A cancer diagnosis changes your daily life in a lot of ways, including how and what you eat.
When you’re in cancer treatment, your body needs more nutrients than it did before. You still need food for fuel, but you also need to eat to support healing, help manage treatment side effects and protect your strength.
The thing is: cancer treatment can make it harder for you to eat. If you’re going through chemotherapy, radiation, surgery or other cancer treatment, here’s what you need to know about how healthy eating can support your body.
Why nutrition matters during cancer treatment
When you have cancer, your nutritional needs increase. Your treatments can break down muscle, affect appetite and change how your body uses nutrients.
A healthy diet during treatment can help:
- Maintain your strength and energy
- Prevent unintentional weight and muscle mass loss
- Support your immune system
- Make side effects less severe
- Promote recovery after surgery and other treatments
- Keep your treatment schedule from being interrupted
- Improve your overall quality of life
“When your body is not well nourished it may break down muscle for energy, which can lead to weakness and slower recovery,” said Beril Hezer, a registered dietitian with Banner MD Anderson Cancer Center.
Why eating can be hard during treatment
Many people with cancer experience side effects that affect their eating habits. Cancer treatment can affect your appetite, taste, smell and digestion.
Common challenges include:
- Nausea and vomiting
- Taste changes
- Being more sensitive to smells
- Mouth sores
- Sore throat
- Dry mouth
- Difficulty chewing or swallowing
- Diarrhea
- Constipation
- Loss of appetite or feeling full early
- Fatigue
“These symptoms are real and common and they can make eating feel like a chore instead of a pleasure. They can make even favorite foods unappealing,” Hezer said.
What to eat during cancer treatment
There is no one perfect diet for cancer patients. The goal is a balanced diet that provides enough calories and protein to support healing.
When you’re feeling well, aim for balanced eating that includes fruits and vegetables, whole grains, lean proteins, beans and legumes, seafood and dairy or fortified alternatives. The Mediterranean diet is a good choice.
During active treatment, your priorities may shift. If side effects are making it hard for you to eat, focus on:
- Eating regularly, even small amounts
- Including protein at meals and snacks
- Choosing higher-calorie options if weight loss is a concern
“Sometimes that may mean eating foods that aren’t ‘perfect.’ If a homemade milkshake, mashed potatoes or toast is what feels tolerable, that’s okay. During treatment, nourishment comes before perfection,” Hezer said. “Cancer treatment is already physically and emotionally demanding. Food should not become another source of anxiety.”
Prioritize protein
Protein helps repair tissue, maintain muscle and fight infection. Try to include protein at every meal or snack. If large meals feel overwhelming, try small, frequent meals throughout the day.
Good protein options include:
- Eggs
- Dairy products like yogurt and milk
- Nut butters and seeds
- Tofu and other soy foods
- Fish and seafood
- Poultry and lean meats
Choose healthy fats
Fats give you concentrated energy, which can be helpful if you don’t have much of an appetite. They can help increase calories without large portions.
Focus on healthier fats from:
- Olive oil
- Canola oil
- Nuts and seeds
- Avocados
- Fatty fish
Include fruits, vegetables and whole grains
Carbohydrates give your body energy. Whole grains, fruits and vegetables also provide fiber, vitamins and antioxidants.
If it’s hard for you to tolerate raw vegetables, try cooked or blended options like soups and smoothies.
Stay hydrated
Hydration helps manage side effects and supports your recovery.
Aim to drink fluids throughout the day. Pale yellow urine usually means you’re well hydrated.
Water is best but you can also hydrate with:
- Broth-based soups
- Milk
- Yogurt
- Smoothies
- Electrolyte waters
- Sports drinks, if recommended
Limit alcohol during cancer treatment and talk with your care team before drinking. “The safest recommendation during cancer treatment is to avoid alcohol. For patients who find that difficult, we recommend at minimum avoiding alcohol during active treatment,” Hezer said.
How to manage common side effects with food
These tips can help you meet your nutrient needs when you’re dealing with side effects.
Nausea and vomiting:
- Eat small, frequent meals instead of three large meals
- Choose bland foods like crackers, toast, rice or applesauce
- Avoid greasy, fried, spicy or strong-smelling foods
- Sip liquids slowly throughout the day
Sensitivity to smells:
- Eat cold or room-temperature food
- Use kitchen ventilation
- Ask someone else to cook, if possible
- Avoid foods with strong odors
Sore mouth or throat:
- Choose soft, moist foods such as yogurt, oatmeal, mashed potatoes, scrambled eggs or smoothies
- Avoid acidic, spicy, salty or rough-textured foods
- Let hot foods cool before you eat them
- Stay well hydrated
Dry mouth:
- Add sauces, broths or gravies to foods
- Sip water often throughout the day
- Choose moist foods like yogurt, pudding, smoothies or blended soups
- Try sugar-free gum or lozenges to stimulate saliva if appropriate
Taste changes:
- Rinse your mouth with a mixture of one teaspoon of baking soda in a 16.9 ounce bottle of water before eating to freshen your taste buds
- If food tastes metallic, use plastic utensils instead of metal
- Marinate meats or use herbs and spices to enhance taste (but don’t use lemon, lime or other citrus juices if you have mouth sores)
- Try different food temperatures
- If red meat doesn’t taste good to you, try poultry, eggs, dairy, beans or smoothies for protein
- Suck on lemon, ginger or peppermint drops, if approved by your care team
Fatigue:
- Eat small meals or snacks every two to three hours to keep up your energy levels
- Keep ready-to-eat options available, like protein drinks, yogurt, nut butter with crackers or hard-boiled eggs
- Accept help from family or friends with grocery shopping or meal prep
- Prepare and freeze meals on higher-energy days
Early Fullness:
- Eat smaller portions more often
- Try not to drink large amounts of fluid right before meals
- Focus on higher-calorie, higher-protein foods in smaller volumes
Diarrhea:
- Choose low-fiber foods temporarily
- Avoid spicy or greasy foods
- Drink fluids with electrolytes
Constipation:
- Increase fiber gradually
- Drink more fluids
- Stay as physically active as possible
Always talk with your care team about side effects. Prescription medications may help.
Do you need a special diet during cancer treatment?
It’s common to see advice online suggesting that certain diets can cure cancer or that sugar must be completely eliminated.
“Most patients do not need a restrictive ‘anti-cancer’ diet during treatment,” Hezer said. “There is no evidence that eliminating entire food groups will cure cancer. In fact, overly restrictive diets can lead to unintended weight loss and muscle loss.”
There is no strong evidence that strict diets like keto cure cancer. There is also no proof that vitamins, herbs or supplements alone can treat cancer. Healthy eating during cancer treatment focuses on balance, not restriction.
“Nutrition during treatment is individualized. Some people may need higher calorie foods. Others may need to adjust texture or fiber intake. The right approach depends on your diagnosis, treatment plan and symptoms,” Hezer said.
Before starting supplements or making major diet changes, speak with your care team.
The role of a registered dietitian in your care team
A registered dietitian, especially one trained in oncology nutrition, can be a valuable part of your care team. “Oncology dietitians specialize in the nutrition challenges that come with cancer and its treatment,” Hezer said.
They can:
- Estimate your calorie and protein needs
- Create a personalized nutrition plan
- Help manage side effects
- Address weight loss
- Support people with cancer who also have diabetes, kidney disease or food allergies
- Provide evidence-based guidance tailored to your diagnosis
Nutrition advice online can be confusing. A dietitian can help separate facts from myths.
After treatment: Building long-term healthy eating habits
When you’re finished with cancer treatment, a plant-based eating pattern can support long-term health. This includes:
- More fruits and vegetables
- Whole grains
- Legumes
- Lean proteins
- Limiting red meat
- Reducing processed foods
- Limiting alcohol
Combined with regular physical activity, healthy eating can help keep you well and may reduce the risk of cancer recurrence.
The bottom line
Cancer treatment increases your body’s nutritional needs, even when side effects make it harder to eat. A balanced diet with enough protein and good hydration can support healing and improve your quality of life.
You don’t have to figure it out alone. Reach out to Banner Health for help creating a plan that works for you.
