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  <div class="title"><h3>9.8 - Legumes/pulses to reduce protein and mineral deficiencies</h3><br><h3 class="ch-owner">Nick Moroz, University of Guelph, Canada  </h3></div>
  <div class="title"><h3>9.8 - Legumes and seeds as folate sources for pregnant women</h3><br><h3 class="ch-owner">Nick Moroz, University of Guelph, Canada  </h3></div>
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<p>Suggested citation for this chapter.</p>
<p>Suggested citation for this chapter.</p>
<p>Moroz,N. (2022)Legumes/pulses to reduce protein and mineral deficiencies, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org</p>
<p>Moroz,N. (2022) Improving human nutrition, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org</p>
       <h3 class="title-bg">Introduction to Legumes and Pulses</h3>
       <h3 class="title-bg">Folate Deficiency </h3>
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           <p>Legumes, known for their podded fruits and unique flower structure, consist of many staple crops of the bean and pea family that are mainly grown for their grain seed, which is called a pulse (Graham & Vance, 2003). Legumes include chickpeas, beans, lentils, peanuts, and more podded plants (Messina, 1999). Legumes also play an important role in traditional diets in many regions of the world (Messina, 1999). Legumes play an essential role in global soil nitrogen levels as most legumes have symbiotic nitrogen-fixing bacteria that grow in root structures called nodules and ‘fix-nitrogen’ from the air (Herridge, Peoples, & Boddey, 2008). As such, legumes are important for crop rotation, soil health, and high in protein content.</p>
           <p>This chapter will outline how folate deficiency can be detrimental to one’s health, while also outlining various sources of folate found in many seeds and legumes grown throughout the developing world. Folate deficiency (FD) results from a reduced intake of folate – a generic term that encompasses both naturally occurring food folate as well as folic acid (NIH, 2016). FD can also occur due to heightened folate demands during pregnancy or because of impaired absorption occurring from mal-absorption disorders (Merck Manuel, 2016). Folate is a water soluble-B vitamin complex that is naturally available in foods while also frequently enriched in foods or provided as food supplements (NIH, 2016). Folic acid is the term used for the fully oxidized form of the vitamin complex used in dietary supplements and in fortified foods (NIH, 2016). </p>  
<p>Pulses simply refer to the dried grain seed of any particular legume and are separate from leguminous oil seeds by their lower fat content in comparison (WHO/FAO, 2007). Pulses are an important source of energy, dietary protein, fibre, minerals and vitamins required for healthy livelihoods (Boye, Zare, & Pletch, 2010). Pulses are a vital source of dietary protein for a large portion of the world’s population, especially in regions where consumption of animal protein is limited by scarcity or self-imposed by cultural and religious factors (Boye et al., 2010). Nutritionally, pulses contain high amounts of protein (18-32%) and essential amino acids that might not be readily available, gaining pulses recent attention for their potential to fight malnutrition and disease (Boye et al., 2010).</p>
<p>Folate deficiency is thought to contribute to the prevalence of many major diseases and severe birth defects (Basset, Quinlivan, Gregory, & Hanson, 2005). To help understand the common causes of folate deficiency, they are listed on the table 1. Inadequate intake can be the result of diseases that impacts absorption, use of various drugs, of simply inadequate dietary intake (Merck Manuel, 2016). </p>  
<p>The diets of subsistence level farmers in Africa and South Asia usually contain an adequate supply of carbohydrates through readily accessible grain products (maize, rice, etc.) but are often low in protein content (Broughton et al., 2003). Good supply of dietary proteins are often found in animal products, but scarcity of these products can prevent adequate protein intake (Broughton et al., 2003). Legumes are a notable solution to a lack of protein access, as legumes can provide the protein necessary for a health diet when other sources are unavailable (Broughton et al., 2003). In fact, dietary proteins are mainly acquired from legumes/pulses in many parts of the world (Broughton et al., 2003). By complementing other foods that are a primary source of carbohydrates, legumes that provide dietary proteins fulfill many human nutritional needs (Broughton et al., 2003).</p>
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<p>Often a mono-carbohydrate diet of a single cereal grain is indicative of a population that is malnourished because cereals lacks the protein, vitamins, and minerals required for a healthy diet (Boye et al., 2010). However, pulses are normally high in protein, vitamin, and mineral composition. Cereals provide adequate carbohydrates but lack in protein, whereas pulses often provide adequate protein but lack in carbohydrates (Boye et al., 2010). Complementing locally grown grains with pulses and blending the different nutritional advantages of these crops could potentially address protein malnutrition problems worldwide (Boye et al., 2010). Legumes and cereal combinations in cultural diets have been key to survival of many peoples, and these combinations in cultural foods can be around the globe (FAO, 2016). Often, a diverse diet that includes various legumes, cereals, fruits, and vegetables, each providing its unique nutrient supply, provides the best chance for adequate nutrition in all required nutrients for human health.</p>
<p>Of vital importance, pulses are an important source of dietary minerals, with the potential to provide all 15 essential minerals required in a human diet if consuming adequate and diverse amounts (Wang et al., 2003). It should be noted that the mineral concentrations of minerals key to human metabolism (Fe, Zn, Ca, etc.) are low compared to animal food products (Wang et al., 2003).</p>  
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       <h3 class="title-bg">The Common Bean: A Case Study</h3>
       <h3 class="title-bg">Health Issues Resulting from Folate Deficiencies </h3>
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<p>The common bean (Phaseolus vulgaris L.) is the most widely directly consumed grain legume in humans (Broughton et al., 2003). Global production exceeds 23 million metric tonnes and is twice that of the chickpea, the second most important grain legume (Broughton et al., 2003). The common bean represents half the grain legumes consumed globally, despite having lower than standard yields and sub-optimal seed quality (Broughton et al., 2003). It is the primary source of protein for humans in Mexico and Brazil (Broughton et al., 2003). Countries in Africa, such as Rwanda and Burundi, have reported that average national consumption of beans is greater than 40 kg per person per year, providing the second most important source of protein and third most important source of calories within these nations (Broughton et al., 2003). The high protein and mineral content of beans, especially in Fe and Zn, is important in areas with a high prevalence of micronutrient deficiencies, and should be complemented with starchy grains such as maize or root crops (Broughton et al., 2003). Beans are a major staple crop of eastern and southern Africa, often grown by resource-poor farmers (Broughton et al., 2003).</p>
<p>Folate deficiency is associated with multiple cancers, cardiovascular disease, and Neural Tube Defects (NTDs) (Basset et al., 2005; NIH, 2016). Folate is a critical factor for the synthesis of the components of DNA, namely for the synthesis of purines and pyrimidines, as well as for the development of the fetal nervous system, red blood cells, and other cellular components (Merck Manuel, 2016). Furthermore, folate is important during phases of rapid cell growth, such as during fetal development, due to heightened cellular demands (NIH, 2016). Because this vitamin complex is an imperative cofactor for the synthesis of DNA precursors, one can see the range of adverse health effects that can occur in FD individuals. This section will briefly discuss the adverse health outcome resulting from FD starting with NTDs – a severe defect due to FD during pregnancy.</p>
<p>NTDs result in dangerous malformations that occur during fetal development, including various malformations of the spine (spina bifida), skull, and brain (anencephaly) in a newborn following a folate deficient pregnancy (NIH, 2016; Merck Manuel, 2016). NTDs are a failure for the neural tube to close at the upper or lower end between days 21 to 28 of post-conception pregnancy (NIH, 2016). As such, NTDs should be of concern for all pregnant women. Women lacking in folate intake are at risk of having children with NTDs, along with other complications such as low birth weight and early delivery (NIH, 2016). However, multiple clinical trails have clearly shown that a substantial proportion of NTDs can be easily addressed by taking folic acid pre-conceptionally (NIH, 2016). This evidence has led to required food fortification programs that have reduced by NTD rates by 25%-30% in the USA, and researchers believe this rate could be reduced even more if access inequalities are addressed (NIH, 2016). Risk of NTD is not always dependent solely on folate status, but rather a combination of other factors, such as obesity and low intake of other key nutrients, that may affect NTD risk (NIH, 2016).</p>
<p>While the relationship between FD and NTD is well established, the implications if FD in other major diseases are less certain. FD has been inversely associated with risk of multiple cancers (including colorectal, pancreatic, and more) as folate may influence the development of cancers due to its importance in DNA replication and cell division (NIH, 2016). However, further research is needed due to the high uncertainties around the role of folate in carcinogenesis, cardiovascular disease, and many health issues (NIH, 2016). What is certain is that folate is a key micronutrient for metabolism and many bodily processes (NIH, 2016).</p>
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       <h3 class="title-bg">Legumes are High in Protein Content</h3>
       <h3 class="title-bg">Absorption of Folate and Folic Acid</h3>
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<p>As pulses are a rich source of protein, they contain high amounts of essential amino acids, including lysine, aspartic acid, and arginine (Boye et al., 2010). Pulses provide a well-balanced amino acid intake when paired with cereals and other foods rich in tryptophan and amino acids containing sulfur, as these metabolites are less prevalent in pulses (Boye et al., 2010). Table 1.1 shows that pulses are very high in protein content and as contain significant amounts of caloric energy, while some pulses are also rich in fats. In addition to their nutritional properties, pulse proteins provide water holding and fat binding functional properties that are also beneficial (Boye et al., 2010). Finally, fava beans are notable, and included in table 1.1 due to their drought resistance.</p>
<p>As can be discerned in table 1, FD in isolation is not as common as its coexistence with multiple other nutrition deficiencies associated with mal-absorptive disorders, drug intake, and poor diet (NIH, 2016). Considering the causes of poor folate uptake into the human body, the following groups are considered at heightened risk of FD: 1. People with alcohol dependence, as alcohol interferes with folate absorption and accelerates its breakdown (NIH, 2016). 2. Women of childbearing age, as FD increases the risk of NTDs, and these women should obtain 400 micrograms/day of folic acid (NIH, 2016; WHO, 2012). 3. Pregnant women, as the demands for folate intake increase due to the growing fetus’s need for cellular division and DNA synthesis (NIH, 2016). These women require 600 micrograms/day. 4. People with mal-absorptive or digestive-tract disorders, as these medical conditions can lower the natural folate absorption into the body (NIH, 2016). Generally, poor absorption of folate and increased demands predispose people to the greatest risk of FD. Additionally, prolonged cooking destroys folate and can predispose people to inadequate intake (Merck Manuel, 2016). This is important information for subsistence farmers and those without access to enriched gains who may meet folate dietary needs through local raw green vegetables, legumes, and intake of seeds.</p>
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       <h3 class="title-bg">Legumes Complement Cereals that are low in Protein and Essential Amino Acids</h3>
       <h3 class="title-bg">Natural Sources of Folate and Folate Fortification/Supplementation</h3>
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<p>Proteins in legumes such as beans can be predominantly stored as the protein phaseolin, a key indicator of the quality of bean seeds (Broughton et al., 2003). Phaseolin and many proteins in the legume family are deficient in amino acids that contain sulfur, including methionine (Broughton et al., 2003). The proteins contained in the seeds of cereals often contain these sulfur-containing amino acids, but are themselves deficient in other essential amino acids that are highly concentrated in pulses (Broughton et al., 2003). This is why a combined consumption of cereals and legumes can prevent nutritional deficiencies (Broughton et al., 2003). A balanced diet that provides all the essential nutrients occurs when cereals and legumes are consumed in a portion ratio of 2-cereal portions for every 1-legume portion (Broughton et al., 2003). As legume yields are often low, increased legume production to fulfill this nutritional ratio would benefit millions of malnourished people worldwide (Broughton et al., 2003).</p>
<p>Consumption of a diversity of foods and vegetables is key to providing adequate supply of folate, among other vitamins and minerals. Beans and dark green vegetables are some of the foods with the highest natural folate concentrations (NIH, 2016). Many of the leafy greens are also high in iron, folate, and vitamin A. Natural folate can be found in beans and dark green leafy vegetables such as spinach, turnips, and seaweed. Folate can also be found in nuts, seeds, diary/egg products and meats, (NIH, 2016). Some of these products can be seen from table 2. The benefits of legume consumption for folate are further outlined in table 4.</p>
<p>Table 1.2 shows that pulses are high in amino acids that are not as prevalent in cereals, notably lysine and arginine, in which lysine is an essential amino acid. This table also shows how methionine levels (a sulfur-containing amino acid) are lower in pulses and must be obtained from alternative foods such as cereals.</p>  
<p>Many countries (U.S., Canada, South Africa, Chile) have now established folic acid fortification programs, mainly enriching breads, cereals, flours, and other grain products with folic acid (NIH, 2016). The highest amounts of folate are now found among folic acid-enriched cereals (USDA, 2017). The U.S. Food and Drug Administration’s fortification program has aimed to increased folic acid intake by 100 micrograms per day (NIH, 2016). As such, folic acid supplementation is an effective disease-prevention measure for helping to addressing folate deficiency on a large scale. It should also be noted that the National Institute of Health reports that folic acid is more bioavailable (85% availability) than folates naturally present in foods, which are said to have 50% bioavailability and requiring higher intake (NIH, 2016).</p>  
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       <h3 class="title-bg">Minerals are Highly Concentrated in Legumes and the Seed Coat of Cereals</h3>
       <h3 class="title-bg">Eat Seeds and Legumes for Higher Natural Folate and Mineral Nutrition</h3>
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<p>Cereals are often consumed as an energy source while legumes provide micronutrients for human nutrition (Broughton et al., 2003). Legumes are a much greater source of micronutrients when compared to cereals because of their higher natural abundance of minerals and because many cereals have their seed coat remove prior to eating (Broughton et al., 2003). Polishing of cereals and removing the seed coat, also known as the bran, reduces the mineral content as these coatings contain a significant amount of minerals, giving this coating its rigid structure (Broughton et al., 2003). Conversely, many pulses are consumed whole, without the removal of the their outer layers, conserving their mineral content (Broughton et al., 2003). For example, beans supply high levels of iron, phosphorus, magnesium, and moderate levels of zinc, calcium and other minerals (Broughton et al., 2003). Beans often provide 10-20% of the adult requirement for many nutrients for those with restricted dietary consumption, defined as 15-20 kg/year (Broughton et al., 2003). Therefore, legume consumption in combination with cereals should be considered in addressing micronutrient deficiencies worldwide (Broughton et al., 2003).</p>
<p>In general, the seeds of fruits and vegetables are very high in iron, zinc, folate and other minerals (USDA, 2017-a). The seed’s outermost layer, known as the pericarp, contains the highest concentration of minerals, helping to strengthen this protective outer layer of the seed. This means that the pericarps of fruit and vegetable seeds are generally the area of the seed highest in mineral content. Seeds are often referred to as nutrient “sinks” because seeds accumulate nutrients for long-term storage from their parent plants (Zhang et al., 2007). The amount of folate in seeds is significant, as seen in table 1.3.</p>
<p>Increasing the seed mineral density of grain legumes (pulses) is of interest, as these foods can contain all 15 essential minerals require in human nutrition (Wang et al., 2003). However, some mineral deficiencies, notably Fe and Zn deficiency, can still be prevalence in regions where legumes provide a considerable portion of the human diet (Wang et al., 2003). One possible solution is smaller pulses, or legume-seeds. Smaller seeds have a higher seed coat surface area in comparison to the seed volume. As the seed coat is the part of the seed that has the highest concentration of minerals, consumption of smaller seeds would mean more mineral intake per volume of pulses consumed. Additionally, research to understand how minerals move into has grained increased interest in order to optimize mineral-uptake conditions (Wang et al., 2003).</p>
<p>Seeds can also provide the necessary protein and fat content needed to fight many micronutrient deficiencies, as fat intake is important for micronutrient absorption (Wickens, 1995; FAO/WHO, 2002). Pumpkin and squash seeds kernels can provide more than 30 grams of protein per 100 grams of seeds (USDA, 2017-b).</p>
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<p>As such, seed of fruits and vegetables should be considered in malnutrition interventions by relief organizations, in addition to the possible fortification of staple crops. Seeds and legumes keep for a long period of time, acting as a reliable food source throughout the year in drought-stricken regions. Considering the seeds of local fruits and vegetables as well as legume pulses (legume grains) may be an advantageous folate/nutrition source, especially give that pulses and seeds can be stored and keep over the dry season, when other crops are not available.</p>
<p>Legumes also contain an outer layer “coating” structure that is high in minerals and folate. For example, the red layer surrounding kidney beans is good source of minerals, including folate. The high folate content of various legumes can be seen in table 4. From table 4, analysis of the species name of Kidney, Pinto and Black beans shows that many frequently consumed beans are in fact the same species, Phaseolus vulgaris, also known as “the common bean.” Phaseolus vulgaris exists in various varieties. Table 4 shows that although the legume species is the same, nutritional concentrations can differ between varieties, even if their pulses look similar.</p>
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<p>Despite the natural sources of folate, many products may not be the staple crops of a particular region. Furthermore, the strong enrichment programs that exist in some nations may not exist in others. Therefore, when addressing FD in regions endemic with FD, it is important to increase folate intake by promoting food choices or enriched staple crops that are accessible for each particular region.</p>
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       <h3 class="title-bg">Antinutrients, Diet Composition, and Nutrient Bioavailability/Digestibility</h3>
       <h3 class="title-bg">Critical Analysis of Folate Deficiencies and Supplementation Guidelines</h3>
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<p>Pulses seeds contain some undesirable “antinutrients” that interfere with normal protein digestibility and uptake of micronutrients (Boye et al., 2010). For example, phytic acid and trypsin inhibitors are antinutrients in some pulses that reduce micronutrient uptake and protein digestibility, respectively (Campos-Vega, Loarca-Piña, & Oomah, 2010; Welch & Graham, 2004). There are numerous other antinutrients in plant-foods that can impair human nutrition, but there are also many nutrients that increase of vitamins and minerals uptake and stimulate nutrition (Welch & Graham, 2004). Additionally, antinutrients may have some beneficial properties for human health, complicating the literature (Campos-Vega et al., 2010; Welch & Graham, 2004). Most legumes are mainly composed of proteins that are highly digestible and have high protein content (Boye et al., 2010).</p>
<p>Folic acid supplementation can address anemia but not the potentially permanent neurological damage that can result from vitamin B12 deficiency (NIH, 2016). As such, it is important to beware the affects of masking affect that folate supplementation can have in covering up vitamin B12 deficiency (NIH, 2016). Folate should not be consumed over the recommended upper limits due to possible health risks (NIH, 2016).</p>
<p>The composition of one’s diet is highly important in determining the bioavailability of nutrients found in plant foods (Welch & Graham, 2004). Plant food processing and preparation techniques can influence the amount of bioavailable micronutrients, sometime reducing the nutrient uptake (Welch & Graham, 2004). An example of this is combining foods rich in animal proteins (e.g. beef, poultry) with plant foods that have high antinutrient concentrations (e.g. phytic acid), which can lower the uptake of Fe and Zn from the meal (Welch & Graham, 2004).</p>  
<p>As part of a micronutrient deficiency supplementation program, the WHO recommends iron and folic acid supplementation in menstruating women in areas of high anemia prevalence. It is recommended that the supplemental dose of folate be seven times the 400 micrograms daily recommended dose to improve red call folate concentrations and reduce the risk of NTDs in menstruating women (WHO, 2011). Also note that as the neural tube closes by the 28th day of pregnancy, folic acid supplementation after this day will not prevent NTDs (WHO, 2012).</p>  
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       <h3 class="title-bg">Resources Moving Forward</h3>
       <h3 class="title-bg">More Resources Moving Forward</h3>
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<p>FAO Kids – Health benefits of pulses, clearly outlined. Retrieved from: http://www.fao.org/documents/card/en/c/37152a05-f15f-4373-a3f3-e355ac6cc83e/</p>
<p>National Institute of Health Office of Dietary Supplements: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/</p>
<p>What are Pulses? – 2016 International Year of Pulses. Retrieved from: http://iyp2016.org/resources/what-are-pulses</p>
<p>Merck Manuel Professional Version Folate Information: http://www.merckmanuals.com/en-ca/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/folate</p>
<p>Importance of Legumes in African Culture, N2Africa. Retrieved from: http://www.n2africa.org/rationale/ImportanceLegumes</p>  
<p>Scientific Book on the health benefits of eating seeds and nuts:
Preedy V. R., Watson R. W., Patel V.B. (2011). Nuts and Seeds in Health and Disease Prevention. Academic Press. London, UK.</p>
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       <h3 class="title-bg">References</h3>
       <h3 class="title-bg">References</h3>
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<p>1.Boye, J., Zare, F., & Pletch, A. (2010). Pulse proteins: processing, characterization, functional properties and applications in food and feed. Food Research International, 43(2), 414-431.</p>
      <p>1. Basset, G. J., Quinlivan, E. P., Gregory, J. F., & Hanson, A. D. (2005). Folate synthesis and metabolism in plants and prospects for biofortification. Crop Science, 45(2), 449-453.</p>


<p>2.Broughton, W. J., Hernandez, G., Blair, M., Beebe, S., Gepts, P., & Vanderleyden, J. (2003). Beans (Phaseolus spp.)–model food legumes. Plant and soil, 252(1), 55-128.</p>
<p>2. FAO/WHO, Joint (2002). Human vitamin and mineral requirements. Chapter 7. Rome, Food and Agriculture Organization of the United Nations and World Health Organization.</p>


<p>3.Campos-Vega, R., Loarca-Piña, G., & Oomah, B. D. (2010). Minor components of pulses and their potential impact on human health. Food research international, 43(2), 461-482.</p>
<p>3. Merck Manuel, Professional Version. (2016). Folate (Folic Acid), Nutritional Disorders. Merck & Co., Inc. Retrieved from: http://www.merckmanuals.com/en-ca/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/folate</p>


<p>4.FAO. (2016). FAO Kids – Health benefits of pulses. Rome, Food and Agricultural Organization of the United Nations. Retrieved from: http://www.fao.org/documents/card/en/c/37152a05-f15f-4373-a3f3-e355ac6cc83e/</p>
<p>4. NIH, National Institute of Health. (2016 – last update). Folate. NIH, Office of Dietary Supplements. Retrieved from: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/</p>


<p>5.Graham, P. H., & Vance, C. P. (2003). Legumes: importance and constraints to greater use. Plant physiology, 131(3), 872-877.</p>  
<p>5. USDA (United States Department of Agriculture)-a, 2017. USDA Food Composition Databases. Retrieved from: https://ndb.nal.usda.gov/ndb/search/list</p>


<p>6.Herridge, D. F., Peoples, M. B., & Boddey, R. M. (2008). Global inputs of biological nitrogen fixation in agricultural systems. Plant and Soil, 311(1-2), 1-18.</p>
<p>6. USDA (United States Department of Agriculture)-b, 2017. USDA Food Composition Databases. Retrieved from:
https://ndb.nal.usda.gov/ndb/nutrients/report/nutrientsfrm?max=25&offset=0&totCount=0&nutrient1=417&nutrient2=&nutrient3=&subset=0&sort=c&measureby=g</p>


<p>7.Messina, M. J. (1999). Legumes and soybeans: overview of their nutritional profiles and health effects. The American journal of clinical nutrition, 70(3), 439-450.</p>
<p>7. WHO. (2011). Guideline: Intermittent iron and folic acid supplementation in menstruating women. Geneva, World Health Organization.</p>  


<p>8.Wang, T. L., Domoney, C., Hedley, C. L., Casey, R., & Grusak, M. A. (2003). Can we improve the nutritional quality of legume seeds?. Plant Physiology, 131(3), 886-891.</p>
<p>8. WHO. (2012). Guideline: Daily iron and folic acid supplementation in pregnant women. Geneva, World Health Organization.</p>  


<p>9.Welch, R. M., & Graham, R. D. (2004). Breeding for micronutrients in staple food crops from a human nutrition perspective. Journal of experimental botany, 55(396), 353-364.</p>
<p>9. Wickens, G.E. (1995). Edible Nuts. Rome, Food and Agriculture Organization of the United Nations</p>


<p>10.WHO/FAO, Joint Committee. (2007). Codex Alimentarius. Cereals, pulses, legumes and vegetable proteins. 1st Edition. FAO, Rome, Italy.</p>
<p>10. Zhang, W. H., Zhou, Y., Dibley, K. E., Tyerman, S. D., Furbank, R. T., & Patrick, J. W. (2007). Nutrient loading of developing seeds. Functional Plant Biology, 34(4), 314-331</p>

Revision as of 12:12, 24 June 2022

9.8 - Legumes and seeds as folate sources for pregnant women


Nick Moroz, University of Guelph, Canada

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Suggested citation for this chapter.

Moroz,N. (2022) Improving human nutrition, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Folate Deficiency

This chapter will outline how folate deficiency can be detrimental to one’s health, while also outlining various sources of folate found in many seeds and legumes grown throughout the developing world. Folate deficiency (FD) results from a reduced intake of folate – a generic term that encompasses both naturally occurring food folate as well as folic acid (NIH, 2016). FD can also occur due to heightened folate demands during pregnancy or because of impaired absorption occurring from mal-absorption disorders (Merck Manuel, 2016). Folate is a water soluble-B vitamin complex that is naturally available in foods while also frequently enriched in foods or provided as food supplements (NIH, 2016). Folic acid is the term used for the fully oxidized form of the vitamin complex used in dietary supplements and in fortified foods (NIH, 2016).

Folate deficiency is thought to contribute to the prevalence of many major diseases and severe birth defects (Basset, Quinlivan, Gregory, & Hanson, 2005). To help understand the common causes of folate deficiency, they are listed on the table 1. Inadequate intake can be the result of diseases that impacts absorption, use of various drugs, of simply inadequate dietary intake (Merck Manuel, 2016).

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Health Issues Resulting from Folate Deficiencies

Folate deficiency is associated with multiple cancers, cardiovascular disease, and Neural Tube Defects (NTDs) (Basset et al., 2005; NIH, 2016). Folate is a critical factor for the synthesis of the components of DNA, namely for the synthesis of purines and pyrimidines, as well as for the development of the fetal nervous system, red blood cells, and other cellular components (Merck Manuel, 2016). Furthermore, folate is important during phases of rapid cell growth, such as during fetal development, due to heightened cellular demands (NIH, 2016). Because this vitamin complex is an imperative cofactor for the synthesis of DNA precursors, one can see the range of adverse health effects that can occur in FD individuals. This section will briefly discuss the adverse health outcome resulting from FD starting with NTDs – a severe defect due to FD during pregnancy.

NTDs result in dangerous malformations that occur during fetal development, including various malformations of the spine (spina bifida), skull, and brain (anencephaly) in a newborn following a folate deficient pregnancy (NIH, 2016; Merck Manuel, 2016). NTDs are a failure for the neural tube to close at the upper or lower end between days 21 to 28 of post-conception pregnancy (NIH, 2016). As such, NTDs should be of concern for all pregnant women. Women lacking in folate intake are at risk of having children with NTDs, along with other complications such as low birth weight and early delivery (NIH, 2016). However, multiple clinical trails have clearly shown that a substantial proportion of NTDs can be easily addressed by taking folic acid pre-conceptionally (NIH, 2016). This evidence has led to required food fortification programs that have reduced by NTD rates by 25%-30% in the USA, and researchers believe this rate could be reduced even more if access inequalities are addressed (NIH, 2016). Risk of NTD is not always dependent solely on folate status, but rather a combination of other factors, such as obesity and low intake of other key nutrients, that may affect NTD risk (NIH, 2016).

While the relationship between FD and NTD is well established, the implications if FD in other major diseases are less certain. FD has been inversely associated with risk of multiple cancers (including colorectal, pancreatic, and more) as folate may influence the development of cancers due to its importance in DNA replication and cell division (NIH, 2016). However, further research is needed due to the high uncertainties around the role of folate in carcinogenesis, cardiovascular disease, and many health issues (NIH, 2016). What is certain is that folate is a key micronutrient for metabolism and many bodily processes (NIH, 2016).

Absorption of Folate and Folic Acid

As can be discerned in table 1, FD in isolation is not as common as its coexistence with multiple other nutrition deficiencies associated with mal-absorptive disorders, drug intake, and poor diet (NIH, 2016). Considering the causes of poor folate uptake into the human body, the following groups are considered at heightened risk of FD: 1. People with alcohol dependence, as alcohol interferes with folate absorption and accelerates its breakdown (NIH, 2016). 2. Women of childbearing age, as FD increases the risk of NTDs, and these women should obtain 400 micrograms/day of folic acid (NIH, 2016; WHO, 2012). 3. Pregnant women, as the demands for folate intake increase due to the growing fetus’s need for cellular division and DNA synthesis (NIH, 2016). These women require 600 micrograms/day. 4. People with mal-absorptive or digestive-tract disorders, as these medical conditions can lower the natural folate absorption into the body (NIH, 2016). Generally, poor absorption of folate and increased demands predispose people to the greatest risk of FD. Additionally, prolonged cooking destroys folate and can predispose people to inadequate intake (Merck Manuel, 2016). This is important information for subsistence farmers and those without access to enriched gains who may meet folate dietary needs through local raw green vegetables, legumes, and intake of seeds.

Natural Sources of Folate and Folate Fortification/Supplementation

Consumption of a diversity of foods and vegetables is key to providing adequate supply of folate, among other vitamins and minerals. Beans and dark green vegetables are some of the foods with the highest natural folate concentrations (NIH, 2016). Many of the leafy greens are also high in iron, folate, and vitamin A. Natural folate can be found in beans and dark green leafy vegetables such as spinach, turnips, and seaweed. Folate can also be found in nuts, seeds, diary/egg products and meats, (NIH, 2016). Some of these products can be seen from table 2. The benefits of legume consumption for folate are further outlined in table 4.

Many countries (U.S., Canada, South Africa, Chile) have now established folic acid fortification programs, mainly enriching breads, cereals, flours, and other grain products with folic acid (NIH, 2016). The highest amounts of folate are now found among folic acid-enriched cereals (USDA, 2017). The U.S. Food and Drug Administration’s fortification program has aimed to increased folic acid intake by 100 micrograms per day (NIH, 2016). As such, folic acid supplementation is an effective disease-prevention measure for helping to addressing folate deficiency on a large scale. It should also be noted that the National Institute of Health reports that folic acid is more bioavailable (85% availability) than folates naturally present in foods, which are said to have 50% bioavailability and requiring higher intake (NIH, 2016).

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Eat Seeds and Legumes for Higher Natural Folate and Mineral Nutrition

In general, the seeds of fruits and vegetables are very high in iron, zinc, folate and other minerals (USDA, 2017-a). The seed’s outermost layer, known as the pericarp, contains the highest concentration of minerals, helping to strengthen this protective outer layer of the seed. This means that the pericarps of fruit and vegetable seeds are generally the area of the seed highest in mineral content. Seeds are often referred to as nutrient “sinks” because seeds accumulate nutrients for long-term storage from their parent plants (Zhang et al., 2007). The amount of folate in seeds is significant, as seen in table 1.3.

Seeds can also provide the necessary protein and fat content needed to fight many micronutrient deficiencies, as fat intake is important for micronutrient absorption (Wickens, 1995; FAO/WHO, 2002). Pumpkin and squash seeds kernels can provide more than 30 grams of protein per 100 grams of seeds (USDA, 2017-b).

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As such, seed of fruits and vegetables should be considered in malnutrition interventions by relief organizations, in addition to the possible fortification of staple crops. Seeds and legumes keep for a long period of time, acting as a reliable food source throughout the year in drought-stricken regions. Considering the seeds of local fruits and vegetables as well as legume pulses (legume grains) may be an advantageous folate/nutrition source, especially give that pulses and seeds can be stored and keep over the dry season, when other crops are not available.

Legumes also contain an outer layer “coating” structure that is high in minerals and folate. For example, the red layer surrounding kidney beans is good source of minerals, including folate. The high folate content of various legumes can be seen in table 4. From table 4, analysis of the species name of Kidney, Pinto and Black beans shows that many frequently consumed beans are in fact the same species, Phaseolus vulgaris, also known as “the common bean.” Phaseolus vulgaris exists in various varieties. Table 4 shows that although the legume species is the same, nutritional concentrations can differ between varieties, even if their pulses look similar.

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Despite the natural sources of folate, many products may not be the staple crops of a particular region. Furthermore, the strong enrichment programs that exist in some nations may not exist in others. Therefore, when addressing FD in regions endemic with FD, it is important to increase folate intake by promoting food choices or enriched staple crops that are accessible for each particular region.

Critical Analysis of Folate Deficiencies and Supplementation Guidelines

Folic acid supplementation can address anemia but not the potentially permanent neurological damage that can result from vitamin B12 deficiency (NIH, 2016). As such, it is important to beware the affects of masking affect that folate supplementation can have in covering up vitamin B12 deficiency (NIH, 2016). Folate should not be consumed over the recommended upper limits due to possible health risks (NIH, 2016).

As part of a micronutrient deficiency supplementation program, the WHO recommends iron and folic acid supplementation in menstruating women in areas of high anemia prevalence. It is recommended that the supplemental dose of folate be seven times the 400 micrograms daily recommended dose to improve red call folate concentrations and reduce the risk of NTDs in menstruating women (WHO, 2011). Also note that as the neural tube closes by the 28th day of pregnancy, folic acid supplementation after this day will not prevent NTDs (WHO, 2012).

More Resources Moving Forward

National Institute of Health Office of Dietary Supplements: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/

Merck Manuel Professional Version Folate Information: http://www.merckmanuals.com/en-ca/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/folate

Scientific Book on the health benefits of eating seeds and nuts: Preedy V. R., Watson R. W., Patel V.B. (2011). Nuts and Seeds in Health and Disease Prevention. Academic Press. London, UK.

References

1. Basset, G. J., Quinlivan, E. P., Gregory, J. F., & Hanson, A. D. (2005). Folate synthesis and metabolism in plants and prospects for biofortification. Crop Science, 45(2), 449-453.

2. FAO/WHO, Joint (2002). Human vitamin and mineral requirements. Chapter 7. Rome, Food and Agriculture Organization of the United Nations and World Health Organization.

3. Merck Manuel, Professional Version. (2016). Folate (Folic Acid), Nutritional Disorders. Merck & Co., Inc. Retrieved from: http://www.merckmanuals.com/en-ca/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/folate

4. NIH, National Institute of Health. (2016 – last update). Folate. NIH, Office of Dietary Supplements. Retrieved from: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/

5. USDA (United States Department of Agriculture)-a, 2017. USDA Food Composition Databases. Retrieved from: https://ndb.nal.usda.gov/ndb/search/list

6. USDA (United States Department of Agriculture)-b, 2017. USDA Food Composition Databases. Retrieved from: https://ndb.nal.usda.gov/ndb/nutrients/report/nutrientsfrm?max=25&offset=0&totCount=0&nutrient1=417&nutrient2=&nutrient3=&subset=0&sort=c&measureby=g

7. WHO. (2011). Guideline: Intermittent iron and folic acid supplementation in menstruating women. Geneva, World Health Organization.

8. WHO. (2012). Guideline: Daily iron and folic acid supplementation in pregnant women. Geneva, World Health Organization.

9. Wickens, G.E. (1995). Edible Nuts. Rome, Food and Agriculture Organization of the United Nations

10. Zhang, W. H., Zhou, Y., Dibley, K. E., Tyerman, S. D., Furbank, R. T., & Patrick, J. W. (2007). Nutrient loading of developing seeds. Functional Plant Biology, 34(4), 314-331

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