What to Eat During Cancer Treatment: A New Zealand Dietitian’s Guide

Cancer treatment can be tough on the body—and what you eat can make a real difference to how you feel, how well you cope with side effects, and how strong your body stays during and after treatment. This guide offers practical advice, tailored to Kiwis, about what to eat (and what to avoid) during chemotherapy, radiation, or other cancer therapies.

How Does Cancer Treatment Affect Your Nutrition?

Treatments like chemotherapy, radiation therapy, immunotherapy, and hormone therapy can all impact your appetite, digestion, and metabolism. Common side effects include:

• Nausea and vomiting
• Fatigue and poor appetite
• Constipation or diarrhoea
• Loss of taste or smell
• Unintentional weight loss or sometimes weight gain (especially if on steroids or hormone therapy)

Your specific type of cancer and treatment plan will influence how your body responds. For example, patients with breast cancer may gain weight due to hormone changes and steroid medications, while those with gastrointestinal or pancreatic cancers may experience weight loss due to malabsorption or appetite loss.

Why a Balanced Diet Matters During Cancer Treatment

A nutritious diet during cancer treatment helps:

• Maintain muscle mass and energy levels
• Support immune function
• Reduce inflammation and support healing
• Manage side effects like constipation and diarrhoea
• Improve your ability to tolerate treatment

If possible, it’s ideal to work with a registered dietitian before, during, and after your cancer treatment.

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Top Cancer-Friendly Foods to Include

1. Plant-Based Proteins and Lean Animal Protein

Protein is vital for cell repair, immunity, and maintaining strength. Aim to include protein in every meal.

• NZ lentils, chickpeas, and beans
• Unsalted nuts and seeds
• Free-range chicken, eggs, or white fish (e.g., hoki, tarakihi)

2. Healthy Fats to Reduce Inflammation

Include sources of omega-3 fatty acids and monounsaturated fats:

• Avocado (grown locally in the Bay of Plenty and Northland)
• Extra virgin olive oil
• Walnuts, flaxseed
• Oily fish like salmon or sardines

3. Wholesome Carbohydrates and Fibre

Support gut health and energy with complex carbohydrates:

• Rolled oats, brown rice, wholegrain bread (e.g., Vogels)
• Kūmara, pumpkin, and parsnip
• Fruits such as bananas, berries, kiwifruit (especially golden kiwifruit to support digestion)

4. Micronutrients from Whole Foods

Your immune system and recovery need key vitamins and minerals:

• Dark leafy greens like spinach and silverbeet
• Citrus fruits and capsicums for vitamin C
• Eggs and mushrooms for vitamin D
• Fortified plant milks and cereals if needed

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Managing Side Effects with Food

Nausea:

• Sip ginger tea, peppermint tea, or suck on lemon slices
• Eat small, bland meals more frequently

Appetite Loss:

• Eat small snacks every 2–3 hours
• Smoothies with protein powder, nut butter, or Greek yoghurt

Constipation:

• Drink plenty of water
• Add high-fibre foods like kiwifruit, pears, or psyllium husk

Diarrhoea:

• Eat banana, white rice, dry toast, or boiled potatoes
• Choose rehydration drinks like SOS or Hydralyte (available in NZ)

Loss of Taste:

• Experiment with herbs, spices, citrus juice, and marinades

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Foods to Avoid During Cancer Treatment

Some foods can increase inflammation, infection risk, or digestive distress:

• Fried or highly processed foods
• Sugary soft drinks or sweets
• Raw or undercooked eggs, seafood, or meat
• Unpasteurised dairy products
• Unwashed fruits or vegetables

Always read labels carefully and prepare food safely. Your immune system may be suppressed, so food hygiene is especially important.

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Should You Take Supplements?

Refer to our blog here for more on this.

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Get Personalised Nutrition Support

Every cancer journey is different—and your nutrition plan should be too. At Kylie Russell Dietitian, we offer individualised nutrition support for people undergoing cancer treatment across New Zealand. Whether you're trying to manage nausea, rebuild strength, or simply make food more appealing, we’re here to help.

Book an online consult or reach out with questions—support is just a click away.

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