The new advice comes after a well-publicised French study suggested people who eat mainly organic food have a lower risk of cancer than those who eat little bio.
Raphaëlle Ancellin, prevention project manager at the Institut National du Cancer, said: “We cannot make recommendations based on this study alone, we need more research.
“However, the Haut Conseil de la Santé Publique is amending its diet guidance in 2019, expanding the present ‘eat more fruit and veg and cut processed food, red meat and charcuterie’ to a more complete message: eat more fruit, veg and whole grains, be environmentally aware and buy local, buy seasonal and possibly organic.”
The study, of nearly 70,000 people, found a 76% reduction in lymphoma blood cancer risk – one of the most common cancers in farm workers who have a higher exposure to pesticides – and a 34% reduction for post-menopausal breast cancer.
There are limits on the work by Emmanuelle Kesse and the team at Université Paris 13 and the Institut National de la Santé et de la Recherche Médicale (Inserm).
It does not show organic food is the direct cause of the reduced risk as it is accepted that people who eat more organic food have healthier overall lifestyles and eating habits. The findings on lymphoma were also a small part of the overall result, so may not be statistically significant.
Dr Kesse said the “likeliest explanation” for finding a 25% reduction in overall cancer risk for organic food-eaters was “the presence of synthetic pesticide residues, more common and at higher doses in foods from conventional agriculture”.
Research agency Inra said the results suggested a diet rich in organic foods could limit cancers – but said it was not possible to identify cause and effect from a single study. It said other explanations included potentially higher levels of micro-nutrients in organic foods.
Dr Kesse study ran from May 2009 to November 2016 with 69,000 volunteers – average age 44, with 78% women – listed on the NutriNet-Santé website as ready to do food research.
A total of 1,340 cancers appeared, including breast cancer (34%), prostate cancer (13%), skin cancer (10%) and bowel cancer (7%).
There were fewer cases in people who ate mainly organic food – 269 against 360 in those eating the least organic food.
The numbers involved in the lymphoma findings were small. Fifteen people who ate the least organic food had non-Hodgkin’s lymphoma, against two among the high-organic eaters.