In a study published last month in Annals of Internal Medicine, Dena Bravata from Stanford’s Centre for Health Policy argues there isn’t much difference between organic and conventional foods if consumers are making a decision based solely on their health.
The researchers analysed 237 papers including studies of populations consuming organic and conventional diets, and studies that compared either the nutrient levels or the bacterial, fungal or pesticide contamination of various vegetables and meats grown organically and conventionally.
“Some believe that organic food is always healthier and more nutritious,“ said study author Crystal Smith-Spangler, who is an instructor of medicine at Stanford. “We were a little surprised that we didn’t find that.”
Based on their review of the health outcomes, nutrition and safety of organic and conventional foods, the study authors argued there is limited evidence for the superiority of organic foods.
“The evidence does not suggest marked health benefits from consuming organic versus conventional foods,” they wrote in the report.
The study did however find that organic produce is 30% less likely to be contaminated with pesticides than conventional fruits and vegetables.
“Our research shows organic consumers are more interested in what’s not in their food – such as pesticides and antibiotics – than what is,” said Liza Oates, who is currently researching the health effects of organic diets at RMIT University.
“This review has confirmed that organic foods have lower levels of pesticide residues and antibiotic-resistant bacteria. The fact that they failed to find strong evidence that organic foods have more nutrients is relatively predictable,” Ms Oates said.
She added that research in the US has shown eating organic food has a dramatic effect on pesticide residues in children.
“Substituting non-organic fruits and vegetables with organics for five days resulted in an almost complete reduction in organophosphate pesticide residues.”
However Tim Crowe, associate professor of nutrition at Deakin University, said pesticide levels are always checked in Australia and found to be within safe limits.
Professor Crowe said while there’s a very strong perception that organic foods are going to be much better for us, and for our health, studies have found little evidence of a major difference.
“The biggest health problems facing Australians are to do with over consumption of food, not inadequate consumption of fruit and vegetables,” Professor Crowe said.
If you get a feel good health effect from eating organic fruit and vegetables, by all means eat them, but I’d be more worried about eating five serves of fruit and veg a day rather than eating organic food.”
But taste, environmental benefits, and animal welfare issues are other important aspects of organically grown food said Rosemary Stanton, nutritionist and visiting fellow at University of New South Wales.
“Animal welfare is a major issue for many people and reducing use of pesticides is always wise. Many permissable pesticide residue limits have been reduced over time,” Dr Stanton said.
She said taste is another factor with some studies showing better taste from organically produced foods, although added this is a difficult area and may also reflect the varieties of crops grown in large commercial conventional farming versus the varieties that may be grown by smaller organic farmers. “I think in home, school and community gardens, organically grown produce is definitely to be preferred since exposure of growers to chemical substances can be problematic and the general public has no training in appropriate use of pesticides.”