The following are excerpts from a paper I originally wrote a couple years back, and they underscore the mythology behind the mainstream belief that organic food is more nutritious than their conventional counterparts (and my sources are from reputable scientific journals, not a gardening catalogue). Enjoy.
“There is no way to be sure a particular food on the supermarket shelf has been produced organically, regardless of what the label says, because there are so many different criteria, and most are hard to verify scientifically.” Some allegedly organic meat farmers are permitted to use antibiotics on their livestock once a year, and this would technically disqualify them from the organic label (Ravillious, 2006).
… Agriculture is very inconsistent. “Valid comparison studies between organic and conventionally produced foods require that the plants are cultivated in similar soils, under similar climatic conditions, are sampled at the same time and are analysed using the same validated methods” (Williamson, 2007). Furthermore, genetic variation in plants and animals contribute to differences in product quality and nutritional content, whether it is organic or not (Magkos, 2003). In fact all foods show a natural variation in nutrient levels which depend on factors such as climate, ripeness, crop variety, freshness and storage conditions (Williamson, 2007).
Although conventional crops do use pesticides, there is no reason to avoid these foods for that reason. According to a study done by the Pesticide Residues Committee, pesticide residues were found to be absent in about 70% of the tested produce. In the remaining 30%, residues were below the maximum residue levels and therefore pose no health concerns for consumers (Williamson, 2007).
While comparing organic and conventionally produced grains, potatoes and vegetables, there were no major differences in mineral, trace element or B vitamin levels. In vegetables there were no differences found in levels of vitamin A or beta-carotene. (Williamson, 2007). There was however a trend towards higher levels of vitamin C and several other micronutrients in some organic produce in a range of anywhere from 9-42%, however much more research is required to confirm these findings.
Studies on fruits, once again, do not reveal any significant differences in nutrient content between conventional and organic produce. Vitamins B1, B2 and ascorbic acid levels remained similar. Concentrations of trace minerals and elements such as magnesium, iron and copper were also not found to be significantly different (Magkos, 2003).
In dairy products such as milk and cheese, there were found to be significantly higher levels of alpha-linolenic acid, conjugated-linolenic acid, vitamin E, and beta-carotene in organically fed cows (Williamson, 2007). It is yet to be determined however, whether these levels are higher because of the changes in diet, or because of the lower milk yield in organic cattle (Williamson, 2007). There were no significant differences in many other nutrients found in milk, such as calcium, zinc, vitamin B2 or vitamin B12, therefore drinking organic milk is unlikely to make much of a difference in terms of micronutrient intake (Williamson, 2007). In addition, these findings must be dealt with cautiously when one takes into consideration the natural genetic variation between animals of the same species in product quality (Magkos, 2003). No two cows have the same milk.
In some organically produced vegetables and legumes, it was found that there was a lower protein content, but higher protein quality, which means a higher proportion of amino acids. (Willaimson, 2007). To determine whether this is healthier than conventional produce also requires further research. Furthermore, because vegetables and potatoes are not a significant source of protein in the average diet, any differences in protein content would only be of importance in the case of extreme vegetarian or vegan diets. (Magkos, 2003)
Essoussi, L.H., & Zahaf, M (2008). Decision making process of community organic food consumers: An exploratory study. Journal of Consumer Marketing. 25, 95-104.
John Paull. (2006). The Farm as Organism: The Foundational Idea of Organic Agriculture. Elementals: Journal of Bio-Dynamics Tasmania. 80, 14-18.
Magkos, Faidon, Arvaniti, Fotini, & Zampelas, Antonis (2003). Organic Food: Nutritious Food or Food For Thought? A Review Of The Evidence. International Journal of Food Sciences and Nutrition. 54, 357-371.
Ravilious, K. (2006). Buyer beware: When you shell out for a premium food how do you know you’re getting what you pay for? Kate Ravilious investigates the rise of food fraud. New Scientist.192, 40-44.
Williamson, C.S. (2007).Is Organic Food Better For Our Health? Nutrition Bulletin. 32, 104-108.