JustTheScience

The organic food industry has grown dramatically over the last several years, and it’s a natural assumption that eating organic foods is better for you.  Organic foods are grown in an environment perceived to be free of harmful pesticides and herbicides, and in some instances are deemed to be more nutritional than those grown in a conventional manner.  Are there any significant differences between organic and normally raised agricultural products?

One well known difference between organically and non-organically grown produce are the chemicals, or lack thereof, utilized during the growing process.  Studies have found negative effects resulting from acute exposure to pesticides (Grandjean et al 2006) and herbicides (Kamel et al 2003) on farm workers and their children (if exposed prenatally).¹²  For the consumers of produce from farms that utilize pesticides and herbicides, however, it’s been shown that actual exposure to these chemicals is relatively small.   Leblac et al (2000) determined that an average person’s exposure to pesticides is 4% of an individual’s maximum recommended exposure. ³  Galal-Gorchev H. (1991) found that a person’s exposure to pesticide residue is well below established acceptable daily intake levels in the 21 western countries that supply data on the matter. ⁴   Juhler et al (1999) determined dietary exposure to pesticides does not affect male spermazoa,⁵ and Safe (1995) found an individual’s exposure to estrogenic compounds from organochlorine pesticides is 0.0000025% of the daily intake of estrogenic flavonoids in the diet.⁶  While organic farming has been shown to lower pesticide residues in food by 2/3, much organic produce is not pesticide free due to legacy contamination and drift from other fields (Baker et al 2002). ⁷

As far as differences in nutritional value between organic and conventionally grown produce, much of the current literature is suggesting a need for further research, although some slightly notable differences have been found. A review of 55 articles on the subject found conventionally produced crops had significantly higher nitrogen content, and organically produced crops had significantly higher acidity and phosphorus content.  These differences were attributed to the difference in production methods and none of them had a material impact on the food’s nutritional value (Dangour et al 2009) (Bourne and Prescott 2002). ^8 9  A study by Magkos et al (2003) found higher levels of ascorbic acid in organically grown leafy vegetables and potatoes and lower protein levels in some organic vegetables and cereals, but found this evidence to be inadequate to make a definitive argument.  A study by Caris-Veyrat et al (2004) found that organic tomatoes had higher levels of antioxidants (vitamin C, carotenoids, and polyphenols) than conventionally grown tomatoes, but when both types of tomatoes were fed to people for 3 weeks, no difference was found in antioxidant levels in the bloodstream between those that consumed organic or conventional. ^10 11   Similarly, Tarozzi et al (2005) found that organic red oranges have a greater total antioxidant activity than those grown conventionally, but did not investigate whether or not the organic oranges would alter antioxidant levels in the bloodstream  ¹²

1. Pesticide Exposure and Stunting as Independent Predictors of Neurobehavioral Deficits in Ecuadorian School Children [↩]
2. Neurobehavioral performance and work experience in Florida farmworkers [↩]
3. Estimation of the dietary intake of pesticide residues, lead, cadmium, arsenic and radionuclides in France [↩]
4. Dietary intake of pesticide residues: cadmium, mercury, and lead [↩]
5. Human Semen Quality in Relation to Dietary Pesticide Exposure and Organic Diet [↩]
6. Environmental and Dietary Estrogens and Human Health: Is There a Problem? [↩]
7. Pesticide residues in conventional, IPM-grown and organic foods: Insights from three U.S. data sets [↩]
8. Nutritional quality of organic foods: a systematic review [↩]
9. A Comparison of the Nutritional Value, Sensory Qualities, and Food Safety of Organically and Conventionally Produced Foods [↩]
10. Organic food: nutritious food or food for thought? A review of the evidence [↩]
11. Influence of Organic versus Conventional Agricultural Practice on the Antioxidant Microconstituent Content of Tomatoes and Derived Purees; Consequences on Antioxidant Plasma Status in Humans [↩]
12. Antioxidant effectiveness of organically and non-organically grown red oranges in cell culture systems [↩]