**Abstract**

Gut health is fundamental for human well-being and prevents chronic degenerative diseases and is influenced by the interaction between gut microbiota and food components. In recent years, interest in phenolic compounds has increased due to their health benefits such as antioxidant, antidiabetic, antimicrobial, anti-atherosclerotic, anti-inflammatory, anticarcinogenic, cardio- and neuro-protective properties. Legumes are an essential source of phytochemicals, particularly flavonoids and phenolic acids, distributed mainly in the seed coat, and have been reported to exhibit multiple biological effects. Flavonoids present in legumes have been shown to regulate metabolic stability and membrane transport in the intestine, thus improving bioavailability. Seed processing such as cooking allows the release of phenolic compounds, improving polyphenols digestion and absorption at the intestinal level, maintaining their protective capacity in the oxidative process at the cellular level, and modulating the gut microbiota. All these actions improve gut health, avoiding diseases like irritable bowel syndrome, inflammatory bowel disease, obesity, diabetes, colitis, and colorectal cancer. The effect of the consumption of legumes such as chickpea, pea, and bean, as well as the contribution of phenolic compounds to gut health, will be reviewed in this study.

**Keywords:** Legumes, biological effects, phenolic compounds, seed processing, chronic degenerative diseases, gut microbiota, gut health

## **1. Introduction**

Eating habits are an important factor in the structure, formation, function, and modulation of the gut microbiota, which plays a crucial role in health; environmental factors, antibiotics, and lifestyle also contribute to the dysbiosis of the gut microbiota responsible for gastrointestinal diseases, like colon cancer. Several studies have shown that the gut has a greater impact than food processing and nutrient absorption. Gut health is a function of the gut barrier and gut microbiota essential elements for better health [1–6].

Plants contribute diverse bioactive compounds to the diet [7, 8], including phenolic compounds. Legumes are part of the basic foods with great nutritional relevance due to their content of diverse phenolic compounds that promote health [5, 9]. These compounds are distributed in the whole seed and are mainly responsible for the seed coat color that depends on the composition and concentration [10–14]. The potential health benefits of phenolic compounds in the diet depend on their absorption and metabolism, which in turn are determined by their structure, including their conjugation with other phenols, degree of glycosylation/acylation, molecular size, and solubility [9, 15–17]. During seed processing, phenolic compounds can undergo various changes, altering their antioxidant activity [18, 19].

However, the presence of phenolic compounds and their mechanisms of action in preventing colon cancer or inflammation are probably mediated by the functional composition of the gut microbiota [20–22]. Epidemiological studies have confirmed that regular consumption of legumes has been associated with lower risk due to immunomodulatory effects and prevention of chronic and metabolic diseases, such as cardiovascular diseases, diabetes, cancer, and obesity, in addition to improving gut health [11, 16, 20, 23, 24].

During the absorption of phenolic compounds, like hydroxycinnamic acids (p-coumaric, caffeic, and ferulic) in free and conjugated forms, they are metabolized by the gut microbiota (e.g., genera *Bifidobacterium*, *Lactobacillus*, and *Escherichia*) are able to release them [8]. Moreover, flavonoid glycosides are deconjugated by microbial glucuronidases and sulfatases in the colon, releasing aglycones such as quercetin, myricetin, and kaempferol that can be metabolized by different genera of intestinal bacteria, including *Clostridium* sp., *Eubacterium* sp., *Enterococcus* sp., among others, to form hydroxyphenylacetic and hydroxyphenylpropionic acids as major metabolites leading to increased bioavailability of phenolic compounds [24].

Chickpea, pea, and bean seeds are among the most widely consumed food legumes worldwide. The genus *Cicer* comprises about 44 species. The chickpea (*Cicer arietinum* L.) has two commercial varieties 'Desi' and 'Kabuli' and their characteristics vary according to geographical distribution, shape, size, and color. The color of the Desi variety is dark in comparison with the Kabuli chickpea, which has a fine, light-colored covering and is the most widely consumed [20, 23].

*Pisum sativum* L., commonly known as pea, represents one of the oldest and most widespread cultivated legumes worldwide due to its wide availability, low cost, and high nutritional value [1, 16], they are small seeds with a green or yellow spherical shape. Quality characteristics depend on biological factors between the environment and genetics [25]. Another important legume in food is the genus *Phaseolus*, which includes species such as *P. vulgaris*, *P. lunatus*, *P. coccineus*, *P. acutifolius,* and *P. dumosus*; among these, the most cultivated in Mexico is the common bean (*P. vulgaris*) that has more than 70 varieties grouped according to their color in black, yellow, red, brown, white, purple, and pinto [14, 26, 27].

Phenolic compounds constitute an important group of secondary plant metabolites and influence the diversity and quantity of gut microbial species, allotting prebiotic effects to phenolic compounds, mainly flavonoids involved in modulating the taxonomic composition of the gut microbiota, increasing the relative abundance of beneficial species, and inhibiting the proliferation of bacterial species associated with negative implications [7, 24].
