5 diet and cancer myths debunked

A man with a puzzled expression

From organic food to artificial sweeteners, our experts separate fact from fiction regarding what you should – or should not – be eating

1. Will I benefit from eating organic foods?

Organic fruit and vegetables are grown without using artificial fertilisers, pesticides or other chemicals. Although organic foods are often more expensive, they’re becoming increasingly popular because of media claims that organic produce is more nutritious and that artificial fertilisers and pesticides may increase the risk of some diseases, including cancer.

However, there is currently no strong evidence to support the idea that organic foods can help protect against cancer compared with produce that is grown conventionally. The UK has regulations on the amounts of pesticides in food to make sure that their levels are well within safe limits.

So when it comes to eating well for cancer prevention, the bottom line is to enjoy fruit, vegetables, wholegrains and pulses however you can – fresh, frozen, canned, conventional or organic are all good for you!

2. What are superfoods and will they lower my risk of cancer?

Superfoods are a group of particular foods that are claimed to provide health-enhancing benefits, including protecting against cancer – it is said that they contain higher amounts of particular nutrients compared with other foods. However, more often than not, research studies use levels of nutrients that can’t be replicated in real food. For cancer prevention, it’s the overall balance of our diet and lifestyle that’s important.

Based on the most recent evidence, we recommend eating a varied, plant-based diet, rather than eating lots of specific foods. Plant foods are a good source of nutrients that keep our bodies healthy. Aim to eat delicious plant foods, such as wholegrains, fruit, vegetables and pulses, with every meal – fill three-quarters of your plate with them and then add a smaller serving of lean meat, fish or vegetarian protein.

3. Can burnt foods give me cancer?

There are claims that overcooking starchy foods, such as toast, chips or roast potatoes, can increase your risk of developing cancer. When starchy foods, like bread or potatoes, are cooked until they are dark brown, a compound called acrylamide is formed. Animal studies have shown a link between eating overcooked foods that contain acrylamide and cancer risk. However, these studies were in animals.

We funded research into the link between acrylamide and cancer risk on a large study of people across Europe. Interestingly, this study didn’t find any strong evidence for a link between eating overcooked starchy foods that contain acrylamide and cancer risk in humans.

It is clear that there are some unanswered questions on this topic and more research is needed – but if you do want to reduce the level of acrylamide in your diet, the UK Food Standards Agency suggests that you aim for a golden yellow colour when baking, toasting or roasting starchy foods like potatoes, parsnips and bread.

4. Should I become a vegetarian to lower my risk of cancer?

There is no direct evidence linking fish or lean poultry to an increased cancer risk, so we don’t suggest cutting out meat and other animal products altogether to lower the risk of cancer. Instead, we recommend a balanced diet that includes plenty of wholegrains, pulses, fruit and vegetables, limits red meat consumption to no more than 3 portions (350–500g cooked weight) per week, and avoids processed meat.

In 2020, our researcher Prof Marc Gunter published a paper showing that eating fish decreased the risk of colorectal cancer, and we know that meat and fish can provide an important source of nutrients as part of a balanced and healthy diet. But a vegetarian diet can also be healthy providing it’s nutritionally balanced. Our advice is to follow the three-quarters/one-quarter rule by filling up three-quarters or more of your plate with plant foods and one-quarter or less with animal foods like meat, fish and dairy, or alternatives like tofu or Quorn. Eating a nutritionally balanced vegetarian diet is one way you could follow our Cancer Prevention Recommendations.

5. Do sugar or artificial sweeteners increase my risk of cancer?

There is no strong evidence to directly link sugar or artificial sweeteners to cancer risk. However, foods that are high in added sugar also tend be high in calories, and sometimes fat, without being nutritious or filling. Eating high-calorie foods too often or in large quantities can lead to weight gain, and there is strong evidence that being overweight or obese increases the risk of 12 cancers. That is why we recommend cutting down on high-calorie foods and avoid sugary drinks, and eating a healthy balanced diet that is rich in nutritious and filling foods, such as wholegrains, fruit, vegetables and pulses.


> Read more: Myths and controversies about what causes cancer