Organic Food Has Higher Antioxidants, Says Largest Comparative Study to Date

Nutritional OutlookNutritional Outlook Vol. 17 No. 6
Volume 17
Issue 6

This meta-analysis now throws the biggest support to date for the demand spike for organic foods.

Back in 2012, a group of Stanford University researchers published a study that found no evidence that organic foods are more nutritious than their conventional counterparts. In new meta-analysis published today in the British Journal of Nutrition, however, a different group of researchers found that there are benefits to going organic-including a significantly higher level of antioxidants.

Levels of antioxidants were substantially higher in organic produce compared to non-organic produce, specifically:

  • 19% higher phenolic acids
  • 69% higher flavanones
  • 28% higher stilbenes
  • 26% higher flavones
  • 50% higher flavonols
  • 51% higher anthocyanins

“Among the composition differences detected by the meta-analyses carried out in the present study, the higher antioxidant activity and higher concentrations of a wide range of antioxidants/(poly)phenolics found in organic crops/crop-based foods may indicate the greatest potential nutritional benefits,” write the study authors, who also examined other crop composition differences in their meta-analysis.

“Based on the differences reported, results indicate that a switch from conventional to organic crop consumption would result in a 20–40% (and for some compounds more than 60%) increase in crop-based antioxidant/(poly)phenolic intake levels without a simultaneous increase in energy…”

Why are antioxidants more plentiful in organic crops? It’s likely part of the plants’ own mechanism of self-protection, the researchers posit. Plants may produce higher levels of antioxidants when trying to protect themselves from pests and disease.

However, the researchers caution, no formal studies have yet confirmed a causal link between antioxidant content and pest incidence. Nor do the meta-analysis authors claim that higher antioxidant levels are healthier, noting that “there is still a lack of knowledge about the potential human health impacts of increasing antioxidant/(poly)phenolic intake levels and switching to organic food consumption.”

Organic produce may offer other benefits, though. The researchers confirm a four-fold reduction in the amount of pesticide residues in organic foods compared to non-organic, as well as a significantly lower level of the heavy metal cadmium.

This is the largest meta-analysis comparing organic and non-organic produce to date. The researchers looked at 343 peer-reviewed studies comparing the two types.

Comparing organic and non-organic crops presents numerous challenges, they point out. Variations in farming practices and geographic conditions make it difficult to obtain homogenous samples. Additionally, many studies available for meta-analyses use different experimental designs-some are replicated field experiments while others are farm and retail surveys-while many use different methodologies (weighted versus unweighted meta-analyses). “As a result, there is still considerable controversy” as to whether organic produce is beneficial, the researchers write. They say, however, that their study took the above differences into account.

This meta-analysis now throws the biggest support to date for the demand spike for organic foods over the last 20 years-a market that, in the United States, now represents 4%, or $32.3 billion, of the total food market.


Jennifer Grebow
Nutritional Outlook magazine


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