Using Nutrition to Combat Cancer Treatment Side Effects

Maintaining adequate nutrition during cancer treatment is important for sustaining strength, minimizing side effects and supporting the best treatment response possible. At the same time, treatment can cause shifts in energy, appetite and taste that make it harder to eat regularly or enjoy the foods you usually do.

A registered dietitian can help you navigate these changes by offering practical adjustments tailored to your diagnosis, treatment plan and symptoms. Even small changes can make a world of difference in managing treatment-related side effects.

What cancer treatment side effects can affect your diet? 

Depending on the type of treatment you receive—whether it is radiation, chemotherapy or immunotherapy—and the area of the body being treated, side effects may vary greatly. Some of the most common side effects of cancer treatment that can affect how much or how well you eat include:

• Loss of appetite and weight loss
• Nausea and vomiting 
• Constipation or diarrhea
• Increased fatigue 
• Difficulty chewing or swallowing 
• Dry mouth
• Mouth sores 
• Changes in taste or smell

How can you eat differently to combat these side effects? 

The suggestions below offer small changes you can try to help maintain good nutrition during your treatment, based on the specific symptoms you are experiencing. Many people need more calories and protein during cancer treatment, so finding strategies that help you eat a bit more in ways that feel manageable for you is important for your health.

Low appetite

• Eat five to eight small, frequent meals and snacks throughout the day.
• Try scheduling meals regardless of your hunger cues. 
• Eat bigger meals when your appetite is the largest. 
• Choose high-calorie drinks like milkshakes, smoothies and protein drinks when full meals feel less appealing.
• Add extra calories to foods you tolerate to make smaller portions more nutritious. 
   

Nausea and vomiting 

• Eat small, frequent meals with bland or starchy foods at room temperature. 
• Avoid greasy, high-fat and highly seasoned foods. 
• Drink adequate liquids to prevent dehydration (at least 8 cups per day). 
• Limit exposure to food odors that might trigger nausea or vomiting. 
• Time meals when nausea medications are most effective.
   

Constipation

• Increase your fiber intake with whole grains, raw fruits and vegetables, beans, nuts and seeds. 
• Choose whole-grain breads, cereals and pastas. Opt for brown rice instead of white. 
• Drink plenty of fluids (at least 8 cups per day). 
• Avoid stool-bulking foods such as white rice, white bread, bananas, applesauce, hard cheese, peanut butter, oatmeal and potatoes without skin.
   

Diarrhea

• Limit foods and beverages that contain sugar alcohols, high-fructose corn syrup and lactose, which might make diarrhea worse.
• Drink adequate fluids to prevent dehydration. Replace every loose stool with 1 cup of fluid. 
• Drink electrolyte-containing fluids to replace gastrointestinal losses. 
• Eat stool-bulking foods such as white rice, white bread, bananas, applesauce, hard cheese, peanut butter, oatmeal and potatoes without skin.
   

Fatigue

• Choose foods that are ready to eat or easy to prepare, such as pudding, tuna, cereal bars, trail mix, crackers and cheese and eggs. 
• Use ready-to-drink high-calorie and high-protein drinks.
• Make extra food on days you have more energy and freeze the leftovers.
• Accept help from friends and family in meal preparation and grocery shopping, or use online meal and grocery delivery services.
   

Difficulty swallowing

• Eat soft foods that are easy to chew and swallow. 
• Moisten foods with sauces, gravies or broth.  
• Cook food until tender and cut it into small pieces. 
• Drink beverages high in calories and protein.
   

Dry mouth

• Moisten foods with sauces, gravies or broth. 
• Choose foods and drinks that are sweet or tart to stimulate saliva (papaya and pineapple juice help stimulate saliva best). 
• Chew sugar-free gum or suck on sugar-free candy to stimulate saliva (xylitol-containing). 
• Drink plenty of fluids (at least 8 cups per day).  
   

Mouth sores

• Eat soft foods that are easy to chew and swallow. 
• Try cold or room-temperature foods instead of hot foods. 
• Avoid acidic, spicy and sharp or crunchy foods. 
• Drink with a straw to bypass painful mouth sores. 
• Use a homemade mouth rinse of ¼ teaspoon baking soda, 1/8 teaspoon salt and 1 cup warm water.
   

Taste changes

• If food tastes bland: Add stronger flavors like onions, garlic, feta, sour cream or acidic marinades and dressings.
• If food tastes metallic: Use plastic cutlery instead of metal, choose fresh or frozen foods over canned and try tart flavors or vinegar. 
• If food tastes overly sweet: Add some salt or lemon juice, drink herbal teas or dilute juices and sweetened beverages with water.
• If food tastes salty: Add honey or sugar to balance the flavor, try low-sodium products like Mrs. Dash or boil foods to mellow saltiness.

Find Nutrition Support That Meets Your Needs

Simple diet changes can sometimes make the biggest difference during cancer treatment. You know your body best and how it will respond to a specific diet change, but you do not have to make adjustments on your own. A registered dietitian who specializes in cancer nutrition can provide individualized guidance throughout your treatment journey.