How to Manage Cancer Side Effects with Nutrition

How to Manage Cancer Side Effects with Nutrition

Reviewed by Jasper Clinical Board

Last updated 5/24/21

Eating well can play an important role in helping you manage the side effects of cancer and cancer treatment. Good nutrition can help you maintain a healthy weight, feel more energetic, lower your risk of infection and aid in healing and recovery.
Different side effects can require different approaches, so be sure to talk to your healthcare team or a registered dietitian to find the strategies that work best for your situation.
Here are nutrition tips that can help with the most common cancer side effects.
Reduced appetite and weight loss
Reduced appetite can be the result of fatigue, nausea, or changes to the way your body digests food, as well as the emotional impacts of going through cancer treatment. Not eating enough can also cause fatigue. If you find it difficult to eat three full meals, try eating small portions more frequently, and always have snacks nearby. Choose high-calorie, high-protein foods, as this will help you compensate for any missed meals. Examples include nut butters, protein drinks, protein bars, beans, eggs, and high-fat milk products.
Weight gain
Some people gain weight during cancer treatment as a result of chemotherapy-induced food cravings (especially for carb-rich, starchy foods), or as a side effect of steroid medications. Stress, anxiety and depression can also contribute to overeating and weight gain. A plant-based diet is a good way to maintain a healthy weight. This doesn’t mean you need to cut out all meat and dairy products, just that a majority of each meal (two-thirds or more) should be minimally processed, whole plant foods. This includes fruits, vegetables, whole grains, nuts, seeds, and legumes like peas, beans and lentils. Lean proteins like fish, chicken or lean red meat can make up the rest of the meal. If you have carbohydrate cravings, whole grains paired with a protein can help satisfy you and keep you feeling full longer. 
Changes in taste and smell
Radiation treatments to the head or neck sometimes cause changes in taste and smell. People experiencing these side effects often find tart and sweet flavors more pleasant. If your food has a metallic taste, try drinking lemon water before meals or flavor food with vinegar or acidic dressings. If food tastes too bitter or salty, you can flavor it with a little sugar or another sweetener.
Difficulty swallowing and mouth sores
If you have cancer of the head or neck, you may have difficulty swallowing solids, liquids or both. And chemotherapy treatments can cause your mouth and throat to feel irritated and painful. Cool foods like applesauce, smoothies and ice cream can be soothing while still being soft enough to swallow easily. If you have mouth sores and are able to swallow, frozen fruits and berries are also very soothing.
Other soft foods like soup, broth, mashed potatoes, oatmeal and nutritional puddings can balance out your diet. You may also be able to eat vegetables like broccoli or peppers if they are softened by cooking. If you have difficulty swallowing liquids, you can buy thickening agents to add to beverages and soups to make them safe to drink.
Radiation, chemotherapy and some medications can cause dry mouth. This means your mouth produces less saliva, or produces saliva that is thicker and stickier. If this is the case, make sure you’re drinking at least eight glasses of water a day and avoid caffeine. Sweet and sour foods can improve saliva production, so try chewing gum or add lemon to your water.
Nausea and vomiting are common side effects of cancer treatment. Avoiding spicy, greasy, strong smelling and acidic foods often helps to reduce these side effects. You may also find that your body is better able to handle small but frequent meals. Bland foods like rice, pretzels, crackers, toast, applesauce and bananas are great options when you need a snack.
When you do experience vomiting, it’s very important to keep yourself hydrated. Water, sports drinks, broth, herbal tea, fruit juice and watermelon will help you replenish your body’s fluids and salts. 
The impact of frequent diarrhea (occurring two or more times a day) is very similar to vomiting, and the strategies listed above are a good start to managing this side effect, particularly when it comes to staying hydrated.
To reduce diarrhea, eat foods that are high in pectin, like bananas, applesauce, and peaches. You should also eat foods that are potassium-rich, as this is another mineral you are likely to lose. Examples include bananas, applesauce, peaches, potatoes and beans.
It is best to steer clear of foods that are high in fiber, as well as caffeine and dairy products that contain lactose. Also avoid anything that causes gas or cramps, like carbonated drinks and cruciferous vegetables (broccoli, brussel sprouts, and bok choy, among others).
As your diarrhea begins to improve, you can eat small servings of low-fiber foods like yogurt, rice, dry toast and low-fat cottage cheese.
Some medications can cause constipation, which in turn causes discomfort and reduces appetite. If you find your bowel movements are painful or difficult, or they are occurring less frequently than usual, make sure you are eating foods that are high in fiber. This includes fruits, raw vegetables, nuts, seeds and whole grains. Increase your fluid intake by drinking water, watered-down juice, and unsweetened hot tea. Avoid foods that cause gas or cramps, like carbonated drinks and cruciferous vegetables.
If you have or have had cancer close to your bowels, it’s possible that you’re experiencing bowel obstruction, rather than constipation. Consult with your healthcare team if you are unsure. In the case of bowel obstruction, it’s best to avoid foods that are high in fiber, but it is still important to increase your fluids and avoid foods that cause gas or cramps.
Also known as acid reflux, heartburn is a burning sensation in the belly, chest and throat caused by stomach acid. It can be a side effect of radiation treatments to the chest and abdomen, as well as some chemotherapy drugs. You should avoid eating spicy and acidic foods like curries, hot peppers, citrus fruits and tomato products, and limit caffeine and alcohol. It’s also helpful to eat dinner at least two hours before going to bed, as lying down can worsen heartburn.
Nutrition strategies to avoid
Misinformation about nutrition is everywhere. Social media, reality shows, even well-meaning loved ones may all share advice that is more harmful than helpful. Always check that your information is coming from reputable sources and check with your healthcare team when you are unsure. 
Here are some aspects of your diet to approach with special caution.
  • Consult your healthcare team before taking supplements. While you may be tempted to take vitamins or herbal and dietary supplements to improve your health, many of these products can interfere with cancer treatments and medications. Do not take any supplements without consulting your healthcare team, even if they seem to lessen your side effects.
  • This is probably not the best time to experiment with popular diets. Even a diet touting health benefits may not be a good fit for your needs during cancer treatment. Talk to your healthcare team about what changes if any you should make to your diet and how to best meet your current and long-term nutritional needs. 
  • Reducing sugar can be a healthy step, but adopting an extreme sugar-elimination diet is probably not safe. Sugar occurs naturally in fruits, vegetables, grains and other foods that you will need for a healthy, balanced diet. If you want to reduce sugar, talk to your healthcare team about your plans. They can help you focus on reducing foods with added sugars, like soft drinks and desserts, if that makes sense for your current nutrition needs. If you’re having trouble getting enough nutrition, you may need to balance concerns about sugar with the need to get enough calories. Your healthcare team can help you choose the best strategy for your needs. 
The bottom line
While no change in diet will solve every problem and side effect, what you eat can have a big impact on your comfort and health. Keep in mind that for most people it’s best to focus on eating a healthy, balanced diet, rather than sticking to a rigid set of rules. Make a plan with your healthcare team or a registered dietitian to ensure you get the nutrition you need, both during treatment and to support your long-term health. Check in regularly if you encounter new side effects or have trouble with eating. Your team will be familiar with these challenges and should be able to help you manage them.

The content on this website is intended to provide the best possible information for you, but should not be considered—or used as a substitute for—medical advice. If you have questions about your diagnosis or treatment, please contact your health care provider(s). For questions or comments about this content, please email us at