Health and immune responses in a rat model after intake of organically or conventionally grown foods

Summary

The consumption of organic foods has been increasing during the last decade and organic products are becoming more visible on the market. Consumer perceptions of organic foods being of better quality, more nutritious and healthier are some of the main reasons driving the organic market. Scientific research on organic foodstuffs is very contradictory and conclusive research on possible impact on human and animal health is lacking. The definition of health and potential biomarkers of health is also debated heavily. One aspect is the fact that the immune system can be modulated by nutrients and that the immunological defense system is imprinted during gestation and the early lifespan. So optimization of plant-derived food by cultivation system could be a very cost effective method or disease prevention, since diet-induced healthimprovements would carry no costs for the health sector. The objective of this PhD thesis is to study if the intake of diets produced of crops from well-controlled field experiments leads to differences in biomarkers characterizing health and well-being using a rat model. Furthermore, the hypothesis that the intake of organically produced diets during pregnancy and lactation/suckling can affect the immunological status and function of both the mothers and the offspring is also investigated. To investigate the potential health effects of eating organic foods, it was decided to follow the whole food chain from field to fork, using a rat model for measuring the potential health benefits. Food products were obtained from continuing field studies and two long-term feeding studies with rats were performed to study the influence of cultivation system, year, and location on the nutritional composition of the crops and healthrelated biomarkers. The results from these two studies are presented in Paper I and Paper II. A single food item, carrots was used in Paper I and it was found that nitrate and protein in carrots was affected by cultivation system, while the measured health biomarkers in rats were not affected. In Paper II complete diets were used and it was found that cultivation system, harvest year and locations had a little impact on the nutritional quality. Besides from plasma IgG levels, none of the measured health biomarkers were affected by cultivation system. Paper III investigated if there was an effect of maternal consumption of organically or conventionally produced feed on the modulation of immunological tolerance in offspring. The first step was to develop an oral tolerance model (pilot study), which was employed on second generation rats who’s mothers originated from the study described in Paper II. Except from PGE2, cultivation system had little of rats fed diets of organically versus conventionally grown crops in their response to a novel dietary antigen was observed. In conclusion, it was found that cultivation system, harvest year and location had a small effect on the nutritional quality of the foods and that cultivation system had no clear effect on the measured health-related or immunological biomarkers.