It's often a split-second decision. You're in the produce aisle, and those organic apples on display look nice. You like the idea of organic — but they're a few bucks extra. Ditto for the organic milk and meat. Do you splurge? Or do you ask yourself: What am I really getting from organic?

Scientists have been trying to answer this question. And the results of a huge new meta-analysis published this week in the British Journal of Nutrition adds to the evidence that organic production can boost key nutrients in foods.

The study finds that organic dairy and meat contain about 50 percent more omega-3 fatty acids. The increase is the result of animals foraging on grasses rich in omega-3s, which then end up in dairy and meats. The findings are based on data pooled from more than 200 studies, and research in the U.S. has pointed to similar benefits.

"Omega-3s are linked to reductions in cardiovascular disease, improved neurological development and function, and better immune function," writes study co-author Chris Seal, a professor of food and human nutrition at Newcastle University in the U.K. "So we think it's important for nutrition," Seal told us. That said, organic meat and dairy contain far lower concentrations of omega-3s than what are found in fish such as salmon.

The findings are part of a growing body of evidence documenting how farming methods can influence the nutritional content of foods ...Read More