Mentha is a perennial, aromatic, and curative herb which has extensive global distribution. Genus Mentha belongs to the family Lamiaceae and comprises 25–30 known species. Mentha grows vigorously at low temperatures but could undergo a wide range of environmental conditions. Normally, it can reach a height of 10 to 20 cm or more. This genus emerged from Midland countries and progressively expanded worldwide by either artificial or natural genesis [1]. They are now predominantly found in Eurasia, Australia’ South Africa, and North America. According to various studies, Mentha plants have superabundant ingredients of phenolic compounds distinctly phenols, flavonoids, terpenes, quinines, and polysaccharides ^[2][3][2,3]. These phytochemicals paved the way for significant utilization in the production of pharmaceuticals food and beverage industry ^[1][4][5][1,4,5]. Numerous species of Mentha are used as spices and for herbal teas. Generally, every part, for instance, the leaves, stems, and roots of Mentha, have been used in tribal and traditional medicines ^[6][7][6,7]. Economically, highly important species are Mentha aquatica L. (M. aquatica), Mentha longifolia L. (M. longifolia), Mentha × piperita L. (M. × piperita), Mentha spicata L. (M. spicata), and Mentha arvensis L. (M. arvensis). All these species possess potential phytochemicals, such as iso-menthol, iso-menthone, cineol, limonine, piperitone, carvacrol, dipentene, linalool, thujone, piperitenone oxide, and phellandrene, which play an important role in pharmacy, food, flavor, ointment, and associated industries ^{[1][8][9][10]}[1,8,9,10]. The utilization of Mentha sp. in the food industry will provide a cost-effective and biocompatible route to control diabetes and obesity [11]. Diabetes is a sort of metabolic disorder accrued due to hyperglycemia with raising of glucose levels in the blood, caused by a lack of insulin or a reduction in the insulin level [12]. The extensive use and economic importance of Mentha are due to its nutritional value and ability to replace sugar ^[6][13][14][6,13,14]. The application of Mentha phytoconstituents in food items as preservatives and additives will help to reduce the risk of diabetes and cardiovascular diseases.

The frequency of diabetes and cardiovascular diseases are increasing across the world due to diets consisting of high-fat foods and less exercise [15]. The high amount of triglycerides, flavors, and synthetic preservatives in food reduces food nutritional values and leads to diabetes, obesity, and other chronic diseases ^[16][17][16,17]. It has been reported that 30–80% of people are at risk of diabetes and obesity due to dietary habits and lack of physical activities [18]. Various approaches, such as insulin pills and the utilization of sugar-free food, are adopted to control diabetes and obesity ^[19][20][19,20]. These approaches adversely affect patients’ nutrition status and food enjoyment and severely decline the patient’s quality of normal life. Consequently, it intensifies the utilization of natural products, such as phytoextracts and essential oils, to boost the nutritional values of food and reduce the risk of diabetes and obesity ^[21][22][21,22]. In the last two decades, continuous efforts have been made to control metabolic disorders via natural routes, such as ingestion of dietary products. Several chemical drugs are used in food processing, but research has revealed adverse side effects, encouraging the use of active natural compounds ^{[23][24][25][26]}[23,24,25,26]. Plant-derived extracts, in pure form or adulterated form, provide endless opportunities as healthy and biocompatible food products ^[27][28][27,28]. Currently, epidemiological researchers suggested many medicinal and aromatic plants for their nutritional and preservative abilities ^[29][30][29,30]. The aqueous extracts of medicinal plants can be used in dietary products to provide plant-based food nutrition to human beings ^[31][32][31,32]. Aqueous extracts are usually obtained from the aqueous phase through a physical process that does not influence their composition [33]. However, prior to the use of these extracts at mass scale, thorough investigations, such as cytotoxicity, antioxidant, antidiabetic activities, and lipid oxidation potential, are necessary to ensure their efficacy and safety through proof-of-concept research for potential health claims ^[34][35][34,35]. Mentha is a medicinal and economically important plant that is regularly used for the treatment of vomiting and nausea, its antiallergic effects, its antifungal and antibacterial effects, its antidiabetic effects, the treatment of obesity, the treatment of gastrointestinal diseases, its anticarcinogenic effects, and pain relief ^[1][36][37][1,36,37].

2. Genus Mentha: Morphology and Systematics

2.1. Morphology

Mentha L. is a perennial herb, spread through long slender rhizomes. The rhizomes spread rapidly, and consequently, various populations of this species comprise a progression of clones. The rhizomes sections spread especially along wetlands and riverbanks, resulting in vegetative multiplication and dispersal [38]. The plant has broad ovate leaves rounded or sometimes lanceolate at the base with pubescents and thick-veined leaves (Figure 1). The flowers are arranged in a large whorl with a triangular teeth calyx, and anthers exerting from the corolla. The flowers are mostly protandrous, and usually, self-pollination occurs ^[1][38][1,38].

2.2. Systematics

Mentha was depicted by Carl Linnaeous from a plant specimen collected from Sweden, who named it M. canadensis L. Bentham pursued Linnaeous in keeping M. canadensis L. as a subglabrous assortment (var. glubrata Benth.) and a villose one (var. villosaBenth.) [39]. However, recent information based on physiological, anatomical, and molecular attributes have demonstrated that Mentha can be grouped into 42 species, hundreds of subspecies, varieties, and cultivars, and 15 hybrids [40]. The scientific classification of Mentha is exceptionally unpredictable and there is no consensus. Mentha is generally classified into five sections, i.e., Eriodontes, Mentha, Preslia, Audibertia, and Pulegium [41]. Recently, Zahra et al. [42] reported that phylogenetically, M. arvensis, M. spicata, and M. × piperita show 98% identity when using matK sequencing.

3. Essential Oil and the Chemical Composition of the Studied Species of Mentha

In a true sense, essential oils are not really oils; they are in fact volatile chemicals, produced by living organisms, and are mostly extracted by distillation ^[43][44][43,44]. Mentha species contain essential oils with different chemical compositions; for example, in M. pulegium L., natural compounds have been reported to account for 96.9% of the chemical profile, including oxygenated monoterpenes, monoterpenes hydrocarbons, oxygenated sesquiterpenes, and non-terpene hydrocarbons. The essential oils separated from leaves of M. pulegium contain carvone (56.1%), limonene (15.1%,) E-caryophyllene (3.6%,), oleic acid (3.2%), and 1,8-cineole (2.4%) [45]. Variations in the essential oil composition and its chemical composition were also observed in some species of Mentha. Major compounds in M. × piperita were observed, including 1-menthone, isomenthone, menthol, menthyl acetate, caryophyllene, and germacrene-D. The study reported a sufficient amount of oil composition, varying from 0.63% germacrene-D to 51% menthol. This indicates that Mentha species contain menthol in maximum quantity [46]. Therefore, the plant has the potential to be used as a medicinal ingredient in the food industry to reduce the risk of cardiovascular diseases. The same study reported 12 essential oil compounds in M. longifolia with different concentrations of oil compounds from April to July. Another study reported pulegone (86.64%) as a major constituent from M. pulegium, possessing antioxidant, quorum sensing, antiinflammatory and antimicrobial activities, indicating that the plant has the potential to reduce the risk of cardiovascular diseases [46]. The chemical composition of Peppermint oil was reported to include oxygen-containing substances, such as menthone (20%), menthol (45–50%), and sesquiterpenes about 3% [47]. It has been reported that M. spicata contains major essential oil compounds, including oxygenated monoterpenes (approximately 67%), sesquiterpenes hydrocarbons (7.5%), monoterpene hydrocarbons (approximately 20%), oxygenated sesquiterpenes (1.2%), and other compounds (1.7%) [47]. Piperitrone (81.18%) and piperitenone oxide (94.8%) were also reported from M. spicata [47]. Detailed information of the essential oils and its composition is provided in Table 1 of some common Mentha species (Table 1). The presence of essential oils indicate that Mentha exhibit high antioxidant, antiinflammatory, and antimicrobial potential, which would help to control the risk of cardiovascular diseases by using Mentha species compounds in food products ^[48][49][48,49]. The essential oils of Mentha are using in aromatherapy. Many food and beverages industries are using Mentha as food additive and flavoring agent. Due to aromatic compounds and secondary metabolites, fresh or dried leaves of Mentha are used in chewing tobacco, confectionaries, analgesic balm, perfumes, candies, and the tobacco industry [66]. Some researchers found potential antidiabetic effects of Mentha ^[67][68][67,68]. The use of Mentha in food industry will open new avenues for epidemiologists to control diabetes and cardiovascular diseases.

4. Health Benefits of Mentha

Mentha is a much desired and demanded herb due to its medicinal and therapeutic use. The use of Mentha species has been reported in China since the rule of Ming [69]. Mentha became an official item of Materia medical in London Pharmacopeia [70]. In the 18th century, it was commonly used as a medicinal herb ^[71][72][71,72]. Various health benefits of Mentha species have been reported ^[50][64][50,64]. Mentha species have shown analgesic activity during in vivo experiments on mice [61]. Mentha species showed antibacterial and antifungal activities against different bacterial and fungal strains [73]. Mentha species have traditionally used against various diseases and have the potential to be used for cardiovascular diseases [68]. Several studies have indicated that Mentha species contain free radical species and nonradical species, e.g., hydrogen peroxide, which is harmful for molecules of microbes, such as proteins, lipids, nucleic acids, and carbohydrates. Extracts and essential oils of Mentha species have shown several health benefits (Figure 2) ^[74][75][74,75]. Some studies found that mint enable lungs surfactants to filter the air and perform better pulmonary action. Methanol from the mint stimulates respiratory muscle strength and increases the end tidal oxygen rate in the human body ^[76][77][76,77]. Mentha plants contain constituents with cytotoxic properties, and could be used in developing anticancer agents; for example, M. longifolia, M. arvensis, and M. × piperita were found to possess cytotoxic activity against breast cancer in humans ^[78][79][78,79] and human laryngeal epidermoid carcinoma [80]. The direct application of Mentha on the skin shows excellent analgesic activity, producing a cooling effect on the skin. Mint oil stimulates blood receptors on the skin and expands blood vessels, resulting in a cold sensation and relaxation [69]. Mentha sp. possesses various secondary metabolites which are useful against different disorders (Table 1). These can be used in the food industry to reduce malnutritional risks in diabetic and cardiovascular patients.