Diet and lifestyle strategies for cancer prevention
By Dr Shireen Kassam, Consultant Haematologist and Lifestyle Medicine Physician
Cancer rates continue to rise and result in almost one in six deaths globally. In the UK, one in two people will develop cancer during their lifetime. Yet more than 40% of cases could be prevented if modifiable risk factors were addressed.
This article summarises the best strategies for lowering cancer risk. Remember, this does not mean you can lower your risk to zero, it just means that you can shift the odds in your favour. Most studies relating to lifestyle focus on the commonest cancer, that is, lung, breast, prostate and colorectal cancers. However, much of our knowledge can be applied to other less common cancers too.
Eat a diet rich in healthy plant foods
One in 20 cancers are thought to be due to an unhealthy diet, although this estimate may be as high as a third of all cancer. The best available evidence demonstrates that adhering to a plant-based diet, centred around fruit, vegetables, whole grains, beans, nuts and seeds, whilst being low or absent in animal-sourced foods and ultra-processed products, is associated with a significantly lower risk of cancer. This is supported by the fact that people following meat free diets, vegetarians and vegans, have a significantly lower risk of cancer, with some studies demonstrating greater benefits for those on a 100% plant-based or vegan diet. Plant-based diets are particularly beneficial for reducing the risk of cancer affecting the gastrointestinal tract. However, diet quality matters. Plant-based diets high in refined grains, processed foods and sugar do not afford the same benefits.
The reasons for this lowering of cancer risk are the ability of a plant-based diet to address key drivers of cancer. Plant-based diets support the health of the gut microbiome and hence the immune system. They reduce inflammation and cellular stress, promote insulin sensitivity and hence glucose regulation and lower levels of growth hormones, including oestrogen and insulin-like growth factor. In addition, this way of eating avoids foods known to increase the risk of cancer, namely processed and red meat, which have been shown to directly damage DNA and hence promote cancer development. At the same time, plant-based diets are high in nutrients such as fibre, which are associated with a significantly lower risk of cancer.
Be physically active
Both aerobic and strength-building activity is associated with a lower risk of cancer. Meeting international recommendations of 150 minutes moderate aerobic activity per week and strength exercises twice per week, whilst minimising sedentary time is a good place to start. Like with all healthy habits, the more you do the better. However, recent data suggests that aiming for 7000 steps per day may be the sweet spot for better health, including reducing cancer-related mortality, with little benefit accrued from doing more.
Regular physical activity can lower the risk of at least 13 different cancers types through a number of mechanisms, including lowering insulin resistance, lowering levels of growth hormones (oestrogen and insulin-like growth factor), supporting the gut microbiome, improving immune function, reducing inflammation, improving transit of food through the gut, favourably altering the expression of certain genes and preventing the shortening of telomeres (caps at the end of chromosomes).
Nutritional supplements are not useful
The aim should be to get as many of the essential nutrients directly from healthy plant-based foods. Higher nutritional doses of certain nutrients in the form of supplements have not been shown to be useful for reducing the risk of cancer, and in fact have often had unintended, negative consequences.
The main exception is that if consuming a meat-free diet, vitamin B12 is essential in the form of a supplement or through consumption of fortified foods (e.g. plant-based dairy alternatives, nutritional yeast). Vitamin D supplementation is required for all diet patterns if sun exposure is inadequate, particularly in the winter months in the Northern Hemisphere. Whether a supplement with preformed long-chain omega-3 fats (DHA/EPA) is required for people avoiding eating fish remains an open question.
Avoid tobacco and alcohol
It is well established that smoking tobacco causes cancer and still remains the commonest cause of cancer globally. It is associated with an increased risk of at least 16 different cancers. So avoiding tobacco is essential for lowering cancer risk with numerous benefits for quitting in current smokers.
When it comes to alcohol consumption, don’t be fooled by industry marketing. There are no health benefits of drinking, even small amounts of alcohol. Alcohol consumption is a direct cause of cancer, as reiterated by the 2025 US Surgeon General’s report, and accounts for 5-6% of all cancers globally. So, there is no safe limit of alcohol when it comes to preventing cancer.
Reduce your risk of chronic conditions
An important yet overlooked focus for cancer prevention should be prevention of other chronic conditions, including overweight and obesity, cardiovascular disease, type 2 diabetes, respiratory and kidney diseases, and autoimmune and inflammatory conditions. This is because having an underlying chronic condition increases the risk of cancer, in part, because of the shared mechanisms that drive most of these conditions. In fact, obesity is now the second commonest cause of cancer after tobacco and is responsible for around 5% of all cancers. Plant-based diets, physical activity and avoiding tobacco and alcohol can also reduce the risk of these chronic conditions.
Healthy habits work in real life
Scientists have evaluated the impact of the World Cancer Research Fund cancer prevention recommendations in prospective cohort studies. The results show that participants most adherent to these recommendations significantly reduce their future risk of cancer with a dose-effect, such that the greater the adherence the greater the observed benefit.
Healthy habits benefit people with increased genetic risk
The genes we inherit contribute up to 12% of the risk of developing cancer. However, even if you are at a higher risk of developing cancer, you can significantly lower this risk by adopting healthy habits. In some studies, the higher your genetic risk the greater the impact of cancer prevention recommendations. For example, people carrying the BRCA1 and BRCA2 genes benefit from regular physical activity and people at higher risk of colorectal cancer benefit from eating a healthy plant-based diet.
It is never too late to make lifestyle changes
The good news is that it is never too late to positively impact your risk of cancer. Large studies have shown that even if you adopt healthy habits later in life, you can significantly reduce your future risk of developing cancer.
Getting started
Any action you take to adopt healthier habits, the better for preventing cancer. Here are some ideas to get you started.
1) Swap as many of your favourite recipes with meat for beans, lentils or soya. Chicken curry to tofu curry, beef chilli to bean chilli. There are so many free plant-based recipes available online. Find our meal swap ideas here.
2) Add in vegetables such as those from the cruciferous and allium family and mushrooms, which have specific anti-cancer properties.
3) Swap your dairy milk to fortified soya milk and yogurt.
4) Make fruit, nuts and seeds your go to snacks.
5) Add movement to your day such as a 20-minute walk after lunch or add some strength exercises using your own body weight to your weekly routine.
6) Try some alcohol-free drinks next time you are in a pub or bar or homemade mocktails. There are so many new delicious varieties on the market now.
7) If you smoke cigarettes, use the free NHS support services to help you to quit.
You can find further, more detailed information in our articles on breast cancer, prostate cancer, alcohol and dairy. We have factsheets on cancer prevention and bowel cancer. Get started with a healthy plant-based diet using our Plant-Based Eatwell Guide.