Is organic food healthier than conventional food?

Not really! That is, if you compare the nutritional benefits. Considering that sometimes you may have to pay as much as twice what conventional food costs.

The only benefit that organic food has over conventionally grown produce is that it may reduce your exposure to pesticide residues and antibiotic-resistant bacteria. And even that is marginal – since pesticide levels found in conventionally grown produce were found to be within safety limits.

Bursting the myth that organic food is healthier than the conventional alternative is a paper published in the September 4 issue of Annals of Internal Medicine.

"There isn't much difference between organic and conventional foods, if you're an adult making a decision based solely on your health," said Dr Dena Bravata, a senior research affiliate with Stanford University's Centre for Health Policy and senior author of the paper.

"People choose to buy organic foods for many different reasons. One of them is perceived health benefits," added Crystal Smith-Spangler, who led the team of researchers from the university and Veteran Affairs Palo Alto Health Care.

More than 200 studies were reviewed, comparing either the health of people who consumed organic or conventional foods or nutrient and contaminant levels in unprocessed foods such as fruits, vegetables, grains, milk, eggs, chicken, pork and meat.

Key findings:

• No significant differences between populations by food type for allergic reactions;
• Two studies reported significantly lower urinary pesticide levels among children consuming organic versus conventional foods;
• Biomarker and nutrient levels in serum, urine, breast milk and semen in adults did not show clinically meaningful differences;
• Phosphorus levels were significantly higher than in conventional foods, although this difference is not clinically significant;
• Organic produce had a 30 per cent lower risk of containing detectable pesticide levels;
• E-coli contamination risk did not differ between organic and conventional foods;
• Bacterial contamination of retail chicken and pork was common but not related to farming methods. But when bacteria did lurk in chicken and pork, germs in non-organic meats had a 33 per cent higher risk of being resistant to multiple antibiotics.

"The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods," the research team concluded. "Consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria."

Organic products have soared in popularity in the United States, with sales skyrocketing from $3.6 billion in 1997 to $31.4 billion in 2011. Today, organic foods account for 4.2 per cent of retail food sales, according to the United States Department of Agriculture (USDA).

This is because of a general perception that organic foods are safer and healthier. And this may be true, to a point.

USDA standards stipulated that organic farms avoid the use of synthetic pesticides and fertilizers, hormones and antibiotics. The regulations also require organic livestock to have access to pastures during grazing season.

The US Organic Trade Association was quick to capitalize on some of the findings with its executive director and CEO, saying on its  website: "Consumers seeking to minimize their exposure to pesticide residues will find that foods bearing the USDA Organic label are the gold standard."

"And, because organic livestock practices forbid the use of antibiotics, including the routine use of low level antibiotics for growth, organic meat contains less antibiotic-resistance bacteria."

However, sounding a word of caution, some nutrition experts have called for more research to fully explore the potential health and safety differences between organic and conventional foods, saying it was premature to say organic foods are not any healthier than non-organic foods.

"Right now I think it's all based on anecdotal evidence," said Chensheng Lu, who studies environmental health and exposure at the Harvard School of Public Health.

"If I was a smart consumer, I would choose food that has no pesticides. I think that's the best way to protect your health."