Do organic beat conventional vegetables for immune system support?

Writing in the Journal of the Science of Food and Agriculture​​, Italian and Danish researchers report that organic carrots were associated with an increase in immune T cells when fed to lab mice.

“Works on health benefits of organic foods are scarce up to now, the majority of them looking at antioxidant activity, whereas immunological studies are extremely rare, and exclusively related to systemic immune response,”​ explained the researchers.

“To our knowledge, this is the first study on the impact of organic food on intestinal immunity.”​

Debate​

The study adds to the debate on the potential health benefits of organic produce. Earlier this year a review published in the Annals of Internal Medicine​ ​(Vol. 157, pp. 348-366) concluded that organic produce offers no benefits over conventional farming methods when it comes to nutrition and health.

Stanford University scientists wrote that organic food consumption does reduce exposure to any detectable pesticide residues by around 30%, but noted that pesticide levels are generally within the allowable limits for safety anyway.

The new study, led by Marianna Roselli from the National Research Institute of Food and Nutrition in Rome, found that organic carrot consumption was associated with an “immune stimulation”​.

“The results presented in this study provide novel information on the health effects deriving from organic food consumption, indicating an immune stimulation by organic carrots, especially by the ‘more organic’ carrots, on both intestinal and peripheral immunity, including an expansion of T cells,” ​they wrote.

“In addition, this study reinforces the concept of the safety of organic products.”​

Study details​

For their study, Dr Roselli and her co-workers investigated the effects of Danish carrots grown organically or conventionally. Three different types of organic cropping systems were used. Italian carrots were also grown in one organic cropping system and one conventional system.

Groups of lab mice were then fed the different carrots for 30 days, and the immune responses measured.

Results showed that consumption of the ‘more organic’ carrots “induced some changes in lymphocyte populations, including an increase in regulatory T cells”​, said the researchers.

“It is widely accepted that any condition inducing an increase in regulatory T cell levels, locally and/or systemically, is considered beneficial. Thus the increase of regulatory T cells suggests a positive effect exerted both locally and systemically by the two ‘more organic’ carrots of the Bolero variety, as compared to the conventionally-grown Danish carrots diet. ​

“This is the first evidence of a regulatory T cell increase induced by organic food consumption.”​

The researchers were affiliated with the National Research Institute of Food and Nutrition in Rome, La Sapienza University (Rome), Aarhus University (Denmark), and the Italian Association for Organic Agriculture (AIAB).

Source: Journal of the Science of Food and Agriculture​​
November 2012, Volume 92, Issue 14, pages 2913–2922, doi: 10.1002/jsfa.5667
“Impact of organic and conventional carrots on intestinal and peripheral immunity”​
Authors: M. Roselli, A. Finamore, E. Brasili, G. Capuani, H.L. Kristensen, C. Micheloni, E. Mengheri