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The present study aims to explore and compare consumer perception and scientific evidence related to food quality and food safety aspects of organic versus conventional vegetables.

Primary data on consumer perception were gathered in 2006‐2007 through a consumer survey with Flemish adults (n=529) and compared with scientific evidence from literature. Consumers of organic and conventional vegetables were selected by means of a convenience sampling procedure. Subjects were asked to complete a self‐administered questionnaire concerning the perception of the nutritional and toxicological value of organic relative to conventional vegetables. Data processing and analysis included descriptive analysis (frequency distributions), data reduction (Cronbach's alpha test, factor analysis), bivariate analysis (correlations, t‐test, ANOVA) and multivariate analysis (stepwise multiple regression).

It was found that organic vegetables are perceived as containing less contaminants and more nutrients, and as such, being healthier and safer compared to conventional vegetables. However, not enough evidence is currently available in the literature to support or refute such a perception, indicating a certain mismatch between consumer perception and scientific evidence. The gap between perception and evidence is larger among older consumers with children. The perception is stronger when the consumption frequency is higher, but is independent of gender, place of residence (rural or urban), education and income level. Also non‐users, on average, perceive that organic vegetables have a nutritional and toxicological advantage over conventional vegetables.

A non‐probability convenience sampling method was applied which limits generalisation of the findings beyond the sample characteristics.

This paper is original in comparing consumer perception and scientific facts related to both nutritional and safety aspects of organic versus conventional vegetables.

The increasing demand for organic foods is explained mainly by consumers' concerns about the quality and safety of foods and their perception that organically produced foods are healthier and safer than conventional foods. Based on internationally available concentration data of organic and conventional vegetables (carrots, tomatoes, lettuce and spinach) and potatoes, the paper aims to investigate the scientific validity of nutrition claims as “no vegetable/potato has higher amounts of nutrient X than organic vegetables/potatoes” and “no vegetable/potato has lower amounts of contaminant Y than organic vegetables/potatoes”.

Detailed nutrient and contaminant databases were developed for organic and conventional vegetables separately. Non‐parametric (Mann‐Whitney test) methods were used to detect significant differences between both types of vegetables. A chi‐square test was used to compare the incidence of pesticide residues in organic and conventional vegetables.

From a nutritional and toxicological point of view, organic vegetables and potato in general are not significantly better than conventional vegetables and potatoes. For some nutrients and contaminants organic vegetables and potatoes score significantly better but for others they score significantly worse. Therefore, it becomes difficult to justify general claims indicating a surplus value of organic over conventional vegetables and potatoes. More data from controlled paired studies are needed to reconsider the use of claims for these organic plant foods in the future.

Only a limited number of studies comparing the nutrient and/or contaminant concentration of organic and conventional vegetables are available (“paired studies”). Additionally, the majority of the studies are of moderate or poor quality. The implication is that more of those paired studies are heavily needed. Another limitation of the study is the fact that most pesticide residue data originated from the USA, the EU and Australia.

So far only few studies compared both nutrient and contaminant contents between organic and conventional plant foods. This paper covers therefore an important, not well‐explored research sub area.