Organic food is grown without the use of pesticides
Soup made using organic vegetables was found, in their experiments, to contain six times the level of salicylic acid.
This has been linked in other studies with a protective effect against heart attacks, cancer and strokes.
The same team has already conducted research which claimed to find higher levels of the acid in the blood of vegetarian Buddhist monks compared to meat eaters.
Controversial theory
Biochemist John Patterson, who led the research at Dumfries and Galloway Royal Infirmary, told New Scientist magazine: "I'm not an evangelist for the organic food movement, but there was a fairly substantial difference."
Salicylic acid occurs naturally in plants, although there is no firm explanation as to why organic plants should produce or retain more of it.
These are grown without the assistance of many modern chemical pesticides or fertilisers.
Many believe that they are no more nutritious than conventionally farmed produce, despite the higher price tag.
Patrick Holden, director of the Soil Association, said: "This adds to the body of evidence showing the health benefits of organic food.
"Previously, two independent studies have shown organic crops to contain higher levels of vitamin C, magnesium and iron.
"The organic food studied also showed higher levels of other minerals.
"The Food Standards Agency must look seriously at all the available research."