Comparison between conventional and organic agriculture in terms of nutritional quality of food - a critical review

The consumption of organic foods has been increasing over the last decades and organic products are becoming more visible on the market. Consumers perceive that organic foods are of better quality, more nutritious and healthier, and these perceptions are some of the main drivers of the organic market. Scientific research on organic foodstuffs is contradictory, and knowledge regarding the effect of cultivation system on the nutritive value and the possible relationship with human health could be further explored. Although some systematic differences in the nutritional content, i.e. nitrogen, protein, vitamin C, phosphorous and phenolic compounds of plant products grown under different cultivation systems have been observed, it is a difficult task to prove the claim that organic food improves human well-being or health after consumption. The aim of this review is to give an overview of the research on nutritional quality of food, comparing conventional and organic agriculture; i.e. the nutrient content of plant products and livestock products, digestibility or bioavailability of the nutrients, preference and the potential health effects after consumption. We established a systematic approach for the identification of components and nutrients that can affect human health, and considered different models (animal and human) in which the potential health effects had been tested. In addition, we found it essential to identify suitable health-related biomarkers as measures for nutritive quality. Reviewing the existing scientific literature on potential relationships between agricultural practice and health, nutritional factors such as vitamin E/antioxidant status and the fatty acid composition appear to be interesting in relation to cultivation systems effect on health. It was concluded that while agricultural practice (i.e. organic and conventional) together with other factors, such as year, location and genotype had an effect on the nutritional quality of the foods, no clear effect could be established on health-related biomarkers.