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Quantitative analysis of nitrate and nitrite contents in vegetables commonly consumed in Delta State, Nigeria

Published online by Cambridge University Press:  08 March 2007

I. Onyesom  and
P. N. Okoh
I. Onyesom*
Affiliation:
Department of Biochemistry, PO Box 144, Delta State University, Abraka, Nigeria
P. N. Okoh
Affiliation:
Department of Biochemistry, PO Box 144, Delta State University, Abraka, Nigeria
*
*Corresponding author: Dr I. Onyesom, email [email protected]
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Abstract

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Plasma thiocyanate has been reported to be high among cassava-eating populations such as that in Nigeria because of the cyanide content of cassava. Thiocyanate, which is secreted into the stomach contents of animals, has been demonstrated to catalyse the formation of nitrosamines (potent carcinogens) in the stomach from secondary amines and nitrite. The main source of the nitrite precursor in this environment is vegetables, primarily eaten as the chief supplier of proteins. The present study attempts to analyse the levels of nitrate and nitrite in vegetables commonly grown and consumed in Delta State, Nigeria. The nitrate and nitrite contents in green vegetable (Amaranthus spp.), bitter leaf (Vernonia amygdalina), pumpkin (Telfaria occidentalis) and water leaf (Talinum triangulare) grown in different localities of the state were determined by standard analytical procedures. The results show that those vegetables grown in the industrialised urban centres of the state had higher nitrate (223 (sd 71) mg/kg dry weight; P<0·05) and nitrite (12·6 (sd 1·7) mg/kg dry weight; P>0·05) levels when compared with the same species (188 (sd 77) mg nitrate/kg dry weight and 10·9 (sd 1·1) mg nitrite/kg dry weight) cultivated in less industrialised suburbs. We conclude that frequent consumption of such vegetables whose nitrate and nitrite contents are high by cassava-eating individuals might put them at risk of developing stomach cancer and other possible results of nitrate and/or nitrite toxicity. In order to avoid an outbreak in our communities, appropriate agencies should monitor and regulate the release of chemicals into the environment. In the meantime, the cultivation and consumption of vegetables grown in industrialised areas of the state should be discouraged.

Keywords

ThiocyanateVegetablesNitratesCassavaNitrites
Type
Research Article
Information
British Journal of Nutrition , Volume 96 , Issue 5 , November 2006 , pp. 902 - 905
Copyright
Copyright © The Nutrition Society 2006

References

Armijo, R, Gonzalez, A, Orellana, M, Coulson, AH, Sayre, JW & Detels, R (1981) Epidemiology of gastric cancer in Chile: nitrate exposure and stomach cancer frequency. Int J Epidemiol 10, 57–58.CrossRefGoogle ScholarPubMed
Association of Official Analytical Chemists (1975) Official Methods of Analysis, 13th ed., pp. 653–664. Benjamin Franklin Station, DC: Association of Official Analytical Chemists.Google Scholar
Atawodi, SE, Maduagwu, EN, Preussmann, R & Spiegelhalder, B (1991) Potential of endogenous formation of volatile nitrosamines from Nigerian vegetables and spices. Cancer Lett 57, 219–222.CrossRefGoogle ScholarPubMed
Bassett, J, Denney, CR, Jeffery, HG & Mendham, J (1986) Vogel's Textbook of Quantitative Inorganic Analysis, 4th ed. London: ELBS/Longman.Google Scholar
Beatson, CG (1978) Methaemoglobinaemia – nitrates in drinking water. Environ Health 86, 31–33.Google Scholar
Boyland, E & Walker, SA (1974) Effect of thiocyanate on nitrosation of amines. Nature 284, 601–602.CrossRefGoogle Scholar
Corre, WJ & Breimer, T (1979) Nitrate and Nitrite in Vegetables. Wageningen, The Netherlands: Centre for Agricultural Publishing and Documentation.Google Scholar
Dutt, MC, Lim, HY & Chew, RKH (1987) Nitrate consumption and the incidence of cancer in Singapore. Food Chem Toxicol 25, 515–518.CrossRefGoogle ScholarPubMed
Dykhuizen, N & Leifert, C (1996) Antimicrobial effect of acidified nitrite on gut pathogens: importance of dietary nitrate in host defence. Antimicrob Agents Chemotherap 40, 1422–1425.CrossRefGoogle Scholar
Eminedoki, DG, Monanu, MO & Anosike, EO (1994) Thiocyanate levels of mainly dietary origin in serum and urine from a human population sample in Port Harcourt, Nigeria. Plant Foods Hum Nutr 46, 277–285.CrossRefGoogle ScholarPubMed
Grunderson, DJ (1981) Effect of nitrogen fertilizer on nitrate contents of field vegetables. J Sci Food Agric (Camb) 37, 373–383.Google Scholar
Hartman, PE (1983) Review: Putative mutagens and carcinogenesis in foods – nitrate/nitrite ingestion and gastric cancer mortality. Environ Mutagens 5, 111–121.CrossRefGoogle Scholar
Iwegbue, CMA (2005) Heavy metals and physiochemistry of soils, sediments and surface water of crude oil impacted area in the Niger Delta. M. Phil Thesis, Rivers State University of Science and Technology, Port Harcourt, Nigeria, pp. 198.Google Scholar
Janzowkski, C & Eisenbrand, G (1995) Aspects to be considered for risk assessment concerning endogenously formed N-nitroso compounds. In Health Aspects of Nitrate and its Metabolites (Particularly Nitrite), Proceedings of the International Workshop, Bilthoven, Netherlands, 8–10 November 1994, pp. 313–330. Strasbourg: Council of Europe Press.Google Scholar
Lijinsky, W & Epstein, SS (1970) Nitrosamines as environmental carcinogens. Nature 225, 21–23.CrossRefGoogle ScholarPubMed
Lijinsky, W, Taylor, HW, Snyder, C & Nettesheim, P (1973) Malignant tumours of liver and lung in rat fed aminopyrine or heptamethyleneimine, together with nitrite. Nature 244, 176–178.CrossRefGoogle ScholarPubMed
Maduagwu, EN & Umoh, IB (1988) Dietary thiocyanate and N-nitrosation in vivo in Wistrar rats. Ann Nutr Metab 32, 30–37.CrossRefGoogle Scholar
Miroslav, R & Vladimir, BN (1999) Practical Environmental Analysis. Cambridge, UK: Royal Society of Chemistry.Google Scholar
Mirvish, SS (1983) The etiology of gastric cancer, intra-gastric nitrosamide formation and other theories. J Natl Cancer Inst 71, 630–636.Google Scholar
Okoh, PN (1984) An assessment of the protein, mineral and vitamins losses in sun-dried Nigerian vegetables. Nutr Rep Int 29, 359–364.Google Scholar
Okoh, PN (1992) The metabolic fate of cyanide in animals. Nig J Physiol Sci 8, 1–9.Google Scholar
Okoh, PN, Ikediobi, CO & Olugboji, O (1988) The fate in the rate of ingested dhurrin present in malted sorghum grain. Food Chem 29, 299–301.CrossRefGoogle Scholar
Okonkwo, PO, Nwokolo, C & Onwuamaeze, CI (1981) Dietary nitrate and carcinogenesis in the Nigerian environment. Nig J Nutr Sci 2, 9–13.Google Scholar
Risch, HA, Jain, M, Choi, NW, Fodor, JG, Pfeiffer, CJ, Howe, GR, Harrison, LW, Craib, KJP & Miller, AB (1985) Dietary factors and the incidence of cancer of the stomach. Am J Epidemiol 122, 947–949.CrossRefGoogle ScholarPubMed
Walker, R (1990) Nitrates, nitrites and N-nitroso compounds: a review of the occurrence in food and diet and the toxicological implications. Food Addict Contam 7, 717–768.CrossRefGoogle Scholar
Zhu, L, Gunn, C & Beckman, JS (1992) Bacterial activity of peroxynitrite. Arch Biochem Biophys 295, 452–454.CrossRefGoogle Scholar