Nutritional value of leafy vegetables of sub-Saharan Africa and their potential contribution to human health: A review

Chemical Composition Analysis, Antioxidant, and Antibacterial Activities of Eggplant Leaves

Agricultural by-products represent one of the biggest pollutants for the environment, therefore, investigating new sources for the extraction of bioactive compounds is a topic of great interest for the entire scientific community. This work is aimed at studying the chemical composition (pigments, phenolics, volatile compounds) and biological activities (antioxidant and antimicrobial properties) of young and mature leaves of five eggplant cultivars (Solanum melongena L.) grown in Tunisia (Tizona, A1014, Nawel, A336, and Mirval). Pigment analysis showed no statistical variations between the two types of leaves, whereas higher levels of anthocyanins were recorded in young leaves of three out of five cultivars (24.7-52.8 mg 100 g^-1 ). Total phenolic compounds (966.5-2072.6 mg 100 g^-1 ) and o-diphenols (343.9-741.2 mg 100 g^-1 ) contents varied significantly according to leaf age and cultivar. However, no statistically significant variation between young and mature leaves was found in flavonols and tannins content. As for volatile profiles, 62 constituents were characterized with non-terpene derivatives (52.0-61.6 %) and apocarotenes (19.9-35.6 %) as major chemical classes. Regarding the antioxidant activity, methanol extracts of Tizona cultivar mature leaves displayed important antiradical properties using DPPH, ABTS, and phosphomolybdenum assays (IC₅₀ 0.1, 0.2 and 0.01 mg mL^-1 , respectively). With regards to reducing power determination, the most active extract was obtained from mature A1014 leaves. Further, young Mirval leaves proved to be significantly active from a bactericidal point of view against Candida albicans and Staphylococcus aureus of 3.1 mg mL^-1 and 0.2 mg mL^-1 MBC, respectively. In conclusion, eggplant leaves are a noteworthy source of antioxidant and antimicrobial compounds with potential use in the pharmaceutical, the cosmetics and the food industries.

Natural variation in specialised metabolites production in the leafy vegetable spider plant (Gynandropsis gynandra L. (Briq.)) in Africa and Asia

The improvement and promotion of leafy vegetables, used for both food and medicine, benefits greatly from detailed knowledge of their health-promoting specialised metabolites. In the present study, we investigated the global metabolite variation in the leaves of 48 accessions of the leafy vegetable Gynandropsis gynandra using two complementary analytical platforms: liquid-chromatography mass spectrometry (LC-MS) for an untargeted comparison of non-volatile semi-polar metabolites and gas-chromatography mass spectrometry (GC-MS) for an untargeted comparison of volatile metabolites. Our results revealed large variation in 936 semi-polar compounds including flavonoids, terpene glycosides, glucosinolates and various phenolic compounds. Unsupervised multivariate analysis indicated the variation in levels of the semi-polar metabolites was mainly driven by geography, with accessions from both West Africa and Asia forming a group clearly separated from East African accessions. Detected volatile metabolites included various sesquiterpenes, aldehydes, ketones, and sulphur-containing isothiocyanates. Variation in these compounds was however not geographically specific, but most likely linked to the taste and aroma of the leaves. The relative abundance in glucosinolates and isothiocyanates in the leaves allowed the clustering of accessions into two main groups that could be used for further plant-herbivore interaction studies. This study revealed both the broad spectrum of phytochemicals present in Gynandropsis gynandra leaves and the substantial variation in metabolite profiles among accessions from different regions of the world. Our results provide a basis for the development of breeding programs aiming at improving the levels of specialised metabolites in this tropical leafy vegetable for increased resistance against pests and diseases and improved human health.

What is food-to-food fortification? A working definition and framework for evaluation of efficiency and implementation of best practices

Food-to-food fortification (FtFF) is an emerging food-based strategy that can complement current strategies in the ongoing fight against micronutrient deficiencies, but it has not been defined or characterized. This review has proposed a working definition of FtFF. Comparison with other main food-based strategies clearly differentiates FtFF as an emerging strategy with the potential to address multiple micronutrient deficiencies simultaneously, with little dietary change required by consumers. A review of literature revealed that despite the limited number of studies (in vitro and in vivo), the diversity of food-based fortificants investigated and some contradictory data, there are promising fortificants, which have the potential to improve the amount of bioavailable iron, zinc, and provitamin A from starchy staple foods. These fortificants are typically fruits and vegetables, with high mineral as well as ascorbic acid and β-carotene contents. However, as the observed improvements in micronutrient bioavailability and status are relatively small, measuring the positive outcomes is more likely to be impactful only if the FtFF products are consumed as regular staples. Considering best practices in implementation of FtFF, raw material authentication and ingredient documentation are critical, especially as the contents of target micronutrients and bioavailability modulators as well as the microbiological quality of the plant-based fortificants can vary substantially. Also, as there are only few developed supply chains for plant-based fortificants, procurement of consistent materials may be problematic. This, however, provides the opportunity for value chain development, which can contribute towards the economic growth of communities, or hybrid approaches that leverage traditional premixes to standardize product micronutrient content.

Potential of food-to-food fortification with cowpea leaves and orange-fleshed sweet potato, in combination with conventional fortification, to improve the cellular uptake of iron and zinc from ready-to-eat maize porridges

An emerging tool in the fight against the high prevalence of micronutrient deficiencies in sub-Saharan Africa is the production of nutritionally enhanced staple food products, through food-to-food fortification with micronutrient-dense fruits and vegetables. This study investigated food-to-food fortification with cowpea leaves (CL) and orange-fleshed sweet potato (OFSP) in combination with conventional micronutrient fortification and fermentation on the mineral and antinutrient contents and Caco-2 cellular uptake of iron and zinc from ready-to-eat maize porridges. The amount of iron and zinc taken up from maize porridges (0.05 and 0.06 mg/100 g, db, respectively) was increased more after fortification with CL, compared to OFSP (0.32 and 0.23 mg/100 g, db versus. 0.11 and 0.04 mg/100 g, db, respectively). Despite the moderate cellular uptakes of iron and zinc from the CL fortified porridges (2.71% and 3.10%, respectively) compared to the OFSP fortified porridges (6.51% and 5.22%, respectively), the CL fortified porridges had much higher high iron and zinc contents (12.2-14.1 and 7.6-8.9 mg/100 g, db versus. 2.1-3.7 and 1.5-2.7 mg/100 g, db, respectively). This highlights the importance of increasing both the mineral content and bioavailability when fortifying a product. Even when a food product contains substantial antinutrients such as CL, if the mineral content and contents of bioavailability enhancers are high enough, the amounts of bioavailable iron and zinc can still be improved.

How Many Wild Edible Plants Do We Eat—Their Diversity, Use, and Implications for Sustainable Food System: An Exploratory Analysis in India

Wild edible plants are still eaten by a large section of the global population and ensure both affordable food and nutritional security. We tested this in an Indian context, where an enormous diversity of such plants constitutes a significant part of the rural diet and their acceptance has been high. In this study, we assessed the diversity of wild edible plant resource and the importance of species based on the use and its pattern. We have also shortlisted a set of plants to make an informed decision on prioritization. We found a great variety of plants (1,403 species) from 184 families were consumed across India, although the first 44 families (24%) contributed largely to the (75%) diversity. Leguminosae followed by Compositae, Poaceae, Malvaceae, and Rosaceae, were the families with the highest number of species. We note that a few species from the large pool were extensively used throughout the country while another few were valued for their multiple edible plant parts. Leafy shoots (722 species) followed by fruits (652 species) were the two most-eaten plant parts. Our results strengthen the fact that: (a) wild edibles have been an integral part of the diet; (b) their widespread assimilation into local food culture suggests an untapped potential to ensure easy availability and access to micronutrients for sustainable food systems, and thus in social welfare; and (c) they should be incorporated into the national food policy for formal cultivation and promotion.

Study of Edible Plants: Effects of Boiling on Nutritional, Antioxidant, and Physicochemical Properties

The consumption of vegetables in Mexico includes a wide variety of plants that grow naturally as weeds in the fields. The intake of these vegetables is very important in the Mexican diet because these plants supply an important input of nutrients and compounds such as fiber, vitamins, minerals, and antioxidants. Thus, the plants may be universally promoted as healthy. However, there is little information about these vegetables of popular consumption, especially in terms of the nutritional changes caused by boiling. To determine the influence of boiling on five plants of popular consumption in Mexico, the nutritional composition (proximal analysis, dietary fiber, and oxalates), antioxidant compounds (ascorbic acid, phenolics), antioxidant activity (measured by ABTS and DPPH assays), and physicochemical characteristics (water retention capacity, viscosity, color, and SEM) were evaluated. The boiling affected the nutritional composition of plants, mainly soluble compounds as carbohydrates (sugars and soluble fiber), ash, ascorbic acid, and phenolic compounds and caused changes in food hydration and color. Therefore, it is recommended that these plants be consumed raw or with short boiling times and included the cooking water in other preparations to take advantage of the nutrients released in the food matrix. In the future, to complete studies, 3 to 5 min of cooking should be considered to minimize undesirable modifications in terms of the vegetables' composition.

A Review of Indigenous Food Crops in Africa and the Implications for more Sustainable and Healthy Food Systems

Indigenous and traditional foods crops (ITFCs) have multiple uses within society, and most notably have an important role to play in the attempt to diversify the food in order to enhance food and nutrition security. However, research suggests that the benefits and value of indigenous foods within the South African and the African context have not been fully understood and synthesized. Their potential value to the African food system could be enhanced if their benefits were explored more comprehensively. This synthesis presents a literature review relating to underutilized indigenous crop species and foods in Africa. It organizes the findings into four main contributions, nutritional, environmental, economic, and social-cultural, in line with key themes of a sustainable food system framework. It also goes on to unpack the benefits and challenges associated with ITFCs under these themes. A major obstacle is that people are not valuing indigenous foods and the potential benefit that can be derived from using them is thus neglected. Furthermore, knowledge is being lost from one generation to the next, with potentially dire implications for long-term sustainable food security. The results show the need to recognize and enable indigenous foods as a key resource in ensuring healthy food systems in the African continent.

Drying of African leafy vegetables for their effective preservation: the difference in moisture sorption isotherms explained by their microstructure

The problem of malnutrition and nutrition deficiency, as well as droughts that lead to reduction in food supply and starvation, is well documented for Sub-Saharan Africa. Reducing post-harvest losses of five species of African leafy vegetables (ALVs) by preservation through drying is studied herein. Energy efficient gentle drying conditions using superabsorbent polymers and a temperature of 40 °C were shown to preserve most leaf structures and vitamins. The microbial safe moisture content of the ALVs was found to be ≤14% dry basis. Dried Slender Leaf and Nightshade leaves could be rehydrated to the equilibrium moisture content of fresh leaves upon dry storage, while it was not possible for Jute Mallow, Cowpea and Amaranthus. This was attributed to different palisade parenchyma cell lengths. An increased amount of starch granules as observed in the microstructure of Cowpea and Nightshade leaves is suggested to explain their fibrous texture upon cooking. These results show that the ALVs can be effectively preserved using the same drying method and that this can be used to fight micro-nutrient deficiencies during droughts.

Hydrothermally Treated Soybeans Can Enrich Maize Stiff Porridge (Africa's Main Staple) without Negating Sensory Acceptability

Maize-based stiff porridge, a starchy protein-deficient staple food, dominates among the populations in sub-Saharan Africa (SSA). Unfortunately, this is often consumed along with leafy vegetables since the majority of the population in this region lack resources for the purchase of high protein animal source foods, a situation that exacerbates protein-energy malnutrition. Considering this, the current study evaluated the effect of enriching maize-based stiff porridge with flour made from hydrothermally treated soybeans on consumer acceptability. A total of nine experimental flours were prepared from maize and maize-soybean mixtures following a 32 factorial design involving two factors, namely maize flour type (whole maize, non-soaked dehulled maize, and soaked dehulled maize) and soybean flour proportion (0%, 20%, and 30%). A total of 125 adult consumers from a rural setting in Malawi evaluated maize-based stiff porridges made thereof using a 7-point hedonic scale. Subsequently, the participants were asked to guess an ingredient that was added to some of the test samples. The 10% and 20% soybean-enriched maize-based stiff porridges scored 5/7 and above, with some being statistically similar to plain maize-based stiff porridges. No participant recognized that soybeans were incorporated into the maize-based stiff porridges. The study has clearly demonstrated the potential of enriching maize-based stiff porridge with hydrothermally treated soybeans without compromising consumer acceptability. This innovation could significantly contribute towards reducing the burden of energy-protein under-nutrition in SSA.

African Adansonia digitata fruit pulp (baobab) modifies provitamin A carotenoid bioaccessibility from composite pearl millet porridges

Food-to-food fortification of staple cereal products using nutrient-dense plants shows promise to address multiple micronutrient deficiencies including vitamin A, iron and zinc in Sub-Saharan Africa. However, there is limited information on the potential interaction effects that such food-to-food fortified strategies may have on individual micronutrient bioavailability. The main objective of the current study was to investigate the impact of incorporating Adansonia digitata (baobab fruit pulp), a mineral-rich plant material, on the delivery of carotenoids from a composite cereal porridge. Formulations of native fruit/vegetable-cereal composites were screened for interactions which could influence both bioaccessibility and subsequent intestinal uptake of provitamin A carotenoids. Proportions of pearl millet flour and plant materials were dry blended to provide composite cereal porridges with total provitamin A carotenoid concentrations ranging from 3590.7 ± 23.4 to 3698.5 ± 26.5 μg/100 g (fw) and baobab concentrations ranging from 0 to 25% (dw).While there were no significant differences in provitamin A carotenoid bioaccessibility from porridge formulations containing 5 or 15% baobab, inclusion of 25% baobab resulted in a significant (p < 0.05) decrease in bioaccessibility (13.3%) as compared to the control (23.8%). Despite the reduced bioaccessibility, 6 h uptake efficiency of provitamin A carotenoids by Caco-2 human intestinal cells was not significantly altered by 25% baobab inclusion. These findings suggest that the inhibitory effects on carotenoid micellarization (bioaccessibility) observed with increased baobab addition may not ultimately limit the bioavailability of carotenoids.

Edible Leafy Vegetables from West Africa (Guinea-Bissau): Consumption, Trade and Food Potential

Wild Edible Plants are common in the diet of rural communities of sub-Saharan Africa. In Guinea-Bissau, West Africa, wild plant resources are widely used in human diet, but very few studies have addressed them. The aim of this study is to reveal: (1) the wild and semi-cultivated leafy vegetables consumed in Guinea-Bissau; and (2) the nutritional composition of those plants traded at the largest country market in Bissau. Our results revealed that 24 native or naturalized species with edible leaves are currently consumed by Guinea-Bissau population. Five of them were found at the market: dried leaves of Adansonia digitata, Bombax costatum and Sesamum radiatum, and fresh leaves and shoots of Amaranthus hybridus and Hibiscus sabdariffa. The analysis of the nutritional properties revealed that leaves contain a significant amount of protein (10.1–21.0 g/100 g, dry basis), high values of macronutrients and micronutrients, as well as of phenolic compounds (13.1–40.3 mg GAE/g) and a considerable antioxidant capacity (DPPH 111.5–681.9 mg Eq Trolox). Although price and availability vary among the leafy vegetables analyzed, these traditional foods appear to be a good dietary component that can contribute to food security in Guinea-Bissau and in other West African countries, as these species are widely distributed in this region.

Association between vitamin content, plant morphology and geographical origin in a worldwide collection of the orphan crop Gynandropsis gynandra (Cleomaceae)

The variability in nutrient content and morphology in Gynandropsis gynandra is associated with the geographic origin of the accessions and provides a basis for breeding for higher levels of vitamin C, carotenoids or tocopherols in higher-yielding cultivars. We examined the variation in carotenoids, tocopherols and ascorbic acid as well as morphological traits in a worldwide germplasm of 76 accessions of the orphan leafy vegetable Gynandropsis gynandra (Cleomaceae) using greenhouse experiments and high-performance liquid chromatography analysis. The levels of carotenoids and tocopherols accumulating in the leaves varied significantly across accessions and were linked with the geographical origin and morphological variation. The main carotenoids included lutein, β-carotene, α-carotene and violaxanthin. A twofold to threefold variation was observed for these compounds. The main tocopherols detected were α-tocopherol and γ-tocopherol with a 20-fold variation. A ninefold variation in vitamin C concentration and independent of geographical origin was observed. Overall, the accessions were grouped into three clusters based on variation in nutrient content and morphology. West African accessions were short plants with small leaves and with high tocopherol contents and relatively low carotenoid contents, Asian accessions were short plants with broad leaves and with relatively low carotenoid and high tocopherol contents, while East-Southern African plants were tall with high contents of both carotenoids and chlorophylls and low tocopherol contents. Carotenoids were positively correlated with plant height as well as foliar and floral traits but negatively correlated with tocopherols. The absence of a significant correlation between vitamin C and other traits indicated that breeding for high carotenoids or tocopherols content may be coupled with improved leaf yield and vitamin C content. Our study provides baseline information on the natural variation available for traits of interest for breeding for enhanced crop yield and nutrient content in Gynandropsis gynandra.

Evaluation of nutritional value of Asystasia mysorensis and Sesamum angustifolia and their potential contribution to human health

Wild indigenous vegetables make considerable contributions to food baskets among subsistence farmers in sub-Saharan Africa. The aim of this study was to evaluate the proximate analysis, mineral composition, vitamin C content, β-carotene content, and GC-MS profile of crude methanolic extracts of Asystasia mysorensis and Sesamum angustifolia. Crude extracts obtained through sequential extraction using ethyl acetate and methanol were screened for the presence of secondary metabolites. Functional groups present were determined with a Shimadzu FT-IR spectrophotometer, while β-carotene content and ascorbic acid content were evaluated using a Shimadzu HPLC and Shimadzu UV-VIS spectrophotometer, respectively. Secondary metabolites present in the extracts were determined qualitatively using a Shimadzu GC-MS system equipped with a NIST spectral database. From the results obtained, the two plants could supply the recommended daily requirement for micronutrient and vitamin C content needed for a healthy diet. The total phenolic and flavonoid contents in S. amgustifolia were higher as compared to A. myorensis; hence, their consumption is highly beneficial as some compounds identified in the GC-MS profile have been reported to have medicinal properties. The findings on the mineral and chemical composition, GC-MS profile of A. mysorensis and S. angustifolia indicate that their consumption may provide the recommended nutritional requirements needed for a healthy diet.

Total phenolic content and antioxidant activity of methanolic extract of selected wild leafy vegetables grown in Bangladesh: A cheapest source of antioxidants

Nowadays, more attention has been paid on wild plants as new source of natural antioxidants. Therefore, methanolic extracts of 10 traditionally consumed wild leafy vegetables of Bangladesh were analyzed for their total phenolic content (TPC) and free radical scavenging activity. Folin–Ciocalteu method followed by spectrophotometric measurement was used to quantify the TPC of the selected wild leafy vegetables. Free radical scavenging activity was examined utilizing 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay. Different concentrations of the plant extract were applied to ascertain the dose response relationship in inhibiting DPPH free radical. The results revealed that the TPC ranged from 102.20 to 710.42 mg GAE/100g dry weight (DW). The highest TPC was observed in Bauhinia acuminata (Shetokanchan) while Leucas aspera (Shetodhron) exhibited the lowest TPC among the undertaken vegetables. The studied samples proportionately inhibited DPPH with increasing concentrations. At high concentration (500 µg.mL-1), the percentage inhibition of DPPH radical by plant extract ranged from 68.1 ±2.65 % to 93.1 ±1.23 %. The highest DPPH radical inhibition was observed in Bauhinia acuminata (Shetokanchan) (93.10 ±1.23 %), followed by Commelina benghalensis (Bat baittashak) (91.97 ±1.31 %), Hydrocotyle sibthorpiodes L. (Sakumubakla) (91.83 ±2.13 %). The lowest DPPH radical inhibition among the studied samples was observed in Leucas aspera (Shetodhron) (68.1 ±2.65 %). IC50 values measured by DPPH assay in this study ranged from 11.64 to 313.79 µg.mL-1. The study findings indicated that the samples under study possesses strong activity against DPPH, and thus could be used as natural antioxidants in the food and/or pharmaceutical industry.

Iron, Catechin, and Ferulic Acid Inhibit Cellular Uptake of β-Carotene by Reducing Micellization

Green leafy vegetables have low β-carotene bioavailability, which we hypothesized to be, at least in part, due to high contents of fiber, minerals, and phenolics. We investigated the effects of pectin (40-120 μg/mL), iron (50-150 μg/mL), ferulic acid (30-90 μg/mL), and catechin (50-150 μg/mL), in a model system, on β-carotene micellization (in vitro digestion) and intestinal absorption (Caco-2 cell model). Iron, pectin, ferulic acid, and catechin on average reduced ( p < 0.05) β-carotene micellization (1.49 ± 0.05 μmol/L) by 66.9, 59.3, 43.2, and 51.7%, respectively. Iron reduced micellization by precipitating bile salts from solution and ferulic acid and catechin by inhibition of pancreatic lipase. β-Carotene uptake by Caco-2 cells (2.63 ± 0.22%) was reduced ( p < 0.05) by 37.4, 70.1, 77.0, and 75.1%, respectively, when it was digested with pectin, iron, ferulic acid, or catechin. However, when individual test compounds were added to already micellized β-carotene, they did not inhibit β-carotene uptake. The large reductions in β-carotene micellization observed in vitro warrant further investigation in humans using model green leafy vegetable systems to elucidate their relevance under real-life conditions.

Duplicate portion sampling gives the most accurate iron intake estimate: Implications for iron status of female students

Iron deficiency (ID) is one of the most common nutritional problems in the developing world, affecting primarily women of childbearing age. Poor dietary iron intake is a major reason of ID. Accurate measurement of iron intake is of crucial importance to combat the problem. The daily dietary iron intake of 67 female students aged between 20-30 years (a mean BMI of 21.8±3.4 kg/m²) was evaluated using three assessment methods: atomic absorption spectrometry of 3-day food duplicate samples, and food composition tables (FCTs) in combination with either food frequency questionnaire (FFQ) or dietary records. Iron status was examined using hematological and biochemical tests. The dietary iron intake determined by duplicate portion sampling (DPS; 4.12±1.84 mg/day) was significantly lower than the FCT-based estimates (P<0.001), and it was less than ¼ of the recommended dietary allowance of 18 mg/day. No significant correlation was found between DPS technique and FCT-based assessment methods. Fifty percent of the participants had small or depleted iron stores (serum ferritin< 30 ng/mL), but only 4.5% had ID anemia (serum ferritin< 12 ng/mL and hemoglobin<12 g/dL). Dietary iron intakes and FFQ-based intakes of vitamin C were not significantly correlated with all the investigated hematological parameters. In order to take some steps toward more practical approaches to combat this health problem, development of an accurate iron intake assessment seems to be the first priority. In this regard, improvement and validation of national FCTs would be a promising solution.

[Effect of quinoa extract consumption on iron deficiency-induced anemia in mice]

OBJECTIVES

To determine the effect of quinoa extract consumption on iron deficiency-induced anemia in mice.

MATERIALS AND METHODS

Thirty male M. musculus albino mice of the Balb/c strain, with an average weight of 24±32.7 g, were used. Three groups of ten mice each were formed: 1) a negative control group of iron-sufficient (IS) mice that received 40g/d of balanced feed for 7 weeks; 2) a positive control group of iron-deficient (ID) mice that received 40g/d of feed rich in iron for 7 weeks; and 3) an experimental group of ID mice that received 40 g/d of feed rich in iron for 7 weeks and 20 g/d of quinoa extract (QE) from week 5. Hemoglobin levels were measured.

RESULTS

At the end of the treatment, a significant difference was found in hemoglobin levels between the positive (ID mice: 8.9±1.1 g/dL) and experimental (ID+QU mice: 11.4±0.5 g/dL) groups (student's t, p<0.05). No significant difference was found in hemoglobin levels at the end of the induction period between the positive (IS mice: 9.1±1.1) and experimental (ID mice: 9.3±0.7) groups (student's t, p>0.05).

CONCLUSIONS

Under experimental conditions, quinoa has an antianemic effect based on the results of hemoglobin levels.

Content of Iron and Vitamin A in Common Foods Given to Children 12⁻59 Months Old from North Western Tanzania and Central Uganda

Improving infant and young child feeding is an effective intervention to improve child growth. A cross-sectional study followed by observation of selected households was used to establish the most popular foods given to children 12⁻59 months old in Bukoba and Kiboga districts of Tanzania and Uganda, respectively. Six meals were identified: maize-based porridge, steamed-mashed banana served with beans, banana cooked with beans, banana cooked with groundnut sauce, stiff porridge (Ugali) served with beans and sardines, and cassava cooked with beans. Raw ingredients were transported to Universität für Bodenkultur, Austria, within 48 h and meals prepared following community validated procedures within 24 h by project team members that involved graduate students from East Africa and Europe. High-performance liquid chromatography (HPLC) analysis and microwave digestion followed by flame atomic absorption spectroscopy were used in establishing provitamin A carotenoids and iron content, respectively. Findings indicated no trace of vitamin A or iron in the maize-based porridge, whereas 2.28 mg/100 g ep (edible portion) and 1.18 mg/100 g ep of iron were recorded in stiff-porridge served with beans and sardines and banana cooked with beans, respectively. Banana-based foods had 23 to 43 vitamin A RAE (retinal activity equivalent) µg/100 g ep. With estimated average requirements of iron and vitamin A for children 1⁻3 years being 5 mg/day and 275 RAE µg/day, respectively, these foods are poor sources of these nutrients in their current form. Thus, there is a need to explore opportunities for modifying preparation methods and incorporating nutritious and diverse ingredients into the foods prepared for infants and young children in Eastern African countries.

Provitamin A Carotenoids, Tocopherols, Ascorbic Acid and Minerals in Indigenous Leafy Vegetables from Tanzania

The essential micronutrients in indigenous leafy vegetables (ILVs) could substantially contribute to the micronutrient supply in rural communities in Tanzania, but concentrations differ between species. Provitamin A carotenoids, tocopherols, ascorbic acid, minerals, and phytate were analysed in 13 different species using HPLC-, ICP-OES, and photometric techniques. Eight of the 13 ILVs, including Amaranthus ssp. and Sesamum angustifolium, had high β-carotene concentrations (2.91–4.84 mg/100 g fresh weight), which could provide ≥50% of vitamin A’s recommended nutrient intake (RNI). Six ILVs including Cleome hirta and Sonchus luxurians had high iron contents (34.5–60.4 mg/100 g, >50% RNI); Amaranthus ssp. represented the ILV with high calcium, magnesium and zinc contents (85%, 207% and 21% of RNI per 100 g); Cleome hirta and Cleome gynandra had high ascorbic acid contents (>15 mg/100 g, 34–35% of RNI), while Sesamum angustifolium was the only ILV with a high tocopherol content (7.34 mg α-TE/100 g). The highest phytate concentration was found in Amaranthus ssp., which could negatively affect its role as a very good source of minerals. Results indicate that the analysed ILVs could make a substantial contribution to the vitamin A and iron supply in the diets of rural Tanzanian populations.

Lycium europaeum Extract: A New Potential Antioxidant Source against Cisplatin-Induced Liver and Kidney Injuries in Mice

This study was designed to assess the protective effects of Lycium europaeum methanol extract (LEM) on liver and kidney injuries induced by cisplatin. The phytochemical composition, the antioxidant activity, and hepatorenal injury biomarkers were investigated. Results revealed that LEM exhibited a significant antioxidant activity in vitro on DPPH radical and H₂O₂ scavenging assays. In the animal studies, treatment with LEM significantly reduced the effects of cisplatin intoxication on serum liver biomarkers and serum renal biomarkers. Meanwhile, LEM diminishes significantly the effect of cisplatin on the level of lipid peroxidation in liver and kidney tissues. The activities of the antioxidant enzymes (reduced glutathione, glutathione peroxidase, superoxide dismutase, and catalase) were increased in groups pretreated with LEM and quercetin. Additionally, the normal histological structures of the liver and kidney were restored after treatment with LEM. This work clearly demonstrated that L. europaeum may be useful as a drug with hepato-nephroprotective potentials.

Consumption patterns of wild edibles by the Vasavas: a case study from Gujarat, India

BACKGROUND

Wild edibles continue to be a significant contributor to the global food basket in much of the developing world. A consensus has now been formed that information on wild edibles is an important part of ethnobotanical knowledge and hence elucidating region-specific patterns of habitat management and consumption assists policy making with regard to natural conservation, human nutrition, and human health. Using an original data set from Gujarat, India, the present research aims to document the collective knowledge of wild edibles possessed by the local Vasava tribe, as well as the habitat usage and consumption trends of these species.

METHODS

Data were collected using three approaches: key informant interviews to record the local knowledge of wild edibles and methods of collection, village group discussions to quantify past and present consumption trends, and expert interviews to elucidate the reasons for changing consumption patterns.

RESULTS

Through key informant interviews, 90 species of wild edibles from 46 botanical families were identified along with their Vasavi names, plant parts utilized, habitats, and cooking methods. Of these, 60 species were also used medicinally and 15 carried economic value. Different habitats were preferred for collection at different times of the year. Village group discussions unanimously concluded that the consumption of wild edibles has significantly reduced over time. Expert interviews identified the decreased availability of these species in their natural habitats as the most important reason for their reduced consumption.

CONCLUSION

The present study has demonstrated that the Vasavas' collective knowledge of wild edibles is vast and that these species contribute to their dietary diversity throughout the year. The finding of the present study, namely that anthropogenically managed habitats were often preferred over natural environments for the collection of wild edibles, suggests that conservation efforts should be extended beyond wild and human-uninhabited landscapes.

From lesser-known to super vegetables: the growing profile of African traditional leafy vegetables in promoting food security and wellness

There are hundreds of traditional leafy vegetables and wild food plants of horticultural and nutritional significance in Africa. These lesser-known crops and wild food plants that are highly adapted to harsh growing conditions thrive with little care and are available when other sources of food fail or are out of season. They are rich in micronutrients and are often the cheapest sources of many essential vitamins and minerals in many localities. Many of them are very important functional foods in African traditional diets and are rich in nutraceuticals, including polyphenols, tannins, flavonoids and flavonols, that exert demonstrable antioxidant, free radical scavenging and enzyme inhibition activities and have antimicrobial properties that provide scientific justification and possible mechanisms for their use in the management of a wide range of ailments, including diet-related, non-communicable diseases such as diabetes, hypertension and cardiovascular diseases. African traditional leafy vegetables are invaluable in promoting food security and wellness in Africa on account of their availability and affordability, their great nutritional value, chemotherapeutic and health-promoting properties and other unique qualities. Long recognised by the rural populace as quality food items, they are becoming more popular even with the more affluent urban elites. There is the need to develop improved management practices for these super vegetables to promote their cultivation and boost their exploitation for food security and wellness in Africa. © 2018 Society of Chemical Industry.

A comprehensive review on beneficial dietary phytochemicals in common traditional Southern African leafy vegetables

Regular intake of sufficient amounts of certain dietary phytochemicals was proven to reduce the incidence of noncommunicable chronic diseases and certain infectious diseases. In addition, dietary phytochemicals were also reported to reduce the incidence of metabolic disorders such as obesity in children and adults. However, limited information is available, especially on dietary phytochemicals in the commonly available traditional leafy vegetables. Primarily, the review summarizes information on the major phytochemicals and the impact of geographical location, genotype, agronomy practices, postharvest storage, and processing of common traditional leafy vegetables. The review also briefly discusses the bioavailability and accessibility of major phytochemicals, common antinutritive compounds of the selected vegetables, and recently developed traditional leafy vegetable-based food products for dietary diversification to improve the balanced diet for the consumers. The potential exists for better use of traditional leafy vegetables to sustain food security and to improve the health and well-being of humans.

A roadmap for breeding orphan leafy vegetable species: a case study of Gynandropsis gynandra (Cleomaceae)

Despite an increasing awareness of the potential of "orphan" or unimproved crops to contribute to food security and enhanced livelihoods for farmers, coordinated research agendas to facilitate production and use of orphan crops by local communities are generally lacking. We provide an overview of the current knowledge on leafy vegetables with a focus on Gynandropsis gynandra, a highly nutritious species used in Africa and Asia, and highlight general and species-specific guidelines for participatory, genomics-assisted breeding of orphan crops. Key steps in genome-enabled orphan leafy vegetables improvement are identified and discussed in the context of Gynandropsis gynandra breeding, including: (1) germplasm collection and management; (2) product target definition and refinement; (3) characterization of the genetic control of key traits; (4) design of the 'process' for cultivar development; (5) integration of genomic data to optimize that 'process'; (6) multi-environmental participatory testing and end-user evaluation; and (7) crop value chain development. The review discusses each step in detail, with emphasis on improving leaf yield, phytonutrient content, organoleptic quality, resistance to biotic and abiotic stresses and post-harvest management.

Determination of Mineral Constituents, Phytochemicals and Antioxidant Qualities of Cleome gynandra, Compared to Brassica oleracea and Beta vulgaris

The study compared mineral, chemical and antioxidant qualities of Cleome gynandra, a wild leafy vegetable, with two widely consumed commercial vegetables, Brassica oleracea and Beta vulgaris. Mineral nutrients were quantified with inductively coupled plasma mass spectrometry (ICP-MS), phenolic compounds using ultra-high performance liquid chromatography coupled to a mass spectrometer (UHPLC-MS) and β-carotene and vitamin C using high performance liquid chromatography with a photodiode array detector (HPLC-PDA). The antioxidant potential was evaluated using 2,2-diphenyl-1-picryl hydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. Cleome gynandra had highest concentrations of phosphorus, potassium, calcium, iron, zinc, ascorbic acid, total phenolics, and flavonoids; whereas sodium, magnesium, manganese, copper and β-carotene were higher for B. vulgaris. The significantly higher antioxidant activity (P ≤ 0.05) exhibited by C. gynandra in comparison to the two commercial vegetables may be due to its significantly high levels of vitamin C and phenolic acids. These findings on the mineral, chemical and antioxidant properties of C. gynandra provide compelling scientific evidence of its potential in adding diversity to the diet and contributing toward the daily nutritional requirements of millions of people for food and nutritional security.

Multivariate analysis as a key tool in chemotaxonomy of brinjal eggplant, African eggplants and wild related species

The brinjal eggplant (Solanum melongena L.) is an important vegetable species worldwide, while African eggplants (S. aethiopicum L., S. macrocarpon L.) are indigenous vegetable species of local significance. Taxonomy of eggplants and their wild relatives is complicated and still unclear. Hence, the objective of the study was to clarify taxonomic position of cultivars and landraces of brinjal, its wild relatives and African eggplant species and their wild ancestors using chemotaxonomic markers and multivariate analysis techniques for data processing, with special attention paid to the recognition of markers characteristic for each group of the plants. The total of 34 accessions belonging to 9 species from genus Solanum L. were used in the study. Chemotaxonomic analysis was based on the profiles of cuticular n-alkanes and methylalkanes, obtained using gas chromatography-mass spectrometry and gas chromatography with flame ionization detector. Standard hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used for the classification, while the latter and two-way HCA allowed to identify markers responsible for the clustering of the species. Cultivars, landraces and wild forms of S. melongena were practically identical in terms of their taxonomic position. The results confirmed high and statistically significant distinctiveness of all African eggplant species from the brinjal eggplant. The latter was characterized mostly by abundant long chain hydrocarbons in the range of 34-37 carbon atoms. The differences between both African eggplant species were, however, also statistically significant; S. aethiopicum displayed the highest contribution of 2-methylalkanes to the total cuticular hydrocarbons, while S. macrocarpon was characterized by elevated n-alkanes in the range of 25-32 carbon atoms. Wild ancestors of both African eggplant species were identical with their cultivated relatives. Concluding, high usefulness of the chemotaxonomic approach in classification of this important group of plants was confirmed.

Intercropping Induces Changes in Specific Secondary Metabolite Concentration in Ethiopian Kale (Brassica carinata) and African Nightshade (Solanum scabrum) under Controlled Conditions

Intercropping is widespread in small-holder farming systems in tropical regions and is also practiced in the cultivation of indigenous vegetables, to alleviate the multiple burdens of malnutrition. Due to interspecific competition and/or complementation between intercrops, intercropping may lead to changes in plants accumulation of minerals and secondary metabolites and hence, alter nutritional quality for consumers. Intercropping aims to intensify land productivity, while ensuring that nutritional quality is not compromised. This study aimed to investigate changes in minerals and secondary plant metabolites in intercropped Brassica carinata and Solanum scabrum, two important African indigenous vegetables, and evaluated the suitability of this combination for dryer areas. B. carinata and S. scabrum were grown for 6 weeks under controlled conditions in a greenhouse trial. Large rootboxes (8000 cm3 volume) were specifically designed for this experiment. Each rootbox was planted with two plants, either of the same plant species (mono) or one of each plant species (mixed). A quartz sand/soil substrate was used and fertilized adequately for optimal plant growth. During the last 4 weeks of the experiment, the plants were either supplied with optimal (65% WHC) or low (30% WHC) irrigation, to test the effect of a late-season drought. Intercropping increased total glucosinolate content in B. carinata, while maintaining biomass production and the contents of other health related minerals in both B. carinata and S. scabrum. Moreover, low irrigation led to an increase in carotene accumulation in both mono and intercropped S. scabrum, but not in B. carinata, while the majority of kaempferol glycosides and hydroxycinnamic acid derivatives of both species were decreased by intercropping and drought treatment. This study indicates that some health-related phytochemicals can be modified by intercropping or late-season drought, but field validation of these results is necessary before definite recommendation can be made to stakeholders.

Incorporating orange-fleshed sweet potato into the food system as a strategy for improved nutrition: The context of South Africa

Orange-fleshed sweet potato (OFSP) is considered the single most successful example of biofortification of a staple crop, and presents a feasible option to address vitamin A deficiency. Though initially promoted as part of a crop-based approach focusing on production and consumption at household level, it evolved into small-scale commercial production, predominantly in Sub-Saharan Africa. This paper reviews OFSP initiatives in relation to the South African food environment and food supply systems, also identifying opportunities for scaling out OFSP in a situation where sweet potato is not eaten as a staple. Current per capita consumption of sweet potato is low; the focus is thus on increasing consumption of OFSP, rather than replacing cream-fleshed varieties. For the major OFSP variety, Bophelo, 66g consumption can be sufficient to meet the recommended daily allowance for 1-3year old children (300μRE vitamin A). Despite a national Vitamin A supplementation programme and fortified staple foods in South Africa, 43.6% of children under 5years of age were reported to be vitamin A deficient in 2012, indicating a stronger need to promote the consumption of Vitamin A-rich foods, such as OFSP. To increase availability of and access to OFSP, all aspects of the food supply system need to be considered, including agricultural production, trade, food transformation and food retail and provisioning. Currently, small-scale commercial OFSP producers in South Africa prefer to deliver their produce to local informal markets. To enter the formal market, small-scale producers often have difficulties to meet the high standards of the retailers' centralised procurement system in terms of food quality, quantity and safety. Large retailers may have the power to increase the demand of OFSP, not just by improving availability but also by developing marketing strategies to raise awareness of the health benefits of OFSP. However, currently the largest scope for scaling out is through a number of public sector programmes such as the National School Nutrition Programme, Community Nutrition and Development Centres, Small-holder Farmer programmes and Agriparks. Though the major approach is focused on unprocessed, boiled OFSP, there are unexploited opportunities for processing of OFSP. However, the nutritional quality of products should be a main consideration within the context of the co-existence of undernutrition, overnutrition and micronutrient deficiencies in the country.

Status of Underutilised Crops in South Africa: Opportunities for Developing Research Capacity

Underutilised crops represent an important component of agro-biodiversity with potential to contribute to climate change adaptation, food security and sovereignty in poor rural areas. However, despite emerging research interest, they continue to occupy the peripheries of mainstream agriculture. There is a need to consolidate the gains made and propose a coherent strategy for translating underutilised crops into mainstream agriculture. The status of underutilised crops in South Africa (past, present and on-going research) was reviewed with a view to identifying existing gaps, opportunities and challenges for developing future research capacity. The review confirmed that several underutilised crops are drought tolerant, adapted to low levels of water use and thus suitable for cultivation in most marginal production areas typical of semi-arid and arid cropping systems. In addition, several are nutrient dense and could be used to improve dietary diversity among poor rural people. These characteristics make them ideal for inclusion in climate change adaptation and promotion of food sovereignty. There is need for a paradigm shift away from practices that have promoted a few major crops to an agro-ecology based land use classification system that recognises diversity and strengthens food networks. There is a need to identify those underutilised crops that show the greatest potential for success and can be fitted into semi-arid and arid cropping systems and prioritise them for future research, development and innovation.

Indigenous leafy vegetables of Eastern Africa - A source of extraordinary secondary plant metabolites

Indigenous African leafy vegetables vary enormously in their secondary plant metabolites whereat genus and the species have a great impact. In African nightshade (Solanum scabrum), spiderplant (Cleome gynandra), amaranth (Amaranthus cruentus), cowpea (Vigna unguiculata), Ethiopian kale (Brassica carinata) and common kale (Brassica oleracea) the specific secondary metabolite profile was elucidated and gained detailed data about carotenoids, chlorophylls, glucosinolates and phenolic compounds all having an appropriate contribution to health beneficial properties of indigenous African leafy vegetables. Exemplarily, various quercetin glycosides such as quercetin-3-rutinoside occur in high concentrations in African nightshade, spiderplant, and amaranth between ~1400-3300μg/g DW. Additionally the extraordinary hydroxycinnamic acid derivatives such as glucaric isomers and isocitric acid isomers are found especially in amaranth (up to ~1250μg/g DW) and spiderplant (up to 120μg/g DW). Carotenoids concentrations are high in amaranth (up to101.7μg/g DW) and spiderplants (up to 64.7μg/g DW) showing high concentrations of β-carotene, the pro-vitamin A. In contrast to the ubiquitous occurring phenolics and carotenoids, glucosinolates are only present in the Brassicales species Ethiopian kale, common kale and spiderplant characterized by diverse glucosinolate profiles. Generally, the consumption of a variety of these indigenous African leafy vegetables can be recommended to contribute to different benefits such as antioxidant activity, increase pro-vitamin A and anticancerogenic compounds in a healthy diet.

Children and Wild Foods in the Context of Deforestation in Rural Malawi

There is growing recognition of the contribution of wild foods to local diets, nutrition, and culture. Yet disaggregation of understanding of wild food use by gender and age is limited. We used a mixed methods approach to determine the types, frequencies, and perceptions of wild foods used and sold by children in four villages in southern Malawi that have different levels of deforestation. Household and individual dietary diversity scores are low at all sites. All households consume one or more wild foods. Across the four sites, children listed 119 wild foods, with a wider variety at the least deforested sites than the most deforested ones. Older children can name more wild foods than younger ones. More children from poor households sell wild foods than from well-off households. Several reasons were provided for the consumption or avoidance of wild foods (most commonly taste, contribution to health, limited alternatives, hunger, availability, local taboos).

Traditional African Foods and Their Potential to Contribute to Health and Nutrition

The nutritional state of large segments of the African population remains alarming despite the positive socio-economic development that is taking place. The most significant nutritional problems include undernutrition, iron deficiency and vitamin A deficiency. Malnutrition and deficiencies also exacerbate a number of other diseases and health conditions. Besides undernutrition, the prevalence of overnutrition and obesity on the African continent are rising, as are the associated health conditions such as diabetes and coronary heart diseases. This chapter outlines the unique nutritional and bioactive properties of Traditional African Foods (TAFs) and their potential to contribute to the alleviation of undernutrition, overnutrition and associated health problems. Special emphasis is placed on vegetables, fruits, cereals, edible insects, small fish species, mushrooms, legumes, sesame, tuber and root crops. Some of the identified health benefits of these TAFs include lowering of serum cholesterol, anti-carcinogenic, anti-diabetic and anti-inflammatory, cardiovascular disease prevention and anti-hypertensive properties.

The impact of dietary risk factors on the burden of non-communicable diseases in Ethiopia: findings from the Global Burden of Disease study 2013

BACKGROUND

The burden of non-communicable diseases (NCDs) has increased in sub-Saharan countries, including Ethiopia. The contribution of dietary behaviours to the NCD burden in Ethiopia has not been evaluated. This study, therefore, aimed to assess diet-related burden of disease in Ethiopia between 1990 and 2013.

METHOD

We used the 2013 Global Burden of Disease (GBD) data to estimate deaths, years of life lost (YLLs) and disability-adjusted life years (DALYs) related to eight food types, five nutrients and fibre intake. Dietary exposure was estimated using a Bayesian hierarchical meta-regression. The effect size of each diet-disease pair was obtained based on meta-analyses of prospective observational studies and randomized controlled trials. A comparative risk assessment approach was used to quantify the proportion of NCD burden associated with dietary risk factors.

RESULTS

In 2013, dietary factors were responsible for 60,402 deaths (95% Uncertainty Interval [UI]: 44,943-74,898) in Ethiopia-almost a quarter (23.0%) of all NCD deaths. Nearly nine in every ten diet-related deaths (88.0%) were from cardiovascular diseases (CVD) and 44.0% of all CVD deaths were related to poor diet. Suboptimal diet accounted for 1,353,407 DALYs (95% UI: 1,010,433-1,672,828) and 1,291,703 YLLs (95% UI: 961,915-1,599,985). Low intake of fruits and vegetables and high intake of sodium were the most important dietary factors. The proportion of NCD deaths associated with low fruit consumption slightly increased (11.3% in 1990 and 11.9% in 2013). In these years, the rate of burden of disease related to poor diet slightly decreased; however, their contribution to NCDs remained stable.

CONCLUSIONS

Dietary behaviour contributes significantly to the NCD burden in Ethiopia. Intakes of diet low in fruits and vegetables and high in sodium are the leading dietary risks. To effectively mitigate the oncoming NCD burden in Ethiopia, multisectoral interventions are required; and nutrition policies and dietary guidelines should be developed.