People buy organic food for a variety of reasons—to save the environment, support small farmers, limit their exposure to chemical pesticides and, in many cases, to eat a healthier diet. A new research review has found that the last reason may not be as valid, although other studies disagree. 

In a review published in the Sept. 4, 2012 issue of Annals of Internal Medicine, Stanford University researchers looked at 240 nutrient analysis studies and human trials and found that there was no strong evidence that organic fruits, vegetables, grains, milk, eggs, chicken, pork and beef  are “significantly more nutritious than conventional foods.” 

However, the researchers did note that phenols—antioxidant plant compounds—were noticeably higher in organic versus conventionally grown produce, and organic milk and chicken had more omega-3 fatty acids than their conventional counterparts. 

That’s good news, said John Shaw, executive director and CEO of the Natural Products Association. “The benefits of [phenols and omega-3s] on brain and heart health have been well established through numerous scientific studies.” 

The researchers also found that organic fruits and vegetables are 30 percent less likely to be contaminated with pesticides than conventional produce, and organic chicken and pork have 33 percent less risk of contamination with bacteria resistant to three or more antibiotics.

Charles Benbrook, PhD, chief science consultant with The Organic Center, took umbrage with the Stanford study, noting that it didn’t mention a British research review published last year in Critical Reviews in Plant Sciences. In that review, which Benbrook said “covered essentially the same literature as the Stanford team,” researchers found that conventional farming increases the amount of nitrogen in soil, which in turn decreases nutrients in plants. As a result, organic fruits and vegetables have an average of 12 percent more nutrients than conventional produce, the researchers concluded.

“The [research] team went on to estimate that consumption of organic fruits and vegetables, by virtue of their average 12 percent higher nutrient levels, would extend life expectancy by 17 days for women and 25 days for men,” Benbrook said.

In addition, he said, other studies comparing organic and conventional apples, strawberries, grapes, tomatoes, milk, carrots, grains and several other raw foods found that “vitamin C, antioxidants and [phenols] tend to be higher in organic food about 60 to 80 percent of the time, while vitamin A and protein is higher in conventional food 50 to 80 percent of the time.”

Learn more about eating organic:

• 5 Reasons to Buy Organic
• Nutrition for New Moms
• Choosing Organic Foods
• New Food Guidelines Fall Short