Organic tomatoes grown without the use of pesticides have more vitamin C and other beneficial compounds than those grown using conventional farming methods, according to a Brazilian study.
Despite being smaller, their nutrients are more potent because they've had to fight harder to survive, the researchers said.
When pesticides and fertilisers are sprayed on non-organic tomato crops, they provide a protective barrier against pests.
But when organic tomatoes are left to "fend for themselves" they experience more stress, so increase their sugar, vitamin C and antioxidant concentrations, to protect themselves.
The study compared tomatoes from two Brazilian farms located 1.5km from each other.
The tomatoes grown organically were fertilised using manure and vegetable compost, while the conventionally grown tomatoes used inorganic fertiliser and pesticide FASTAC 100.
The researchers looked at fruit from 30 plants from each farm and found the organic tomatoes had 57 percent more vitamin C and double the amount of phenolic compounds, which are healthy properties believed to help the body fight oxidative stress and reduce the chances of cancer, heart disease and dementia.
The organic tomatoes were also 40 percent smaller.
Liza Oates, a lecturer in the Master of Wellness program at RMIT University, told ninemsn that this is just one study and the findings won't necessarily apply to other regions.
"This is attempting to determine whether organic diets are better by looking at individual nutrients but it's much more complicated than that," said Oates, who is currently completing a PhD on health, wellness and organic diets.
"It's interesting and adds to the body of information but it's the nutrients in the human that are important, not the nutrients in the tomato."
Oates said organic produce does have more phytochemicals, but scientists are unsure whether that actually boosts human health.
"It's complicated — a lot of things happen in the journey from the paddock to the plate to the person that can influence whether those nutrients actually end up in the tissues of the human being," she said.
"These things degrade in transport and storage. Different humans absorb them differently and have different demands for them. If you want more of that particular nutrient in your diet, that might be something that you can use, but that's not enough for us to say that organic diets have more nutrients and organic diets are healthier."
Natasha Murray, spokesperson for the Dietitians Association of Australia, told ninemsn that it's up to individuals to decide what they think is best for them.
"Whether they're organic or not, fruit and veggies still have fibre, vitamins and minerals," she said.
"What's most important is that people are getting two serves of fruit and five serves of veggies a day."
The study was published in the journal Public Library of Science ONE.