Diet and cancer

Learn more about your diet and how it can raise or lower your risk of developing cancer.

An unhealthy diet increases your risk of cancer

The food and drink that you consume regularly make up your diet. It is hard to study the effects of diet on cancer because your diet includes foods that may protect you against cancer and foods that may increase your risk of cancer. The genes you inherit can also affect the way your diet influences your cancer risk.

Researchers have to carry out very large studies to see which specific foods influence our risk of cancer. Many of these studies are ongoing and are starting to provide us with clearer answers.

Looking at current scientific evidence, it is reasonable to link parts of our diet with cancer of the bowel, breast, mouth, oesophagus (foodpipe) and stomach

Eat your way to good health

Your diet has a powerful effect on your health, including your chance of getting cancer. But we don’t blame you if you feel confused by all the different messages you hear about what to eat and what not to eat. When all is said and done, you can reduce your risk of cancer by eating a healthy, balanced diet. This means that your diet is:  

  • Rich in fruit and vegetables
  • High in fibre
  • Low in red and processed meat, saturated fat and salt

You can start to eat your way to good health at any time, from childhood to old age. No matter when you start, you will begin to be healthier. And eating your way to good health doesn’t just protect you against cancer and other diseases. It will also provide you with lots more energy and the key ingredients for looking and feeling great at any age.

The five fundamentals of healthy eating

The five fundamentals of healthy eating will set you on the right path to reducing your cancer risk and eating your way to good health. It is also important to remember that a healthy diet will help you to maintain a healthy body weight, which can itself reduce the risk of many cancers.

Fruit and vegetables are a vital part of a healthy diet. They are an excellent source of many important nutrients such as vitamin A, vitamin C, vitamin E and folate, and are a superb source of fibre. Research tells us that people who eat at least five portions a day have a lower risk of heart disease, stroke and cancer of the mouth, stomach and oesophagus (foodpipe).

Our advice

We recommend that you eat plenty of fruit, vegetables and salad – at least five portions a day. Choose a wide variety of brightly coloured fruit and vegetables as this will help you get a broad range of nutrients.

What counts as a portion?

This table gives you examples of what counts as one portion of fruit and veg. When we refer to a cup, we mean an average disposable plastic cup. This is the same as around one handful.

FruitVegetables
1 medium banana ½ cup of cooked carrots, turnips or parsnips
1 medium apple, orange, peach or pear   ½ cup of cooked cauliflower or broccoli
2 small plums, apricots, or mandarins½ cup of peppers or mushrooms
6  strawberries½ cup of cooked peas
10 grapes½ cup of cooked lentils, red kidney beans or chick peas
½ cup of blueberries1 cup of lettuce, tomato or cucumber

Top tips

  • Smoothies, vegetable soups, stews and casseroles are a great way to rack up your five a day.
  • Remember fruit juices are high in sugar, so keep to one serving per day (150 ml).
  • Stock up on canned fruit and vegetables. They won’t go off, so you can buy them in bulk. Buy those canned without added salt or sugar. 
  • Buy fruit and vegetables loose rather than pre-packaged. Loose fruit and veg are usually much cheaper.
  • In a restaurant, try to order a starter, side vegetable or salad that will count as one portion.
  • If you’re having a takeaway, think about how you can add a portion of vegetables. If you have a Chinese, for example, add stir-fried vegetables. When ordering a pizza, ask for extra peppers or mushrooms on top. 

Fibre is an important part of a healthy diet. A diet high in fibre has many health benefits. It can help prevent heart disease, diabetes, weight gain, and improve digestive health. Eating lots of fibre will also reduce your risk of bowel cancer. Fibre-rich foods include:

  • Fruit and vegetables
  • Wholemeal and wholegrain bread
  • Brown rice and pasta
  • Pulses such as peas, beans and lentils.

Our advice

We recommend that you increase the fibre in your diet by choosing wholegrain foods whenever possible, such as wholemeal bread and brown rice or pasta. Many fruits and vegetables also contain lots of fibre, especially peas, spinach, pears, berries, apples, and avocados. Other fruit and vegetables that contain fibre include Brussels sprouts, green beans, broccoli, corn, spinach, carrots and oranges.

Top tips

  • Swap corn flakes for bran flakes and add some raisins.
  • Try adding pulses such as beans or lentils to soups and salads.
  • Substitute wholegrain flour for half or all of the white flour when baking. Wholegrain flour is heavier than white flour so use a bit more yeast or let the dough rise longer.
  • Try adding crushed bran cereal or porridge oats to muffins and cakes.
  • Make snacks count by eating raw vegetables, fruit or a handful of dried fruit.

Meat is rich in valuable nutrients such as protein and iron. But eating lots of red and processed meat can increase your risk of bowel cancer and possibly stomach cancer. Red meat includes beef, pork and lamb. Processed meat includes sausages, rashers, bacon, ham and salami.

Our advice

We recommend that you do not eat more than 500g of cooked lean red meat every week. This is the same as about 800g of raw lean meat. We advise you to limit or avoid processed meat altogether. How much is 500g of red meat? The following table is a rough guide to the weight in grammes of cooked meat.

Red meatCooked weight
Pork or lamb chop75g
‘Quarterpounder’ beefburger90g
Medium portion of roast beef, lamb or pork   90g
Medium steak145g

Top tips

  • Instead of rashers and sausages for breakfast, have poached or scrambled eggs.
  • Have spicy chicken on your pizza, instead of pepperoni.
  • Replace red meat with fish, chicken or other forms of poultry whenever possible.
  • Try a meat-free day every week. Use peas, beans or lentils instead of meat in your recipes.

All types of fats and oils are very high in calories. While fats are a necessary part of our diet, a high-fat diet can increase your risk of cancer, heart disease and other conditions. And there is evidence that eating too much saturated fat may increase your risk of breast cancer.

Some fats and oils help protect against heart disease, but they are just as high in calories as other more harmful fats and oils.

Our advice

Eat as little fat as possible. In particular, try to cut down on saturated fats. Saturated fats are found in fatty meat, biscuits, crisps, pastries, cream and butter.

We are not telling you not to enjoy foods such as biscuits, crisps and chocolate as an occasional treat. But the key is not too much and not too often!

Top tips

  • Choose reduced fat spreads as they contain less fat and more water.
  • Choose lean cuts of meat and semi-skimmed or skimmed milk.
  • Use oil in cooking very sparingly. Try steaming, baking, braising or grilling instead.

In Ireland we take almost twice as much salt as we need. Too much salt can also increase your blood pressure and your risk of heart disease and stroke. Foods that are high in salt can also increase your risk of stomach cancer.

Many foods contain salt, such as breads and processed foods like meats, ready meals and pizzas, sauces, crackers, cakes, snack foods and cereals. Food does not have to taste salty to have high levels of salt in it.

Our advice

Try not to eat too many salty foods and cut out salt when cooking and at the table. Always check the label of processed foods and ready meals for salt content. As a rule of thumb, more than 1.3g is considered a lot of salt and less than 0.3g is considered a little salt.

Top tips

  • Use mainly fresh ingredients when cooking
  • Choose foods low in salt – try spicy flavours instead
  • Cut out salt when cooking and at the table
  • Flavour foods with black pepper, herbs, lemon juice, garlic and spices

Look at the label

Be careful when reading claims on food packaging as they can be misleading. For example, ‘light’ or ‘reduced fat’ food may have less fat than a similar product but they can still be high in fat or sugar. Looking carefully at food labels can help you to make better choices. Safefood has produced this booklet of guidelines to help you (pdf, 233KB).

Dietary supplements and ‘superfoods’

The best source of nourishment is food and drink, not dietary supplements. You can get all the nutrients you need from a healthy, balanced diet. Unless your doctor or dietician suggests supplements, you do not need them.

Likewise, there are often stories in the media about specific foods or so-called ‘superfoods’ that are meant to be particularly good for us. But you should not rely on superfoods to reduce your risk of cancer. Nothing beats a healthy, balanced diet.

More information on healthy eating

Healthy recipes

101 Square Meals

101 Square Meals is a low-cost, healthy-eating cookery book supported by MABS, Safefood and the HSE. You can:

Further information on healthy eating

The HSE and the Department of Health and Children have produced  The National Health Eating Guidelines, which define the Irish Government recommendations on healthy eating and a balanced diet.  They provide a consistent and evidence-based approach for healthy eating advice:   https://www.hse.ie/eng/about/who/healthwellbeing/our-priority-programmes/heal/healthy-eating-guidelines/ 

Irish Nutrition and Dietetic Institute www.indi.ie