Fruits are good sources of vitamins, minerals, antioxidants and dietary fibre require for normal metabolic activity of the body. Despite these enormous nutritional potential, fruits also bioaccumulates some antinutrients and toxic substances that may have harmful effects on health at high concentrations. Thus, the research was conducted to evaluate the antinutrients and toxic substances (oxalate, phytate, nitrate and cyanide) in some fruits sold in Lapai, Nigeria. The oxalate and pytate contents were analysed by titrimetric method while cyanide and nitrate were determined by Colourimetric method. Ten different fruits namely, Daucus carota (carrot), Cucumis sativus (cucumber), Citrullus lanatus (water melon), Musa acuminate (banana), Carica papaya (pawpaw) Abelmoschus esculetus (okra), Capsicum frutescens (hot pepper), Lycopersicon esculentum (tomatoes) Capsicum annuum (bell pepper) and Solanum melongena (garden egg) were used for the study. The results showed that the concentrations of nitrate, phytate and cyanide in the fruits are within the tolerable levels and can be well accommodated in our body except that the concentration of cyanide in C. lanatus (405.7 ± 21.78 mg/kg) is higher than the acceptable level of 200 mg/kg fresh weight. Similarly, the concentration of oxalate in the fruits was above the tolerable level and may cause nutritional problems. The study suggests that though fruits are generally consumed fresh in order to maximise their eminent nutritional potential, we should be mindful of the phytotoxin contents and their attendant health problems at high concentrations.
Key words: Fruits, Nitrate, Cyanide, Oxalate, Phytate and Phytotoxins
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