Doctor who survived breast cancer names ‘three food types’ linked to disease

Dr Liz O’Riordan was a noted specialist breast cancer surgeon for many years, but was herself diagnosed with stage 3 breast cancer in 2015

Dr Liz O’Riordan, a specialist in breast cancer treatment who was herself diagnosed with the disease, has offered a unique perspective on cancer.

In 2015, Dr O’Riordan was diagnosed with stage 3 breast cancer. Despite undergoing a mastectomy and chemotherapy, the disease returned in 2018.

A regrettable side effect of her treatment was a loss of function in her left arm, leading to her retirement from surgery. She now dedicates her time to writing and public speaking.

In her latest book, The Cancer Roadmap, Dr O’Riordan delves into recent research on bowel cancer and highlights three types of food that we should consider avoiding.

Red meat

She states that there are “only three food types directly linked to to cancer formation”, identifying red meat, processed meat, and certain ultra-processed foods as potential culprits in cancer cases.

In her book, she notes: “Red meat, like beef, lamb, pork and venison, has been classified as a Group 2A carcinogen. This means there is convincing evidence to show that it probably causes bowel cancer.”

However, Dr O’Riordan emphasises that it’s not necessary to completely eliminate red meat from your diet. As a guideline, she suggests consuming red meat no more than three times a week, with a maximum weekly intake of about 250g.

Processed meat

However, while red meat should only be eaten in moderation, processed meat carries a significantly higher risk: “Processed meat has been classified as a Group 1 carcinogen,” Dr O’Riordan says. “That means that processed meat definitely causes cancer – in particular bowel cancer.”

Processed meats include tasty treats such as ham, bacon, salami, chorizo and frankfurters.

She goes on to explain that, even though processed meat is classified in the same group as tobacco and alcohol, that doesn’t mean it’s as dangerous. The classifications simply relate to how certain scientists are that the substance is associated with the onset of cancer.

Dr O’Riordan says that the risk of bowel cancer increases by 1.18 times for every 50 grams of processed meat you eat per day. While a fondness for the odd rasher of bacon may not cause much in itself, she says, when combined with other risk factors, the threat can be significant: “If you are overweight, drink alcohol and don’t exercise as well, it can all add up.”

Ultra-processed foods

Ultra-processed foods [UPFs] carry the greatest threat of all, Dr O’Riordan says. A 2023 study found that people who ate the most UPFs had a 10% increased chance of developing cancer in their lifetime.

She says that not all UPFs carry the same risk: “It was only animal-based products and artificially sweetened drinks that increased the risk,” Dr O’Riordan writes: “Breads, cereals and plant-based UPFs had no impact.”

Dr O’Riordan provides an example, stating “if a woman lives until she’s 80, her lifetime risk of getting cancer is 40%. If she ate a lot of UPFs, her risk increases from 40% to 44%. That’s an extra four in 100 people who would get cancer if they regularly eat a lot of UPFs.”

She further explains that the authors of the studies have admitted that they can’t conclusively prove that UPFs are the sole cause of the increase in cancer rates: “There may be other factors at stake,” she says, “And there are lots of different types of UPF. Not all of them are bad for us.”

A gourmet burger made in a high-end restaurant is vastly different from one you might purchase from a fast-food takeaway, which again differs greatly from the kind of budget burger you might pick up from a supermarket freezer.

In an ideal world, we’d all be preparing our own burgers, buns and sauces from scratch at home, she adds. But in our fast-paced society, that’s not always feasible.

The key is to understand the risks, and keep them in mind when planning your weekly shop. For more information about cancer, visit the NHS website.