Scraping charred bits off toast with a knife at breakfast or cutting burnt parts from grilled pork belly at dinner has become a familiar sight in Korea. The long-held belief that eating burnt food causes cancer has solidified into accepted health wisdom. But how much of this belief is scientifically verified?
British daily The Mirror recently reignited the debate over the causal relationship between burnt food and cancer, compiling research findings reported to date. Not all "burnt food" carries the same risk—the danger level varies depending on the type of food.
'French Fry Shock' Sparked Acrylamide Fears
The controversy began in April 2002 when researchers from Sweden's National Food Administration and Stockholm University announced their findings. They reported that acrylamide, a chemical compound, was detected at high concentrations when starch-rich foods such as french fries, oven-baked potatoes, and cereals were cooked at high temperatures.
This substance forms naturally during the Maillard reaction, which creates the savory flavor and brown color in food. The researchers classified it as a "probable human carcinogen" and emphasized the need for dietary management.
The European Food Safety Authority (EFSA) heightened concerns in 2015, stating that acrylamide could potentially increase cancer risk for consumers of all ages.
Proven in Animals, Unproven in Humans
Concerns about acrylamide's dangers predated the 2002 study. The U.S. National Toxicology Program in 1991 evaluated acrylamide as "reasonably anticipated to be a human carcinogen" after finding sufficient evidence of carcinogenicity in animal studies.
However, the key issue is the actual effect on humans. The U.S. National Toxicology Program, synthesizing multiple human epidemiological studies, explained that no consistent association has been confirmed between dietary acrylamide exposure and specific cancers. Unlike animal study results, it remains difficult to conclude that acrylamide consumed at normal dietary levels causes cancer.
Fatima Saleh, associate professor at Beirut Arab University, noted: "Nearly 30 years have passed since acrylamide was classified as a 'probable human carcinogen,' but evidence supporting clear carcinogenicity in humans remains inconsistent. However, the classification could change as more human studies accumulate."
Neil Iyengar, medical oncologist at Memorial Sloan Kettering Cancer Center, also assessed that while the hypothesis exists that carcinogens can form when food is overcooked or burnt, it is difficult to view this as a definitive causal relationship. For now, it remains at the "hypothesis" level.
Acrylamide is a chemical used in various industrial processes including paper, dye, and plastic production, as well as drinking water and sewage treatment. In food, it forms when vegetables containing asparagine are heated at high temperatures with certain sugars. It is also found in tobacco smoke.
Why Burnt Meat Is More Dangerous Than Burnt Bread
Experts advise distinguishing between the burnt parts of starchy foods (bread, potatoes) and meat. Unlike acrylamide from burnt bread, grilling or charring meat over direct flame produces heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH).
These two substances have shown clear carcinogenicity in animal experiments, and some human epidemiological studies have reported they increase the risk of colorectal cancer and other cancers.
The International Agency for Research on Cancer (IARC) under the World Health Organization (WHO) classified processed meat as a Group 1 carcinogen and red meat as a Group 2A probable carcinogen in 2015. HCA and PAH generated during high-temperature cooking were cited as one factor explaining increased cancer risk.
The key takeaway is that not all burnt food produces the same chemicals. The substances formed and potential risk factors vary depending on the food's composition.
