ABSTRACT
The study examined the nutrients and phytochemicals composition of some lesser – known vegetables in Nigeria (Mucuna pruriens and Phyllantus nuriri) and their effects on iron and beta carotene status of rats. Leaf extract was collected from each vegetable. The leaves were separately plucked, sorted and extraneous materials were removed. Then they were washed with deionized water and were pulverized to get the concentrates. Standard methods were used to determine the proximate, some minerals, and vitamins composition as well as phytochemical constituents of the extracts. Animal study was carried out to ascertain the bioavailabihty of these nutrients. Twenty male adult rats were used for the study. They were divided into four groups according to their body weights. The animals were housed individually in metabolic cages. The rats were fed standard rat chow. The extracts were made to provide 0.11 mg/day iron to the rats. The study lasted for twenty eight days. The rat study showed that feeding rats with rat chow supplemented with Mucuna pruriens and Phyllantus nuriri extract improved the hemoglobin levels. Mucuna pruriens contained 11.47% carbohydrates, 3.20% protein, 1.25% ash and 3.82% crude fibre, while Phyllantus nuriri contained 15.47% carbohydrate, 3.87% protein, 3.02% ash and 3.20% crude fibre. The vegetables had significant quantities of calcium (23.45mg and 34.71mg), iron (7.45mg and 11.27mg), Vitamin C (26.16mg and 20.13mg/100mg), vitamin E (3.06mg and 3.62mg) and 3 – carotene (3.62 and 3.65mg) per l00g sample. Anti – nutrients and toxicant levels of the vegetables were low. Mucuna pruriens had 0.004mg phytate and 0.62mg oxalate while Phyllantus nuriri had 1.28mg phytate and 1.31 mg oxalate. Phytochemicals were present in these vegetables. Mucuna pruriens contained 0.003% alkaloids, 0.54% tannins, 7.01% saponins, 3.16% flavonoids, 12.47% cyanogenic glycosides and 1.06% phenols. Phyllantus nuriri had 1.68% alkaloids, 0.68% tannins, 3.95% saponins, 6.22% flavonoids, 1.17% cyanogenic glycosides and 0.21% phenols. The hemoglobin level for Phyllantus nuriri group was 23.73%, while the Mucuna pruriens group was 16.57%. The serum iron, red blood cell count and beta – carotene levels of rats were significantly improved. The recommendations are that the consumption of these vegetables could be useful in addressing some micronutrients and diet – related non – communicable diseases because of their rich and micronutrient and phytochemical constituents. Nutrition educators should use the information from this study to counsel families on the consumption of these lesser – known vegetables. Students should also be assisted to carryout the same study on humans to see the nutritional effect. Organoleptic evaluation of these vegetables should be carried out to evaluate acceptability.
CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Green leafy vegetables constitute an indispensable constituent of human diet, especially in local delicacies. It is estimated that over 60 species of green leafy vegetables are used as food. Apart from the well-known and easily cultivated green leafy vegetables serving as sources of micronutrients, several wild and ornamental plants are traditionally ‘important supplement sources of food nutrients. They are used for various purposes ranging from food for man and animals, to therapeutic and manure for plants. Some of the vegetables are underutilized.
Seasonality partly precipitates micronutrient deficiency, especially during off-season when green leafy vegetables are unavailable. The anti-nutrient content of vegetables, limit the availability of micronutrient present in the vegetables. The issue of micronutrient deficiencies and their consequences on health, learning capability and productivity of affected people constitute a major public health problem globally and is of increasing prominence in Nigeria. The current rate of micronutrient deficiency is 24% among mothers and 48% among pregnant women in Nigeria (FMOH, 2006). There have been several attempts by Nutritionists the world over to proffer adequate solutions to this problem. Part of the efforts is to document the nutrient composition of some green leafy vegetables, which still grow as wild crop or semi-wild crop or unpopular vegetables in many areas in Nigeria ecosystem, which could contribute to the micronutrient intake of the populace.
Mucuna pruriens leaves and Phyllanthus nuriri leaves are unpopular vegetables in Nigeria. Mucuna is a leguminous plant (NAS, 1979). A number of species are available in Nigeria for example M. utilis (“Agbara-orji ”), M. Flagellipes-(“ukpo’), M Sloanie (“ukpa ’). The leaf of Mucuna pruriens is commonly known as “agbara nkita” among the Ibos of Eastern Nigeria. The leaves of mucuna are used as medicine or for therapeutic purposes. In the local communities, these leaves are used for the treatment of anaemia (Ezekwesili, 2005).
Phyllanthus nuriri leaf is another wild vegetable, which comes under the botanical family called Euphorbiaceae. The most common species of this family in most West African nations are Phyllanthus amaru and Phyllanthus nuriri popularly called “chancea piedra” in many parts of the world. Among the Ibos of eastern Nigeria it is called “okwonwa”. In the local communities, it is used in the treatment of anaemia and malaria (Uzoma, 2004).
1.2 Statement of the Problem
Micronutrient deficiencies and their consequences on health, learning capabilities and productivity of affected people constitute a major problem of public health globally. The problems are of increasing prominence in Nigeria. The deficiencies affect children, pregnant and lactating mothers, and the general populace including adolescents. Green leafy vegetables are rich sources of micronutrients. Little or no information exists in literature for some unpopular, wild or semi-wild vegetables that moderately survive during off seasons. Changes in food habits in Nigeria have greatly affected consumption of local vegetables. Urbanization and globalization have not helped matters either. Many people in different communities do not consume some of the indigenous vegetables due to ignorance of their nutrients composition. Consumption of some vegetables has been known to be associated with poverty.
Based on these observed facts, there is the need to evaluate the nutrients composition of wild, semi-wild and unpopular vegetables used by some communities for therapeutic purposes. The result of the evaluation may shed light to the micronutrients and the possible phytochemicals that are responsible for the therapeutic actions. The vegetables could be integrated into family meals to address micronutrient problems and their therapeutic uses could be scientifically explored. Since animal food sources of micronutrients are more expensive, there is need to identify those foods that will enhance household food security and improve micronutrient status of the populace. Iron found in vegetables are in a form that is not easily absorbed unless taken with enhancers or processed in a way it will be made available. Biological study on the vegetables with rats will provide evidence – based information on their use for treatment of anaemia.
1.3 General objective of the study
The general objective of this study was to determine the nutrients, anti – nutrients and phytochemicals composition of Mucuna pruriens and Phyllantus nuriri leaves and their effects on iron and beta carotene status of rats.
1.4 Specific objectives
The specific objectives of the study were to:
- Determine the levels of some nutrients and anti – nutrients contained in Mucuna pruriens and Phyllanthus nuriri leaves.
- Determine the levels of some phytochemicals in Mucuna pruriens and Phyllanthus nuriri leaves.
- Determine the effects of the leaf extracts on iron and beta carotene status of rats.
1.5 Significance of the Study
The nutrient composition of the vegetables has not been adequately documented. It is hoped that the result of this study would provide information on the nutrient composition of these vegetables commonly used for therapeutic purposes. The result would serve as baseline information for Nutritionists, Dieticians and Community Health workers to promote the consumption of these lesser-known vegetables if found adequate. The result could also spur interest on other less utilized vegetables that are locally available with a view to using them fill the micronutrient gap that is experience globally.
The study hopefully would generate interest on Mucuna pruriens and Phyllantus nuriri leaves as wild vegetables that could be consumed during off-season to help address micronutrient deficiency in Nigeria.
The result would provide evidence based information on the use of vegetables for treatment of anaemia.
