Cancer Research UK           October 1, 2014 
There are often stories in the media about specific foods that are meant to be particularly good for us. But you shouldn’t rely on so-called 'superfoods' to reduce the risk of cancer. They cannot substitute for a generally healthy and balanced diet.
Eating any one specific food is unlikely to have a major impact on preventing cancer, or any other diseases for that matter. But eating a healthy and varied diet is a great way of helping to reduce your risk.
What are 'superfoods'?
The term ‘superfood’ is used to describe foods with apparently special health-related powers. These include blueberries, broccoli, garlic, raspberries, green tea and many more. Typically, such foods are hailed as having the power to prevent or even cure many diseases, including cancer.
But the term ‘superfood’ is really just a marketing tool, with little scientific basis to it. It’s certainly true that a healthy diet can help to reduce the risk of cancer but it is unlikely that any single food will make a major difference on its own.
What the science tells us
Many so-called ‘superfoods’ contain natural chemicals that have been shown to have positive health effects in laboratory studies. These include antioxidants, vitamins and minerals. It is true that some of these ingredients can affect cancer cells in a laboratory setting, including killing them and stopping them from growing.
However, this is a long way from saying that eating these foods will have the same effects. There are several reasons why 'superfoods' might not have the same effects in actual people as their individual ingredients do in a laboratory experiment.
Human beings are very complex. The interactions between the food we eat and our bodies are much more complex than those between a purified chemical and cells in a tube.
Foods contain many chemicals. Laboratory studies are usually carried out using a purified ingredient from a particular food. So if researchers want to test the effect of an antioxidant contained in blueberries, they will use a purified version of that chemical rather than fresh blueberries. But our diets are made up of hundreds of different types of food with thousands of different nutrients. An isolated chemical may behave very differently in a test tube than when it is eaten as part of food.
The dose may be different. Often, scientists have to use very large doses of these purified compounds to see any effects in their studies. Typically these doses are much higher than what we would actually get in our diet. So even eating very large portions of a ‘superfood’ might not provide enough of a specific ingredient to a sufficient amount to have any effect on our health.
Opening the door to more research 
Laboratory studies on nutrients in our food are opening the way for more scientific research. We are funding studies to understand how the chemicals in some foods affect cancer cells. This could form the basis of potential new cancer treatments.
We are funding Prof William Steward and his research team to look at the curry spice curcumin, which could be useful in stopping cancer cells from developing. We are funding early-stage research to see whether high doses of this chemical are tolerated in humans and whether the cancer-preventing effects remain. Again, this doesn’t mean that curry can help to prevent cancer, since curcumin is just one of the chemicals in a curry.
We are also funding Prof Peter Sasieni, to study a supplement called di-indolylmethane (DIM) in a clinical trial called CRISP-1. DIM is found in vegetables such as broccoli, cauliflower or cabbage and has the potential to prevent cervical cancer
Why you should not rely on 'superfoods' to reduce your risk of cancer
We know that eating a healthy balanced diet can help you to reduce your risk of cancer. So-called ‘superfoods’ can certainly play a role but they are unlikely to give you added health benefits over and above what you would get from eating a varied and healthy diet.