This week the British Journal of Nutrition published new meta-analysis that adds to the evidence that organic production can boost key nutrients in foods. The findings add to another large meta-analysis published in 2014, also in the British Journal of Nutrition, which found that organic crops – ranging from carrots and broccoli to apples and blueberries – have substantially higher concentrations of a range of antioxidants and other potentially beneficial compounds.
For instance, organic crops had about 50 percent more anthocyanins and flavonols compared with conventional crops. Anthocyanins are compounds that give fruits and vegetables, such as blueberries, their blue, purple and red hues.
Consumption of these compounds is linked to a variety of benefits, including anti-inflammatory effects. And flavonol compounds — found widely in fruits and vegetables — have also been shown to protect cells from damage, which can help fend off to disease.
Another difference between organic and conventional crops is the way plants get nitrogen. In organic systems, which rely heavily on crop rotation and composting, there's typically less nitrogen available.
As a result, organic crops tend to grow more slowly, and produce more of what scientists call secondary plant metabolites. And these compounds also may be health-promoting when we eat them.
A study of tomatoes conducted at the University of California, Davis, back in 2008 found that organic tomatoes have almost double the concentration of a beneficial flavonoid known as quercetin, compared with conventional tomatoes grown on an adjacent field.
The 2014 meta-analysis in the British Journal of Nutrition pointed to other differences in organic crops as well, including lower levels of pesticide residues on produce and lower concentrations of the metal cadmium, which is naturally occurring in soil.
And these findings — according to Carlo Leifert, a professor of agriculture at Newcastle and co-author of the latest study — suggest there are indeed benefits to buying and eating organic. "Taken together, the studies on crops, meat and milk suggest that a switch to organic fruit, vegetables, meat and dairy products would provide significantly higher amounts of dietary antioxidants and omega-3 fatty acids," Leifert wrote in a release about the new papers.
But, plenty of sceptics remain. An analysis by researchers at Stanford University published several years ago concluded there was no good evidence that organic fruits and vegetables were more nutritious overall.
There are echoes of this finding in the newer meta-analysis studies. Although organic crops had higher levels of antioxidants, they did not consistently contain higher levels of vitamins. For instance, as we've reported, Vitamin E levels didn't vary much between organic and conventional crops.
