Knowledge for better food systems

Paper compares organic food to conventionally-produced food

This study, undertaken by UK researchers from the University of Newcastle uses the extensive data set of 343 peer-reviewed publications in a meta-analysis to investigate ‘differences in composition between organic and non-organic crops/crop-based foods’. It suggests that there are ‘statistically significant’ differences between the production methods particularly with regard to a range of antioxidants.

The results indicate that organic crops and processed crop-based foods have a higher antioxidant activity and contain higher concentrations of a wide range of nutritionally desirable antioxidants/(poly)phenolics,  and lower concentrations of the potentially harmful, toxic metal Cd. It also found a a four times higher frequency of occurrence of pesticide residues in conventional crops.

Abstract

Demand for organic foods is partially driven by consumers’ perceptions that they are more nutritious. However, scientific opinion is divided on whether there are significant nutritional differences between organic and non-organic foods, and two recent reviews have concluded that there are no differences. In the present study, we carried out meta-analyses based on 343 peer-reviewed publications that indicate statistically significant and meaningful differences in composition between organic and non-organic crops/crop-based foods. Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/ crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95% CI 5, 33) %, 69 (95% CI 13, 125) %, 28 (95% CI 12, 44) %, 26 (95% CI 3, 48) %, 50 (95% CI 28, 72)% and 51 (95% CI 17, 86)% higher, respectively.

Many of these compounds have previously been linked to a reduced risk of chronic diseases, including CVD and neurodegenerative diseases and certain cancers, in dietary intervention and epidemiological studies. Additionally, the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cd. Significant differences were also detected for some other (e.g. minerals and vitamins) compounds. There is evidence that higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral Nand P fertilisers, respectively) prescribed in organic farming systems. In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.

Citation

Barański, M., Średnicka-Tober, D., Volakakis, N., Seal, C., Sanderson, R., Stewart, G. B., Benbrook, C., Biavati, B., Markellou, E., Giotis, C., Gromadzka-Ostrowska, J., Rembiałkowska, E., Skwarło-Sońta, K., Tahvonen, R., Janovská, D., Niggli, U., Nicot, P., Leifert, C., Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses, British Journal of Nutrition, doi:10.1017/S0007114514001366

The full paper is freely available here.

The UK’s organic certification body, the Soil Association provides a summary of the research which you can find here.

The paper has attracted considerable attention, commentary and criticism. The Science Media Centre provides an analysis of the study here together with  a round up of expert reactions to the study here. The study authors’ response to these criticisms can be found here.

For more resources on various aspects of organic farming and food (covering nutrition-related and environmental dimensions) see here.

You can read related research by browsing the following categories of our research library:
 

Add comment

Member input

Plain text

CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Comments

Geoff Beacon's picture
Submitted by Geoff Beacon (not verified) on

 I have just read the commentry and criticisms of this study and the responses from the authors.  I am distrustful of some "big science" which may have engendered my delight at the authors' excellent responses.

Given that this topic is so high profile in what seems to be a David and Goliath situation I wondered how the battle for the public mind went.

Were both sides adequately heard?

Did the commentators respond to the authors' responses?

P.S. It's good to see scientists on both sides. I didn't find that in Food: Scientists vs amateurs.

Simon Ward's picture
Submitted by Simon Ward (not verified) on

I am not sure that understanding is pushed much further forward by comparing organic and conventional production trials. Yield of valued components maybe as valuable as concentration and we know that, in the main, yield of organic produce per unit area is low in contrast to conventional (and the arguement as to whether more food is important will continue to run). I suspect that a conventional farmer could sacrifice yield, or manipulate husbandry in other respects, to produce much the same results without going "organic" and in doing so provide other benefits such as cheap food and more reliable supply. What exactly should be limited nitrogen fertiliser, fungicide, weed control, etc. to achieve the outcome?

Peter Melchett's picture
Submitted by Peter Melchett (not verified) on

Simon Ward asks whether non-organic farmers could 'sacrifice yield, or manipulate husbandry in other respects' to produce the same nutritional differences in their crops as a recent meta-analysis has shown is achieved by organic farming. He asks whether non-organic farmers should limit 'notrogen fertiliser, fungicide, weed control, etc.' to achieve this. Quite a bit of research has been going on to look at what causes the differences in nutritional composition of organic and non-organic crops, and the authors of the latest meta-analysis (http://research.ncl.ac.uk/nefg/QOF) do state that the key explanation for nutritional differences is the use of manufactured nitrogen fertiliser in non-organic systems. They also note that the significantly higher levels of cadmium in non-organic crops (a negative) are the result of the use of mined phosphate fertilisers in non-organic farming. The paper also found significantly lower incidence of pesticides in organic food.

Obviousy any farmer can chose to adopt systems similar to organic without being certified as organic. Organic certification is simply a mechanism to ensure food sold as organic is subject to independent inspection and verification at every stage of the food chain, so people can trust what they buy.The importance of feeding reasonable levels of grass to ruminants (cattle and sheep), ensured by organic standards, is recognised by a new standard for grass reared and finished meat, available for organic and non-organic beef and sheep farmers.

The difficulty for non-organic farmers is that you avoid the of manufactured nitrogen fertiliser, the other way of supplying crops with nitrogn is through legumes - typically in this country a two to four year break crop of red clover, which is utilised by livestock. So this usually involves the re-introduction of mixed farming for arable (all crops) farms. The lower yields for some arable crops which result from the slower release from legume-derived nitrogen rather than manufactured nitrogen mean that, generally speaking, weeds, pests and diseases can be controlled by crop rotation rather than pesticides, and there you are with more or less the essential of an organic system.

Peter Melchett, Policy Director, Soil Association

Region

Region: 

Global

While some of the food system challenges facing humanity are local, in an interconnected world, adopting a global perspective is essential. Many environmental issues, such as climate change, need supranational commitments and action to be addressed effectively. Due to ever increasing global trade flows, prices of commodities are connected through space; a drought in Romania may thus increase the price of wheat in Zimbabwe.

View global articles

Source

Doc Type