Is Organically Grown Food More Nutritious?
There are many difficulties in assessing the nutritive value of organic vs. conventionally produced foods. The first is that the difference in terms of health effects is not large enough to be readily apparent. In other words, if people stayed well on an organic diet but got violently ill as a result of consuming food grown with chemical fertilizers and pesticides, then the difference would be perfectly obvious; however, this is not the case, and a more subtle difference, such as an 8% increase in the incidence of allergies, for example, is much more difficult to detect and easier to overlook.
A second reason is that it is difficult to conduct and interpret agricultural research investigating nutrient content. Factors such as sunlight, temperature and rainfall, which influence the nutrient content of plants, vary from year to year. Additional changes in the nutrient content of a crop can occur during storage and shipping. For these reasons, it is difficult both to plan effective studies and to make sense of the results. Furthermore, these considerations often make it difficult to compare the results of different studies.
Finally, many of the studies that have been done are relatively old and not performed according to modern standards. In particular, the older studies do not include a rigorous statistical analysis. This factor alone can make these studies difficult to evaluate. As a result, they have been dismissed by some as valueless.
What is the evidence?
There are more than 30 studies comparing the nutrient content of organic crops and those produced conventionally with chemical fertilizers and pesticides. In these studies, various individual nutrients in individual crops were compared, such as zinc in organic versus conventional carrots, or Vitamin C in organic versus conventional broccoli. In the more than 300 comparisons performed in these studies, organic crops had a higher nutrient content about 40% of the time, and conventional crops had a higher nutrient content only about 15% of the time. Overall, organic crops had an equal or higher nutrient content about 85% of the time. These results suggest that, on average, organic crops have a higher nutrient content.
For three individual nutrients — Vitamin C, nitrates and protein quality – there is enough evidence to suggest that organic crops are superior to conventional ones. Compared to crops grown with chemical fertilizers and pesticides, organically grown crops generally have a higher Vitamin C content, a lower content of carcinogenic nitrates and better protein quality. Further work is needed on other nutrients before any definitive conclusions can be drawn.
The most relevant studies are not those that simply assess nutrient content, but are those that feed organic or conventional feed to animals and then look at how healthy they are. There are 14 such animal studies that have been performed over the last 70 years. In ten of these, the organically- fed animals fared better; in one, the animals fed organic feed came in second among several chemically-fertilized feeds; and three studies showed no difference, possibly due to weaknesses in the study designs. The positive effects are most striking in sick or otherwise vulnerable animals such as newborns and in sensitive areas of reproduction such as sperm motility.
It is particularly interesting to see that the fertility of animals fed fodder grown with chemical fertilizers and pesticides declined over several generations.
The Co-op Connection is published by La Montanita Co-op Supermarket.