Plant Antinutrients- Enzyme Inhibitors

August 19, 2020

Plants produce a variety of substances as part of their defense behaviour in order to protect their integrity. Because of the high protein content and beneficial nutritional value, legumes play an important role in human diet.

Legumes provide energy, dietary fibre, protein, minerals and vitamins required for human health and provide a well-balanced essential amino acid profiles when consumed with cereals and other foods.

Enzyme inhibitors, a group of antinutritional compounds, found in legumes, can be toxic, unpalatable or indigestible. 

These substances are considered to be ‘antinutrients’ because their uptake often interferes with nutrient absorption. The term ‘enzyme inhibitors’ is suggestive of inhibiting or interfering with different enzymatic activities related to the human digestive system. Also known as Protease inhibitors, these substances work to disrupt the enzymatic ability of the digestive or microbial enzymes that are present in the stomach resulting in the inability to properly digest the plant material.To this group of factors belong amylase inhibitors and protease  inhibitors. 

Protease Inhibitors

Proteases are enzymes that help in the breakdown of proteins into smaller pieces. Hence, l Protease inhibitors are substances which prevent digestion and absorption of proteins and amino acids in the gut.

This class of antinutrient substances are capable of hampering the activities of different proteolytic enzymes, namely- Trypsin, Pepsin, Chymotrypsin and others. All the 3 enzymes are responsible for digestion and absorption of proteins.

Protease inhibitors are widely present in commonly consumed foods and can be a cause of poor protein utilization from the diet. This can ultimately lead to growth issues and malnutrition. However, most of the information on the nutritional effects of the inhibitors has come from experiments with animals. Also animal studies have shown that trypsin and chymotrypsin inhibitors are capable of causing enlargement of the pancreas.

Protease inhibitors have also found therapeutic role in modern medicines for the treatment of HIV and respiratory diseases. But long term use of these medicines have been reported to cause insulin resistance and other metabolic conditions.

Soybean contains the highest amount of protease inhibitors. Other sources include crops such as mung beans, ground nuts, chick-pea beans, potatoes, barley,oats, jowar cucumber seeds, millet, wheat, buckwheat, groundnut, chickpea, pigeonpea, corn, and pineapple.

Amylase Inhibitors

Amylase inhibitors are substances that bind to alpha amylases making them inactive. Alpha amylases are substances that aid in starch digestion. Inhibition of α-amylase is considered a strategy for the treatment of disorders in carbohydrate uptake, by reducing insulin levels, as well as, dental caries. However, the instability of amylase inhibitor under the conditions of the gastrointestinal tract and its heat-labile constituent results in its failure to be used as starch blocker.

Amylase inhibitors are found in cereal grains such as wheat, maize, rice, barley and legumes like kidney beans and cowpea.

Ways to reduce Enzyme inhibitors from foods

Handy practices like soaking, germination and fermentation can reduce the amounts of these antinutrients from foods consumed.

iThrive recommendations: Avoid consuming these foods if you have underlying health issues or reach out to us and we’ll guide towards making these foods safe for consumption


Ria Jain
Functional Nutritionist

Ria has a Master’s in Nutrition and Dietetics and is in a permanent research mode and keeps the rest of us at iThrive (Previously ThriveFNC) updated with her latest findings in the field of Nutrition. Her articles on iThrive's blog are an expression of her research findings. We really don’t know what we’d do without her support and her focus.

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