Legume Genomics and Genetics 2025, Vol.16, No.5, 245-252 http://cropscipublisher.com/index.php/lgg 246 2 Types and Biological Functions of Common Anti-Nutritional Factors 2.1 Inhibitory effects of phytates and oxalates on mineral absorption Not all minerals can be smoothly absorbed by the human body. Sometimes the problem lies in certain natural components in the beans. For instance, phytic acid, which is very common in beans, easily combines with minerals such as calcium, iron, zinc and copper to form insoluble complexes. As a result, the body has difficulty absorbing these nutrients (Nkhata et al., 2018). Oxalic acid is also a "troublemaker", especially hindering calcium absorption and may also increase the risk of kidney stones (Jha et al., 2022). For some people who mainly rely on a plant-based diet, these factors are very likely to be one of the root causes of micronutrient deficiencies. 2.2 Inhibitory mechanisms of protease inhibitors and trypsin inhibitors Some people think that eating bean protein can easily absorb it, but that's not the case. Some anti-nutritional factors - such as protease inhibitors, especially trypsin inhibitors - can interfere with the activity of digestive enzymes. For instance, trypsin and chymotrypsin, which are the "main decomposition forces", are "entangled" by them, thereby reducing the digestibility of proteins (Dangi et al., 2021). In populations where protein sources are already scarce, this inhibition may lead to growth restriction. But the good news is that most of these inhibitors are not heat-resistant, and their content can be significantly reduced after cooking or processing. 2.3 Effects of tannins, saponins, and lectins on the digestive and absorptive systems Tannins, saponins and lectin, these names that sound quite "chemical", are actually hidden in many common beans. Tannin is a type of polyphenolic compound that can combine with proteins and digestive enzymes, reducing the digestibility of proteins and also affecting the absorption of minerals such as iron (Samtiya et al., 2020). The function of saponins is slightly more complex. They can form complexes with proteins and cholesterol. In severe cases, they may even damage cell membranes and cause gastrointestinal discomfort. Lectin, also known as phytohemagglutinin, is a carbohydrate that directly adheres to the intestinal wall cells, affecting the absorption system (Banti and Bajo, 2020). Of course, if the intake is only low, the situation is not serious. There are also studies that have found that these substances have the potential to act as antioxidants and even fight cancer at low doses. The problem is that when beans become the staple food, their side effects can no longer be ignored. 3 Comparative Analysis of Anti-Nutritional Factor Contents in Different Legumes 3.1 Analysis of major anti-nutritional components in soybean, mung bean, and pea Although all beans are rich in plant protein, the content of anti-nutritional factors (ANF) varies. Take soybeans as an example. The levels of phytic acid and trypsin inhibitors are not low, which is why it is often pointed out to affect protein digestion and mineral absorption (Samtiya et al., 2020). The situation of mung beans is slightly better. Although they also contain phytic acid and tannin, some genotypes with low content have been identified through selection and breeding (Sinha et al., 2023). The advantage of peas lies in the fact that they have relatively little ANF (especially tannin) to start with, so they are considered one of the more suitable raw materials for food or feed, especially after breeding improvement (Miki et al., 2009). 3.2 Composition characteristics of anti-nutritional factors in adzuki bean, kidney bean, and chickpea Not all beans are on the same starting line in terms of nutritional safety. For instance, kidney beans are rather "troublesome" due to their high content of lectin and phytic acid - if not handled properly, they not only affect absorption but may also cause toxic reactions (Venketeish et al., 2024). In contrast, chickpeas have a moderate level of anti-nutritional substances. Besides phytic acid, saponins and oligosaccharides, some varieties are even rich in vitamin E (Banti and Bajo, 2020). As for red adzuki beans, although there are relatively few studies on them, preliminary results show that their phytic acid, tannin and saponin contents are generally lower than those of kidney beans. As part of dietary diversification, they have potential to be explored. 3.3 Impact of varieties, origins, and cultivation practices on anti-nutritional factor content The content of ANF in the same kind of bean may vary when grown in different places. In fact, not only the geographical environment but also the cultivation methods and the varieties themselves can affect the final component levels. For crops like chickpeas or lentils, the differences in phytochemical content among different
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