Good nutrition is important for everyone, but even more so if you are living with cancer. A well-balanced diet maintains energy and strength, helps the body heal itself and supports the immune system. Being well nourished can speed recovery after surgery, help cancer treatment work better and improve quality of life. Although there’s not much evidence that specific foods cause or prevent cancer relapse, people who eat a healthy diet have a lower overall cancer risk.
Nutrition for people with cancer differs in some ways from healthy eating guidelines for the general population. The right diet is critical at a time when the body needs more nutrients but cancer symptoms or treatment side effects can make it hard to eat. For example, some people with cancer need a high-calorie diet to prevent weight loss. Some healthy foods, like fresh fruits and raw vegetables, may not be good choices for people with nausea or diarrhea.
A Balanced Diet
A well-balanced diet includes foods that supply the nutrients to maintain your energy, build and repair body tissue and keep the immune system strong.
Fruits and vegetables contain a wide variety of vitamins and minerals as well as phytochemicals with health-promoting properties. Many also contain fiber needed for good digestion.
Carbohydrates are the body’s main source of fuel. Whole-grain bread, brown rice, beans and lentils contain more nutrients and fiber and provide more sustained energy than white bread, white rice and potatoes.
Protein provides essential building blocks for making muscles, bones and other body tissues. People with cancer may need extra protein to repair tissue damaged by surgery or radiation. A healthy diet should include plant-based protein sources like beans, nuts and tofu in addition to lean meat and poultry, seafood and low-fat dairy foods.
Fats and oils are essential for everyone and they are a rich source of calories for people trying to maintain or gain weight. But the type of fat matters. Choose monounsaturated fats (olive oil, avocados) and polyunsaturated fats (nuts, seafood) while limiting saturated fats (meat, cheese, milk) and trans fats (fast food and many commercial products).
Sugar and salt have pluses and minuses. Sugar supplies essential energy for the body and brain. Too much can contribute to obesity and diabetes, but it provides extra calories for people who need to gain weight. Salt can worsen high blood pressure and fluid buildup caused by some cancer drugs, but salty foods can be easier to tolerate if you have nausea.
Water is a major component of the body’s cells. Some experts recommend eight glasses of water a day or the equivalent amount of other fluids. To stay fully hydrated, drink throughout the day before you feel thirsty.
Vitamins and minerals keep the body—including the immune system—working properly. Some vitamins act as antioxidants that help prevent cell damage. A balanced diet is the best way to get vitamins and minerals, but you can also get them in supplements. More is not necessarily better, however, and too much can be harmful.
Managing Symptoms and Side Effects
Cancer and its treatment can make it more difficult to eat well. Cancers affecting the mouth, throat, stomach or intestines are most likely to interfere with nutrition. But radiation therapy and medications used to treat all types of cancer can cause side effects that make it difficult to eat or hold down food.
Fatigue: Treatment-related fatigue can make it harder to shop and prepare meals. Before starting treatment, stock up on groceries and make food in large batches that can be frozen in meal-sized portions. If possible, call on family and friends for help with shopping and cooking. Foods like yogurt, granola bars and whole-grain crackers with cheese or peanut butter provide a lot of nutrients with little effort.
Loss of appetite: Many people don’t feel like eating much during cancer treatment (known as anorexia). Try eating small meals or snacks every few hours rather than three large meals. Take advantage of the times you do feel hungry by keeping on hand nutrient- and calorie-rich snacks that can be eaten with little preparation. Milkshakes and smoothies may be more appealing than solid food, but limit how much you drink before and during meals to keep from filling up too soon. Mild exercise can stimulate the appetite, and some people with cancer swear by medical cannabis.
Weight loss: Many cancer patients experience weight loss, especially muscle loss known as cachexia. Patients undergoing cancer treatment may need more protein and calories than a healthy person. Try to have a snack every few hours instead of waiting until you feel hungry. Include protein-rich foods at each meal or snack. When preparing food, add high-calorie extras like cream, butter, salad dressing, honey or peanut butter. Liquid nutritional supplements can also boost calories.
Weight gain: Some people with cancer gain weight. While it’s important to be well nourished while fighting cancer, keeping a healthy weight improves treatment outcomes and lowers the risk of other conditions like heart disease and diabetes. Hormone-based therapy can cause swelling due to fluid retention—cutting back on salt helps. Even light exercise can keep weight down and muscle strength up.
Mouth and throat problems: Radiation and chemotherapy can cause sores in the mouth and throat and make swallowing difficult or painful. Focus on soft foods and nutrient-rich drinks like shakes and smoothies. These can be sipped through a straw to bypass mouth sores. Many foods can be moistened with sauces or pureed in a blender. Avoid spicy or acidic foods and alcohol. Let hot foods cool to room temperature, but cold foods like ice cream can help numb mouth pain.
Changes in taste or smell: Some medications cause sensory changes that make foods taste different and leave a bitter or metallic taste in the mouth. Spices and other intense flavors may help mask the bad taste, or try using plastic instead of metal utensils. If meat doesn’t taste right, try vegetable protein sources like beans and tofu. Also try sucking on sugar-free mints or candy, and brush your teeth often.
Nausea and vomiting: Nausea from treatment can make you feel terrible and compromise nutrition. Try eating frequent small snacks and sipping fluids throughout the day. Dry, bland and salty foods can lessen nausea. Clear liquids like broth and sports drinks are a good way to replace lost fluids. Avoid greasy, spicy and very sweet foods, those that cause gas and those with strong odors. Peppermint, ginger and cannabis are good for relieving nausea. After eating, rest sitting up instead of lying down.
Diarrhea and constipation: Many cancer medications cause diarrhea, which can lead to dehydration and mineral imbalances, but other drugs cause the opposite problem. Fiber—found in raw fruits and vegetables, whole grains and nuts—helps food move through the digestive tract: Avoid it if you have diarrhea but eat more if constipated. Fried, greasy and high-fat foods can worsen diarrhea. For constipation, drink more fluids and get more exercise.
People undergoing radiation therapy or taking cancer medications can develop low white blood cell counts, which impairs immune function and makes the body more susceptible to infections. Therefore, it is important to follow food safety precautions.
Wash hands with soap and water before handling food. Wash fruits and vegetables well, even those you can peel. Meat, seafood and eggs should be well cooked. Use separate utensils and cutting boards for vegetables and meat. Keep cold foods cold and hot foods hot to kill germs. Avoid unpasteurized dairy products and foods from bulk bins, deli counters and salad bars, which may be contaminated with bacteria. Check expiration dates on food packages and throw out anything that looks, smells or tastes funny.
Tell your doctor or nurse if you are having trouble eating while being treated for cancer. Let them know if you are using any special diets or supplements. It may be helpful to keep a food diary to see if symptoms occur in patterns or if certain foods make you feel better or worse. Your providers may be able to adjust cancer drugs to reduce side effects or prescribe additional medications to stimulate your appetite and control nausea or diarrhea. If malnutrition is a concern, nutrients can be given through a feeding tube or infused directly into the bloodstream. Your provider may refer you to a registered dietitian, who can help you maintain good nutrition before, during and after cancer treatment.
For more information on cancer and nutrition, visit:
American Society of Clinical Oncology (ASCO)
Last Reviewed: October 12, 2017