Consumers shouldn’t pay more for organic food because of what it adds to their diets, research suggests. The only gain may come from what it doesn’t add.

Organic foods that account for $27 billion in U.S. grocery sales offer no more vitamins and nutrients than conventional products, according to a review of 240 studies done at Stanford University in California. The research, published in the Annals of Internal Medicine, did find lower levels of pesticides in produce and antibiotic-resistant bacteria in meat.

U.S. sales of organic food rose sevenfold over a dozen years to $26.7 billion in 2010, according to the Organic Trade Association, based in Brattleboro, Vermont. While the reports studied didn’t address specific health consequences for illnesses such as heart disease or cancer, they offered little evidence there would be any, the researchers wrote.

“There wasn’t any strong evidence to support the idea that organic foods are significantly healthier,” said Crystal Smith- Spangler, the study’s lead author, in a telephone interview.

Organic foods typically are grown without pesticides, synthetic fertilizers or genetically modified organisms; animals aren’t given antibiotics. While the studies found food produced in that manner to be 30 percent less likely to contain trace levels of pesticides, they noted that it was uncommon for any food in the U.S. to have unsafe levels.

Laura Batcha, executive vice president of the industry trade group, said the benefits found by the study supports the value of organic food.

’Reducing Exposure’

“This study confirms that choosing organic foods reduces consumers’ exposure to pesticide residues, and that the overuse of antibiotics in non-organic production leads to higher level of bacteria resistant to antibiotics in meat,” Batcha said in an e-mailed response to questions. “Studies have increasingly shown the importance of minimizing young children’s exposure to even low levels of chemical pesticides.”

Of the studies reviewed, 17 compared groups eating organic and non-organic foods and 223 compared the nutrients, bacteria, fungus and pesticides found in the foods.

The studies looked at a variety of products, including meat, eggs, milk and vegetables. None addressed the longer-term effects of organic foods.

There have been no large studies that followed consumers of organic and non-organic foods to assess whether they had better overall health, or lower rates of heart disease or cancer, Smith-Spangler said.

The only nutrient that researchers found to be significantly higher in organic compared to non-organic foods was phosphorus, of which very few people have a deficiency, Smith-Spangler said.

The researchers received no outside funding to do the analysis, according to the journal report.