October 22, 2018

expert reaction to organic food and cancer relationship

Research published in JAMA Internal Medicine shows that a higher frequency of organic food consumption was associated with a reduced risk of cancer.

A Before the Headlines accompanied this Roundup.

Prof Tim Spector, Professor of Genetic Epidemiology at King’s College London, said:

This is a solid observational cohort study from France and one of the largest to look at organic foods and cancer risk. It has all the usual biases of observational studies. It suggests a small but significant reduction in some common cancers in heavy organic plant eaters. The data is most convincing for non-Hodgkin lymphoma because two previous studies showed the same preventive effects. The data suggest (but do not prove) that eating organic plants low in herbicides and pesticides may modestly reduce risk of cancers. This should stimulate greater scrutiny of the safety of these widely used chemicals in our foods which could have effects directly or indirectly via our gut microbes.”

Prof Tom Sanders, Professor emeritus of Nutrition and Dietetics at King’s College London, said:

“This an observational study, not a controlled trial. The participants who reported eating organic food most frequently were more likely to be non-smokers, had a lower body mass index (less obesity) and drank less alcohol – all factors that would be expected to result in fewer cases of cancer in this group. There were no significant differences in common sites of cancer such as those of the breast, prostate or colon but there was a lower risk of lymphomas.

“Lymphomas can be causes by viruses (e.g. Hodgkin’s lymphoma) but can also be caused by chronic inflammation (e.g. coeliac disease) as well as some chemicals (certain weedkillers). This finding of a lower incidence of non-Hodgkin’s lymphoma is similar to findings in a UK study.

“Although this present study tried to adjust for known risk factors in the statistical analysis, residual confounding is still likely. Consequently, it is uncertain whether this effect is due to lifestyle differences in people who chose organic food or their lack of exposure to chemicals in non-organic food. Furthermore, the number of cases of non-Hodgkin’s lymphoma was small in relation to the more common causes of cancer.

“Their conclusion, that promoting organic food in the general population could be a promising cancer preventive strategy, is overblown.”

Prof Tim Key, Professor of Epidemiology at the University of Oxford, said:

“The observation that people who chose more organic food had a lower risk for non-Hodgkin lymphoma is based on small numbers but is similar to the findings of the only previous prospective study of organic food  and cancer risk (the Million Women Study in the UK), therefore this possible link deserves further research, for example on pesticides.”

* ‘Association of Frequency of Organic Food Consumption With Cancer Risk – Findings From the NutriNet-Sante Prospective Cohort Study’ by Julia Baudry et al. was published in JAMA Internal Medicine at 4pm UK time on Monday 22 October.

Declared interests

None received.