin is an antinutrient found in active form in raw egg whites. It binds very tightly to biotin (vitamin B₇)^[14] and can cause deficiency of B₇ in animals^[15] and, in extreme cases, in humans.^[16]

A widespread form of antinutrients, the

Saponins in plants may act like antifeedants^[20][21] and can be classified as antinutrients.^[22]

Occurrence and removal

Antinutrients are found at some level in almost all foods for a variety of reasons. However, their levels are reduced in modern crops, probably as an outcome of the process of domestication.^[23] The possibility now exists to eliminate antinutrients entirely using genetic engineering; but, since these compounds may also have beneficial effects, such genetic modifications could make the foods more nutritious, but not improve people's health.^[24]

Many traditional methods of food preparation such as

• Antimetabolite
• Biopesticide
• Plant defense against herbivory

References