Four myths about food and cancer
Some misconceptions are surprisingly persistent.
Dr Aoife Ryan looks at foods supposedly linked to the deadly disease.
1. Sugar feeds cancer...
FALSE. Although science has shown that cancer cells consume sugar, no human studies have shown that eating sugar will fuel cancer growth, or conversely that avoiding sugar will halt the growth of cancer cells.
Focusing on the fact that cancer cells consume sugar is an oversimplification of a complex process. When we eat sugar, sugary foods or any carbohydrate, it is broken down or converted to glucose in our body. Every single cell within our body then uses glucose to survive and perform their duties. There's no way to provide our body's cells with the glucose they critically need, and still 'starve' cancer cells of glucose.
In addition, cancer cells need other nutrients to survive - they don't run solely on glucose (or sugar). Diets which promote avoidance of carbohydrates for cancer patients (ketogenic or keto diets) do not have any scientific evidence from human randomised trials, and so, are not recommended for cancer patients at this time. In fact, they may do more harm by causing weight loss, which is already a common feature of cancer.
2. Artificial sweeteners?
FALSE. Extensive studies have been performed to investigate the safety of artificial sweeteners. No evidence was found to link the use of artificial sweeteners and the development of cancer.
Furthermore, as is the case for all food additives, sweeteners are regulated by the European Food Safety Authority (EFSA). This means that they undergo rigorous tests before being allowed to go on the market. They will only be allowed to go on sale if they have been deemed safe to use by the EFSA, which continually reviews the scientific evidence and re-evaluates its decisions.
Research has shown that artificial sweeteners are safe to consume up to a certain level (the acceptable daily intake) in the general population. This excludes infants and young children as the use of artificial sweeteners is not recommended.
3. How about dairy?
FALSE. There is no strong evidence to suggest a link between dairy products and increased cancer risk.
There is strong evidence that dairy products reduce the risk of colorectal cancer. Meanwhile, there is 'limited evidence' that dairy products decrease the risk of pre-menopausal breast cancer, and that diets high in calcium can decrease the risk of both pre- and post-menopausal breast cancer.
The myth that dairy is linked with cancer often comes from concerns the public have surrounding the addition of hormones to milk and meat products.
In Europe, the addition of hormones to milk or meat is strictly banned and the sale of meat from countries where the addition of hormones is allowed is also illegal. As a result, concerns over the presence of these hormones in dairy or meat products in Europe are unfounded.
4. Superfoods prevent cancer...
FALSE. 'Superfoods' are foods that are claimed to possess potent nutritional benefits that enhance health and protect against diseases such as cancer. Claims surrounding superfoods are often very misleading as they are usually based on results of studies looking at the affect of nutrients on cells in the lab. Although these studies yield important results, the findings cannot be automatically translated into our diets.
For one thing, we don't eat nutrients, we eat whole foods. A nutrient in isolation may cause a different response than if consumed within a whole food. Also, the nutrients being investigated are often studied at very high levels; levels much higher than what we would be able to eat in our diet. In reality, there is no such thing as a superfood.
Dr Aoife Ryan PhD RD, is a lecturer in Nutritional Sciences at UCC and a registered dietitian