Nutrition concerns

After some cancer treatments, you may have concerns about nutrition-related side effects. For some people, the side effects of cancer treatment may result in malnutrition and changes in weight. Surgery that removes part of the digestive system will cause specific side effects. These concerns may mean you need to supplement your diet with food-type nutritional supplements. Some people consider taking vitamins and supplements, but it’s best to get your vitamins and minerals from eating whole foods.

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Malnutrition in people with cancer occurs when you eat less energy and protein than your body needs. Factors that increase the risk of malnutrition include:

  • surgery for some cancer types, such as head and neck, lung and gastrointestinal cancers, which may make it difficult to swallow and to digest food
  • increased nutritional needs from cancer and treatments such as chemotherapy, radiotherapy and surgery
  • side effects from cancer treatments that make eating more difficult, such as nausea, vomiting and dry mouth
  • some medicines
  • stress, anxiety and fatigue

Many of the eating issues discussed in Treatment side effects and nutrition can contribute to, or be symptoms of, malnutrition. Other signs include significant weight loss; confusion; dry, brittle hair and nails; and pale or pigmented skin.

Malnutrition can increase your risk of infection and reduce your strength, function and quality of life. It can affect how your body responds to cancer treatment and recovery. It is possible to be malnourished even if you are overweight. Talk to your doctor or dietitian if you think malnutrition is an issue.

Read more about malnutrition

Managing eating side effects caused by surgery

Surgery that removes part of the digestive system, such as the oesophagus, stomach and bowel, will change the way you eat and digest food.

Surgery for bowel cancer

  • When part of the bowel is removed, many people have more frequent bowel movements (diarrhoea). This usually improves in a few months, but it may take longer for some people.
  • Your doctor or nurse might recommend a low-fibre diet to ease digestion.
  • If you have a stoma (a surgical opening in the abdomen that allows faeces to leave the body) after surgery, you may need to make some dietary changes until your body adjusts. The Australian Government’s Improving Bowel Function After Bowel Surgery booklet has useful tips. Visit, or call 1800 33 00 66.

Surgery to the head and neck area

  • Your ability to chew and swallow may be affected after surgery.
  • If you are having difficulty eating or drinking, you may be given a temporary or permanent feeding tube. This tube can help you maintain or gain weight.

Surgery for stomach cancer (partial gastrectomy or total gastrectomy)

  • Removing part or all of the stomach will affect what you can eat and how you eat.
  • The change in structure of the stomach may mean that foods high in sugar move through the stomach faster. This is called dumping syndrome. Dumping syndrome may cause cramps, nausea, racing heart, sweating, bloating, diarrhoea or dizziness. It usually improves with time, though.
  • Dietary changes and medicines can also help.

Surgery for oesophageal cancer (oesophagectomy)

  • Removing the oesophagus will change how you eat.
  • After surgery, you will have a feeding tube, then progress to a liquid diet, followed by a diet of soft or moist foods.
  • If you cough while eating or feel like the food is getting stuck in your throat when you swallow, consult your doctor and dietitian immediately.

Surgery for pancreatic cancer

  • This will cause a significant change to what you can eat and drink.
  • Some people develop diabetes before being diagnosed with pancreatic cancer or soon after surgery.
  • The way diabetes is managed varies from person to person, but it usually includes a combination of dietary changes and medicines.
  • As your body may not be able to make enough enzymes to digest food after surgery, you may need to take enzyme supplements with every meal.
Read more

Changes in weight

Weight loss

This is common in people with cancer because the cancer can burn a lot of energy, and treatment side effects may mean you eat less or lose your appetite.

During active treatment, try to maintain your weight to help you stay strong and recover faster. To help avoid weight loss or to maintain your weight, eat more protein, fat and carbohydrates to increase your energy (kilojoules/calories). This approach is usually temporary to help you keep eating during and after treatment.

How to manage weight loss

  • Treat food like medicine: something you have to have. Set times for meals and snacks rather than waiting until you’re hungry.
  • Carry snacks such as hard-boiled eggs, muesli bars, dried fruit and nuts, crackers and fruit buns.
  • Try food-type nutritional supplements and ready-to-use drinks if travelling or if preparation is difficult. Examples include Sustagen, Ensure, and Resource Fruit Beverage.
  • Choose nourishing and higher kilojoule (calorie) fluids or snacks, for example, drink milk rather than water and choose cheese and biscuits over lollies.
  • Include high-energy and high-protein foods at every meal or snack.

Ways to add energy and protein

What to add

Meals and snacks

full-cream milk, cream or coconut milk

porridge, sauces, desserts, mashed vegetables, egg dishes, cream soups, scrambled eggs, milkshakes

yoghurt or sour cream

dips, salad dressings, fruit, potatoes, soups

butter, margarine or olive oil

bread, toast, mashed potato, cooked vegetables, rice, pasta

cheese (e.g. cheddar, ricotta, fetta, haloumi, cream cheese)

scrambled eggs, sauces, soups, vegetables, casseroles, salads, toast, sandwich fillings, pasta sauce, crackers


egg or chicken sandwiches, potato salad, coleslaw, salad dressing

peanut butter

bread, toast, porridge, crackers, pancakes, scones, fruit, smoothies


toast, sandwich fillings, dips, salads, crackers, smoothies

nuts and seeds

porridge, muesli, yoghurt, salads, baked goods, stir-fries, desserts


toast, sandwich fillings, stir-fries, mashed potato, soups, pasta sauce, salads

Weight gain

Although it is more common to lose weight during treatment, some people gain weight. This can happen for various reasons.

  • Some chemotherapy drugs and steroid medicines can cause your body to retain extra fluid in cells and tissues. This is called oedema, and makes you feel and look puffy.
  • Hormone therapy lowers the amount of hormones in the body, which slows your metabolism.
  • Steroid therapy can increase abdomen size, cause fluid retention and lead to a rounded, puffy face.
  • Feeling stressed or upset can also make some people eat more.
  • Being tired because of the treatment may mean you exercise less.

If you gain weight during treatment and are concerned, speak to your doctor or dietitian about how to best manage it.

Read more about weight changes

Food-type nutritional supplements

If treatment side effects mean you cannot eat a balanced diet, or you are losing weight without trying, food-type nutritional supplements can increase nutrient intake.

  • Used as snacks between meals.
  • Sold by many pharmacies and supermarkets.
  • Can be bought without a prescription.

If you are having trouble swallowing, talk to a speech pathologist for directions on thickening the supplement.

Types of food-type nutritional supplements

Oral supplements – Most are powder-based and often come in different flavours. There are many types to suit different nutrition needs, for example, high fibre, low lactose or low glycaemic index. You can sprinkle it on food or stir it through drinks or meals. Examples include Enprocal, Ensure, Fortisip, Proform and Sustagen Hospital Formula.

Liquid supplements – Most are milk-based and often come ready-to-drink. They are available in different flavours and can be low in lactose, gluten free or have a low glycaemic index. Examples include Ensure Plus, Resource Plus, Resource Protein, Resource 2.0, and Sustagen Ready To Drink. Some liquid supplements come as a clear fluid and these are often fruit flavoured. They can be a good choice if lactose-free or low-fat supplements are needed. Examples include Enlive Plus, Fortijuice, and Resource Fruit Beverage.

Food-type supplements – These are available as different flavoured soups, custards, jellies, puddings and dessert powders.

Make your own – You can use the enriched milk recipe to add extra nourishment to food and drinks.

Read more about nutritional supplements

Vitamins and mineral supplements

Vitamins and minerals are an essential part of a healthy diet and play an important role in the body’s immune system. It’s best to get your vitamins and minerals from eating whole foods, as the body absorbs them better. If you are able to eat a variety of foods, you usually won’t need to take vitamin and mineral supplements. 

Many vitamin and mineral supplements contain levels of antioxidants (such as vitamins C and E) that are much higher than the average amount of nutrients needed each day for optimal health. These are called Nutrient Reference Values. More research is needed to determine the impact of using antioxidants and other vitamin supplements during chemotherapy or radiotherapy treatment. It’s best for people having these cancer treatments to avoid vitamin and mineral supplements, except to treat a known deficiency of a certain nutrient.

If your appetite is poor, check with your doctor or dietitian before taking any vitamin or mineral supplements.

Using high doses of vitamins

Some people believe that taking high doses of certain vitamins will strengthen the body’s immune system during cancer treatment. However, there is little evidence to support this claim. In fact, many vitamins and mineral compounds can be toxic at high levels, and may affect how chemotherapy, radiotherapy and other medicines work.

Read more about vitamin and mineral supplements

This information was last reviewed in May 2016
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