New research suggests a plant-based diet can cut cancer risk by a quarter – but you don’t have to quit meat entirely to reap the benefits.
For those among us who love meat, there’s nothing more annoying than the virtue-signalling vegetarians ranting about the benefits of a plant-based diet.
So it might be disappointing to learn that yet another study has added grist to the mill.
Scientists at Loma Linda University in California found that vegans have a 24% lower risk of developing any cancer compared with meat eaters following a similar lifestyle.
The researchers analysed data from an eight-year study of more than 70,000 Seventh-day Adventists. Around half were vegetarian, including vegans and those who ate dairy and eggs.
“The study builds on what we already know,” says Dr Helen Crocker, assistant director of research and policy at the World Cancer Research Fund International (WCRF). “Red and processed meat are strongly linked to bowel cancer, while plant-based diets are rich in fibre and nutrients that help lower overall cancer risk. Vegetarians also tend to have a lower body weight, which is protective.”
But what if we’re not ready to ditch the bacon sandwiches?
“You can reduce your cancer risk without giving up meat,” Crocker says. “The more you follow WCRF recommendations – eat more plant foods and fibre, avoid processed meat and reduce red meat – the lower your risk will be. Even making some of these changes brings benefits.
“Diet is only one part. Maintaining a healthy weight, staying physically active, limiting alcohol and avoiding smoking are all important, alongside diet.”
Here are six science-backed diet strategies to reduce your cancer risk.
Stick to three portions of red meat a week
You don’t need to give up Sunday roasts and beef lasagne – but keeping red meat in check is key.
“We have strong evidence that eating any amount of processed meat, and higher intakes of red meat, increase risk of bowel cancer,” says Raffaella Masselli, a dietitian and health information officer at the WCRF.
“Cooking red meat at high temperatures produces compounds called heterocyclic amines and polycyclic aromatic hydrocarbons linked to colorectal cancer,” explains Masselli. “Processed meats often contain nitrate and nitrite preservatives, which can form cancer-promoting substances, disrupting the bowel lining.”
It’s estimated the risk of bowel cancer rises by 16% for every 50g of processed meat eaten daily – just two slices of ham, or a single sausage. Regularly eating a lot of processed meat, often high in calories and saturated fat, can cause weight gain over time – increasing your risk of 13 types of cancer.
“Aim to avoid processed meat altogether, and limit red meat to three, palm-sized portions a week – around 350-500g cooked weight in total,” says Masselli. “Have a couple of meat-free days a week, switch beef mince for turkey, or bulk out a Bolognese with pulses.”
Cooking method matters too. “Stewing, roasting or steaming is better than frying or grilling at high temperatures,” she says. “If you barbecue, marinate meat first – it helps create a protective layer against the heat.”
Fill three-quarters of your plate with fresh produce
Whether you eat meat or not, the most protective diet is plant-rich – with plenty of fruit, vegetables, wholegrains and legumes, and less processed foods.
“People who eat the most meat often consume fewer plant foods, which is also linked to increased cancer risk – it’s a double hit,” says Dr Frederica Amati, head nutritionist at UK-based wellness company ZOE.
A ZOE study of 21,000 people, published in Nature Microbiology, found meat eaters generally had higher levels of gut bacteria linked to inflammation and colorectal cancer. But those who ate more plant foods had a microbiome composition similar to vegans, with higher levels of protective bacteria.
“Plant-based diets are naturally higher in fibre, antioxidants and compounds that keep inflammation in check and protect against DNA damage,” Amati says. “Chronic inflammation can create ideal conditions for cancer.”
Aim for 30 different plant foods a week, she advises. “The more you eat, the less room there’ll be for meat, and the more protective compounds you’ll consume.”
The WCRF recommends filling three-quarters of your plate with wholegrains, vegetables and pulses and the rest with fish, poultry or a small portion of red meat.
Pour live yogurt on your cereal
Good news for dairy lovers: you don’t need to ditch milk and cheese. Studies suggest they may even help protect against bowel cancer, thanks in part to calcium.
Fermented dairy products, such as yogurt and kefir, seem particularly useful, says Dr Sammie Gill, specialist gastroenterology dietitian and spokesperson for the British Dietetic Association.
A review of 61 studies involving 1.9 million people, published in the International Journal of Cancer, linked fermented dairy to a lower cancer risk. Another review of 17 studies found yogurt and cheese may be protective against colorectal cancer.
“The gut microbiome has emerged as a key factor shaping cancer risk,” Gill says. “Fermented dairy contains live microbes that can influence the microbiome and immune response, reducing inflammation.”
Laboratory studies suggest kefir may even suppress tumour growth, thanks to antioxidant and anti-inflammatory compounds.
Try pouring yogurt or kefir onto your cereal, adding it to soups and sauces, or mixing it into mashed potatoes and cooled rice, Gill suggests.
Add beans to your stews
Next time you’re making a chilli or shepherd’s pie, throw in some pulses such as beans or chickpeas. The extra fibre could save your health.
“Higher fibre intakes are associated with lower risk of several cancers,” Gill says. “For every extra 7g a day – half a can of baked beans – you cut your risk of colorectal cancer by 8%.”
A major study in The Lancet found fibre-rich diets reduced colon cancer by up to 24%. Yet most of us manage only half the recommended 30g a day.
Fibre is found in all plant foods – fruit and veg, legumes, wholegrains, nuts and seeds. “Different fibres act differently in the gut,” Gill says. “For example, resistant starch in bananas, cold rice and potatoes is broken down by gut microbes and releases the short-chain fatty acid, butyrate, shown to inhibit tumour cell growth.”
Fibre keeps food moving through the gut, so carcinogens don’t linger, and helps with weight control – another cancer risk factor.
Sneak in extra fibre where you can. “Add veggie toppings to pizza, throw frozen veg into stir fries, or snack on unsalted popcorn, dried fruit and nuts,” Gill advises.
Finely slice your leafy greens
Dark, leafy greens are among the most powerful cancer-fighting foods – but how you prepare them determines the benefits.
Broccoli, kale, cabbage and other cruciferous vegetables contain sulforaphane, a compound that lab studies suggest can reduce inflammation, protect DNA, slow cancer cell growth and even deactivate carcinogens.
A study in the Journal of the American Medical Association found post-menopausal women who ate two daily servings of cruciferous veg had a 20-40% lower risk of breast cancer.
“While more research is needed, consuming a variety of these vegetables is a positive step,” says Tiphaine Boulin, a nutritionist and senior scientific research officer at Breast Cancer UK.
But there’s a catch: cooking destroys the enzyme that triggers sulforaphane. To preserve it, chop your greens an hour before cooking so the reaction has time to take place. The finer you chop, the better.
Lightly steaming or stir-frying preserves the sulforaphane better than boiling, says Boulin. Alternatively, add a pinch of mustard powder to cooked greens (it contains the same enzyme), or eat them raw as crudités. One study found raw broccoli contained 10 times more sulforaphane than boiled.
Snack on walnuts
Swapping crisps for a handful of walnuts a day could be a surprisingly powerful defence.
A new study in Cancer Prevention Research found adults who ate 28g of walnuts a day for three weeks before a colonoscopy had lower inflammation markers and beneficial changes to colon polyps which can be precursors to cancer.
“Walnuts are an exceptional source of health-promoting compounds called ellagitannins,” says Dr Daniel Rosenberg, professor of medicine at the University of Connecticut. “These are broken down by the gut microbiome into urolithin A, thought to reduce inflammation and lower colon cancer risk.”
Long-term data backs this up. In the large Predimed study, people who ate more than three 28g servings of walnuts a week had a 40% lower risk of dying from cancer.
“Walnuts are the only nut rich in omega-3 ALA, and a handful provides 4g of plant-based protein, plus fibre, calcium, vitamin E and other nutrients,” says Dr Rachel Blaine, scientific advisor to the California Walnut Commission.
Eat a rainbow
Loading your plate with colour – from blueberries and raspberries to mango and sweet potato – delivers a broad spectrum of protective nutrients.
“It’s the combination that counts, rather than any single nutrient,” Crocker says. “So, the more variety you eat, the better.”
Phytochemicals give fruit and veg their distinctive colours and, when eaten, act as antioxidants that reduce disease risk. Lycopene in tomatoes protects against prostate cancer, while anthocyanins in blueberries and aubergines promote cellular renewal.
“Red, orange and yellow varieties - like peppers, carrots and apricots – are rich in carotenoids which can lower breast cancer risk, particularly oestrogen receptor-negative types,” says Boulin. “They help protect breast cells from DNA damage and reduce cell proliferation. Aim for at least three different colours on your plate each day.”
The WCRF recommends at least five servings (400g or 15oz) of fruit and non-starchy veg a day.