Title: Lentil and Kale: Complementary Nutrient-Rich Whole Food Sources to Combat Micronutrient and Calorie Malnutrition
Published: November 7, 2015
Read or download the PDF: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663599/pdf/nutrients-07-05471.pdf
Abstract: Lentil (Lens culinaris Medik.) is a nutritious food and a staple for millions of people. Not only are lentils a good source of energy, they also contain a range of micronutrients and prebiotic carbohydrates. Kale (Brassica oleracea v. acephala) has been considered as a health food, but its full range of benefits and composition has not been extensively studied. Recent studies suggest that foods are enrich in prebiotic carbohydrates and dietary fiber that can potentially reduce risks of non-communicable diseases, including obesity, cancer, heart disease, and diabetes. Lentil and kale added to a cereal-based diet would enhance intakes of essential minerals and vitamins to combat micronutrient malnutrition. This review provides an overview of lentil and kale as a complementary nutrient-rich whole food source to combat global malnutrition and calorie issues. In addition, prebiotic carbohydrate profiles and the genetic potential of these crops for further micronutrient enrichment are briefly discussed with respect to developing sustainable and nutritious food systems.
More than 800 million people, or >10% of the world’s population, are suffering from hunger; in certain areas, such as Western Africa and South East Asia, the proportion is >20%. In contrast, Western populations are characterized by significant increases in obesity due to the consumption of calorie-dense foods. This is especially true in the United States, where the 2011–2012 National Health and Nutrition Examination Survey found 35% of adults and 17% of children and adolescents are obese. According to the Global Health Observatory, obesity is linked to 2.8 million deaths per year worldwide. Unbalanced nutrition and obesity are linked to chronic diseases including cardiovascular disease, type 2 diabetes, osteoarthritis, and several cancers. The urgency created by these and similar life-threatening diseases has made healthy eating a priority for both developing and developed countries.
Today’s world populations consume inadequate amounts of vegetables, especially nutritionally robust crops, such as leafy greens, but this manifests in different problems. In developing nations, the biggest problem is micronutrient malnutrition; in Western nations, the primary challenge is obesity but micronutrient malnutrition is also present. Two crops that could be paired to address both obesity and micronutrient malnutrition problems seen throughout the world are lentils (Lens culinaris Medik.) and kale (Brassica oleracea v. acephala). Lentils provide a variety of essential nutrients to a person’s diet, containing high levels of protein (20%–30%), minerals (2%–5%), vitamins (folates), and prebiotic carbohydrates. Because of their numerous health benefits, high yield, and nitrogen benefit in food systems, lentils are a useful candidate for micronutrient biofortification efforts; however, biofortification research efforts are currently limited to selected crops. Although research has been done on lentils, as well as other pulses, the continued improvement of this crop could be very influential not only for micronutrient malnutrition but also for obesity reduction. On the other hand, kale can be consumed either raw or cooked and is one of the oldest cabbage like plants originating from the eastern Mediterranean region. Kale has received recent attention from health and nutrition sectors due to its nutrient profile, despite the information on which it is based on old varieties, based on a very small sample size, and missing several nutrients kale is likely to contain in considerable amounts of minerals, folates, carotenoids, and prebiotic carbohydrates. With that caveat, kale places high on the list of healthiest foods or also known as a supper food. Kale ranked 15th in a Centers for Disease Control study ranked 47 “powerhouse” fruits and vegetables (a serving providing ≥10% of 17 essential nutrients; that are strongly associated with reducing the risk of heart disease and other non-communicable diseases. Thus, the objective of this review paper is to review the potential of lentils and kale as nutrient-dense whole foods to decrease malnutrition, rates of obesity, and chronic disease-related mortality and make suggestions for future work in this regard.
Brassica vegetables, such as kale and collard greens (Brassica olceracea var. Acephala), are very important to many agricultural systems around the world. The estimated annual value of brassica vegetables in the USA is approximately $1 billion. Broccoli, cabbage, cauliflower, and Brussels sprouts are the most valuable brassica crops; however, no production statistics are currently available for leafy green brassicas in the USA. Kale, traditionally a less recognized crop, is becoming a significant specialty crop in the Southern US as a result of its suitability to southern fall and winter growing conditions. Kale is a traditional leafy green brassica used as a garnish on plates and salad bars but is gaining popularity as a primary ingredient in either raw or cooked form. Georgia, North Carolina, and South Carolina have emerged over the last five years as the leading kale producing states. From some 500 acres producing only 15% of US kale in 2001, the Carolinas have emerged as kale leaders, currently producing more than two-thirds of America’s annual kale output. Most of the kale produced in this region is sold in a variety of fresh and processed forms that are nationally distributed. Carolina kale is marketed by market class (curly, dinosaur, red Russian, ornamental), stage of maturity, and packed fresh ready-to-eat/cook. Kale is also a popular leafy green vegetable in northern regions of Asia, and Europe. Between 1993 and 2013, about 72.3% of the world’s brassica vegetables were produced in Asia. The production rate of brassica vegetables for human consumption was 270 million metric tons as of 2012 but is small in comparison with sugarcane, soybean, and maize, for which about one billion tons were produced. Worldwide, the production of meats, sugar, and cereal grains has greatly overshadowed the production of more diverse and healthful vegetable crops, including nutritionally crucial cultivars such as brassica greens.
These green vegetable crops can provide much needed nutrients to consumers and are often proclaimed as health foods because of their nutrient-rich composition. Brassica vegetables contain numerous micronutrients, such as antioxidants, carotenoids, glucosinolates, polyphenols, vitamins, and minerals important to human health. Available data indicate that kale is rich in several vitamins (A, K, C, and probably folate), essential minerals (potassium, calcium, magnesium), and dietary fiber. It is likely that kale can also provide other nutrients including carotenoids, folate, and prebiotic carbohydrates, although these have not been characterized. Brassica greens are also known to contain phytochemicals such as folic acid, ascorbic acid, riboflavin, and carotenes. Flavonoids act in the body as antioxidants and capture free radicals. This means that they may have a lessening effect on the likelihood of developing chronic diseases such as cancer. Other phytochemicals found in vegetables such as brassicas are categorized as anti-nutrients. These chemical compounds are known to disrupt many physiological pathways and lessen the absorption of beneficial nutrients. Included in this group are oxalates, phytate, and tannins.
Despite its gaining popularity, kale remains an understudied vegetable. In the Science Direct database, 636 publications are returned using “kale” as a keyword but only four relevant studies when using “kale and nutrition”. These include three studies from Brazil, Turkey, and Pakistan, and one study from the USA. No studies of kale nutritional quality appear to have been carried out in the last few decades. However, significant genomic research on broccoli has been carried out at the University of Wisconsin, University of California, University of Georgia, and Cornell University. The specific focus of these research studies was on genomics and gene identification to determine mutation profiles of brassica.
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