Organic fruits and vegetables contain as much as 70% more antioxidants than non-organic produce, according to a new study. Just eating organically provides amounts of antioxidants equivalent to one to two extra portions of fruits and vegetables a day, the researchers say.
The study will be published July 15 in the British Journal of Nutrition.
Analyzing 343 studies in the largest research effort of its kind, an international team of experts led by Newcastle University found that organic crops and crop-based foods are up to 70 percent higher in a number of key antioxidants than conventionally grown crops. (For example, a team from Washington State University looked at a 2010 study that compared the nutritional and sensory quality of organic and conventional strawberries grown in California.)
The study also showed that conventional crops were four times more likely to contain pesticide residues than were organic crops, and contained about 50% higher cadmium levels (a toxic heavy metal). Cadmium can cause kidney failure, bone softening and liver damage. It can accumulate in the body, so even at low levels chronic exposure is dangerous.
Overall, organic crops had 18 to 69% higher concentrations of antioxidant compounds, which are said to have many health benefits, helping to prevent coronary heart disease, stroke and certain cancers.
One reason organic food may have higher levels of antioxidants is that it is grown without high levels of (largely chemical) fertilizers. Heavily fertilized crops grow faster and bigger, but lose their nutrients – a “vital insight” gleaned from the study, according to Professor Charles Benbrook, one of the authors of the study and a research professor at the Center for Sustaining Agriculture and Natural Resources at Washington State University.
“How farmers feed their plants helps determine the nutritional profile of the food harvested from them,” he said, adding, "The findings of this study strongly support the existence of health benefits stemming from consumption of plant-based organic food and beverages.”
Having to fight a little for survival — rather than being fed chemicals and coated with pesticides — is apparently what spurs plants to create antioxidants (various forms of which help them use fuel efficiently and repel pests).
The findings contradict those of a 2009 UK Food Standards Agency-commissioned study, which found there were no substantial differences or significant nutritional benefits from organic food.? But the FSA-commissioned study based its conclusions on only 46 publications covering crops, meat and dairy, while the Newcastle-led meta-analysis is based on data from 343 peer-reviewed publications on composition difference between organic and conventional crops that is newly available.
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"The much larger evidence base available in this synthesis allowed us to use more appropriate statistical methods to draw more definitive conclusions regarding the differences between organic and conventional crops," says Dr Gavin Stewart, the meta-analysis expert on the Newcastle team.
And yes, your backyard planter beds will work just fine. Just add sun and water.