Heavy Metals and Proximate Composition of Forest Leafy Vegetables in Oil Producing Area of Nigeria

Abstract

This work investigated heavy metals content of Forest Leafy Vegetables (FLVs) consumed in Port Harcourt, Nigeria. Fresh samples of eight commonly consumed FLV species were obtained from two major markets in Port Harcourt. FLVs were dried, digested and analysed with flame Atomic Absorption Spectrophotometer (AAS) for heavy metals.  Proximate analysis of FLVs was carried out using standard method of AOAC. Concentrations of Iron (Fe) ranged from 4.69ppm (Heinsia crinata) - 8.97ppm (Gongronema latifolia), Manganese was highest in Liasanthera africana (6.03ppm) and lowest in O.gratissimum (0.45ppm) while Magnesium levels ranged from 0.609 – 1.630ppm. P.guineense accumulate highest Pb (1.004ppm) compared to Ocimum basilicum Pb (0.380ppm). Copper was highest in H.crinata (1.165ppm) and lowest in O.gratissimum (0.218ppm). O. gratissimum had lowest Cadmium (0.022ppm), Arsenic (0.003ppm), Mercury (0.002ppm) and Zinc (0.044ppm). P.guineense contains highest concentration of Chromium (3.792ppm) while H. crinata possess the lowest (0.409ppm). Nickel was highest in O.bassilicum (0.665ppm) and least in G.latifolia (0.388ppm). FLVs were rich in crude protein, fat and crude fibre. O.bassilicum (21.00%) was the richest in crude protein while H.crinata has the lowest level (11.55%). Crude fibre content of the FLVs range from 11.0% to 14.0% while fat content varied between 2.4% for O. bassilicum and 4.0% for H. crinata. FLVs sourced from natural forests in crude oil exploration areas in Nigeria is safe for consumption, since heavy metals of FLVs samples were less than maximum limits recommended by FAO/WHO.  Proximate analyses showed that the FLVs possess useful nutritional contents required for healthy growth.

Key Words: Forest leafy vegetables, Heavy metals, Proximate composition, Nigeria