The Nitrate Content of Vegetable and Salad Crops Offered to the Consumer as from “Organic” or “Conventional” Production Systems

Abstract

This paper briefly reviews the source and extent of ingested nitrates in the human diet. In response to the possible health risk, several countries in Europe have set maximum and/ or recommended concentrations of tissue nitrate in vegetables and salad crops. The consequence of adopting such limits in Great Britain is considered.In order to assess the range of nitrate concentrations in vegetables and salad crops, a market survey was conducted over two winters (1985 and 1986) with samples being taken from commercial outlets. Food offered as conventionally and organically produced was sampled. Samples of both organically and conventionally produced leafy winter vegetables contained high nitrate levels, some exceeding recommended and maximum levels in certain European countries. Various approaches to the minimisation of the dietary intake of nitrate are discussed.

Quality of organically and conventionally grown potatoes: Four-year study of micronutrients, metals, secondary metabolites, enzymic browning and organoleptic properties

“…The observation that organic potatoes contain significantly lower levels of nitrate than conventionally produced tubers are in agreement with findings from several other controlled field experiments and farm surveys (Guziur et al 2000;Rembialkowska 1999;Schuphan 1974;Stopes et al 1988;Š torková-Turnerová and Prugar 1988), and are conceivably related to the lower nitrogen input in organic farming (Rembialkowska 1999). A similar trend, i.e., lower nitrates in organically grown tubers, was documented in a three-year study concerned with evaluation of several factors including the way of cultivation on the composition of seven potato varieties grown in Czech Republic.…”

Nitrate and nitrite content in organically cultivated vegetables

“…Conversely, Nilsson (1979) found higher nitrate levels in organic cabbages than in those fertilized with soluble NPK, whereas Ahonen et al (1987) and Stopes et al (1988) did not obtain significant differences between conventional and organic cabbages.…”

Nutritional quality and safety of organic food. A review

“…In the human diet, about 80% of nitrates are provided by vegetables, while nitrate levels in fruits, cereals and legumes are very low (French Inventaire National de la Qualité Alimentaire, 1982;Stopes et al, 1988;Cornée et al, 1992). Animal products contain very low levels of nitrates while processed meat can contain added nitrites as a preservative.…”

“…Because the habitual average level of nitrate intake is in the range 120-280 mg/d (French Inventaire National de la Qualité Alimentaire, 1982;Cornée et al, 1992;Stopes et al, 1988) and close to the maximum daily dose defined by the FAO/OMS JECFA (i.e. 220 mg/60 kg person), and a marked increase in vegetable and fruit consumption is widely recommended (WHO, 2004;PNNS, 2001), organic vegetables can make this recommended increase safer regarding the nitrate issue.…”