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Mineral content of traditional leafy vegetables from western Kenya
F. O. Orech a; D. L. Christensen b; T. Larsen c; H. Friis d; J. Aagaard-Hansen e; B. A. Estambale f a Center for Food Science and Technology, University of Maryland Eastern Shore, Princess Anne, Maryland, USA b Department of Epidemiology, Institute of Public Health, University of Copenhagen, Copenhagen N, Denmark c Danish Institute of Agricultural Sciences, Foulum, Tjele, Denmark d Department of Human Nutrition, University of Copenhagen, Frederiksberg, Denmark e DBL - Institute for Health Research and Development, Charlottenlund, Denmark f Institute of Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya First Published on: 05 June 2007 To cite this Article: Orech, F. O., Christensen, D. L., Larsen, T., Friis, H., Aagaard-Hansen, J. and Estambale, B. A. (2007) 'Mineral content of traditional leafy vegetables from western Kenya', International Journal of Food Sciences and Nutrition, 58:8, 595 - 602 To link to this article: DOI: 10.1080/09637480701350288 URL: http://dx.doi.org/10.1080/09637480701350288
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International Journal of Food Sciences and Nutrition, December 2007; 58(8): 595602
Mineral content of traditional leafy vegetables from western Kenya
F. O. ORECH1, D. L. CHRISTENSEN2, T. LARSEN3, H. FRIIS4, J. AAGAARD-HANSEN5 & B. A. ESTAMBALE6 1
Center for Food Science and Technology, University of Maryland Eastern Shore, Princess Anne, Maryland, USA, 2Department of Epidemiology, Institute of Public Health, University of Copenhagen, Copenhagen N, Denmark, 3Danish Institute of Agricultural Sciences, Foulum, Tjele, Denmark, 4Department of Human Nutrition, University of Copenhagen, Frederiksberg, Denmark, 5DBL*Institute for Health Research and Development, Charlottenlund, Denmark, and 6Institute of Tropical and Infectious Diseases, University of Nairobi, Nairobi, Kenya
Abstract Socio-economic changes that have taken place in Africa have influenced people’s eating habits in both rural and urban set-ups. Most people prefer introduced foods to traditional foods, including plant foods whose consumption is widely regarded as a primitive culture manifesting poor lifestyles. However, recent studies on traditional plant foods have shown that some are highly nutritious; containing high levels of both vitamins and minerals. They also have potential as a remedy to counter food insecurity since most are well adapted to the local environment, enabling them to resist pests, drought and diseases. This paper describes the mineral (calcium, iron and zinc) contents in some 54 traditional vegetable species collected from Nyang’oma area of Bondo district, western Kenya. Atomic absorption spectroscopy was used to determine the mineral content. We found that most traditional leafy vegetables, domesticated and wild, generally contain higher levels of calcium, iron and zinc compared with the introduced varieties such as spinach (Spanacia oleracea), kale (Brassica oleracea var. acephala) and cabbage (Brassica oleracea var. capitata). The results of this study could contribute towards identification, propagation and subsequent domestication and cultivation promotion of nutrient-rich and safe species within the farming systems of the local communities in Kenya, sub-Saharan Africa or elsewhere.
Keywords: Traditional leafy vegetables, calcium, iron, zinc, kenya
Introduction The agricultural revolution that began more than 10,000 years ago created a dramatic shift in the human food supply and resulted in a significant reduction in dietary diversity (Grivetti 1976, 1978, 1981; Grivetti and Ogle 2000). In Kenya, traditional leafy vegetables are notably the most important group of wild plants consumed in the western region and constitute the cheapest sources of macronutrients and micronutrients, especially providing vitamins (A, B and C), minerals (calcium, iron, fluorine, magnesium, phosphorus, potassium, sodium and zinc), dietary fibre and
Correspondence: F. O. Orech, center for Food Science and Technology, University of Maryland Eastern Shore, Princess Anne, MD, 21853, USA. E-mail:
[email protected] or
[email protected] ISSN 0963-7486 print/ISSN 1465-3478 online # 2007 Informa UK Ltd DOI: 10.1080/09637480701350288
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protein (Johns and Kokwaro 1991; Mwajumwa et al. 1991; Humphry et al. 1993; Nordeide et al. 1996; Uiso and Johns 1996; Mathenge 1997; Shackleton et al. 1998; Maundu et al. 1999a, b). Some species are also used in treatment of different ailments (Geissler et al. 2002; Olsen and Nielson 1999). However, few data are available on the nutrient and toxin composition of many indigenous plant foods, including traditional leafy vegetables (Uiso and Johns 1996). According to the World Health Organization (2000), mineral deficiencies are widespread in developing countries. Calcium deficiency is associated with weak bones and teeth, cardiovascular diseases, diabetes, hypertensive disorders of pregnancy, obesity and cancer of the colon. Iron deficiency may cause anaemia, which can reduce work capacity and resistance to fatigue. In pregnant women, iron-deficiency anaemia is associated with an increased risk of maternal mortality, foetal growth retardation, premature births, low birth weight and high susceptibility to infections, and even mortality. Zinc deficiency causes growth retardation or failure in the foetus, infants and adolescents and can also cause diarrhea, skin and eye lesions, delayed sexual maturation and behavioural changes. This paper explores the mineral content of a spectrum of both domesticated and wild traditional leafy vegetables commonly consumed by the Luo people living in western Kenya. The Luo live along the shores of Lake Victoria and are among the largest communities in Kenya, estimated to number about 3 million. Their main occupation is fishing and subsistence farming; with maize, sorghum, millet, and cassava as staple crops. They also keep goats, sheep, cows, poultry and sometimes donkeys for rural transport. The main rainfall season is between February and June but there is usually a shorter period of rain in October and November. The Lake Victoria basin receives an average annual rainfall of 7501,000 mm. The population is far from prosperous and is consequently vulnerable to drought periods and a decline in agricultural produce together with cash income (Ogoye-Ndegwa et al. 2003). Therefore, traditional leafy vegetables, most of which are procured from the wild, may play a very crucial role of providing macronutrients and micronutrients and also serve as remedy to reduce food insecurity in the area, in addition to providing the poor, especially women, with financial income. The aims of this study were to assess the calcium, iron and zinc contents of traditional leafy vegetables, and compare them with the introduced varieties such as spinach. Methods Collection of the vegetable ethnoflora from different sites Based on a list of 72 Luo names of traditional leafy vegetables compiled by OgoyeNdegwa et al. (2002), plant specimens commonly consumed in Bondo district, western Kenya were collected from different ecological sites. Elderly women, believed to be the custodians of knowledge on identification, preparation and use of traditional leafy vegetables, willingly helped in plant collection. According to Martin (1995), the plants were first photographed in their natural habitats and the herbarium specimens prepared in triplicate, photographed, and labelled with vernacular/botanical names, a collection number and the names of collectors. The specimens were spread in newspapers (about 30 cm 40 cm) when folded and placed in a plant press and into a plant dryer at the Nyang’oma Research
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Training Site for 5 days. The plants were then prepared for deposition at the University of Nairobi and East Africa Herbaria. Verification of the traditional leafy vegetable species collected was according to Agnew and Agnew (1994), Terry and Michieka (1987) and the Flora of Tropical East Africa Orech et al. (2005). Collection, treatment and storage of samples for nutritional analysis Fresh leaf samples of 500 g were collected, weighed precisely and air-dried while avoiding direct sunlight. The dried samples were stored, and later ground and analysed for calcium, iron and zinc. Mineral analyses The prepared plant specimens were put in black plastic bags, which were labelled with details regarding weight and a number identifying the plants, and these were analysed for calcium, iron and zinc, which were measured by atomic absorption spectrophotometry (PU 9400 X; Phillips Scientific, Cambridge, UK). The samples (0.5 g) were dry-ashed in silica crucibles at 5258C for 6 h; ashes were dissolved in hot dilute hydrochloric/nitric acid (pro analysis/Suprapur). Atomic absorption spectrophotometry measurements were calibrated on commercial standards (Tritisol; E. Merck, Darmstadt, Germany). Relative standard deviations for the determination ranged within 0.4% (calcium), 1.3% (iron) and 0.6% (zinc) (n 40). Standard curves were controlled by independently produced chloride solutions of the respective metals Larsen et al. (2003). Results The study showed that both domesticated and wild traditional leafy vegetables have potential as sources of calcium, iron and zinc. A total of 54 species of traditional leafy vegetables were collected for nutritional analyses; of these, 19 species (Table I), were domesticated in farmlands and kitchen gardens, and 35 species were wild (Table II). Seventeen vegetable species exhibited relatively high concentrations of the essential minerals investigated. The vegetable species with the highest concentration of calcium were Erucastrum arabicum (722 mg/g), Colocasia esculenta (649 mg/g), Sida rhombifolia (610 mg/g), Erythrococca bongensis (600 mg/g), Tribulus terrestris (583 mg/g), Vigna schimperi (487 mg/ g), Justicia calyculata (416 mg/g), Cucurbita maxima (394 mg/g) and Vigna luteola (379 mg/g), respectively. The traditional vegetables with the highest concentration of iron were Portulaca quadrifida (373.6 mg/g), Gynandropsis gynandra (202.4 mg/g), E. arabicum (103.9 mg/g), Commelina africana (73.3 mg/g), Asystasia mysorensis (63.5 mg/g), Bidens pilosa (40.4 mg/ g), S. rhombifolia (39.0 mg/g) and Talinum portulacifolium (35.6 mg/g), respectively. The traditional leafy vegetables with the highest values of zinc concentration were E. arabicum (7.45 mg/g), T. terrestris (3.17 mg/g), S. rhombifolia (2.38 mg/g), Manihot esculenta (2.30 mg/g), G. gynandra (2.28 mg/g), J. calyculata (1.66 mg/g), P. quadrifida (1.62 mg/g), Brassica juncea (1.19 mg/g) and Ludwigia stolonifera (1.11 mg/g), respectively.
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Table I. Concentration of calcium, iron and zinc in 19 domesticated traditional leafy vegetable species.
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Name Amaranthus hybridus L. A. lividus L. subsp. polygonoides (Moq.) Probst. A. spinosus L. Brassica juncea (L.) Czern. Capsicum frutescens L. Carica papaya L. Chenopodium opulifolium Schrad. ex. Koch. & Ziz Colocasia esculenta (L.) Schott. Corchorus olitorius L. Crotalaria ochroleuca G. Don. Cucurbita maxima Duchesne ex. Lam Gynandropsis gynandra (L.) Briq. Lycopersicon esculentum Mill. Ipomoea batatas (L.) Lam. Phaseolus vulgaris L. Sesamum indicum Solanum nigrum L. Vigna unguiculata (L.) Walp. Manihot esculenta Crantz.
Luo name
Calcium (mg/g)
Iron (mg/g)
Zinc (mg/g)
Ododo Mayom Osoi, Soi
381 119
17.2 6.5
0.63 0.31
Ododo mar Kudho Kandhira It Pilu Pilu It Kipoyo Nyatigatiga
223 270 152 301 151
2.7 6.1 11.4 8.7 2.7
0.23 1.19 0.43 0.39 0.59
Nduma Apoth Madongo Mitoo Madongo Susa Akeyo or Dek It Nyanya It Rabuon It Oganda Nyim Osuga Boo It Omuogo
649 157 132 394 309 180 98 119 161 199 85 228
5.4 20 4.9 15.2 202.4 2.9 5.8 0.3 9.1 20.7 5.2 3.3
0.64 0.46 0.49 0.59 2.28 0.37 0.25 0.26 0.27 0.88 0.24 2.3
Note: Mineral concentrations are reported on a mg/g fresh weight basis.
The median calcium content was 180 (interquartile range [IQR] 132301) in domesticated vegetables and 186 (IQR 129318) in the wild species. For iron, the median content was 6.1 (IQR 3.315.2) among domesticated plants, but 19.5 (IQR 5.937.7) in the wild plants (P 0.01). Among the domesticated vegetables, G. gynandra (202.4 mg/g), along with other vegetables like Solanum nigrum, Corchorus olitorius, Amaranthus hybridus, C. maxima and Capsicum frutescens, contained reasonably high levels of iron. Among the wild traditional leafy vegetables, the iron content was higher compared with the domesticated species and the vegetables P. quadrifida and E. arabicum contained exceptionally high levels of iron (373.6 mg/g and 103.9 mg/g, respectively). The median zinc content was 0.46 (IQR, 0.270.64) in domesticated traditional leafy vegetables, and 0.68 (IQR, 0.510.98) in the wild vegetable species. Among domesticated plants, the highest level was found in A. hybridus, B. juncea, Chenopodium opulifolium, C. olitorius, Crotalaria ochroleuca, C. maxima, G. gynandra, M. esculenta and S. nigrum. Three wild plants*namely, E. arabicum, S. rhombifolia and T. terrestris*had levels above 2 mg/g, but the highest was 7.45 mg/g found in E. arabicum. The leaves of cultivated A. hybridus, B. juncea, G. gynandra, S. nigrum and wild Achyranthes aspera, Asystasia gangetica, E. arabicum, J. calyculata, L. stolonifera, P. quadrifida, S. rhombifolia and T. terrestris possessed high levels of calcium, iron and zinc, indicating that they have possible significance in the provision of micronutrients in the diet of people living in the Nyang’oma area.
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Mineral content of Kenyan traditional leafy vegetables Table II. Concentration of calcium, iron and zinc in 35 wild traditional leafy vegetable species.
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Name Achyranthes aspera L. Amaranthus graecizans L. subsp. silvestris (Vill.) Brenan* Aspilia kotschyi (Sch. Bip. ex Hochst.) Oliv. Asystasia gangetica (L.) T. Anderson A. mysorensis T. Anderson Basella alba L. Bidens pilosa L. Boerhavia diffusa L. Cleome hirta (Klotzsch) Oliv. Coccinia grandis (L.) Voigt Commelina africana L. C. benghalensis Wall. Cyphostemma cyphopetalum (Fresen.) Wild & R.B. Drumm Erucastrum arabicum Fisch. & C.A. Mey Erythrococca bongensis Pax. Ipomoea sinensis (Desr.) Choisy subsp. sinensis Justicia calyculata Deflers Lagascea molis Cav. Launaea cornuta (Hochst. Ex Oliv. & Hiern) C. Jeffrey Ludwigia stolonifera Brenan. Oxalis latifolia kunth Oxygonum sinuatum (Meisn.) Dammer Penterhinum inspidum E. Mey Physalis minima L. Portulaca quadrifida L. Polygonum senegalense Meisn. Senna occidentalis L. Sesamum calycimum Welw. var. angustifolium (Oliv.) Ihlenf. & Siedenst. Sida acuta Burm. F. S. rhombifolia L. Talinum portulacifolium (Forssk.) Asch. ex Schweinf Tribulus terrestris L. Trichodesma zeylanicum (Burm. F.) R. Br. Vigna luteola var. luteola (Jacq.) Benth V. schimperi Baker.
Luo name
Calcium (mg/g)
Iron (mg/g)
Zinc (mg/g)
Ayucha, Tungu Ombok Alika
332 167
30.8 5.9
0.46 0.35
Nyamand Dhiang’ Nyohonyoho Atipa Nderma Onyiego Obudo Nyadeg Dani Nyamit Kuru Kalapuk Angayo, Nyandhodho Bwombwe Matindo
247 120 318 27 217 239 153 186 147 178 165
26.4 36.7 63.5 1.2 40.4 19.2 15.7 1.7 73.3 4.8 5.3
0.62 1.30 0.53 0.08 0.80 0.38 0.68 0.25 0.93 0.52 0.70
Kabich Samba Hariadho Nyawend Agwata Piu Piu Branget Achak
722 600 86 415 145 107
103.9 19.5 57.5 37.7 10.6 11.3
7.45 0.84 0.55 1.66 1.00 0.56
Nyasgumba Awayo Nyatie Gweno Okuuro Nyatonglo Obwanda Aurao Nyayado Onyulo
198 101 191 231 50 156 260 88 129
34.8 23.6 47.6 26.3 17.3 373.6 7.7 4.5 26.2
1.11 0.41 0.77 0.74 0.62 1.62 0.98 0.23 0.68
Adongo Nyar Yuora Owich Amondi
190 610 118
11.2 39.0 35.6
0.78 2.38 0.82
Okuro Nyalak Dede Boo Dhok Dindi, Lesoriadore
583 174 379 487
3.2 3.2 6.8 3.9
3.17 0.51 0.65 0.26
Note: Mineral concentrations are reported on a mg/g fresh weight basis.
Discussion Domesticated and wild vegetables play a role in livelihoods in providing an improved diet in terms of nutritional value and diversity, and in supplementing the food needs of poorer households, as well as at times of famine. They also provide opportunities for income generation. The study in Nyang’oma shows that there are a large number of locally available wild plants that contribute to the local diet. These vegetables are predominantly used to supplement relish in meals and they have been established to contain significant nutritional value.
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While the iron content of spinach (Spinacia oleracea) found in most parts of Africa is known to be 0.0017 mg/100 g edible portion (Food and Agriculture Organization 2004), the values observed in this study were higher for both the domesticated and wild traditional leafy vegetables. Studies by Kinabo et al. (2004) reported contents of zinc in S. nigrum to be 0.57 mg/100 g edible portion, results far lower than the levels found in most domesticated and wild traditional leafy vegetables in this study (Tables I and II). Other studies by Ogle and Grivetti (1985) showed values of zinc in Amaranth and S. nigrum grown in Swaziland to be 1.2090.44 mg/100 g and 1.3490.45 mg/100 g, respectively. However, the results shown in this study are of fresh air-dried plant materials. Therefore, there is a possibility that, when cooked, the mineral composition in most species may be lowered depending on the methods used for preparation. The wild vegetables from the Nyang’oma area comprise 65% of the 54 species collected and identified from varied ecological habitats, which included scrubs, thickets, riverines and lakeshores located within and around the villages. Since different ecological habitats possess specific soil types and each species possesses its own mineral uptake capability, as described in other studies by Ogle and Grivetti (1985) and Raja et al. (1997), the study has shown these variations through the diverse calcium, iron and zinc compositions in different vegetable species growing in different habitats in the same area. Traditional leafy vegetables therefore are important in improving health, elevating household food security and increasing household income among women; hence, necessary actions are needed to promote their production and consumption both in rural and urban areas of sub-Saharan countries or elsewhere. Presently, their nutritional and economic advantages are not widely recognized by many people (Smith et al. 1996). However, the bioavailability of the high nutrient compositions should be further investigated since antinutrients such as oxalates and glucosinolates may be present in some species and thus reduce nutrient uptake after consumption. Conclusion Local people should benefit nutritionally from these vegetables, and efforts to identify and analyse them for their nutritional and toxic potential should be a priority. Traditional leafy vegetables’ mineral bioavailability determination is vital since not all minerals are available in a form absorbable by humans. It is hoped, therefore, that bioavailability studies may be conducted in the near future.
Acknowledgements The authors acknowledge the DBL*Institute for Health Research and Development sponsorship of the project and Mrs Dorte Agnholt of the Danish Institute of Agricultural Sciences for assisting in the mineral analysis. They also thank the outstanding work of the field assistant Miss Perez Ochwal and of Mr Simon Mathenge, the plant taxonomist at the University of Nairobi Herbarium, who aided in plant verification. The authors also appreciate the cooperation of the respondents who fully participated in the project.
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References Agnew ADQ, Agnew A. 1994. Upland Kenya wild flowers. 2nd ed. Nairobi: East Africa Natural History Society. Food and Agriculture Organization. 2004. Tables of food composition for use in Africa. FAO and US Department of Health. Available online at: www.fao.org/docrep/003/x6877E/x6877E01.htm (accessed 17 February 2007). Geissler PW, Harris SA, Prince RJ, Olsen A, Odhiambo RA, Oketch-Rabah H, Madiega PA, Anderson A, Mølgaard P. 2002. Medicinal plants used by Luo mothers and children in Bondo District, Kenya. J Ethnopharmacol 83:3954. Grivetti LE. 1976. Dietary resources and social aspects of food use in a Tswana tribe. PhD Thesis, University of California: USA. Grivetti LE. 1978. Nutritional success in semi-arid land. Examination of Twana agro-pastoralists of the Eastern Kalahari, Botswana. Am J Clin Nutr 31:12041220. Grivetti LE. 1981. Cultural nutrition. Anthropology and geographical themes. Annu Rev Nutr 1:4768. Grivetti LE, Ogle BM.. 2000. Value of traditional foods in meeting macro- and micronutrient needs: the wild plant connection. Nutr Res Rev 13:3146. Humphry CM, Clegg MS, Keen CL, Grivetti LE. 1993. Food diversity and drought survival. The Hausa example. Int J Food Sci Nutr 44:116. Johns T, Kokwaro JO. 1991. Food plants of the Luo of Siaya district, Kenya. Econ Bot 45(1):103113. Kinabo J, Mukeni A, Nyaruhucha CNM, Msuya J, Ishengoma J. 2004. Nutrient content of foods commonly consumed in Iringa and Morogoro regions. Proceedings of the 2nd Collaborative Research Workshop on Food Security. TARP II SUA Project, Morogoro, 2830 May 2003. Larsen T, Thilsted HS, Biswas SK, Tetens I. 2003. The leafy vegetable amaranth (Amaranthus gangeticus) is a potent inhibitor of calcium availability and retention in rice-based diets. Br J Nutr 90:521527. Martin GJ. 1995. Ethnobotany: a people and plants conservation manual. London: Chapman and Hall. Mathenge L. 1997. Nutrition value and utilization of indigenous vegetables in Kenya. In Guarino L, editor. Traditional African vegetables. Proceedings of the IPGRI International workshop on Genetic Resources of Traditional Vegetables in Africa: Conservation and Use, ICRAF-HQ, Nairobi, 2931 August 1995. Rome: Institute of Plant Genetic and Crop Plant Research. pp 7677. Maundu PM, Ngugi GW, Kabuye CHS. 1999a. Traditional food plants of Kenya. Nairobi: Kenya Resources Centre for Indigenous Knowledge (KENRIK), National Museums of Kenya. pp 1258. Maundu PM, Njiro EI, Chweya JA, Imungi JK, Seme EN. 1999b. The biodiversity of traditional vegetables: Kenya. In: Chweya JA, Eyzaguirre PB, (editors). The biodiversity of traditional vegetables. Rome: International Plant Genetic Resource Institute (IPGRI). pp 5383. Mwajumwa LBS, Kahangi EM, Imungi JK. 1991. The prevalence and nutritional value of some Kenyan indigenous leafy vegetables from three locations of Machakos District. Ecol Food Nutr 26:275280. Nordeide MB, Hatløy A, Følling M, Lied E, Oshaug A. 1996. Nutrient composition and nutritional importance of green leaves and wild foods in an agricultural district, Koutiala, in Southern Mali. Int J Food Sci Nutr 47:455468. Ogle BM, Grivetti LE. 1985. Legacy of the chameleon. Edible wild plants in the Kingdom of Swaziland, South Africa. A cultural, ecological, nutrition study. Part IV*nutritional analyses and conclusion. Ecol Food Nutr 17:4164. Ogoye-Ndegwa C, Aagaard-Hansen J. 2003. Traditional gathering of wild vegetables among the Luo of western Kenya-a nutritional anthropology project. J Ecol Food Nutr 42:6989. Ogoye-Ndegwa C, Abudho D, Aagaard-Hansen J. 2002. ‘New learning in old organizations’: children’s participation in a school-based nutrition project in western Kenya. Develop Practice 12(3&4):449460. Olsen A. & Nielsen B. S. (1999). Undersogelser af lægeplanter benyttet af Luo folker I Kenya [Investigations of medicinal plants used by the Luo of Kenya]. Dissertation, Royal Danish School of Pharmacy, Denmark (in Danish). Orech FO, Akenga T, Ochora J, Friis H, Aagaard-Hansen J. (2005). Potential Toxicity of Some Traditional Leafy Vegetables Consumed in Nyang’oma Division, Western Kenya. Africa Journal of Food, Agriculture, Nutrition and Development. Rural Outreach Program. Vol. 5, Number 1. http: www.bioline.org.br/request?nd05014. Accessed 19/4/2007 Raja TK, Othman OC, Bahemuka TE. 1997. Levels of crude protein and some inorganic elements in selected green vegetables of Dar es Salaam. J Food Sci Technol 34(5):419422. Shackleton SE, Dzerefos CM, Shackleton CM, Mathabela FR. 1998. Use and trading of wild edible herbs in central lowveld savannah region, South Africa. Econ Bot 52:251259.
Downloaded By: [Orech, F. O.] At: 15:46 13 November 2007
602
F. O. Orech et al.
Smith GC, Clegg MS, Keen CL, Grivetti LE. 1996. Mineral content of selected plant foods common to Southern Burkina Faso and to Niamey, Niger, West Africa. Int J Food Sci Nutr 47:4153. Terry PJ, Michieka RW. 1987. Common weeds of East Africa/Magugu ya Afrika Mashariki. Rome: Food and Agriculture Organization of the United Nations. pp 1168. Uiso FC, Johns T. 1996. Consumption patterns and nutritional contribution of Crotalaria brevidens (Mitoo) in Tarime District, Tanzania. Ecol Food Nutr 35:5969. World Health Organization. 2000. Available online at: http://www.who.int/nut/#mic (accessed 17 February 2007).
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