Inorganic nutrients and heavy metals in some wild edible plants consumed by rural communities in Northern Uganda: Implications for human health

For centuries, wild edible plant species have sustained local communities across Africa by supplementing households’ diets in seasons of food shortage. Wild edible plants contain inorganic nutrients, which are essential for the proper functioning of organisms. However, their nutritional contents have not been well researched and are generally poorly understood. This study aimed to quantify the levels of inorganic micro-and macronutrients as well as heavy metals (Mg, Ca, K, Fe, Zn, Cd, Hg and Pb) in selected wild edible plants traditionally consumed among the Acholi communities in northern Uganda, and associated health risks of consuming them. The leaves and young stems of 12 wild edible plants, viz: Acalypha rhomboidea, Asystacia gangetica, Crassocephalum sacrobasis, Crotalaria ochroleuca, Heterotis rotundifolia, Hibiscus cannabinus, Hibiscus sp., Hibiscus surattensis, Ipomoea eriocarpa, Maerua angolensis, Senna obtusifolia and Vigna membranacea were air-dried and crushed to powder. The powders were then macerated using aqua regia solution and analyzed in triplicates using the Atomic Absorption Spectrophotometry (AAS). The target hazard quotient (THQ) of Pb was calculated for non-carcinogenic health risks. Mg, Ca, K, Fe, Zn and Pb were detectable in all the wild edible plants sampled. All inorganic nutrients (mg/100gdw), were below the Recommended Daily Allowance (RDA); Mg (9.4 ± 0.19 to 10.4 ± 0.15), Ca (119 ± 5.82 to 1265 ± 14.9), Fe (3.29 ± 0.02 to 11.2 ± 0.09), Zn (0.52 ± 0.02 to 2.36 ± 0.03). Hg and Cd were below detectable limits in all the samples tested. The content of Pb (0.69 ± 0.11 to1.22 ± 0.07) was higher than the CODEX and EU limits of 0.1 ppm (0.001 mg/g) but was below the recommended threshold of 1. The health risk assessment revealed no potential hazards both in children and adults. However, there is a need to study the bioavailability of Pb when the vegetables are consumed due to factors such as indigestion and antinutritional compounds.