Dr Kellie Millard

Consultant Dietitian

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Oncology nutrition

Nutrition during cancer treatment and recovery

Practical nutrition support for maintaining strength, managing treatment side effects and meeting changing nutritional needs.

Reviewed June 2026

Cancer and its treatment can affect appetite, taste, digestion, swallowing, energy levels and the body's nutritional needs. The most appropriate way of eating may change throughout treatment and recovery.

During treatment, maintaining intake, strength and hydration may be more important than following an idealised healthy diet. Advice intended for cancer prevention or long-term health may need to be temporarily adjusted when someone is losing weight or struggling to eat.

Unplanned weight loss is not always beneficial. It may indicate malnutrition and loss of muscle, even in someone who began treatment in a larger body.

Your nutrition priorities may change

Before treatment, the goal may be to improve nutritional status and prepare for surgery or therapy. During treatment, the priority may shift towards preventing weight loss, maintaining muscle, managing symptoms and making food easier to eat.

After treatment, nutrition can support healing, rehabilitation, management of ongoing symptoms and a gradual return to a balanced long-term eating pattern.

Energy helps protect weight and strength

When appetite is reduced, meals may need to provide more energy in a smaller volume. This can involve adding nourishing fats, dairy foods, nut pastes, avocado, sauces or prescribed nutrition supplements.

The right approach depends on your symptoms, treatment, weight history and other medical conditions.

Protein supports healing and muscle

Protein needs may increase during treatment, after surgery or when recovering from infection, weight loss or reduced intake. Try to include a protein food several times across the day.

  • Eggs
  • Fish, chicken and lean meat
  • Milk, yoghurt and cheese
  • Tofu, tempeh and soy milk
  • Beans, chickpeas and lentils
  • Nuts, seeds and nut pastes
  • Oral nutrition supplements when recommended

Managing common treatment effects

Strategies should be adjusted to the cause and severity of the symptom. Persistent or worsening problems should be reported promptly rather than managed with diet alone.

Poor appetite or early fullness

  • Eat small amounts every two to three hours rather than waiting for a large appetite
  • Choose nourishing drinks when solid food is difficult
  • Eat the most substantial meal when your appetite is usually best
  • Keep easy snacks available
  • Avoid filling up on large volumes of low-energy drinks immediately before meals

Nausea

  • Try small, frequent meals and snacks
  • Choose plain, dry or cold foods when smells are difficult
  • Sip fluids regularly between meals
  • Avoid lying flat immediately after eating
  • Take prescribed anti-nausea medication as directed and report uncontrolled symptoms

Taste and smell changes

  • Try foods at different temperatures
  • Use herbs, marinades or tart flavours when appropriate
  • Use plastic cutlery if foods have a metallic taste
  • Try alternative protein foods when meat is unappealing
  • Maintain good mouth care and discuss persistent changes with your treatment team

Sore or dry mouth

  • Choose soft, moist foods with sauces or gravies
  • Sip fluids regularly
  • Avoid foods that are very dry, sharp, acidic or spicy when they cause pain
  • Use prescribed mouth-care products
  • Ask for early dietetic review if pain is reducing your intake

Chewing or swallowing difficulty

  • Seek assessment rather than simply avoiding more foods
  • Use the texture and fluid consistency recommended by your treating team
  • Add sauces, yoghurt, custard or other moisture where appropriate
  • Ask about oral nutrition supplements or enteral nutrition when intake is inadequate
  • Report coughing, choking, a wet voice or food sticking

Diarrhoea or constipation

  • Drink enough fluid unless you have a prescribed fluid restriction
  • Follow advice about fibre because the appropriate amount may differ according to the cause
  • Discuss persistent symptoms with your treatment team
  • Do not begin a highly restrictive elimination diet without assessment
  • Ask whether medications, treatment or reduced activity may be contributing

Does sugar feed cancer?

Cancer cells use glucose, but healthy cells also rely on glucose for energy. Removing sugar or all carbohydrate from the diet does not selectively starve cancer.

Extremely restrictive diets may reduce energy, protein, fibre, vitamins and minerals. For someone already eating poorly or losing weight, this can increase the risk of malnutrition and make treatment more difficult to tolerate.

The role of cakes, sweets and sweetened drinks depends on your needs. They do not need to dominate the diet, but foods providing additional energy can sometimes be useful when intake is very limited.

Supplements and alternative cancer diets

Vitamins, minerals, antioxidants, herbal products and concentrated extracts can interact with cancer medicines or be unsuitable during surgery, chemotherapy, radiotherapy or immunotherapy.

Tell your oncology team about every supplement you take, including products described as natural. Do not begin a high-dose supplement, detox, fasting program or restrictive anticancer diet without discussing it with your treating team.

Food safety

Some treatments weaken immune defences and increase the consequences of foodborne infection. Wash hands and food preparation surfaces, keep raw and cooked foods separate, cook high-risk foods thoroughly and refrigerate perishable foods promptly.

Follow the specific food-safety advice given by your cancer centre. Requirements vary according to treatment and blood results.

When can a dietitian help?

  • Unplanned weight loss or loss of muscle
  • Poor appetite or difficulty finishing meals
  • Nausea, vomiting, diarrhoea or constipation
  • Taste changes, mouth pain or dry mouth
  • Chewing or swallowing difficulties
  • Tube feeding or oral nutrition supplements
  • Nutrition before or after surgery
  • Managing diabetes during cancer treatment
  • Stoma, bowel or gastrointestinal surgery nutrition
  • Questions about supplements, complementary therapies or restrictive diets
  • Returning to a balanced eating pattern after treatment

Contact your treatment team promptly

  • Being unable to keep fluids down
  • Signs of dehydration, such as very little urine, dizziness or increasing weakness
  • Rapid or ongoing unplanned weight loss
  • Coughing, choking or difficulty breathing while eating or drinking
  • Severe mouth or throat pain preventing intake
  • Persistent vomiting or diarrhoea
  • Fever or symptoms of infection during treatment
  • New confusion, severe weakness or reduced alertness

Follow the emergency instructions provided by your cancer centre. Call 000 for a medical emergency.

References

  1. 1. Cancer Council NSW — Nutrition and cancer
  2. 2. Cancer Council NSW — Eating well after a cancer diagnosis
  3. 3. Cancer Council NSW — Treatment side effects and nutrition
  4. 4. Cancer Council NSW — Weight loss and cancer
  5. 5. Cancer Council NSW — Common questions about nutrition and cancer
  6. 6. National Cancer Institute — Nutrition during cancer treatment
  7. 7. eviQ — Information for patients and carers
This information is general and does not replace advice from your oncologist, cancer nurse, dietitian or treating healthcare team.

Resource prepared by Dr Kellie Millard, Accredited Practising Dietitian and Credentialed Eating Disorder Dietitian.