Burnt toast and cancer – how strong is the evidence?

Toast in a toaster with a question mark

Dr Giota MitrouDr Giotra Mitrou is Director of Research Funding & Science External Relations at World Cancer Research Fund International.

There have been some interesting headlines in the news recently on how overcooking starchy foods, like toast or potatoes, can increase cancer risk. We wanted to look at how strong the evidence is.


Acrylamide and cancer

Research in animals

When starchy foods are cooked until they are a dark brown, a compound called acrylamide is formed. The Food Standards Agency in the UK has brought out some interesting guidelines that say we should avoid over-cooking starchy food to reduce our acrylamide intake, which will then reduce our cancer risk.

These guidelines were brought out in response to a survey, which found the UK population is frequently eating many foods that contain acrylamide. Animal studies have shown a link between eating these overcooked foods that contain acrylamide and cancer risk, however, these studies were in animals. Have we found the same evidence in humans?

Research in humans

We funded some research into the link between acrylamide and cancer risk on a large study of people across Europe. This involved looking into the acrylamide intake and risk of endometrial and ovarian cancers in 368,010 women from 10 different European countries. Interestingly, this study didn’t find any strong evidence for a link between eating foods containing acrylamide and cancer risk in humans.

It is clear that there are some unanswered questions on this topic and more research is needed to fully understand the link between the level of exposure to foods containing acrylamide and the risk of different cancer types.

What we recommend

We know that more research is needed – but if you did want to reduce the level of acrylamide in your diet, the Food Standards Agency suggests that you aim for a golden yellow color when baking, toasting or roasting starchy foods like potatoes, parsnips and bread. It is also important that the food industry take notice of these guidelines when producing and preparing starchy foods.

While the debate continues as to whether we should be concerned about acrylamide – there is strong evidence that many other lifestyle factors have a significant impact on cancer risk. These include not smoking, maintaining a healthy weight, avoiding alcohol and getting enough physical activity.

This means that are some simple steps that individuals can take to reduce their cancer risk, but as for burnt toast – the jury remains out.