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The purpose of this review was to synthesize the availability of antinutrients, clear their effect on the human body, and commemorate possible paths to disable them. This review provides links to the available literature as well as enables a systematic view of the recently published research on the topic of plant-based antinutrients.

Nutrients are associated with positive effects on human health. Antinutrients, on the other hand, are far less popular for the contemporary man. They are highly bioactive, capable of deleterious effects as well as some beneficial health effects in man, and vastly available in plant-based foods. These compounds are of natural or synthetic origin, interfere with the absorption of nutrients, and can be responsible for some mischievous effects related to the nutrient absorption. Some of the common symptoms exhibited by a large amount of antinutrients in the body can be nausea, bloating, headaches, rashes, nutritional deficiencies, etc . Phytates, oxalates, and lectins are few of the well-known antinutrients.

Modern society has easy access to a vast informational database. The pursuit of sustainable green and healthy lifestyle leads to a series of food choices. Therefore, it is of importance to provide reliable, comprehensive and up-to-date information about food content including both nutritional and antinutritional elements.

1. INTRODUCTION Food is an essential part of people’s lives. Despite the world produces enough food for everyone, over 800 million people still go to bed hungry [1FAO. IFAD and WFP 2015.]. Furthermore, malnutrition and hunger-related diseases cause over 60% of deaths [2UNICEF. 2007. The State of the World’s Children. Women and Children The Double Dividend of Gender Equality ]. Eliminating hunger and malnutrition is one of the most fundamental challenges facing humanity [3Lomborg B, Ed. Global Crises, Global Solutions 2004.

[http://dx.doi.org/10.1017/CBO9780511492624] ]. Moreover, food sufficiency is not the last aspect of importance; food nutritional quality is of critical demand as well as the effects of the accepted food portion, in particular. From this point of view, the topic of the present review antinutrients raises essential questions about human health and contributes to the under-standing of what people actually eat and what the possible resulting effects can be. Antinutritional factors are primarily associated with compounds or substances of natural or synthetic origin, which interfere with the absorption of nutrients, and act to reduce nutrient intake, digestion, and utilization and may produce other adverse effects. Antinutrients are frequently related to plant-based, raw or vegan diets and are naturally synthesized in plants [4Gemede HF, Ratta N. Antinutritional factors in plant foods: potential health benefits and adverse effects. Int J Nutr Food Sci 2014; 3(4): 284-9.

[http://dx.doi.org/10.11648/j.ijnfs.20140304.18] ]. Some of the common symptoms exhibited by a large number of antinutrients in the body can be nausea, bloating, headaches, rashes, nutritional deficiencies, etc. [5]. On the other hand, such chemical compounds can be evidently advantageous to humankind when consumed wisely. In fact, plants, for their own defense, primarily use antinutrients. Although people’s sensitivity to antinutrients widely differs adequate food processing is initially recommended to reduce antinutritional factors [6Soetan K, Oyewole O. The need for adequate processing to reduce the anti-nutritional factors in plants used as human foods and animal feeds: A review. Afr J Food Sci 2009; 3(9): 223-32. [http://dx.doi.org/10.3109/08039489709090718].]. A person cannot eliminate antinutrients once they have been introduced to the body. Eliminating and reintroducing specific foods that contain antinutrients can clear the correlation between symptoms and effects on human health. In this regard, the biochemical effects of the anti-nutritional factors are an object of research interest [7Cheeke PR, Shull LR. Natural toxicants in feeds and livestock 1985.-10Fu PP, Xia Q, Lin G, Chou MW. Genotoxic pyrrolizidine alkaloids- mechanisms leading to DNA adduct formation and tumorigenicity. Int J Mol Sci 2002; 3: 948-64.

[http://dx.doi.org/10.3390/i3090948] ] Most of the secondary metabolites, acting as anti-nutrients, elicit very harmful biological responses, while some of them are widely applied in nutrition and as pharmaco-logically-active agents [11Oakenfull D, Sidhu GS. Saponins: In Toxicants of plant origin, Vol. II, Glycosides. 1989; 97., 12Soetan KO. Pharmacological and other beneficial effects of antinutriional factors in plants. –A review. Afr J Biotechnol 2008; 7(25): 4713-21. [https://doi.org/10.5897/AJB08.024].]. Antinutrients are found in their highest concentrations in grains, beans, legumes and nuts, but can also be found in leaves, roots and fruits of certain varieties of plants. The major antinutrients found in plant-based foods are phytates, tannins, lectins, oxalates, etc. Antinutrients in vegetables, whole grains, legumes and nuts are a concern only when a person’s diet is composed exclusively of uncooked plant foods. Oxalate, for instance, prevents calcium from being absorbed in the body by binding with it [13Jiru K, Urga K. Ethiop. Forms and contents of oxalate and calcium in some vegetables in Ethiopia. J Health Dev 1995; 9(1): 13-8.]. Raw spinach, kale, broccoli and soybeans usually contain oxalates [14Savage G, Klunklin W. Oxalates are found in many different european and asian foods - effects of cooking and processing. J Food Res 2018; 7(3)

[http://dx.doi.org/10.5539/jfr.v7n3p76] ]. When consuming excessive tannins, which are associated with tea, wine, some fruit, and chocolate, enzymes responsible for protein absorption may be inactivated. Phytates are present in grains, nuts and seeds, while peppers, eggplants, and tomatoes contain lectins. Phytates consumption may lead a lower mineral absorption and lectins are able to cause various reactions to the body [15Gupta RK, Gangoliya SS, Singh NK. Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains. J Food Sci Technol 2015; 52(2): 676-84.

[http://dx.doi.org/10.1007/s13197-013-0978-y] [PMID: 25694676] ]. Saponins, on the other hand, have been linked to red blood cells damaging, enzyme inhibition and thyroid function intervention [16Fan Y, Guo DY, Song Q, Li T. Effect of total saponin of aralia taibaiensis on proliferation of leukemia cells. Zhong Yao Cai 2013; 36(4): 604-7.

[PMID: 24134011] ]. There are several approaches to oppose antinutritional factors. Modern biotechnology`s techniques could reduce the level of certain allergens and antinutrients in food. Genome editing biotechnology can create mutations and substitutions in plant and other eukaryotic cells based on nuclease-based forms of engineering such as the TALENS (Transcription Activator-Like Effector Nucleases) or the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/CRISPR-Associated Systems (CAS) [17Gaj T, Gersbach CA, Barbas CF III, Barbas CF. ZFN, TALEN, and CRISPR/Cas-based methods for genome engineering. Trends Biotechnol 2013; 31(7): 397-405.

[http://dx.doi.org/10.1016/j.tibtech.2013.04.004] [PMID: 23664777] , 18Jankele R, Svoboda P. TAL effectors: tools for DNA targeting. Brief Funct Genomics 2014; 13(5): 409-19.

[http://dx.doi.org/10.1093/bfgp/elu013] [PMID: 24907364] ]. Providing an enhanced level of prebiotic in the body can positively influence the effects of antinutrients [19Gibson RS, Perlas L, Hotz C. Improving the bioavailability of nutrients in plant foods at the household level. Proc Nutr Soc 2006; 65(2): 160-8.

[http://dx.doi.org/10.1079/PNS2006489] [PMID: 16672077] ]. A classic approach to remove antinutrients is to treat the product thermally, use methods such as extrusion, autoclaving, hydrotechniques, enzymatic and harvest treat-ments, etc. [20Muzquiz M, Hill GD, Cuadrado C, Pedrosa MM, Burbano C. Recent advances of research in antinutritional factors in legume seeds and oilseeds. Proceedings of the fourth international workshop on antinutritional factors in legume seeds and oilseeds Toledo, Spain. 2004.2004.

[http://dx.doi.org/10.3920/978-90-8686-524-6] ]. The nutritional value of foods strongly depends on their nutritional and antinutritional composition. This review was designed to synthesize the availability of antinutrients, clear their effect on the human body, and commemorate possible paths to disable them.

3. ANTINUTRIENTS AND HUMAN HEALTH While antinutrients can be problematic, some may also provide health benefits. The consumers should be aware of any possible effect whether beneficial and/or negative. Moreover, concentration-dependent effects must be considered. Data may be manipulated in respect of health related advantages so that chronic diseases management becomes possible [32Shahidi F. ACS Symposium Series 1997; 1-9.]. Antinutrients are valuable active ingredients in food and drinks. When used at low levels, phytic acid, lectins and phenolic compounds as well as enzyme inhibitors and saponins have been shown to reduce blood glucose and/or plasma chol-esterol and triacylglycerols. Furtermore, saponins are reported to act effectively in maintaining liver function, preventing steoporosis as well as platelet agglutination [94Kao TH, Huang SC, Inbaraj BS, Chen BH. Determination of flavonoids and saponins in Gynostemma pentaphyllum (Thunb.) Makino by liquid chromatography-mass spectrometry. Anal Chim Acta 2008; 626(2): 200-11.

[http://dx.doi.org/10.1016/j.aca.2008.07.049] [PMID: 18790122] ]. Meanwhile, phenolic compounds from plant sources, phytic acid, protease inhibitors, saponins, lignans and phytoestrogens have been demonstrated to reduce cancer risks. Another group of anti-nutrient compounds, like tannins, were found to possess possible antiviral [95Lü L, Liu SW, Jiang SB, Wu SG. Tannin inhibits HIV-1 entry by targeting gp41. Acta Pharmacol Sin 2004; 25(2): 213-8.

[PMID: 14769212] ], antibacterial [96Akiyama H, Fujii K, Yamasaki O, Oono T, Iwatsuki K. Antibacterial action of several tannins against Staphylococcus aureus. J Antimicrob Chemother 2001; 48(4): 487-91.

[http://dx.doi.org/10.1093/jac/48.4.487] [PMID: 11581226] ] and antiparasitic effects [97Kolodziej H, Kiderlen AF. Antileishmanial activity and immune modulatory effects of tannins and related compounds on Leishmania parasitised RAW 264.7 cells. Phytochemistry 2005; 66(17): 2056-71.

[http://dx.doi.org/10.1016/j.phytochem.2005.01.011] [PMID: 16153409] ]. Some compounds such as phytoestrogens and lignans have also been linked to induction of infertility in humans. There-fore, it is prudent to examine all aspects of food antinutrients, including their potential health benefits and methods of analyses [32Shahidi F. ACS Symposium Series 1997; 1-9.]. The above mentioned implies that antinutrients could be valuable tools for managing various diseases. They might not always be harmful even though they lack nutritional value. What is most important is focusing on dosage intake in order to find the balance between beneficial and hazardous effects of plant bioactives and antinutrients, in addition to the chemical structure, time of exposure and interaction with other dietary components. Many factors influence their activity. They can both be considered as antinutritional factors with negative effects or non-nutritive compounds with positive health effects. Consumers’ awareness is crucial especially when abnormal health conditions are established.

4. DISABLING ANTINUTRIENTS Removing undesirable food components is essential to their quality improvement. Different techniques i.e. soaking, cooking, fermentation, radiation, germination and chemical treatment can come in as handy instruments for antinutritional disabling [98Bains K, Uppal V, Kaur H. Optimization of germination time and heat treatments for enhanced availability of minerals from leguminous sprouts. J Food Sci Technol 2014; 51(5): 1016-20.

[http://dx.doi.org/10.1007/s13197-011-0582-y] [PMID: 24803714] , 99Gupta V, Nagar R. Minerals and antinutrients profile of rabadi after different traditional preparation methods. J Food Sci Technol 2014; 51(8): 1617-21.

[http://dx.doi.org/10.1007/s13197-012-0667-2] [PMID: 25114357] ]. The combination of several of the above-mentioned methods may be more effective in removing anti-nutrients than using a sole technique. Soaking: Soaking can be seen as one of the easiest physical processes to remove soluble antinutritional factors. Soaking in distilled water, 1% NaHCO 3 and mixed salt solu-tions reduced total phenols, ortho-dihydroxyphenols, tannins and phytates by 33, 41, 35 and 21 percentages respectively [100Devi R, Chaudhary C, Jain V, et al. Effect of soaking on anti-nutritional factors in the sun-dried seeds of hybrid pigeon pea to enhance their nutrients bioavailability. JPP 2018; 7(2): 675-80.]. Soaking decreased the total protein, soluble sugar and tannins, in soybean flour [101Agume AS, Njintang NY, Mbofung CM. Effect of soaking and roasting on the physicochemical and pasting properties of soybean flour. Foods 2017; 6(2): 12.

[http://dx.doi.org/10.3390/foods6020012] [PMID: 28231091] ]. Soaking and sprouting grains, nuts, seeds, and beans are an excellent way to deactivate enzyme inhibitors [102Shi L, Mu K, Arntfield SD, Nickerson MT. Changes in levels of enzyme inhibitors during soaking and cooking for pulses available in Canada. J Food Sci Technol 2017; 54(4): 1014-22.

[http://dx.doi.org/10.1007/s13197-017-2519-6] [PMID: 28303052] ]. However, lectin is not affected by this method of deactivation. Fermentation: Fermenting assorted grain flour with L. acidophilus at 37°C for 24 h led to the reduction of phytic acid and polyphenol content [103Binita R, Khetarpaul N. Probiotic fermentation: Effect on antinutrients and digestibility of starch and protein of indigenously developed food mixture. Nutr Health 1997; 11(3): 139-47.

[http://dx.doi.org/10.1177/026010609701100301] [PMID: 9131698] ]. Recent research has shown a general noticeable reduction in the entire antinutrient properties of soybean for a day of fermentation [104Babalola RO, Giwa OE. Effect of fermentation on nutritional and anti-nutritional properties of fermenting Soybeans and the antagonistic effect of the fermenting organism on selected pathogens. Int Res J Microbiol 2012; 3(10): 333-8.]. Ojokoh et al. [105Ojokoh AO, Daramola MK, Oluoti OJ. Effect of fermentation on nutrient and anti-nutrient composition of breadfruit (Treculia africana) and cowpea (Vigna unguiculata) blend flours. Afr J Agric Res 2013; 8(27): 3566-70.

[http://dx.doi.org/10.5897/AJAR12.1944] ] have studied the effect of fermentation on the antinutritional composition of breadfruit and cowpea flours showing a significant reduction of the hydrogen cyanide, oxalate and phytate content. Fermentation is reported to increase the protein content in chickpea by 13% and decrease the content of phytic acid by 45% [106Valdez-González FJ, Gutiérrez-Dorado R, García-Ulloa M, Cuevas-Rodríguez BL, Rodríguez-González H. Effect of fermented, hardened, and dehulled of chickpea (Cicer arietinum) meals in digestibility and antinutrients in diets for tilapia (Oreochromis niloticus). Span J Agric Res 2018; 16(1)

[http://dx.doi.org/10.5424/sjar/2018161-11830] ]. Adeyemo et al. [107Adeyemo SM, Onilude AA, Olugbogi DO. Reduction of Anti-nutritional factors of sorghum by lactic acid bacteria isolated from Abacha - an African fermented staple. Front Sci 2016; 6(1): 25-30.] assessed the effects of fermentation of sorghum at 0, 72 and 120 hours on trypsin inhibitor, protease inhibitor, phytate and tannin. A significant reduction of trypsin inhibitor (69%); protease inhibitor (30%); phytate (60%) and tannin (72%) was observed at 120 h with L. plantarum used as starter culture. On the other hand, L. brevis as starter appeared to be effective at 120h with 58% reduction of trypsin inhibitor; 40% of protease inhibitor; 70% of phytate and 56% of tannin. Sprouting (Germination): Germination is one of the most effective processes for the reduction of anti-nutritive com-pounds i.e. phytate levels [108Vidal-Valverde C, Frias J, Sierra I, et al. New functional legume food by germination: Effect on the nutritive value of beans, lentils and peas. Eur Food Res Technol 2002; 215: 472-6.

[http://dx.doi.org/10.1007/s00217-002-0602-2] ]. The trypsin inhibitor activity, amylase inhibitor activity and phytate content of soy-bean variety MACS-13 decreased with sprouting [109Dikshit M, Ghadle M. Effect of sprouting on nutrients, antinutrients and in vitro digestibility of the MACS-13 soybean variety. Plant Foods Hum Nutr 2003; 58(3): 1-11.

[http://dx.doi.org/10.1023/B:QUAL.0000040357.70606.4c] ]. Kanensi et al. [110Kanensi OJ, Ochola S, Gikonyo NK, Makokha A. Optimization of the period of steeping and germination for amaranth grain. J Agric Food Tech 2011; 1(6): 101-5.] report a lower antinutrient level of germi-nated amaranth seeds. The levels of tannins and phytate were insignificant. To overcome the antinutritional levels, Kajla et al. [111Kajla PS, Sharma A, Sood DR. Effect of germination on proximate principles, minerals and antinutrients of flaxseeds. Asian J Dairy Food Res 2017; 36(1): 52-7.

[http://dx.doi.org/10.18805/ajdfr.v36i01.7459] ] also adopted the germination process in flax seeds. Other authors reaffirm that germination leads to increased nutritional and decreased anti-nutrients content in plant-based foods [112Chauhan ES. Effects of processing (germination and popping) on the nutritional and anti-nutritional properties of finger millet (Eleusine Coracana). Curr Res Nutr Food Sci 2018; 6(2)]. Heating: Cooking whole grains, beans and vegetables can reduce certain antinutrients such as phytic acid, tannins, and oxalic acid. Protease inhibitors are easily denatured by heat treatment due to their protein nature [113Fernando R, Pinto P, Pathmeswaran A. Goitrogenic food and prevalence of goitre in Sri Lanka. J Food Sci 2012; 41: 1076-81.]. Research has shown that antinutrient levels are reduced with controlled heating at a temperature less than boiling for at least 15 minutes [114Udousoro II, Akpan EB. Anthropometric measurements, changes in anti-nutrients contents of edible vegetables under varied temperature and heating time. Curr Res Nutr Food Sci 2014; 2(3)

[http://dx.doi.org/10.12944/CRNFSJ.2.3.06] ]. Autoclaving can also drastically decrease the content of tannins, phytic acid, hydrogen cyanide, trypsin inhibitors and oligosaccharides [6Soetan K, Oyewole O. The need for adequate processing to reduce the anti-nutritional factors in plants used as human foods and animal feeds: A review. Afr J Food Sci 2009; 3(9): 223-32. [http://dx.doi.org/10.3109/08039489709090718].]. Cooking sweet potato leaves with lemon reduced polyphenols with 56% and lowered the oxalate levels [115Mwanri A, Kogi-Makau W, Laswai H. Nutrients and antinutrients composition of raw, cooked and sun-dried sweet potato leaves. Afr J Food Agric Nutr Dev 2011; 11(5): 5142-56.]. Boiling bambara groundnut seeds for a period of 60 min significantly lowers the raffinose content and improves protein digestibility of the seeds [116Adeleke OR, Adiamo OQ, Fawale OS, et al. Effect of processing methods on antinutrients and oligosaccharides contents and protein digestibility of the flours of two newly developed bambara groundnut cultivars. Int Food Res J 2017; 5(9): 1006-14.]. Gamma radiation: Gamma radiation appeared to be a good procedure to decrease the level of trypsin inhibitor, phytic acid and oligosaccharides of broad bean between 5 and 10% [117Al-Kaisey MT, Alwan AKH, Mohammad MH, Saeed AH. Effect of gamma irradiation on antinutritional factors in broad bean. Radiat Phys Chem 2003; 67(3): 493-6.

[http://dx.doi.org/10.1016/S0969-806X(03)00091-4] ]. However, Hassan et al. [118Hassan AB, Osman GM, Rushdi MA, et al. Effect of gamma irradiation on the nutritional quality of maize cultivars (Zea mays) and sorghum (Sorghum bicolor) grains. Pak J Nutr 2009; 8: 167-.

[http://dx.doi.org/10.3923/pjn.2009.167.171] ] documented that a 2 kGy dose had no significant change in the tannin content of two maize cultivars. Similar observations were reported by El-Niely [119El Niely HFG. Effect of radiation processing on antinutrients, in vitro protein digestibility and protein efficiency ratio bioassay of legume seeds. Radiat Phys Chem 2007; 76: 1050-7.

[http://dx.doi.org/10.1016/j.radphyschem.2006.10.006] ] and Fombang et al. [120Fombang EN, Taylor JRN, Mbofung CMF, et al. Use of γ-irradiation to alleviate the poor protein digestibility of sorghum porridge. Food Chem 2005; 91: 695-03.

[http://dx.doi.org/10.1016/j.foodchem.2004.06.042] ]. Low doses of gamma irradiation (0.5 and 1.0 kGy) Faba bean seeds significantly reduced antinutritional factors such as tannin and phytic acid [121Osman AM, Hassan AB, Osman GA, et al. Effects of gamma irradiation and/or cooking on nutritional quality of faba bean (Vicia faba L.) cultivars seeds. J Food Sci Technol 2014; 51(8): 1554-60.

[http://dx.doi.org/10.1007/s13197-012-0662-7] [PMID: 25114347] ]. Gamma radiation can be applied as a safe postharvest method to minimize antinutrients of millet grains [122Mahmoud NS, Awad SH, Madani RM, Osman FA, Elmamoun K, Hassan AB. Effect of γ radiation processing on fungal growth and quality characteristcs of millet grains. Food Sci Nutr 2015; 4(3): 342-7.

[http://dx.doi.org/10.1002/fsn3.295] [PMID: 27247763] ]. Genomic technology: Genomic resources can be used as pathways to RNA interference and removing of antinutrient factors, but this technology has yet to be tried out in vivo [123Pedrosa M. Recent advances of research in antinutritional factors in legume seeds and oilseeds. Wageningen Academic Pub. 2004; 263.]. Shukla et al. [124Shukla VK, Doyon Y, Miller JC, et al. Precise genome modification in the crop species Zea mays using zinc-finger nucleases. Nature 2009; 459(7245): 437-41.

[http://dx.doi.org/10.1038/nature07992] [PMID: 19404259] ] designed zinc-finger nucleases construct to mutate the IPK1 gene in maze, one of the phytic acid biosynthesis genes because corn contains high levels of phosphorus stored in the form of phytic acid. Genome editing technology can increase crop quality but there is an ongoing argument about genetically modified organisms’ safety [125Kim H, Kim S-T, Kim S-G, et al. Targeted genome editing for crop improvement. Plant Breed Biotechnol 2015; 3(4): 283-90.

[http://dx.doi.org/10.9787/PBB.2015.3.4.283] ].