Organic nutrition becomes increasingly popular. Surveys reveal that consumers buy organic products because they expect these to be healthier than conventionally produced products. Is this mysticism or is there a scientific basis for this expectation? If so, this could be of interest to the medical profession. Research can be divided into studies on nutrient content and studies of health effects in consuming organisms. More than 100 studies have made the comparison between nutrient content in organically and conventionally grown products. On average these studies provide findings that organically grown products can be different from conventionally grown products, in that they have higher levels of dry matter, more anti-oxidants, higher or equal amounts of vitamin C and minerals, and a comparable or better protein quality. In dairy, higher amounts of ‘healthy’ fatty acids (e.g. CLAs and omega-3 fatty acids) are often measured in organic produce. Furthermore, less contaminants such as pesticide residues, in most cases lower or equal amounts of nitrate and often lower or equal amounts of mycotoxins, have been described. However, results from such studies can only speculatively be connected to health effects. Less research has been performed, studying actual effects of organic food on physiological processes in consuming organisms. However, in the studies available, interesting results came out. Some recent results are as follows: • In vitro studies: A study in damaged bacteria showed stronger DNA-repair on organic vegetable juices than on conventional juices. In an experiment with cancer cell lines, organic fruit juice reduced cell proliferation compared to conventional juice. • Animal research: Several feeding experiments in animals show an effect on weight gain, as well as on the immune system. Recently the biggest study until now, in the Netherlands, showed that organically fed chicken had a ‘more alert’ immune system and a stronger ‘catch up growth’ after a challenge. These animals also had a lower body weight. Similar results were found in rats in Denmark and in mice in Italy. • In humans: In a prospective cohort study among 2800 children in the Netherlands (KOALA), investigating the relation of life style factors and allergic complaints, a 33% reduction of eczema was found connected to the use of organic dairy products at the age of 2 years. The mothers in this study, who used organic dairy, had a higher amount of CLAs in the breast milk. It is hypothesized that organic nutrition ‘stabilizes’ the physiology of organisms and increases the ‘resilience’. This would implicate a promising role of organic nutrition in prevention and health promotion. It is clear that more research is needed to confirm these observations in the future.