‘No evidence’ organic foods more nutritious: study

A new review of published comparisons claims that organically grown food contains no more of a certain group of important nutrients than conventionally grown food.

WebMD reports that lead author Alan Dangour PhD, a public health nutritionist at the London School of Hygiene & Tropical Medicine said that “We wanted to answer the question, 'Is there any evidence that organic food is nutritionally superior to conventionally grown food? The answer is no. Organic food is not nutritionally superior to conventional food."

The review, Comparison of composition (nutrients and other substances) of organically and conventionally produced foodstuffs: a systematic review of the available literature was published in the American Journal of Clinical Nutrition and reviewed 162 studies comparing organic and conventionally grown food between January 1958 and February 2008.

The researchers evaluated several nutrient categories, including: Calcium, Vitamin C, Magnesium, Nitrogen, Copper, Zinc, Acidity content, Potassium, Phosphorous and Total soluble solids.

They found that while organically produced crops had higher phosphorous and acidity content, conventionally produced crops had higher nitrogen content, while they couldn’t find a discernible difference for the other crop nutrient categories and when comparing animal-source foods, the researchers found no difference in nutrient content.

"Looking at all of the studies published in the last 50 years, we have concluded that there's no good evidence that consumption of organic food is beneficial to health based on the nutrient content," Dr Dangour said.

Organic foods are devoid of additives and produced without chemicals such as fertilisers and pesticides, which makes them more typically at least a third more expensive, while the researchers estimate the global market for organic food to be around $US48 billion per annum.

Differences in pesticide residues weren’t looked at.

The paper has provoked strong disagreement between food researchers around the world, while this Guardian blog argues that it's wrong to believe that nature is always best.

''Our stand is it's beyond scientific doubt that that organic foods are higher in vitamins and important trace minerals and there are far fewer toxic residues in them. And that's the reason that millions of American consumers are paying a premium price for organic production”, US Organic Consumers' Association national director Ronnie Cummins said.

Senior scientist at the US Consumers Union and food safety expert Michael Hansen said one problem with the review is the use of older studies, because newer studies have “clearly shown” significant differences between organic and nonorganic when it comes to nutrient content.

''Most of the studies published before 1980 are flawed for a number of reasons,'' including flawed methodology he said to WebMD, and nutrients in the food supply are declining as a whole.

Colorado based Charles Benbrook PhD, chief scientist for The Organic Center, criticised what he called a lack of focus on polyphenols and antioxidants, which he said are about 25% higher in organically grown foods. The London team "downplays" the differences they did find between the foods, he said.

NBR was unable to contact Organic NZ at the time of publication.