Apples are a good source of fibre and vitamin C – both vital for general good health. But when it comes to fighting off cancer, it's thought the key component may be quercetin, a naturally occurring chemical that can dampen down inflammation in the body and stop cells decaying.

Other similar cancer-fighting chemicals, such as triterpenoids, are found mainly in the skin, which is why some experts believe it's better to eat the whole fruit rather than peel it.

A 2016 study in Italy found eating at least one apple a day could potentially cut the risk of lung cancer by 25% and also offer protection against tumours of the bowel, mouth and breast.

2 Tomatoes

The humble tomato is packed with dietary goodness. But when it comes to cancer, the key ingredient is thought to be lycopene – an antioxidant that gives juicy red tomatoes their distinctive colour. What's unusual is that unlike some other processed foods, tomato-based products like passata and ketchup, which use large amounts of concentrated tomato, are thought to have even higher amounts of lycopene.

Numerous studies suggest the antioxidant can reduce a man's risk of prostate cancer although it's still not certain how much is needed to have an effect.

3 Coffee

A major study in 2019 of almost half-a-million people found a daily coffee could potentially halve the risk of a common type of liver cancer.

The study, by scientists at Queen's University Belfast, showed coffee lovers were 50% less likely to get hepatocellular carcinoma, which accounts for roughly nine out of 10 cases of liver cancer. The coffee bean also contains polyphenols, plant chemicals which appear to stop cancer cells dividing.

But be warned – the content may be slightly lower in decaffeinated coffee. Instant coffee, meanwhile, has fewer disease-fighting antioxidants than the freshly brewed variety.

4 Brown rice

This is one of many types of wholegrains – others include oatmeal, wholemeal bread and corn. Wholegrains are known to be good for promoting general health – particularly cardiovascular health – but they may also have a protective effect when it comes to cancer.