The study, published in the journal PLOS ONE, found tomatoes grown on organic farms were some 40 percent smaller than conventionally grown tomatoes, but contained significantly higher levels of vitamin C, sugar and lycopene -- a substance linked to a lower risk of stroke and some types of cancers, particularly prostate cancer.
Aurelice B. Oliveira, Eneas Gomes-Filho, Maria Raquel A. Miranda of the Universidade Federal do Ceara in Fortaleza, Brazil, and colleagues in Brazil and France, said until recently, the focus has been mainly on yield rather than on micronutritional quality of fresh plant products.
"This might be all right for staple food, but, as far as fruits and vegetables are concerned, it may be argued that taste and micronutritional quality matter more than calorie supply," the researchers wrote in the study.
The researchers explained plants grown under the organic system of agriculture "stressed out" plants, because when tomato plants fought pests without pesticides, they produced more stress compounds such as vitamin C and lycopene to repel insects.
More research is needed to better understand the links between stress and oxidative stress, the researchers said.