Potential health benefits of garden pea seeds and pods: A review

Pea (Pisum sativum L.) is a nutritious pulse crop belonging to the leguminous family, and widely cultivated. In recent time, health and nutritional benefits of the pea and its by‐products enriched with biomolecules, which have gained significant attention to the researchers and consumers. Peas are known for its pivotal nutritional value with high‐quality proteins, dietary fibres, starch, carbohydrates and micronutrients including vitamins and minerals. It is also enriched with phytochemicals, antioxidants, flavonoids, tannins and other phenolic compounds under non‐nutritional category. Dietary fibre extracted from its cotyledon of the cell wall, seed coats and pods proved to accelerate the gastrointestinal activity by developing intestinal microflora. Intermediate amylose maintains blood glucose level by lowering the glycaemic index and reducing starch digestibility of peas. Pea proteins derived peptides have opportunities in nutraceuticals. Furthermore, pea‐derived non‐α‐galactooligosaccharides could mitigate the gas production by colonic bacteria during the fermentation. Anti‐acetylcholinesterase (anti‐AChE) was also traced in the pea pod with some antioxidant properties. The focus of this review paper is to provide a comprehensive profiling of chemical compositions and bioactives of fresh mature peas (specifically garden or field pea seeds) and by‐products of pea processing (pods and peels) that sets a foundation for assessment of their health benefits.


| INTRODUCTION
Pea (Pisum sativum L.), a nutritious agricultural commodity belongs to the Leguminosae family, has potential to withstand freezing temperature which is widely cultivated across the globe (Kour et al., 2020;Tulbek et al., 2017). In terms of productivity, India stands as the second largest producer of green peas next to China and ranks ten among the vegetable crops. The annual global production of green pea and dry pea seeds are approximately 14.5 million tons and 22 million tons, respectively (FAOSTAT, 2019;Mondor, 2020;Senapati et al., 2019). Pea seeds are well known for its pivotal nutrients that can be differentiated in mainly soluble and insoluble fibres, proteins (tryptophan and lysine), complex carbohydrates, vitamin B, folate, minerals namely, calcium, potassium, iron but low content of saturated fat, cholesterol and sodium ( Figure 1). Fresh green pea seeds contain 17-22g carbohydrates, 20-to 50-g starch, 14-to 26-g dietary fibre, 6.2-to 6.5-g protein, 0.4-g fat, 1.0-g ash per 100 g with 9-to 10-mg calcium, 3-to 5-mg sodium, 97-to 99-mg potassium per 100 g and vitamin contents are 0.7-mg riboflavin, 5-to 6-mg thiamine and folate 0.54-mg per kilogramme (Dhaliwal, 2017;Goswami & Shukla, 2019;Hall et al., 2017;Kaiser et al., 2019;Millar et al., 2019;Robinson et al., 2019). It possesses various health benefits by lessening the prevalence of colon cancer, upbringing type-2 diabetes, coronary disease and LDL-cholesterol (Kour et al., 2020;Roy et al., 2010).
Pea protein ranges from 244 to 275 g kg −1 and starch content ranges from 440 to 462 g kg −1 on dry basis (Hood-Niefer et al., 2012). In various countries, processed peas are in high demand which is used after dehulling and utilised as best source of dietary fibre and natural antioxidants. Chloroplast rich fractions are also being isolated from pea vine haulm by physical fractionation method using centrifugation (Torcello-Gómez et al., 2019). Different processing methods namely, soaking, germination, fermentation, pasteurisation, and incorporating advance techniques like pulse electric field or ultrasonication have shown remarkable impact on the efficiency by improving nutritional quality and techno-functional properties of pea and its protein (Ma et al., 2018;Melchior et al., 2020).

| Pea Pods
By-products defining something which has almost negligible use, may excreted out during the processing and create undesirable environmental pollution. Here the pods, or peel of the pea are considered as waste by-products which occupies 55% of the total volume of green peas at the fresh harvested time, the majority of which is disposed as waste and have not generally gained much attention intending to be used ( Figure 1). Peapods are agro-industrial by-products emanating from food industries and represents abundant source of natural food bioactive and phenolic antioxidants (Guo et al., 2019;Hanan et al., 2020). Annually in India, peapod waste is discarded in a large amount of almost 1 million ton. Many peapod waste utilisation has been reported for cellulolytic enzyme production, feed for the animals and ruminants (Vinay, 2018). Various literatures also reported that peapods obtained from mature fresh green peas have remarkable amount of dietary fibre and protein and also calcium as compared to broad bean pod and okra by-products. Biscuits have been reported to be prepared with 20% peapod powder which was highly acceptable (Garg, 2015). Literature also suggested that cake with 5% of pea pod flour is highly admissible and can avoid the addition of synthetic colour as it gives natural green pistachio colour . The utilisation of the by-products is mainly of two reasons, that is, contribution to the diet positively and lesser quantity of anti-nutritional factors (Tassoni et al., 2020). They also contain phenolic antioxidant which comes under bioactive non-nutrient compounds (Troszynska & Ciska, 2002).
'Functional foods' are described as nutrients by addition which gives positive effects on biological metabolic activities by improving general state of health (Rodríguez et al., 2006). Generally the legume by-products possess higher dry matter digestibility, as a result it gives out more energy for metabolism (Tassoni et al., 2020). In recent times, peapod fortified foods are considered to be functional foods as they contain a decent amount of fibres and essential minerals. Pea pods have protein denaturing property that shows anti-cholinesterase activity and anti-inflammatory effect and because of strong antidiabetic properties of pea, it shows shielding effects against various disorders like reproductive damages, alloxan-induced hepatic and renal issues (Mejri et al., 2019). Thus, it enhances enzymatic antioxidant activity, anti-inflammatory effects and inhibit lipid peroxidation which shows a positive effect on health (Mejri et al., 2019;Zhang et al., 2020). Due to its seasonal and perishable nature, peas must be subjected to preservation as it is a rich source of nutrition and highly beneficial for health (Senapati et al., 2019), and thus, it requires further processing. Pea and its by-product have much more positive effects which influence human health. Because of the universal application and recommendation of pea as a nutritional food source, as F I G U R E 1 (a) Freshly obtained garden green peas, (b) separation of green peas from its pods, (c) green pea seeds and (d) green pea pods or pea peels well as being environmental friendly crop, the objective of this review has been focused on nutritional composition, the dietary recommendation for its consumption, effects of their consumption and the role of various biomolecules on chronic diseases.

| Carbohydrates
Pea carbohydrate has unique stability to high range viscosity and temperature in contrast to tuber starch or cereals (Guillon & Champ, 2002). Glucose, galactose arabinose are present in pea's carbohydrate where stachyose and tetrasaccharide are the most abundantly found polysaccharides. Polysaccharide extraction from peapods are also reported which contain galactose, xylose and arabinose as monosaccharides (Belghith-Fendri et al., 2018). Glucose is derived from similar polymers of starch. Cellulose belongs to the largest part of the carbohydrate whereas other pectic polysaccharide derivatives are rhamnose, arabinose, galactose and uronic acids. Peas have 3.73% total oligosaccharides of total solids (Tosh et al., 2013).
Basically, starch has three forms on the basis of digestibility of glucose release and its absorption into the gastrointestinal tract. They are rapidly digestible starch (RDS), slowly digestible starch (SDS) and the third one, resistant starch (RS) (Englyst et al., 1992;Singh et al., 2017). After ingestion, there is a sudden hike of blood glucose quantity because of RDS fraction which is present nearly 9.2% to 10.7% and SDS fraction from 23.3% to 26.5% which gets digested completely but slowdown in small intestine. RS fraction changes its phase by fermenting itself in large intestine but still 10.1% to 14.7% does not get digested in the small intestine (Dahl et al., 2012;Singh et al., 2017). The fractions of starch digested in the small intestine resulting to low glycaemic index which directly impacts the metabolic rate of digestions (Guillon & Champ, 2002). Starch is also composed of a linear glucan chain of amylose and highly branched molecular chain of amylopectin. The ratio of both imparts digestibility and postprandial glucose response. As pea contains 38.% 2± 0.2% apparent amylase (Chung et al., 2010), which results in reduced digestibility and low glucose release that contribute to low glycaemic index (Table 3).
A natural mutation in pea seeds improves the starch assembly and glucose homeostasis (Petropoulou et al., 2020). α-Galactosides one of the oligosaccharides present in pea which may not get easily digested in the gastrointestinal tract. The high fermentability of these oligosaccharides leads to gas production which is responsible for digestive discomfort (Table 5). These non-digestible oligosaccharide food components potentially to be identified as prebiotic agents and has positive impacts on consumer's health.

| Protein
Peas are beneficial protein sources used as functional ingredient for many food industries. A variety of field pea contains 14.5%-28.5% protein where the range goes up to 24.4% to 27.4% Millar et al., 2019;Hood-Niefer et al., 2012;Reichert & MacKenzie, 1982). Pea protein is labelled as a non-allergic food substance with remarkably high nutritional value without any modification in the genetic profile (Ge et al., 2020). Pea protein can broadly be classified into four major groups: globulin, albumin, prolamin and glutelin where the main storage protein is globulin and albumin which accounts for 55%-65% and 18%-25%, respectively, that help in seed germination (Table 1). Globulin is divided into two types namely, legumin (hexameric protein, 320-400 kDa) and vicilin (trimeric protein, 150-180 kDa). Prolamin and glutelin are present in a small amount (Table 1) nearly 3%-5% each (Lu et al., 2020). In crude protein of pea, there are 10%-15% of non-protein nitrogen-containing materials and rest 70%-80% of crude protein are hormones, enzymes, enzyme inhibitors, storage protein and some non-storage proteins. Solubility and modification of pea protein has been reported by using industry-scale microfluidization that will promote food industry to use pea protein without involving exogenous substances .
Quantities of essential amino acids and its bioavailability determine the nutritional profile of protein which is digested by the organism. Pea seeds are rich in threonine, cysteine, methionine, lysine, glycine, alanine, leucin and phenylalanine amino acids (Owusu-Ansah & McCurdy, 1991). The protein content of pea seeds have a high level of lysine, leucine and phenylalanine but relatively less level of sulphur-containing amino acid namely, metheonine and cysteine (Lu et al., 2020;Yi et al., 2021). Total α-galactosides, verbascose, arginine, glutamic, carotenoid pigments have positive correlation with protein content (Reichert & MacKenzie, 1982). One of the proteins found in legume called lectins or phytohemagglutenin is able to agglutinate the red blood cells which is found in the pea (Owusu-Ansah & McCurdy, 1991). Recent study showed that pea protein hydrolysates can inhibit the metabolic by-product, nitric oxide which could damage the cell excessively (Lu et al., 2020). Pasta like sheets were developed using protein and dietary fibre fractions from yellow pea (Muneer et al., 2018). Mixed sumiri gels also developed by pea protein isolates through partial substitution of myofibrillar proteins . Fermentation using co-culture of LAB and yeast may improve the sensory defects in pea protein based products (El Youssef et al., 2020).

| Vitamins and minerals
Peas and its peel are rich in vitamins and minerals and have numerous health benefits (Gawalko et al., 2009;Robinson et al., 2019).
Potassium, a most prominent major mineral element which contains 1.04% of dry and dehulled weight of peas, followed by phosphorus, magnesium and calcium which were 0.39%, 0.10% and 0.08%, respectively and also rich in vitamin B (Dahl et al., 2012;Millar et al., 2019).
In recent past, low phytate lines have been developed to reduce the concentration of phytate that are helpful in improving the mineral absorption (Jha & Warkentin, 2020). Biofortification is an advancing method to improve the nutritional profile of pulse crop which lacks in micro-nutrients such as iron, zinc, folic acid, β-carotene, carotenoids, folates, iodine and many more by genetic engineering, agronomic intervention and plant breeding. Thus peas are rich in iron, zinc, manganese and naturally low phytic groups, which can be used in biofortification and can be a hidden solution for nutrient deficient hunger (Amarakoon et al., 2012;Jha & Warkentin, 2020). Pea seeds reported to be used as zinc biofortification combined with selenium which enhance the bioavailability in food products (Poblaciones & Rengel, 2016, 2017Rehman et al., 2019;Robinson et al., 2019), whereas phosphorous biofortification has been done to increase the soil microbiome in nutrient for higher pea production to combat micronutrient malnutrition (Powers & Thavarajah, 2019).

| Dietary fibres
Dietary fibres (DF) are compounds which restrict digestion (hydrolysis) by enzymes and consist of non-digestible carbohydrates. They are classified as soluble dietary fibre (SDF) and insoluble dietary fibre (IDF) based on the water solubility (Table 1) Mainly the insoluble fibre is derived from cereals whereas the soluble fibre is available in fruits and vegetables that is dissolved in water and fermented in the area of colon (Roberfroid & Slavin, 2000;Slavin, 2003).

| Phytochemicals and Antioxidants
Antioxidants are bioactive molecules having inhibitory function that reduced the damage caused by free radicals reactive species (Chahbani et al., 2018;Ge et al., 2020;Singh et al., 2017). Many bioactive compounds combined together like phenolics, antioxidants and other phytochemicals which are non-nutritive elements present in pea by-products, whereas tannin found to be the essential natural antioxidants ( Table 2). The metabolism of green pea hull phenolics, their absorption and in vivo antioxidant activities were also studied (Guo et al., 2019). Concentration of phenolics present in seed coat of pea depends on the variety of seeds (Fahim et al., 2019). Numerous active phytochemicals determined in pea-like flavonoids along with daidzein, genistein, asparaginase, apigenin,lectin, kaempferol and several phenolic compounds include catechin, coumaric acids, caffeic acids,vanillic acids, ferulic, pisatin, protocatechuic, proanthocyanidin, steroid phytohormone and tannins (Bello et al., 2018). Pea genotypes with different maturity level and seed coat colour showed prominent phenolics, total flavonoids along with high antioxidant activities (Devi et al., 2019;Zhao et al., 2020). Presence of techno-functional properties and phytochemical compositions in pea protein isolates could be used as value added ingredient in formulated foods . Pea residues are considered to be a potential source of bioactive molecules that have been certified to exert a beneficial impact on human health (Tassoni et al., 2020). Exploration of pea germplasm with high polyphenol content is helpful for pea breeding cultivars (Jha et al., 2019).
Oxidative injury can be inhibited by the antioxidative substances which have an active quenching effect against free radicals or damages (Table 5) caused by them (Sies, 1997;Halliwell & Gutteridge, 1997). Antioxidant properties were determined from tannin crude extract from the seed coat of pea by phosphatidylcholine (PC) liposome system. Condensed tannins of coloured seed coat of pea were found to be 1560 mg of catechin equivalent/100g (Troszynska & Ciska, 2002).
Pro-anthocyanidines, condensed tannins present in seed coats (hulls) are also found in the legume seeds. There was a marked difference in the sum of free phenolic acids extracted from soluble esters and glycosides of coloured seed coat and the white seed coat that was 78.53-and 17.17-g/g dry matter, respectively. The hydroxycinnamic acids, coumaric and ferulic were present in white seed coat and phenolic acids like vanillic, benzoic acids, protocatechuic and gentisic were found in coloured seed coat (Troszynska & Ciska, 2002).
The seed coat of peas has high concentration of glycosides, in particular luteolin, quercetin and apigenin and its cotyledon possesses hydroxycinnamic and hydroxybenzoic which have flavonol and flavone glycosides. Cotyledon also has conjugated compounds of malic acids which was p-hydroxybenzoyl-malic acid and trans p-coumaroyl-malic acid whereas seed coat has stilbene the bioactive compounds in different varieties of legume that grown in the cool season including pea using advance methods like UAE (Duenas et al., 2004;Pinchao-Pinchao et al., 2019;Xu et al., 2007).
Phenols acts as a proficient agents that aid in chelating metal catalysts, eliminating free radicals, start-up antioxidant enzymes and impeding oxidases (Heim et al., 2002). TPC (Total polyphenol content) concentration also differs in the colour of pea, for example, yellow pea had 0.85 to 1.14 mg, whereas green pea had 0.65 to 0.99 mg of TPC. Flavonoids are known to be the secondary metabolites of plants, thus TFC (Total flavonoid content) in yellow pea and green pea were 0.09 to 0.17 mg and 0.05 to 0.15 mg, respectively (Table 2).
Simple phenolic condensed to form tannins that show variation in molecular configuration and those phenolic split into hydrolysable and

| In vitro digestibility
The amount of enzyme digestibility differed significantly among species which sub-divided in rapid digestible starch (RDS), slow digestible starch (SDS) and the third component resistant starch (RS) (Chung et al., 2008). The in vitro digestibility of protein in raw pea is reported in some literature where, because of protease inhibitor, the digestibility reduced whereas it was higher in soybean and several other pulses (Dahl et al., 2012;Roy et al., 2010;Tömösközi et al., 2001). The rate of hydrolysis between the native starches in pea was found to be 90% in 3 hr which showed a significant affinity of the digestibility of starches in the short period (Chung et al., 2009). The starch that present in the native form may not be able to provide a functional attribute. The experimental evidence based on enzyme hydrolysis of pea showed that amount of RDS, SDS and RS were found to be 27.0%, 62.9%, 10.0%, respectively, where, in case of gelatinized starch, the RDS, SDS and RS were 94.2%, 0.6%, 5.2%, respectively (Chung et al., 2010). The value of RDS changed in gelatinized starch which was much higher than the previous value.

| Anti-nutritional factor
Anti-nutritional compounds (ANCs) are those molecules that disrupt the digestion process. ANCs are generally non-fibrous natural substances causing negative effects on health in humans as well as in animals which affect growth along with the metabolic activity.
ANCs further systematised into two categories namely, protein associated ANCs and non-protein associated ANCs. Non-protein inhibitor relaxes the veins and arteries to treat blood pressure.
Lectins own the ability to bring down the effect of certain types of cancers by improving innate defence mechanisms and obesity.
Trypsin and chymotrypsin which are protease inhibitors also showed the best result in preventing some cancers along with formidable antiinflammatory properties. ACE inhibitor may also help in the reduction in hypertension (Roy et al., 2010).

| Glycaemic response, blood glucose and insulin resistance
The glycaemic index (GI) is a comparative ranking arrangement that provides a relative analysis of carbohydrate levels in food models by measuring blood glucose levels. Carbohydrates having lower GI values (55 or less) are slow in digestion and absorption. The slow metabolism thus leads to lower hike in the absorption of blood glucose level; consequently decreasing insulin resistance. Pea is established on a lower rank on the glycaemic index table having a GI value of 22. There is a scientific relation between blood sugar, insulin and glycaemic index.
The two key enzymes which are involved in breakdown of starch and intestinal glucose absorption are α-amylase and α-glucosidase, whose inhibition process have been recorded to slow down the transit period of carbohydrates that flows into the bloodstream (Burguieres et al., 2008). The fibre and protein constituents of pea help in the process of slow digestion which, reversibly helps to smooth out the blood sugar level after eating. Excessive sugar intake is the reason to promote various diseases like obesity, diabetes and other heart relating diseases, and now the current research has evinced to unhealthy cholesterol and triglyceride level. The soluble fibre in food lowers the LDL cholesterol which is also known as bad cholesterol and keeps the blood glucose level steady (Table 3). Reduction in triglyceride level in blood plasma and in liver after ingestion of pea fibre supplementation is reported. Starches in the pea with low GI might be treated as an advantageous tool for well-being and distinctly for the elimination of diseases associated with the resistance of insulin (Guillon & Champ, 2002). It is also been reported that pea polysaccharides is potential in ameliorating diabetes-induced injury to pancreatic tissues .

| Intestinal microflora and its fermentability
The microfloras that are present in the gut play an indispensable character in the process of food digestion, enhancing immunity and other metabolic activities (Table 4). Dietary fibre is contemplated as one of the leading sources for energy utilisation by microbes aggregating in the generation of different fermented outcomes; where shortchain fatty acids are treated as principal metabolite having neuroactive properties (Martens et al., 2017). Apart from dietary fibre pea protein modulates both metabolic as well as the adhesive potential of intestinal bacteria to the cell lining and exert a health promoting effects on the local environments (Ge et al., 2020). Gut luminal environment undoubtedly impacts the starch structure by modulating its morphology which later on slows down the glucose availability that eventually lower the post prandial glucose (PPG) level (Petropoulou et al., 2020).
Non-α-galactooligosaccharides from pea showed a potential prebiotic property that proved to mitigate the gas production by colonic bacteria during fermentation (Marin-Manzano et al., 2020).
Uncontrolled immune response of intestinal microbiome leads to prevalence of chronic intestinal inflammation which is termed as inflammatory bowel disease (IBD). The severe inflammatory area includes both the intestine and gives rise to serious chronic diseases: ulcerative colitis and Crohn's disease (Khan et al., 2016). The dietary fibres restore balance in the gut microbiota and influence the homeostasis directly in it.
T A B L E 3 Studies related to the metabolic health benefits and functions of pea and its by-products Along with the pea seed, pea hull fibre has also been associated with modulation of gut microbiota, especially bifidobacteria (Dahl et al., 2012). Low-phytate biofortified pea varieties have positive effects on bioavailability of dietary iron, intestinal gut microbiome and improves brush border membrane (BBM) functionality . Bifidobacteria shows beneficial health benefits in the gut by preventing enteric infections, and suppression of pathogenic bacteria which enhances the immune system of the host (Priyadarshini & Mishra, 2013). The non-digestible oligosaccharides, particularly fructo-oligosaccharide, activate the extension of bifidobacteria, which later on alter the composition of the colonic microbiota notably (Table 3). Although the prebiotic effect have been demonstrated widely in the field of oligofructose, fructo-oligosaccharides including inulin (Guillon & Champ, 2002). Pea fibre affected the gut microbiota along with a high protein diet. There are also some results shown by some group of scientists regarding the fermentability and digestibility of the pea hull fibre.

| Cardiovascular health
Recently cardiovascular disease (CVD) is a prominent cause for increasing rates of death in the developing countries. Hypertension is directly linked with expansion of cardiovascular disease by enhancing blood pressure level (Ge et al., 2020). Higher risk with 72% coronary heart disease (CHD) has been reported due to overweight and found prominent in obese women. Hypercholesterolemia is a major risk factor for CHD which is preventable through lifestyle measures (Anderson & Major, 2002). Higher consumption of dietary fibre is associated with fewer cardiovascular diseases (Slavin, 2013). Experimental data demonstrated that higher intake of dietary fibre may lead to slowing down the process of low-density lipoprotein cholesterol (LDL-C) absorption as well as in fasting glucose concentration (Becerra-Tomás et al., 2019) and decline possibilities of CHD (Table 3). Particularly, the water-soluble varieties of dietary fibre have highlighted in reducing the probability of cardiovascular disease (Bazzano, 2008). The average dietary fibre intake was found to be around 29g per day. Person who consumed DF less than 29 g per day was found to have 38% of inflated risks for hypercholesterolemia and 43%increase in LDL cholesterol as compared to those consume more than the average DF intake (Narayan et al., 2014). Green peas are naturally packed with flavonols, carotenoids, vitamin C and antioxidants which lessen the chances of heart stroke by modifying cardiometabolic risks and various diseases related to heart because of their ability to protect the cells from damage (Papandreou et al., 2019;Perez-Vizcaino & Duarte, 2010;Voutilainen et al., 2006).
They have the properties of high solubility and rapid fermentation that were observed in colonic microflora (  (Guillon et al., 2002;Veenstra et al., 2010).

| Anti-acetylcholinesterase (anti-AChE) and antioxidant properties
The in vitro and in vivo studies have revealed that 32% of antiacetylcholinesterase (anti-AChE) was found in peapod. Some antioxidants and protein denaturing properties were performed by in vitro whereas antidiabetic, cytoprotective and antihyperlipidemic properties were done by in vivo. The pea pods are rich in nutrients as it contains 24.34% carbohydrates, 13.37% crude protein, 51% fibre, 4.5% lipids and 4.5% ash ( Table 1). The imbalance of free radicals is defined as oxidative stress that is closely associated with hyperlipidaemia (Liu et al., 2019). The profile of fatty acid (FA) of pea has mainly linoleic, linolenic and palmitic acids component which showed a promising anti-hyperlipidaemic effect in reducing the risk of diabetes including the oxidative stress level and preventing organ damage namely, liver, kidney and testis (Ge et al., 2020;Mejri et al., 2019) ( Table 3). These are essential fatty acids for human consumption that should be recommended in the diets.

| Cancer prevention
The inclination of population towards the western diet which includes high fat, animal protein and refined carbohydrate effectively lowers their immune system and is prone to carcinogenic effects.
Although diet is not considered to be carcinogenic agent, it may provoke the cancer causing elements (Vohra et al., 2015). The extracts of pea has proven to be pharmacologically active along with its anticancer activity (Bello et al., 2018;Mudryj et al., 2014;Rungruangmaitree & Jiraungkoorskul, 2017). Peas are usually a rich source of biologically active compound, which may have impactful effects that bring down the tumour risk when consumed at certain levels (Mathers, 2002). Generally, the yellow peas are excellent source for having isoflavones: genistein (dimerized) and daidzein (deoxydi-glycosidic), that belongs to phytoestrogens which possess several important functions, including anti-carcinogenic effects.
Genistein evinced the anti-proliferative out-turns on cell growth stimulated by mitogen of breast cancer cells in humans. This is a potential agent to be demonstrated in the field of reduction of breast cancer (Matscheski et al., 2006). Besides there are several pieces of evidences which evinced that pulses which are rich in dietary fibre seem to contribute to lessening the effects of certain type of cancer especially colorectal and rectal cancer (Table 3). Other bioactive compounds found in pulses may have a defensive role against cancer, those are resistant starch, non-starch polysaccharides, oligosaccharides, folate, selenium, zinc, saponins, lectins (Matscheski et al., 2006). The presence of several bioactive micronutrients and phytochemicals in pea makes it a contributor towards a healthy diet and lessen the risk of cancer (Table 5).

| Weight management
Pulse consumption significantly reduced body weight under negative energy balance as well as neutral energy balance conditions (Becerra-Tomás et al., 2019;Mudryj et al., 2014;Venkidasamy et al., 2019). Fibres are known for their low caloric constituents which not only have nutritional attributes but also numerous functional benefits during digestion and assimilation inside the human body (Table 3). Pea fibre binds about 3 times water, however shows lower viscosity compared to wheat and potato fibres. Higher ingestion of fibre is been associated to lower the body weight (Slavin, 2013). Pea protein hydrolysates showed beneficial effects on obesity associated disorders. The pea ingredients are collectively responsible for body weight management having irrespective functions (Ruiz et al., 2020).
Furthermore, long term consumption of pea and its by-products are not adequately addressed and the nutritional values of peas and its pods has not been explored by genetic variation much to its full extent as some genetic traits are still unknown. In future, supplementation and incorporation of pea seeds and its pod could fulfil the emerging popularity of vegan, or flexitarian diet (Rasskazova & Kirse-Ozolina, 2020;Robinson et al., 2019). Also, it can enhance the infant food by supplementing with fibre rich prebiotic oligosaccharide properties as well as improve the efficacy and safety of crop biofortification and mineral bioavailability approach.

| CONCLUSION
The pea which is virtually grown worldwide for its edible seeds is nutritionally very rich and in addition it is ladened with high dietary fibre, antioxidants, numerous important biomolecules and having low glycaemic index and is extremely useful in curing diabetes, cardio problems, certain cancers and many degenerative diseases. The current review provides the nutritional information of peas and its underexploited by-products particularly its pods and focussing primarily on their impact on health and various functional properties. The desirable functionality of pea and its waste make them potentially suitable for food industry. Overall the intent of the authors was to provide the contemporary research information of peas and its by-products which are considered to have huge potential in terms of its various nutrients and biomolecules that are having high credentials to support our various health related diseases and to alleviate the latter at the global context.
T A B L E 5 Pea nutritional bioactive constituents and their effects on human health

Nutritional components Function References
Carbohydrate Resistant starch acts as pre biotic. Increases faecal bulk, reduces colonic pH, reduce post-prandial glycaemic response. Singh et al., 2017;Tassoni et al., 2020 Dietary fibre Low glycaemic response and insulin resistance. Improve cardiovascular health, decrease blood pressure, enhance serum lipid level, lower indicator of inflammation Dahl et al., 2012;Slavin, 2003 Protein Glycosylated protein may escape small intestine, help in haemostatis and improve gastrointestinal microbiota. Dominika et al., 2011 Phenolic compounds Antioxidant protect against disease such as cancer and various inflammatory Martens et al., 2017;Mejri et al., 2019;Ge et al., 2020;Fahim et al., 2019 Isoflavin Anti-cancer activity, DNA repair, induction of apoptosis, cell proliferation migration and invasion

CONFLICT OF INTEREST
There is no conflict of interest declared by the authors.

AUTHOR CONTRIBUTIONS
Tapasya Kumari-Writing the original draft and conducted the review of literature. Sankar Chandra Deka-Conceptualisation, preparation of the final draft, final editing, data curation. Both the authors contributed to the critical review and approved the final manuscript.

ETHICS STATEMENT
This literature did not include any animal or human trial.

DATA AVAILABILITY STATEMENT
The data sources used in the manuscript are available upon request from the corresponding author.