6 mins. read

A plant-based diet: what it really means and how it can reduce your cancer risk

Learn how eating fruits, vegetables, wholegrains and more contributes to a healthy gut and reduces cancer risk

Key takeaways

  • What you eat and drink can make a difference to your risk of developing cancer
  • Evidence is clear that a plant-based diet is best for cancer prevention, however this doesn’t mean you can’t eat animal foods
  • A plant-based diet and healthy gut microbiome have been shown to protect against certain types of cancer, as well as benefit overall health
  • Aim to eat a wide variety of plant-based foods across the week, including vegetables, fruits, wholegrains, nuts and legumes

Most cancers develop as a result of a combination of risk factors, such as getting older and lifestyle. Scientific research from the World Cancer Research Fund (WCRF) has shown that what you eat and drink can make a difference to your cancer risk. According to the evidence, a plant-based diet, containing minimal amounts of added sugar and processed foods, is best for cancer prevention. In this article, Perci dietitian Nichola Williams explains how a healthy diet can help someone reduce their risk of developing cancer, while dietitian Jo Cunningham shares fascinating insights into how a plant-based diet supports the gut microbiome and reduces cancer risk.

What does a plant-based diet look like?

A plant-based diet simply means eating lots of fruits, vegetables, wholegrains, nuts and seeds, legumes, and herbs and spices. It doesn’t mean you can’t eat meat or other animal foods. As a rough guide, each day aim for:

  • 2–3 pieces of fruit (spread the intake out across the day)
  • 5–7 types of vegetables or salad (e.g., 3 at lunch and 4 at dinner)
  • 3 types of wholegrains (e.g., wholewheat pasta, quinoa, buckwheat, oats)
  • 1–2 portions of nuts (or nut butters) and seeds
  • 1–2 types of legumes (beans, chickpeas and lentils)
  • Herbs and spices

The role of diet in reducing cancer risk

Nichola Williams, Consultant dietitian

It’s important to state that no lifestyle can completely eliminate your risk of developing cancer, but by making healthy choices, you can significantly lower it. If we look at populations where relatively few people develop cancer, their diets are rich in wholegrains, fruits and vegetables, and they eat little to no processed foods. It’s predominantly a plant-based, anti-inflammatory diet, in which foods are eaten as close to their natural form as possible. 

Why is a plant-based diet recommended for cancer prevention?

You might have heard the saying, ‘eat the rainbow’. There’s a lot of truth in that. Some of the natural properties of fruit and vegetables have anti-cancer properties. For example, a family of compounds called polyphenols, found particularly in purple fruits and vegetables, are good for gut health, as well as having antioxidant and anti-inflammatory properties. Evidence shows that these polyphenols may play a role in preventing some diseases, including certain types of cancer. 

Zinc, selenium and folate, found in nuts, green vegetables and certain fruits, are involved in the DNA repair process, while the fibre from skins of fruit and vegetables, as well as in wholegrains, has been shown to bulk out stools, contributing to good bowel health and helping to prevent against bowel cancer.

You might have heard the saying, ‘eat the rainbow’. There’s a lot of truth in that.

Nichola Williams, Consultant Dietitian

Can you eat meat on a plant-based diet?

A great cancer prevention diet isn’t about restricting anything, but about eating in moderation. ‘Plant-based’ simply means adding in as many plant-based foods as you can into your diet. This includes fruits and vegetables, wholegrains, pulses, nuts, seeds, herbs and spices. 

You can still eat animal products if you enjoy them, and the evidence says it’s safe to do so. Lean animal foods, for example, fish and chicken, are healthy sources of protein and equally important for a cancer-prevention plate. If you are eating meat, ideally avoid processed meats, such as ham and sausages, which contain known carcinogenic (cancer-forming) properties.

The importance of gut bacteria for cancer prevention

Jo Cunningham, Perci dietitian

A landmark study by the American Gut Project in 2018 found that people who ate 30 or more plants per week had more diverse gut bacteria compared to those who had 10 or fewer plants per week. Robust evidence shows that the greater our gut microbe diversity, the better our health we will be.

What does our gut bacteria do for us?

When you have a varied, plant-based diet, you’re feeding the trillions of microbes living in your large intestine (also known as the gut microbiome). This beneficial bacteria enables us to digest our food efficiently as well as absorb vitamins and minerals effectively, contributing to improved energy and performance. It also plays a role in hormone regulation and neurotransmitter production, which are the chemicals that control our mood and contribute to looking after our mental health. 

Something else found in plants are prebiotics. These are not to be mistaken for probiotics (which are the live bacteria found within supplements or fortified foods). Prebiotics are fibres found within plants that feed the microbes. They have a scientifically proven benefit to our health, for example, improved blood sugar control, appetite regulation and immunity. 

When thinking about what to eat, remember to aim for a wide variety of plant-based foods, with plenty of different colours, textures and flavours. Without variety, our microbes may not get the fuel they need, and die off, which can impact our digestion and overall health. Nourishing your microbes will, in turn, benefit your overall health. 

How does our microbiome relate to cancer prevention?

These clever microbes have a protective role in the development of some cancers. They produce beneficial compounds known as short-chain fatty acids, which have been shown to reduce the risk of colon cancer. Recent studies also found that a diverse gut microbiome may affect how a person responds to cancer treatment – in terms of side-effects – as well as treatment success.

We know that changing your diet can be challenging. Our Cancer Nurse Specialists are knowledgeable about cancer risk and can refer you to other Perci professionals, including our dietitians.

While we have ensured that every article is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. If you have any questions or concerns, please talk to one of our healthcare professionals or your primary healthcare team.


‘Our Cancer Prevention Recommendations,’ WCRF, https://www.wcrf-uk.org/preventing-cancer/our-cancer-prevention-recommendations/

McDonald D, Hyde E, Debelius JW, et al., ‘American Gut: an Open Platform for Citizen Science Microbiome Research’, mSystems 20183(3):e00031-18, May 2018, https://doi.org/10.1128/mSystems.00031-18