I’M AN ONCOLOGIST. THESE SIMPLE HABITS CAN HELP REDUCE YOUR CANCER RISK
Our biweekly series The Expert View brings you specialist health advice from professionals. In this article, we hear from Professor Robert Thomas, a consultant oncologist at Bedford and Addenbrooke’s Hospitals.
While it’s impossible to pinpoint the exact causes of cancer, most of us know the basics when it comes to reducing our risk: eat plenty of fruit and vegetables, exercise regularly and wear suncream. We also know the biggest culprits, such as smoking and drinking too much alcohol, and accept the things we can’t control, like family history.
But a growing body of research suggests there are other, more surprising, habits that may also influence our risk – from how long we spend sitting to how well we sleep. So which everyday behaviours are worth paying more attention to?
Stand up every 30 minutes
Growing evidence suggests it’s a good idea to break up your day with short bursts of activity. Sitting itself isn’t harmful, but staying put for hours at a time can impair glucose regulation, insulin sensitivity and normal metabolic function. Over time, these changes may contribute to chronic low-grade inflammation and hormonal imbalances, which are thought to increase cancer risk.
In a recent study of more than 90,000 Britons, each additional hour spent sitting, reclining or lying down was associated with a 9 per cent higher risk of dying from cancer. Those who were most sedentary were more likely to develop obesity-related cancers, including cancers of the oesophagus, liver, breast and kidney.
Fortunately, replacing just one hour of sedentary time each day with light physical activity was associated with a 12 per cent lower risk of cancer death.
And you don’t need to do it all at once. I encourage my patients to walk a lap of the office, climb a few flights of stairs or simply make a cup of tea. At home, use the advertisement break as your cue to stretch, potter around the house or spend a few minutes in the garden. Those small bursts of movement soon add up.
Head outside first thing
We often hear about the benefits of walking after a meal for digestion and blood sugar control, but getting outside soon after waking has advantages too.
Long-term disruption of the body’s circadian rhythm – as experienced by many shift workers – has been linked to a higher risk of several cancers, including breast, prostate and bowel cancer. But you don’t need to work nights to disrupt your body clock. Spending little time outdoors, particularly in the morning, can weaken the natural light signals that help keep your circadian rhythm on track.
Exposure to morning light helps reinforce your body clock, promoting a healthy sleep-wake cycle and supporting melatonin production later that evening. That could mean a brisk walk, a gentle jog or simply a few minutes of stretching in natural daylight.
If you’re already heading outside for a morning walk or jog, you could also choose to do it before breakfast to maximise the potential health benefits. Extending your overnight fast to around 13 hours and exercising before your first meal encourages your body to draw more on stored fat for fuel and may improve insulin sensitivity and blood sugar control. Depending on your overall diet and lifestyle, it may also help with weight management.
In fact, I always try to make time for a fasted walk around my neighbourhood first thing in the morning. There’s no strong evidence that exercise before breakfast directly lowers cancer risk. However, maintaining a healthy weight, good metabolic health and regular physical activity are all associated with a lower risk of several cancers.
Eat something fermented every day
Researchers are increasingly interested in the role gut health may play in cancer prevention. The strongest evidence is for eating plenty of fibre, which nourishes beneficial gut bacteria and is consistently linked with a lower risk of bowel cancer.
Scientists are also studying how certain healthy bacteria in fermented foods can support cancer patients. These bacteria help the gut and immune system, while reducing “oxidative stress” – a chemical imbalance that damages DNA.
By contrast, a diet high in ultra-processed foods (UPFs) and low in fibre can disrupt the gut microbiome and promote chronic inflammation, which is thought to contribute to cancer development.
I encourage many of my patients to include a fermented food in their daily diet. Live yogurt and kefir are excellent choices, alongside traditionally fermented foods such as kimchi or sauerkraut. But they shouldn’t replace the basics. A diet rich in vegetables, legumes, whole grains, nuts and seeds remains the cornerstone of good gut health, with a target of at least 30g of fibre a day.
Add herbs and spices to your meals
A colourful diet provides phytochemicals – naturally occurring plant compounds responsible for the taste, colour and aroma of many fruits, vegetables, herbs and spices.
Researchers believe these compounds may help protect cells by reducing inflammation, neutralising harmful free radicals (unstable molecules) and supporting normal cell function. Carotenoids, found in brightly coloured vegetables, and isothiocyanates, found in cruciferous vegetables such as broccoli, cabbage and kale, have both been associated with lower rates of certain cancers in population studies.
One of the easiest ways to increase your intake of phytochemicals is to cook generously with herbs and spices. Turmeric, cinnamon and cloves are particularly rich sources of beneficial plant compounds, while herbs such as oregano, rosemary and thyme can add flavour as well as nutritional value.
I focus on getting a wide variety of plant compounds through my diet, but I also take a daily phytochemical supplement (YourPhyto) to help top up my intake. I don’t take a range of other supplements, as many have limited evidence to support their use.
Floss every morning
Good oral health isn’t just important for your teeth. A growing body of research has linked gum disease and poor oral hygiene with an increased risk of several cancers, particularly those affecting the head, neck and the digestive system.
The reasons aren’t fully understood, but chronic inflammation and changes to the oral microbiome are thought to play a role. Studies have linked a history of gum disease and tooth loss with a higher risk of oesophageal cancer, potentially because harmful bacteria in the mouth produce carcinogenic compounds such as nitrosamines – although this doesn’t necessarily mean one causes the other.
Daily flossing helps remove plaque and bacteria from between the teeth, reducing the risk of gum disease. Brushing twice daily, attending regular dental check-ups and flossing every morning are simple habits that may benefit your overall health – not just your teeth.
If you use mouthwash regularly, I encourage my patients to choose an alcohol-free version. It is less likely to irritate the tissues in your mouth and may be kinder to your oral microbiome than alcohol-containing alternatives.
Go easy on the barbecued meat
A bacon sandwich or a blackened barbecue sausage may be tempting, but regularly eating processed and heavily charred meat is associated with a higher risk of bowel cancer.
Cooking meat at very high temperatures produces chemicals known as heterocyclic amines (HCAs), while fat dripping onto flames creates smoke containing polycyclic aromatic hydrocarbons (PAHs). Both have been shown to damage DNA in laboratory studies. Processed meats may also contain N-nitroso compounds, another group of chemicals thought to contribute to cancer risk.
Processed meat is classified by the World Health Organisation as a Group 1 carcinogen, meaning there is strong evidence that it causes cancer in humans, particularly colorectal cancer. Red meat is classified as a Group 2A, or probable carcinogen.
That doesn’t mean you can never enjoy a barbecue. But it’s sensible to limit processed meat, avoid heavily charred portions where possible and include more plant-based meals throughout the week.
Don’t forget about your skin
The link between ultraviolet (UV) radiation and skin cancer is well established. Just a handful of severe blistering sunburns over a lifetime can substantially increase the risk of melanoma.
Whenever you’re spending time outdoors, wear a broad-spectrum sunscreen with an SPF of at least 30, reapply it every two hours if you’re outside for prolonged periods, and seek shade during the hottest part of the day.
If you do get sunburnt, cool the skin and apply a gentle moisturiser to help relieve discomfort while it heals. Some early laboratory research also suggests that olive oil-based aftersun products may help reduce UV-related DNA damage in skin cells, although more research is needed to determine whether this translates into meaningful benefits for people.
Ultimately, no single habit will eliminate your cancer risk. But making small, sustainable changes over time can collectively make a meaningful difference. Staying active throughout the day, eating a predominantly Mediterranean-style diet rich in plant foods, maintaining a healthy weight, protecting your skin, looking after your oral health, avoiding smoking and prioritising good sleep all help to stack the odds in your favour.
As told to Ella Nunn
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