Fibre and breast cancer.

Does a diet high in fibre reduce my risk of breast cancer? 

An increasing number of studies show that a diet high in fibre is linked to a decreased breast cancer risk. Fibre may help prevent breast cancer in several ways. 

Fibre can reduce the levels of oestrogen in the body by stopping oestrogen from being reabsorbed from your gut and helping remove oestrogen from the body. High levels of oestrogen increase breast cancer risk in both men and women. 

Fibre can also help you maintain a healthy weight.

Key facts about fibre and breast cancer risk.

• Dietary fibre has many effects on the body, especially on digestion and your gut microbiome.
• The British Nutrition Foundation recommends that you should eat at least 30g of fibre daily.
• Eating a variety of fibre-rich foods, like those that form the Mediterranean diet, helps create a diverse and stable gut microbiome, which is essential for good gut health.

How could fibre protect against breast cancer?

Many studies find that a diet high in fibre is linked with a lower breast cancer risk.

Eating a lot of fibre may also play a role in survival after a breast cancer diagnosis. A 2021 review of several studies concluded that eating a higher amount of fibre reduces the risk of dying after a breast cancer diagnosis.

Many actions in the body may explain how fibre might reduce the risk of breast cancer. Some of these include reducing the levels of oestrogen in the body. Long-term exposure to oestrogen is a well-established risk factor for breast cancer in men and women.
 
Fibre can stop oestrogens from being reabsorbed from the gut and gather oestrogens in the colon, which increases their excretion. Fibre also helps make short-chain fatty acids, which can have a protective effect against tumour development.

High-fibre diets can help prevent weight gain and obesity.  Being overweight is an established risk factor for postmenopausal breast cancer.

Why is fibre important for your general health?

Eating fibre affects your body in many ways, most notably digestion. But it is also associated with preventive health effects. For example, it affects how fast you digest your food, the size and consistency of your stool, the frequency of your bowel emptying, how hungry or full you feel, and how your body absorbs nutrients.

Some dietary fibres are also prebiotics, which are special plant fibres that help healthy bacteria grow in your gut. When prebiotics are fermented, they produce short-chain fatty acids. They act as an energy source for the cells in the intestine. At the same time, they strengthen your intestines and positively affect blood sugar, fat metabolism and appetite regulation. Eating enough fibre helps good microorganisms in your gut to grow.

Eating more fibre also helps protect against conditions like heart disease, stroke, diabetes, obesity, high cholesterol, high blood pressure, and colon cancer. Getting fibre from different food sources, such as cereals, fruit and vegetables, is important for maximum health benefits.

What is fibre?

Fibre is a type of carbohydrate that your body cannot digest. Most carbohydrates are broken down into sugar molecules called glucose.  Fibre cannot be broken down; instead, it passes through your body undigested. Dietary fibre is found almost exclusively in plants. 

There are two types of fibre, soluble and insoluble. Each has important health benefits and plays different roles in the body. Soluble fibre dissolves in water and forms a gel-like substance in your stomach, slowing digestion. It may help control your blood sugar and cholesterol levels. It is found in apples, oats, peas, beans, brussels sprouts, and avocados.

Insoluble fibre does not dissolve in water. It adds bulk to your stool and helps food move through the stomach and intestines. Insoluble fibre is found in whole wheat flour, bran, nuts, seeds, leafy greens, and the edible skins of many fruits and vegetables.
 

Start your prevention journey today.

Take a moment right now to make one small, healthy choice today to increase how much fibre you eat. Here are 3 tips to help you get started:

• Start your day with fibre. Choose a high-fibre breakfast cereal, oatmeal, or whole-grain toast.
• Add fibre to your meals. Mix vegetables, beans, or lentils into your soups, stews, and salads.
• Snack on fibre. Grab a handful of unsalted nuts, seeds, or a piece of fruit.

Each small action builds momentum. Start today to build a healthier, stronger you for tomorrow.

Further reading

For more information, read our Fibre and Breast Cancer science review.

Last review: May-25 | Next review: May-28.