Fibre, wholegrains and cancer
Eating enough fibre can help protect against certain cancers. But many of us don’t eat enough. Read on to find out how to include more fibre in your diet.
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Fibre is a type of carbohydrate that can’t be fully digested in your gut. It’s found in plant foods such as fruit, vegetables, wholegrains (such as brown rice), pulses (such as beans, chickpeas and lentils), and nuts and seeds.
There are 2 types of fibre:
- Soluble fibre: this type of fibre dissolves in water to form a gel-like substance. It slows down digestion, which can help to control blood sugar levels. Sources of soluble fibre include pulses, oats and fruit.
- Insoluble fibre: this type of fibre doesn’t dissolve in water. It adds bulk to your poo and helps food move through your digestive system more quickly. Sources of insoluble fibre include wholegrains, nuts, seeds, and the skins of fruit and vegetables.
It’s recommended to eat 30 grams of fibre every day. Both types are beneficial, so it’s important to include a variety of fibre-rich foods in your diet.
> Explore our fibre factsheet to learn more about fibre and how to get more in your diet
What are wholegrains?
Wholegrains are the seeds of cereal plants, such as wheat, barley, quinoa, oats, rye, maize (corn) and rice. When we refer to wholegrains, we’re talking about grains that haven’t been refined and are mostly brown in colour. They are a good source of fibre and protein, and have many other beneficial nutrients, such as certain vitamins and minerals.
However, many of the grains we eat are refined. During the refining process, most of the fibre and nutrients are removed, although certain nutrients are put back in, such as some B vitamins, calcium and iron. Refined grains are often white – white flour, bread, pasta and rice.
Resources for you
We have lots of resources to inspire you and your family to eat more fibre and wholegrains, and help reduce your risk of bowel cancer.
What are the links between fibre, wholegrains and cancer?
Our research shows that eating fibre-rich foods, including wholegrains, reduces the risk of bowel cancer.
> Read our Protect yourself against bowel cancer guide
Our research also shows that eating high-fibre foods protects against weight gain, overweight and obesity, and living with overweight or obesity increases the risk of at least 13 types of cancer.
That’s why one of our Cancer Prevention Recommendations is to make wholegrains, vegetables, fruit and pulses (legumes) such as beans and lentils a major part of your usual daily diet.
> Explore our Weight matters guide
Fuller on less
Fibre reduces the risk of bowel cancer in different ways. It makes your poo bulkier and helps it move through your bowel faster, so harmful substances spend less time in your bowel.
Fibre also feeds your gut’s good bacteria, which produce helpful substances that support your bowel health. Eating a high-fibre diet can help to reduce insulin resistance, which is a risk factor for bowel cancer. Insulin resistance is when your body’s cells don’t respond properly to insulin, and this can lead to high blood sugar levels.
And high-fibre foods can help you feel full on fewer calories, which can help protect against weight gain, overweight and obesity.
Wholegrains contain many nutrients such as fibre, vitamins, minerals and phytochemicals. Phytochemicals are found in plant food and have a range of health benefits. These nutrients in combination, and especially because of their fibre content, help wholegrains reduce cancer risk.
Aflatoxins and cancer
Aflatoxins are toxins produced by certain moulds that can grow on grains, especially corn, often under warm and humid conditions.
Food contaminated by aflatoxins increases the risk of liver cancer.
To protect consumers, strict rules are in place to limit aflatoxins in food. But you can also protect yourself further by keeping your grains in a cool, dry place and checking them for signs of mould, unusual colours or odd smells. If you spot mould, throw the food away immediately.
How do I know if a food is wholegrain?
Look for products with “whole” in front of the name such as wholewheat and wholemeal.
Common wholegrain foods you can find in the supermarket:
- Wholemeal (brown) bread, wraps, pittas and chapattis
- Wholegrain breakfast cereals such as shredded wheat, wheat biscuits or bran flakes
- Wholewheat (brown) pasta
- Wholemeal flour
- Brown and wild rice
- Rye bread and crackers
- Oats (including porridge) and oatcakes
Some wholegrain products may have added fat, sugar and salt, so check the food label. Find out how in our Making sense of food and drinks labelling guide.
How can I eat more fibre and wholegrains?
Our cookbooks and recipes site are filled with recipes that use a variety of different wholegrains, fruit, vegetables and pulses.
1. Swap white for wholegrain
Replace white flour, bread, rice and pasta with wholegrain versions.
2. Choose wholegrain breakfast cereals
Start your day with wholegrain breakfast cereals. For an extra fibre boost, add fresh or dried fruit, unsalted nuts or seeds.
3. Eat more fruit and veg
Eat at least 5 portions of different fruit and vegetables every day.
4. Add vegetables and pulses to meals
Include vegetables, beans, lentils or chickpeas in stews, curries, sauces, soups and salads.
5. Keep the skin on
Where possible, leave the skin on fruit, vegetables and potatoes.
6. Choose healthy snacks
Opt for fresh fruit, vegetable sticks with reduced-fat houmous, rye crackers or oatcakes with low-fat soft cheese, a handful of unsalted nuts or plain popcorn.
| Meal | Suggestion | Fibre content (g) |
|---|---|---|
| Breakfast | 40g bran flakes with semi-skimmed milk | 6 |
| 30g nuts | 2.1 | |
| 80g strawberries and 1 banana | 1 and 1.4 | |
| Lunch | Two thick slices wholemeal bread | 6.4 |
| Small tin tuna | ||
| 100g salad: lettuce, red onion, cucumber and tomato | 1.8 | |
| Dinner | Baked potato with skin | 5.7 |
| Half tin no added sugar baked beans | 7.4 | |
| Plain yoghurt and 1 apple | 1.2 | |
| Total fibre: 33 |
Living with cancer
After a cancer diagnosis: follow our Recommendations, if you can.
Fibre and wholegrains can provide your body with a range of beneficial nutrients. However, if you are planning on making changes to your diet, you should always speak to your cancer care team first. This is to ensure that any changes you make provide your body with enough energy (calories), protein, vitamins and minerals to support recovery.
Browse our recipes for people living with cancer
Diet and Cancer Report
Our 2018 Diet and Cancer Report looked at:
- Wholegrains, vegetables and fruit
- Energy balance and body fatness
It found strong evidence that:
- wholegrains DECREASE the risk of colorectal cancer
- foods containing dietary fibre DECREASE the risk of colorectal cancer
- foods contaminated by aflatoxins INCREASE the risk of liver cancer
- consuming foods containing dietary fibre DECREASES the risk of weight gain, overweight and obesity
> Read the relevant chapters in our science and policy library
Preventing cancer. Saving lives
While society continues to search for a cure, our prevention and survival work helps people to live longer, healthier lives – free from the devastating effects of cancer.