Washington (AFP)
Many countries recommend limiting the consumption of red meat and cold cuts to prevent cancer and heart disease, but a review of dozens of studies by independent researchers concludes Monday that the potential risk is low and the evidence uncertain, creating a scientific storm.
In new guidelines, a panel of researchers from seven countries "advises adults to continue their current consumption of red meat," which is an average of three to four servings a week in North America and Europe. Same instruction for deli, according to these recommendations published Monday in the Annals of Internal Medicine, published by the American College of Physicians.
The group has collectively re-analyzed existing studies and believes that they show that reducing red meat consumption would lower cancer mortality by seven deaths per thousand people, which it considers to be a modest drop.
In addition, researchers describe the degree of certainty as "low" or "very low" for deli meats and cardiovascular diseases and diabetes.
"There are very low risk reductions for cancer, heart disease and diabetes, and the evidence is uncertain," says Bradley Johnston, associate professor of epidemiology at Dalhousie University in Canada. director of the NutriRECS group, who wrote the instructions.
"Maybe there is a risk reduction, or maybe not," he told AFP.
With their new analysis, researchers say they want to mature the field of nutritional recommendations, they consider representative of an "old school" who believes that any risk reduction, as small and uncertain as it is, brings societal benefits, whatever the individual tastes.
"We deliver to people our best estimate of the truth, which is uncertain." According to their own preferences, they may decide to reduce or eliminate "meat and sausage," says Bradley Johnston.
"But our recommendation is that for most people, the best approach is to continue, given the very low risk reduction and the uncertainty of the evidence."
- Scientific debate -
These guidelines have been denounced as irresponsible by cancer control organizations and public health experts. They do not dispute the statistical results but the conclusions: although the risk reduction is relatively low, but at the level of a population, the impact is tangible.
The World Cancer Research Fund has indicated that it will not change its instructions.
It's like wearing a bike helmet, says Marji McCullough, an epidemiologist with the American Cancer Society. Some people like to have hair in the wind, she wrote, but "everyone agrees that you need to wear a helmet, because public health recommendations are based on their effect on the entire population. ".
Experts at the Harvard School of Public Health challenge the "low" rating given by the authors of the new guidelines to the meat studies. Most food studies are "observational", that is, they follow people over time trying to record what they consume.
While the method does not allow to find a causal effect, compared to so-called "randomized" studies, but it is more suited to the field, they write.
If the same approach were applied to fruits and vegetables, physical activity or pollution, "none of the guidance on these factors would be supported by evidence of high or even moderate quality," they claim, defending a precautionary principle. .
Santé Publique France therefore recommends limiting the meat products to 150 grams per week and meat other than poultry to 500 grams.
The International Agency for Research on Cancer, an agency of the World Health Organization, classifies red meat as a "probable carcinogen" and charcuterie as "carcinogenic".
For John Ioannidis, professor of medicine at Stanford and a leading critic of food studies, "the way epidemiologists have fervently promoted the existence of good and bad foods for years has diverted us from simpler and more important messages, such as the need to eat in moderation and not become obese ".
"You have to be honest when the evidence is of very poor quality," he told AFP.
© 2019 AFP