Substantial gaps exist in International Agency for Research on Cancer's evaluation of meat and potential cancer risk

OTTAWA, May 7, 2016 /CNW/ - Following a highly debated report by the International Agency for Research on Cancer (IARC), which underscored a relationship between red and processed meat and cancer, Dr. David Klurfeld says the evidence is not adequate for valid conclusions.

Reviewing agents for their carcinogenicity is part of IARC's mandate for the World Health Organization (WHO). Their report was issued in October 2015. Dr. Klurfeld, the National Program Leader for Human Nutrition in the Agricultural Research Service at the U.S. Department of Agriculture, and an IARC Working Group member, presented his research at the Canadian Nutrition Society Conference held today in Gatineau-Ottawa.

Dr. Klurfeld emphasized that while certainty is not essential when making public health decisions, certain standards of evidence must be met. Evidence should include data on human dietary exposure and risk of disease, animal studies, and validated mechanistic studies.

According to Dr. Klurfeld, the decision to rank red meat in Group 2A (probably carcinogenic to humans) and processed meat in Group 1 (carcinogenic to humans) was driven primarily by observational studies and further supported by inconclusive potential mechanisms.

"Observational studies of weak associations should be viewed skeptically, particularly in dietary surveys that include substantial confounding and bias," he said. Confounding occurs when the study results are influenced by other factors. For example, smoking, alcohol intake, lack of exercise or poor overall diets can increase risk of chronic disease.  

His report notes that the Working Group ignored two large trials of low fat diets that reduced red and processed meat but found no reduced risk of colon cancer or polyps. Further he notes that most studies evaluated by IARC used only a single baseline questionnaire with a follow-up that assumed food intake did not change, and could not accurately estimate protein or energy intake.

"Considerable uncertainty remains about the relationship of any dietary factor with cancer," he added.

SOURCE Canadian Meat Council

Nic Canning, Smithcom Ltd., 413-992-7187, [email protected]