Does eating organic foods reduce the risk of cancer? Hard to try



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A large study published this week shows that the largest consumers of organic food in France have less developed cancer than those who do not have cancer. have never eaten illustrate the difficulty. establish a cause-and-effect relationship between food and health.

It is impossible to categorically prove in the laboratory that this or that food reduces the risk of a disease as complex as cancer.

Researchers must monitor a large number of people for a period of time and determine which of them are developing cancer, in the hope of subsequently documenting the specific behavior of those who fall. ill.

Thousands of studies on diet and various diseases have been conducted for decades. Even the biggest are sometimes called into question, like the famous work which showed in 2013 the beneficial effects of the Mediterranean diet against heart disease and that this year had been removed from a prestigious medical journal in because of methodological problems.

With respect to organic foods, only one large study had previously evaluated its effect on cancer, the Million Women Study, with 600,000 Britons in 2014. .

found differences between consumers and non-users of biologics in terms of overall cancer risk, but found a reduction in cancer risk: non-Hodgkin's lymphoma.

The new French study in which participated among others at the University of the Sorbonne at the National Institute of Agricultural Research and at the National Institute of health and to medical research is more detailed although there are fewer participants, about 69,000, mostly women.

His results were published Monday in the American magazine Jama.

The ] hypothesis means that consumers of organic products ingest less synthetic pesticides in fruits, vegetables, and cereals and thus reduce their risk, while some pesticides are suspected to be carcinogens.

inclusion, NutriNet-Santé study volunteers completed a questionnaire (income, physical activity, smoking or non-smoking, body mbad index, etc.) and declared that a biological food had been consumed in the last 24 hours.

four groups depending on the type of ingested food. Then, we counted the number of cancer cases in each group in four and a half years on average.

Of a quarter of those who reported eating a majority of organic foods, the risk of cancer was 25% lower than in the fourth part who never ate them. In absolute terms, the increase was only 0.6 percentage points, or six additional patients per 1,000 population.

"COMPLEX"

The study revealed a statistically significant correlation only for bad cancer. in postmenopausal women and for lymphoma, including non-Hodgkin's lymphoma .

The authors wanted to correct their results by taking into account that consumers of organic products were on average richer, less obese and less smokers.

But other invisible, environmental or lifestyle-related factors may also have an impact. This is the typical problem of these studies.

"People who deliberately consume organic products to the point of declaring them are probably different from others on many other aspects" to AFP Nigel Brockton ] director of investigations of the American Institute for Research Against Cancer (AICR).

This expert recommends, instead of a particular type of food, a set of practices reduce the risk of cancer : normal weight, physical activity, healthy diet, not too much red meat. ..

"The diet is a complex thing," he says. "We would never make a recommendation based on a single study, even if it is statistically significant" he adds. Pesticide traces among participants that elicited Harvard expert reviews in the same issue of Jama. The coauthor Julia Baudry told AFP that this only concerned a small subsample.

The declarative aspect of the study is also a problem for John Ioannidis professor emeritus of medicine. at Stanford, known to have claimed that most of the published studies were false.

"Most people, including myself, can not say exactly how much organic food they eat" told AFP. "The study has a 3% chance of finding something important and 97% spreading absurd and ridiculous results".

As in the case of the consumption of red meats or cigarettes, many other studies will be needed in the same direction to conclude on the effects of organic food.

Meanwhile, American Cancer Society continues to advocate the consumption of fruits and vegetables, organic or not.

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