Europe and international, International

Anti-oxydants, heavy metals,… : Is organic better than conventional?

18 Aug 2014

An international study coordinated by the University of Newcastle (UK) states that organic fruit and vegetables have higher levels of anti-oxydants and lower levels of heavy metals and pesticides residues. What’s about?

 University of Newcastle study conclusions

read the  study summary .

Many medias have reported and approved these conclusions.

The main points :
– The study is in fact a “meta-study” : it is based on 343 previous studies
– The main point which is underlined by the authors is a favorable profile of organic products regarding anti-oxydants levels : 18 to 69% higher
– The higher level of cadmium in conventional products would be due to the use of phosphate fertilizers which are supposed to contain more heavy metals than organic fertilizers
– Pesticides levels are  7 times lower in organic than in conventional
Total nitrogen, nitrate and nitrite levels are lower in organic than in conventional

Evaluation of this study

Genetic Literacy Project, which is linked to the George Mason University in Virginia (USA) has published « Study claiming organic food more nutritious ‘deeply flawed’, say independent scientists » . This article is a scientific press review. Many independent scientists are skeptic about methods and conclusions of the Newcastle study.
– Previously, other meta-studies has shown no significant differences. See in particular Dangour et al, « Nutritional quality of organic foods: a systematic review », published in The American Journal of Clinical Nutrition in 2010)
– The University of Newcastle is directly supported by organic industry, for example The Sheepdrove Trust. Furthermore  some authors like Charles Benbrook are well-known anti-GMO or pro-organic activists.
– The number of studies on which the meta-study is based could be misleading. On Science Media Center, Alan Dangour, London School of Hygiene & Tropical Medicine scientist, realizing that the authors had not filtered the basic studies, states : constatant que les auteurs n’ont pas trié les études prises en compte dans leur méta-étude, explique « Mixing good quality data with bad quality data in this way is highly problematic and significantly weakens confidence in the findings of the current analysis.  It is a shame that greater care was not taken in trying to ensure that the analyses were based only on reliable and scientifically robust data from satisfactory quality studies » Hank Campbell, an other scientist has the same position : read Science2.0
– Other arguments against the study are available here  on the American Council on Science and Health site.
-And, at the end and more important, the signification of the résults are widely overestimated. The nutritional composition of fruits and  vegetables depends on many other factors : fertilization, cropping time, transport and shelf conditionss, etc. With so many variability factors, a simple comparison of products, without taking care of them, is misleading.

In conclusion, Richard Mithen in Genetic Literacy Project states : « The additional cost of organic vegetables to the consumer and the likely reduced consumption would easily offset any marginal increase in nutritional properties, even if they did occur, which I doubt. To improve public health we need to encourage people to eat more fruit and vegetables, regardless of how they are produced. »

We fully agree….