I have cancer – What should I eat?

Cancer treatment can take a toll on the body and make eating difficult. You may lose your appetite, dislike the smell or taste of certain foods that you may have liked before treatment or struggle with nausea, mouth sores or fatigue.

Lee Miaw Sim, Principal Dietitian (Clinical), Department of Dietetics, SGH, guides cancer patients through tailored nutrition plans and gives advice that supports recovery and well-being, both during and after treatment.

While every cancer patient’s experience is different, it is important to eat well during treatment to stay strong and recover. Miss Lee Miaw Sim, Principal Dietitian (Clinical), Department of Dietetics, Singapore General Hospital, shares practical tips so you can nourish your body, even on days when eating feels like a challenge.

When cancer treatment makes eating difficult

Cancer treatments such as chemotherapy, radiation therapy and surgery can cause side effects that affect your appetite and food preferences. For example:

· Chemotherapy may cause nausea, vomiting, changes in taste or smell and dry mouth. Some patients share that food tastes metallic or bitter; others find that swallowing food is more difficult, especially dry or fibrous foods. Others find that they completely lose interest in eating.

· Radiation therapy, especially to the head or neck area, may cause dry mouth, difficulty swallowing or painful ulcers. It can also impact the sense of smell and taste. Some patients report that they find that food tastes bland or metallic, or even smells unpleasant.

· Surgery, especially involving the digestive system, can affect how much a patient can eat and how the body absorbs nutrients. Surgery to the head and neck or oesophagus may also cause structural changes, leading to swallowing difficulties or the need for texture-modified diets.

Side effects to treatment vary depending on the type of cancer and treatment, and individual response. Patients may feel frustrated or anxious about not being able to enjoy food as they used to and their caregivers may worry that they are unable to get enough nourishment to regain their health.

Important nutrients that the body needs

During treatment, your body needs more nutrients to heal, fight infection and keep energy levels up. Key nutrients include:

· Protein: Essential for tissue repair, muscle maintenance, and immune function. Found in eggs, fish, tofu, dairy, meat and legumes.

· Fat: Healthy fat such as omega-3 fatty acids from fatty fish, walnuts, and oils (like canola or flaxseed), provides concentrated energy and may help reduce inflammation.

· Vitamins and minerals: Vitamins such as vitamin A, C, D and E, calcium and magnesium are essential for immune support, healing and bone health. A balanced diet with a variety of fruits, vegetables and whole grains can help you meet these needs. Your physicians may prescribe vitamin or mineral supplementation if you develop any micronutrient deficiency due to an inability to meet your daily requirements from diet alone.

· Calories: Maintaining energy intake is critical to prevent unwanted weight loss and fatigue, especially when appetite is low. Calories should come from a balanced mix of carbohydrates, proteins and fats to meet the body’s energy and nutritional needs.

If you are eating less than usual due to poor appetite and feeling full too quickly, consider fortifying familiar foods to increase the calorie and protein content of meals without adding bulk. For example, try boosting nutrition by adding tofu or grounded meat to porridge or stirring an egg to soup.

An avocado smoothie is easy to consume and energy dense, if you prefer liquids over solid food. (Credit: iStock.com/Lecic)

If you find it easier to consume liquids rather than solid foods, consider nourishing drinks as a way to meet your nutritional needs. For instance, you can blend avocado and honey with full cream milk to create a calorie- and protein-rich smoothie that is both easy to consume and energy-dense.

For the best results, speak with a dietitian who can help you develop an individualised meal plan tailored to your preferences, lifestyle and nutritional requirements. They can offer practical tips to ensure you are meeting your needs while enjoying the foods you like!

Managing weight loss

Have small and frequent meals

When eating full meals becomes difficult, try eating small amounts throughout the day instead. Aim to eat light meals or snacks every 2 to 3 hours. Keep convenient nutritious, calorie-dense snacks like cheese, crackers or yogurt within reach. If swallowing or chewing solid foods is difficult or if you are experiencing nausea, try sipping on nutrient-dense liquids like smoothies, nutritional shakes or homecooked soups.

“Patients undergoing radiation therapy to the head and neck may find it easier to consume pureed meals, texture-modified diets and oral nutrition supplements as recommended by the healthcare team,” advised Miaw Sim.

To increase calorie intake, try eating more calorie-dense foods. Easy ways to do this include spreading peanut butter on toast, adding milk to drinks, or stirring olive oil or peanut oil into porridge or pasta.

In some cases, if you are unable to meet your nutritional needs through food alone, additional nutrition support such as oral nutritional supplements or tube feeding may be necessary.

Try things that work for you

If you notice a change in taste or preference, try foods with a variety of textures, temperatures and seasoning to find foods that you find more palatable. Maintaining good oral hygiene such as rinsing your mouth with baking soda and salt solutions can help to soothe the mouth and remove any lingering aftertaste. If you find certain foods comforting or enjoyable, try to incorporate them into your daily diet. This might include favourite snacks or foods that remind you of home or fond memories.

Do what works for you – but make every bite count

Some days, you may find it hard to eat much, and that’s understandable. Instead of giving up, try taking small, frequent meals and snacks throughout the day to maintain energy and nutrition. Focus on nutrient-dense, easy-to-eat options - such as adding protein like eggs or tofu to simple meals, drinking calorie-rich smoothies, or choosing soft, comforting foods that you tolerate well.

For example, if you can only manage something like kaya toast for a while, consider pairing it with a glass of full cream milk or a smoothie to boost calories and protein. You can also add toppings like peanut butter or an egg to increase nutrient content. The key is to adapt and find what works for you on each day, balancing intake to support your strength and recovery.

“There is no one-size-fits-all approach,” shares Miaw Sim. “Focus on what you can eat and how you can enhance those foods to meet your nutritional needs.”

Miaw Sim reviews a cancer patient's food diary and discusses dietary choices with her to better support treatment and recovery.

Eating well during cancer treatment is not always easy but with patience and the right support, it is possible. If you are struggling with your diet and nutrition, speak to your doctor or dietitian for help to get practical and achievable solutions to suit your lifestyle and symptoms.