Nutrition is a process in which food is taken in and used by the body for growth, to keep the body healthy, and to replace tissue. Good nutrition is important for good health. Eating the right kinds of foods before, during, and after cancer treatment can help the patient feel better and stay stronger. A healthy diet includes eating and drinking enough of the foods and liquids that have important nutrients (vitamins, minerals, protein, carbohydrates, fat, and water) the body needs.Healthy eating habits are important during and after cancer treatment.
Nutrition therapy is used to help cancer patients keep a healthy body weight, maintain strength, keep body tissue healthy, and decrease side effects both during and after treatment.A registered dietitian is an important part of the healthcare team.
A registered dietitian (or nutritionist) is a part of the team of health professionals that help with cancer treatment and recovery. A dietitian will work with patients, their families, and the rest of the medical team to manage the patient’s diet during and after cancer treatment.Cancer and cancer treatments may cause side effects that affect nutrition.
For many patients, the effects of cancer and cancer treatments make it hard to eat well. Cancer treatments that affect nutrition include:
When the head, neck, esophagus, stomach, intestines, pancreas, or liver are affected by the cancer treatment, it is hard to take in enough nutrients to stay healthy.Cancer and cancer treatments may cause malnutrition.
Cancer and cancer treatments may affect taste, smell, appetite, and the ability to eat enough food or absorb the nutrients from food. This can cause malnutrition, which is a condition caused by a lack of key nutrients. Alcohol abuse and obesity may increase the risk of malnutrition.
Malnutrition can cause the patient to be weak, tired, and unable to fight infection or finish cancer treatment. Malnutrition may be made worse if the cancer grows or spreads.
Eating the right amount of protein and calories is important for healing, fighting infection, and having enough energy.Anorexia and cachexia are common causes of malnutrition in cancer patients.
Anorexia is the loss of appetite or desire to eat. It is a common symptom in patients with cancer. Anorexia may occur early in the disease or later, if the cancer grows or spreads. Some patients already have anorexia when they are diagnosed with cancer. Most patients who have advanced cancer will have anorexia. Anorexia is the most common cause of malnutrition in cancer patients.
Cachexia is a condition marked by weakness, weight loss, and fat and muscle loss. It is common in patients with tumors that affect eating and digestion. It can occur in cancer patients who are eating well, but are not storing fat and muscle because of tumor growth.
Some tumors change the way the body uses certain nutrients. The body's use of protein, carbohydrates, and fat may be affected, especially by tumors of the stomach, intestines, or head and neck. A patient may seem to be eating enough, but the body may not be able to absorb all the nutrients from the food.
Cancer patients may have anorexia and cachexia at the same time.
See the Treatment of Symptoms section for more information on side effects from treatment.Chemotherapy and Hormone Therapy Chemotherapy and hormone therapy affect nutrition in different ways.
Chemotherapy affects cells all through the body. Chemotherapy uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Healthy cells that normally grow and divide quickly may also be killed. These include cells in the mouth and digestive tract.
Hormone therapy adds, blocks, or removes hormones. It may be used to slow or stop the growth of certain cancers. Some types of hormone therapy may cause weight gain.Chemotherapy and hormone therapy cause different nutrition problems.
Side effects from chemotherapy may cause problems with eating and digestion. When more than one chemotherapy drug is given, each drug may cause different side effects or when drugs cause the same side effect, the side effect may be more severe.
The following side effects are common:
Patients receiving hormone therapy may need changes in their diet to prevent weight gain.Radiation TherapyRadiation therapy kills cells in the treatment area.
Radiation therapy kills cancer cells and healthy cells in the treatment area. How severe the side effects are depends on the following:
Radiation therapy to any part of the digestive system has side effects that cause nutrition problems. Most of the side effects begin two to three weeks after radiation therapy begins and go away a few weeks after it is finished. Some side effects can continue for months or years after treatment ends.
The following are some of the more common side effects:
Radiation therapy may also cause tiredness, which can lead to a decrease in appetite.SurgerySurgery increases the body's need for nutrients and energy.
The body needs extra energy and nutrients to heal wounds, fight infection, and recover from surgery. If the patient is malnourished before surgery, it may cause problems during recovery, such as poor healing or infection. For these patients, nutrition care may begin before surgery.Surgery to the head, neck, esophagus, stomach, or intestines may affect nutrition.
Most cancer patients are treated with surgery. Surgery that removes all or part of certain organs can affect a patient's ability to eat and digest food.
The following are nutrition problems caused by surgery:
The side effects of immunotherapy are different for each patient and the type of immunotherapy drug given.
The following nutrition problems are common:
Chemotherapy, radiation therapy, and other medicines used before or during a stem cell transplant may cause side effects that keep a patient from eating and digesting food as usual.
Common side effects include the following:
Patients who receive a stem cell transplant have a high risk of infection. Chemotherapy or radiation therapy given before the transplant decrease the number of white blood cells, which fight infection. It is important that these patients learn about safe food handling and avoid foods that may cause infection.
After a stem cell transplant, patients are at risk for acute or chronic graft-versus-host disease (GVHD). GVHD may affect the gastrointestinal tract or liver and change the patient's ability to eat or absorb nutrients from food.
Screening is used to look for health problems that affect the risk of poor nutrition. This can help find out if the patient is likely to become malnourished, and if nutrition therapy is needed.
The healthcare team may ask questions about the following:
A physical exam is done to check the body for general health and signs of disease. The patient is checked for signs of loss of weight, fat, and muscle, and for fluid buildup in the body.Counseling and diet changes are made to improve the patient’s nutrition.
A registered dietitian can work with patients and their families to counsel them on ways to improve the patient's nutrition. The registered dietitian gives care based on the patient's nutrition and diet needs. Changes to the diet are made to help decrease symptoms from cancer or cancer treatment. These changes may be in the types and amount of food, how often a patient eats, and how food is eaten (for example, at a certain temperature or taken with a straw).
A registered dietitian works with other members of the healthcare team to check the patient's nutritional health during cancer treatment and recovery. In addition to the dietitian, the healthcare team may include the following:
The goal of nutrition therapy in patients with advanced cancer is to give patients the best possible quality of life and control symptoms that cause distress.
Patients with advanced cancer may be treated with anticancer therapy and palliative care, palliative care alone, or may be in hospice care. Nutrition goals will be different for each patient. Some types of treatment may be stopped if they are not helping the patient.
As the focus of care goes from cancer treatment to hospice or end-of-life care, nutrition goals may become less aggressive, and a change to care meant to keep the patient as comfortable as possible. See the Nutrition Needs at End of Life section for more information on nutrition at the end of life.
When side effects of cancer or cancer treatment affect normal eating, changes can be made to help the patient get the nutrients they need. Eating foods that are high in calories, protein, vitamins, and minerals is important. Meals should be planned to meet the patient's nutrition needs and tastes in food.
The following are some of the more common symptoms caused by cancer and cancer treatment and ways to treat or control them.Anorexia
The following may help cancer patients who have anorexia (loss of appetite or desire to eat):
If these diet changes do not help with the anorexia, tube feedings may be needed so that you will get enough nutrients each day.
Medicines may be given to increase appetite. See the Medicines to Treat Cachexia and Weight Loss section for more information.Nausea
The following may help cancer patients control nausea:
The following may help cancer patients control vomiting:
The following may help cancer patients with a dry mouth:
The following can help patients who have mouth sores:
The following may help cancer patients who have taste changes:
The following may help cancer patients who have a sore throat or trouble swallowing:
The following may help patients who have symptoms of lactose intolerance:
The following may help cancer patients prevent weight gain:
It is best to take in food by mouth whenever possible. Some patients may not be able to take in enough food by mouth because of problems from cancer or cancer treatment.Nutrition support can be given in different ways.
In addition to counseling by a dietitian, and changes to the diet, nutrition therapy includes nutritional supplement drinks, and enteral and parenteral nutrition support. Nutritional supplement drinks help cancer patients get the nutrients they need. They provide energy, protein, fat, carbohydrates, fiber, vitamins, and minerals. They are not meant to be the patient's only source of nutrition.
A patient who is not able to take in the right amount of calories and nutrients by mouth may be fed using the following:
The nutrients are given in liquid formulas that have water, protein, fats, carbohydrates, vitamins, and/or minerals.
Nutrition support can improve a patient's quality of life during cancer treatment, but may cause problems that should be considered before making the decision to use it. The patient and healthcare team should discuss the harms and benefits of each type of nutrition support. (See the Nutrition Needs at End of Life section for more information on the use of nutrition support at the end of life.)Enteral NutritionEnteral nutrition is also called tube feeding.
Enteral nutrition is giving the patient nutrients in liquid form (formula) through a tube that is placed into the stomach or small intestine. The following types of feeding tubes may be used:
The type of formula used is based on the specific needs of the patient. There are formulas for patients who have special health conditions, such as diabetes, or other needs, such as religious or cultural diets.Parenteral NutritionParenteral nutrition carries nutrients directly into the blood stream.
Parenteral nutrition is used when the patient cannot take food by mouth or by enteral feeding. Parenteral feeding does not use the stomach or intestines to digest food. Nutrients are given to the patient directly into the blood, through a catheter inserted into a vein. These nutrients include proteins, fats, vitamins, and minerals.The catheter may be placed into a vein in the chest or in the arm.
A central venous access catheter is placed beneath the skin and into a large vein in the upper chest. The catheter is put in place by a surgeon. This type of catheter is used for long-term parenteral feeding.
Central venous catheter. A central venous catheter is a thin, flexible tube that is inserted into a vein, usually below the right collarbone, and guided (threaded) into a large vein above the right side of the heart called the superior vena cava. It is used to give intravenous fluids, blood transfusions, chemotherapy, and other drugs. The catheter is also used for taking blood samples. It may stay in place for weeks or months and helps avoid the need for repeated needle sticks.
A peripheral venous catheter is placed into a vein in the arm. A peripheral venous catheter is put in place by trained medical staff. This type of catheter is usually used for short-term parenteral feeding for patients who do not have a central venous access catheter.
Peripheral venous catheter. A peripheral venous catheter is a thin, flexible tube that is inserted into a vein. It is usually inserted into the lower part of the arm or the back of the hand. It is used to give intravenous fluids, blood transfusions, chemotherapy, and other drugs.
The patient is checked often for infection or bleeding at the place where the catheter enters the body.
It is important that cancer symptoms and side effects that affect eating and cause weight loss are treated early. Both nutrition therapy and medicine can help lessen the effects that cancer and its treatment have on weight loss.Different types of medicine may be used to treat loss of appetite and weight loss.
Medicines that improve appetite and cause weight gain, such as prednisone and megestrol, may be used to treat loss of appetite and weight loss. Studies have shown that the effect of these medicines may not last long or there may be no effect. Treatment with a combination of medicines may work better than treatment with one medicine. Patients who are treated with a combination of medicines may have more side effects.
For patients at the end of life, the goals of nutrition therapy are focused on relieving symptoms rather than getting enough nutrients.
Common symptoms that can occur at the end of life include the following:
Patients who have problems swallowing may find it easier to swallow thick liquids than thin liquids.
Patients often do not feel much hunger at all and may want very little food. Sips of water, ice chips, and mouth care can decrease thirst in the last few days of life. Good communication with the healthcare team is important to understand the patient’s changes in nutrition needs.Patients and families decide how much nutrition and fluids will be given at the end of life.
Cancer patients and their caregivers have the right to make informed decisions. The patient's religious and cultural preferences may affect their decisions. The healthcare team may work with the patient's religious and cultural leaders when making decisions. The healthcare team and a registered dietitian can explain the benefits and risks of using nutrition support for patients at the end of life. In most cases, there are more harms than benefits.
The risks of nutrition support at the end of life include the following:
Cancer patients may try special diets to make their treatment work better, prevent side effects from treatment, or to treat the cancer itself. However, for most of these special diets, there is no evidence that shows they work.
Vegetarian or vegan diet
It is not known if following a vegetarian or vegan diet can help side effects from cancer treatment or the patient's prognosis. If the patient already follows a vegetarian or vegan diet, there is no evidence that shows they should switch to a different diet.
A macrobiotic diet is a high-carbohydrate, low-fat, plant-based diet. No studies have shown that this diet will help cancer patients.
A ketogenic diet limits carbohydrates and increases fat intake. The purpose of the diet is to decrease the amount of glucose (sugar) the tumor cells can use to grow and reproduce. It is a hard diet to follow because exact amounts of fats, carbohydrates and proteins are needed. However, the diet is safe.
Several clinical trials are recruiting glioblastoma patients to study whether a ketogenic diet affects glioblastoma tumor activity. Patients with glioblastoma who want to start a ketogenic diet should talk to their doctor and work with a registered dietitian. However, it is not yet known how the diet will affect the tumor or its symptoms.Some cancer patients may take dietary supplements.
A dietary supplement is a product that is added to the diet. It is usually taken by mouth, and usually has one or more dietary ingredients. Cancer patients may take dietary supplements to improve their symptoms or treat their cancer.
Vitamin C is a nutrient that the body needs in small amounts to function and stay healthy. It helps fight infection, heal wounds, and keep tissues healthy. Vitamin C is found in fruits and vegetables. It can also be taken as a dietary supplement.
See the PDQ summary on High-Dose Vitamin C for more information about the use of intravenous high-dose vitamin C as treatment for people with cancer.
Probiotics are live microorganisms used as dietary supplements to help with digestion and normal bowel function. They may also help keep the gastrointestinal tract healthy.
Studies have shown that taking probiotics during radiation therapy and chemotherapy can help prevent diarrhea caused by those treatments. This is especially true for patients receiving radiation therapy to the abdomen. Cancer patients who are receiving radiation therapy to the abdomen or chemotherapy that is known to cause diarrhea may be helped by probiotics.
Melatonin is a hormone made by the pineal gland (tiny organ near the center of the brain). Melatonin helps control the body’s sleep cycle. It can also be made in a laboratory and taken as a dietary supplement.
Several small studies have shown that taking a melatonin supplement with chemotherapy and/or radiation therapy for treatment of solid tumors may be helpful. It may help reduce side effects of treatment. Melatonin does not appear to have side effects.
Oral glutamine is an amino acid that is being studied for the treatment of diarrhea and mucositis (inflammation of the lining of the digestive system, often seen as mouth sores) caused by chemotherapy or radiation therapy. Oral glutamine may help prevent mucositis or make it less severe.
Cancer patients who are receiving radiation therapy to the abdomen may benefit from oral glutamine. Oral glutamine may reduce the severity of diarrhea. This can help the patients continue with their treatment plan.
For information from the National Cancer Institute (NCI) about nutrition and cancer treatment, see Side Effects.
For general nutrition information and other resources, see the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
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This PDQ cancer information summary has current information about nutrition before, during, and after cancer treatment. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
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PDQ® Supportive and Palliative Care Editorial Board. PDQ Nutrition in Cancer Care. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389440]
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Physicians version: CDR0000276584
Date first published: 2003-03-24 Date last modified: 2018-01-04
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