Does eating heavily heated or charred food increase your risk of cancer?
Heavily heated or charred meat likely increases the risk of certain types of cancer, although the associations in humans are associative. By not charring meat and varying cooking methods, you can substantially reduce your exposure to these substances.
Heavily heated meat, such as grilled, fried or barbecued meat, produces small amounts of carcinogenic substances: heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons. The higher the temperature and the longer the cooking time, the more of these substances are formed. In animal research, HCAs demonstrably cause tumours in multiple organs in mice and rats.
In epidemiological research in humans, researchers observe associations with various types of cancer. For colorectal cancer: case-control studies link well-done red meat to an increased risk of colorectal polyps, which can develop into colorectal cancer, although results are sometimes contradictory. For pancreatic cancer the findings are somewhat more concrete: a large cohort study with more than 537,000 participants found a 40 to 50% higher risk in men with the highest intake of grilled or well-done meat. In women, that association was less clear. A specific HCA called PhIP has been linked to breast cancer in women in both animal experiments and epidemiological research. An association with lung cancer has also been found, but that finding stands on its own and requires replication.
Whether you yourself are at risk depends strongly on how your body processes these substances. The amount of HCAs to which people are exposed can already differ by more than 200-fold, depending on how often and how well-done you eat meat. On top of that come hereditary differences in the way your body breaks down these substances and repairs DNA damage. These can influence the ultimate risk by as much as a factor of ten.
Acrylamide, another substance formed when carbohydrate-rich products such as crisps or toasted bread are heated, is also carcinogenic in animal experiments. Whether the amount that people ingest through their daily diet truly causes cancer was, at the time of the available studies, still insufficiently investigated epidemiologically to draw conclusions.
If you want to reduce your exposure, it helps to avoid burning or charring meat, to limit cooking temperatures and to alternate grilling with steaming or boiling. This substantially lowers the amount of HCAs in your food.
Evidence is based on reviews, case-control studies and one large prospective cohort study (NIH-AARP, n>537,000). There are no randomised studies (which are not feasible for this type of question for ethical and practical reasons). Associations in humans are associative; formal causal evidence for cancer in humans is lacking, although mechanistic and animal evidence is strong.
Does eating a lot of sugar increase my risk of cancer?
Drinking large amounts of sugar-sweetened beverages is associated with a noticeably higher risk of certain cancers, particularly early-onset colorectal cancer and liver cancer. The association is observational, but consistent enough to make reducing soft drinks and fruit juice a concrete point of attention.
Does being overweight increase my risk of cancer, and if so, which types?
Excess weight increases your risk of at least 13 types of cancer, including uterine, colorectal, breast and liver cancer. Losing weight reduces that risk, although it remains unclear whether all methods of weight loss are equally effective for immune defence against cancer.
Does eating from plastic packaging increase your risk of cancer?
There is clear evidence that substances that leach from plastic, such as BPA and PCBs, are associated with cancer; for micro- and nanoplastics that evidence in humans is still lacking. Limit your exposure where you can, especially when heating food in plastic containers.
Does red and processed meat really increase your risk of colorectal cancer?
Multiple large studies consistently show that high consumption of red meat, and especially processed meat, raises the risk of colorectal cancer. The evidence is strong enough to warrant consciously limiting your intake of processed meat (sausage, bacon, deli meats).
Does sitting a lot increase my risk of cancer, even if I exercise?
Sitting a lot increases your risk of certain cancers, even if you exercise. In addition to moving regularly, try to reduce your sitting time itself, because the two only partially compensate for each other.
Does a large belly increase my risk of cancer more than being simply overweight?
A large belly increases the risk of several cancer types more than being simply overweight, especially in men. Having your waist circumference measured is therefore more meaningful than paying attention only to the scales.