If you eat organic food, you may be getting as much as two-extra servings of antioxidants per day than if you eat the same conventionally grown fruits and vegetables, says a new study published today (July 11, 2014) in the British Journal of Nutrition. The study also reported organic foods are also significantly lower in toxic heavy metals, such as mercury and lead, and by as much as half for cadmium.
In what is being cited as the the largest study to date on the health of organic food, an international team of experts led by Newcastle University, UK, found that organic crops and crop-based foods are up to 69% higher in a number of key antioxidants than conventionally-grown crops.
Professor Charles Benbrook, one of the authors of the study and a agricultural sustainability scientist based at Washington State University, says: “Our results are highly relevant and significant and will help both scientists and consumers sort through the often conflicting information currently available on the nutrient density of organic and conventional plant-based foods.”
Newcastle University’s Professor Carlo Leifert, who led the study, says: “This study demonstrates that choosing food produced according to organic standards can lead to increased intake of nutritionally desirable antioxidants and reduced exposure to toxic heavy metals," he says. “This constitutes an important addition to the information currently available to consumers which until now has been confusing and in many cases is conflicting.”
“The organic vs non-organic debate has rumbled on for decades now but the evidence from this study is overwhelming – that organic food is high in antioxidants and lower in toxic metals and pesticides," Leifert says. "But this study should just be a starting point. We have shown without doubt there are composition differences between organic and conventional crops, now there is an urgent need to carry out well-controlled human dietary intervention and cohort studies specifically designed to identify and quantify the health impacts of switching to organic food.”
A critic of the study said it was "oversexed." Tom Sanders, a professor of nutrition at King's College London, told The Guardian, there were small differences, but he questioned the study's' credibility. "I am not convinced," he told The Guardian reporter. ""Leifert has had a lot of aggro with a lot of people. He is oversexing [this report] a bit." Sanders and others say the study may be too large, which skews the data in a favorable direction.
The authors of the study say they welcome public and scientific debate on the subject. They say the entire database generated and used for this analysis is freely available on the Newcastle University website for the benefit of other experts and interested members of the public.
The study analysed 343 studies into the compositional differences between organic and conventional crops, the team reported that a switch to eating organic fruit, vegetable and cereals – and food made from them – would provide additional antioxidants equivalent to eating between 1-2 extra portions of fruit and vegetables a day.
It also shows significantly lower levels of toxic heavy metals in organic crops. Cadmium, which is one of only three metal contaminants along with lead and mercury for which the European Commission has set maximum permitted contamination levels in food, was found to be almost 50% lower in organic crops than conventionally-grown ones.
Nitrogen concentrations were found to be significantly lower in organic crops. Concentrations of total nitrogen were 10%, nitrate 30% and nitrite 87% lower in organic compared to conventional crops. The study also found that pesticide residues were four times more likely to be found in conventional crops than organic ones.
The findings contradict those of a 2009 UK Food Standards Agency (FSA) commissioned study which found there were no substantial differences or significant nutritional benefits from organic food. The FSA commissioned study based its conclusions on only 46 publications covering crops, meat and dairy, while Newcastle led meta-analysis is based on data from 343 peer-reviewed publications on composition difference between organic and conventional crops now available.
“The main difference between the two studies is time,” said Leifert. “Research in this area has been slow to take off the ground and we have far more data available to us now than five years ago.” Dr Gavin Stewart, a Lecturer in Evidence Synthesis and the meta-analysis expert in the Newcastle team, added: "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"