Nutritional assessment of selected leafy vegetables

Abstract

Brassica oleracea L. var acephala (leaf cabbage) commonly known as „Chomoullier‟ and Brassica napus L. (leaf „rape‟) are traditional leafy vegetables widely grown in Kenya (East Africa) and Zimbabwe (southern Africa). Urtica urens on the other hand, is a wild leafy vegetable consumed in rural communities of South Africa. A comparative study of the nutritional compositions of the leaves of these vegetable species was carried out. The results showed that the three species were high in moisture, carbohydrate and energy contents. The levels of ash, crude protein and crude fibre in U. urens were consistently higher than those of the two Brassica species. Moreover the crude lipid contents of the Brassica species (6.32% for B. napus and 7.94 for B. oleracea L. var acephala respectively) were significantly higher (P < 0.05) than that of U. urens (1.10%). U. urens was superior in all the micronutrients. Consumption of foods like U. urens that is rich in micronutrients could help in building a strong immune system, thereby helping the body to absorb, utilize and digest nutrients. The significantly higher level of iron in U. urens implies that consumption of this wild vegetable may increase the blood level and may therefore be recommended for anemic patients. In addition, because the cultivation of both Brassica species investigated in this study is not affected by season; hence, large scale production of these vegetables should be encouraged in order to make it available to all. U. urens on the other hand; being a wild vegetable can close the nutritional gap for those that are economically challenged. However, U. urens should be steamed or cooked before ingestion to destroy the stinging hairs.