Evaluation of the micronutrient composition of plant foods produced by organic and conventional agricultural methods.

The aim of the present analysis was to evaluate the micronutrient content of plant foods produced by organic and conventional agricultural methods. Studies were identified from a search of electronic databases (1980-2007, inclusive) as well as manual searches. A total of 66 studies (describing 1440 micronutrient comparisons) were identified. Thirty-three studies (908 comparisons) satisfied the screening criteria which considered cultivar, harvesting, and soil conditions. In studies that satisfied the screening criteria, the absolute levels of micronutrients were higher in organic foods more often than in conventional foods (462 vs 364 comparisons, P=0.002), and the total micronutrient content, expressed as a percent difference, was higher in organic (+5.7%, P<0.001) as compared to conventionally grown produce. The micronutrient content of food groups was more frequently reported to be higher for organic vegetables and legumes compared to their conventional counterparts (vegetables, 267 vs 197, P<0.001; legumes, 79 vs 46, P=0.004). This trend was supported by a mean percent difference in micronutrient content favoring organic vegetables (+5.9%, P<0.001) and legumes (+5.7%, P<0.001). Further research is required to determine the effect of organic agricultural methods on a broader range of nutrients and their potential impact on health.