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This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER.
Good nutrition is important for cancer patients.
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 the important nutrients (vitamins, minerals, protein, carbohydrates, fat, and water) the body needs.
When the body does not get or cannot absorb the nutrients needed for health, it causes a condition called malnutrition or malnourishment.
This summary is about nutrition in adults with cancer.
Healthy eating habits are important during cancer treatment.
Nutrition therapy is used to help cancer patients get the nutrients they need to keep up their body weight and strength, keep body tissue healthy, and fight infection. Eating habits that are good for cancer patients can be very different from the usual healthy eating guidelines.
Healthy eating habits and good nutrition can help patients deal with the effects of cancer and its treatment. Some cancer treatments work better when the patient is well nourished and gets enough calories and protein in the diet. Patients who are well nourished may have a better prognosis (chance of recovery) and quality of life.
Cancer can change the way the body uses food.
Some tumors make chemicals that 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 or intestines. A patient may seem to be eating enough, but the body may not be able to absorb all the nutrients from the food.
Cancer and cancer treatments may 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, or intestines are affected by the cancer treatment, it is very hard to take in enough nutrients to stay healthy.
The side effects of cancer and cancer treatment that can affect eating include:
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 (a condition caused by a lack of key nutrients). Malnutrition can cause the patient to be weak, tired, and unable to fight infections or get through cancer treatment. Malnutrition may be made worse if the cancer grows or spreads. Eating too little protein and calories is a very common problem for cancer patients. Having enough 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 (the loss of appetite or desire to eat) is a common symptom in people 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. Almost all 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 a loss of appetite, weight loss, muscle loss, and general weakness. It is common in patients with tumors of the lung, pancreas, and upper gastrointestinal tract. It is important to watch for and treat cachexia early in cancer treatment because it is hard to correct.
Cancer patients may have anorexia and cachexia at the same time. Weight loss can be caused by eating fewer calories, using more calories, or both.
It is important to treat weight loss caused by cancer and its treatment.
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 the patient stay at a healthy weight. Medicine may be used for the following:
See the Nutrition Therapy in Cancer Care section and the Treatment of Symptoms section for more information.
Screening and assessment are done before cancer treatment begins, and assessment continues during treatment.
Screening is used to look for nutrition risks in a patient who has no symptoms. This can help find out if the patient is likely to become malnourished, so that steps can be taken to prevent it.
Assessment checks the nutritional health of the patient and helps to decide if nutrition therapy is needed to correct a problem.
Screening and assessment may include questions about the following:
A physical exam is also done to check the body for general health and signs of disease. The doctor will look for loss of weight, fat, and muscle, and for fluid buildup in the body.
Finding and treating nutrition problems early may improve the patient's prognosis (chance of recovery).
Early nutrition screening and assessment help find problems that may affect how well the patient's body can deal with the effects of cancer treatment. Patients who are underweight or malnourished may not be able to get through treatment as well as a well-nourished patient. Finding and treating nutrition problems early can help the patient gain weight or prevent weight loss, decrease problems with the treatment, and help recovery.
A healthcare team of nutrition specialists will continue to watch for nutrition problems.
A nutrition support team will check the patient's nutritional health often during cancer treatment and recovery. The team may include the following specialists:
A patient whose religion doesn't allow eating certain foods may want to talk with a religious advisor about allowing those foods during cancer treatment and recovery.
There are three main goals of nutrition therapy for cancer patients in active treatment and recovery.
The main goals of nutrition therapy for patients in active treatment and recovery are to provide nutrients that are missing, maintain nutritional health, and prevent problems. The health care team will use nutrition therapy to do the following:
Good nutrition continues to be important for patients who are in remission or whose cancer has been cured.
The goal of nutrition therapy for patients who have advanced cancer is to help with the patient's quality of life.
The goals of nutrition therapy for patients who have advanced cancer include the following:
See the Nutrition in Advanced Cancer section for more information.
Nutrition support gives nutrition to patients who cannot eat or digest normally.
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. Medicine to increase appetite may be used.
Nutrition support for patients who cannot eat can be given in different ways.
A patient who is not able to take in enough food by mouth may be fed using enteral nutrition (through a tube inserted into the stomach or intestines) or parenteral nutrition (infused into the bloodstream). 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 there are harms that should be considered before making the decision to use it. The patient and health care providers should discuss the harms and benefits of each type of nutrition support. (See the Nutrition in Advanced Cancer section below for more information on deciding whether to use nutrition support.)
Enteral 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. Formula may be given through the tube as a constant drip (continuous feeding) or 1 to 2 cups of formula can be given 3 to 6 times a day (bolus feeding).
Enteral nutrition is sometimes used when the patient is able to eat small amounts by mouth, but cannot eat enough for health. Nutrients given through a tube feeding add the calories and nutrients needed for health.
Enteral nutrition may continue after the patient leaves the hospital.
If enteral nutrition is to be part of the patient's care after leaving the hospital, the patient and caregiver will be trained to do the nutrition support care at home.
Parenteral 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 (thin tube) inserted into a vein. These nutrients include proteins, fats, vitamins, and minerals.
Parenteral nutrition is used only in patients who need nutrition support for five days or more.
The catheter may be placed into a vein in the chest or in the arm.
A central venous 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.
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.
The patient is checked often for infection or bleeding at the place where the catheter enters the body.
Parenteral nutrition support may continue after the patient leaves the hospital.
If parenteral nutrition is to be part of the patient's care after leaving the hospital, the patient and caregiver will be trained to do the nutrition support care at home.
Ending parenteral nutrition support must be done under medical supervision.
Going off parenteral nutrition support needs to be done slowly and is supervised by a medical team. The parenteral feedings are decreased by small amounts over time until they can be stopped, or as the patient is changed over to enteral or oral feeding.
Surgery and Nutrition
Surgery 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 specific types of surgery:
All of these can affect the patient's ability to eat normally. Emotional stress about the surgery itself also may affect appetite.
Nutrition therapy can help relieve nutrition problems caused by surgery.
Nutrition therapy can relieve or decrease the side effects of surgery and help cancer patients get the nutrients they need. Nutrition therapy may include the following:
It is common for patients to have pain, tiredness, and/or loss of appetite after surgery. For a short time, some patients may not be able to eat what they usually do because of these symptoms. Following certain tips about food may help. These include:
Chemotherapy and Nutrition
Chemotherapy affects cells all through the body.
Chemotherapy affects fast-growing cells and is used to treat cancer because cancer cells grow and divide quickly. Healthy cells that normally grow and divide quickly may also be killed. These include cells in the mouth, digestive tract, and hair follicles.
Chemotherapy may affect nutrition.
Chemotherapy may cause side effects that cause problems with eating and digestion. When more than one anticancer drug is given, more side effects may occur or they may be more severe. The following side effects are common:
Nutrition therapy can help relieve nutrition problems caused by chemotherapy.
Patients who have side effects from chemotherapy may not be able to eat normally and get all the nutrients they need to restore healthy blood counts between treatments. Nutrition therapy can help relieve these side effects, help patients recover from chemotherapy, prevent delays in treatment, prevent weight loss, and maintain general health. Nutrition therapy may include the following:
Radiation Therapy and Nutrition
Radiation therapy can affect cancer cells and healthy cells in the treatment area.
Radiation therapy can kill cancer cells and healthy cells in the treatment area. The amount of damage depends on the following:
Radiation therapy may affect nutrition.
Radiation therapy to any part of the digestive system often has side effects that cause nutrition problems. Most of the side effects begin a few 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.
Nutrition therapy can help relieve the nutrition problems caused by radiation therapy.
Nutrition therapy during radiation treatment can help the patient get enough protein and calories to get through treatment, prevent weight loss, help wound and skin healing, and maintain general health. Nutrition therapy may include the following:
Patients who receive high-dose radiation therapy to prepare for a bone marrow transplant may have many nutrition problems and should see a dietitian for nutrition support.
See the Stem Cell Transplant and Nutrition section for more information.
Biologic Therapy and Nutrition
Biologic therapy may affect nutrition.
The side effects of biologic therapy are different for each patient and each type of biologic agent. The following nutrition problems are common:
Nutrition therapy can help relieve nutrition problems caused by biologic therapy.
The side effects of biologic therapy can cause weight loss and malnutrition if they are not treated. Nutrition therapy can help patients receiving biologic therapy get the nutrients they need to get through treatment, prevent weight loss, and maintain general health.
Stem Cell Transplant and Nutrition
Stem cell transplant patients have special nutrition needs.
Chemotherapy, radiation therapy, and medicines used for 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:
Nutrition therapy is very important for patients who have a stem cell transplant.
Transplant patients have a very high risk of infection. High doses of chemotherapy or radiation therapy decrease the number of white blood cells, which fight infection. It is especially important that transplant patients avoid getting infections.
Patients who have a transplant need plenty of protein and calories to get through and recover from the treatment, prevent weight loss, fight infection, and maintain general health. It is also important to avoid infection from bacteria in food. Nutrition therapy during transplant treatment may include the following:
See the Low White Blood Cell Counts and Infections section for more information.
When side effects of cancer or cancer treatment affect normal eating, changes can be made to help the patient get the nutrients needed. Medicines may be given to increase appetite. Eating foods that are high in calories, protein, vitamins, and minerals is usually best. 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 loss of appetite or desire to eat) is one of the most common problems for cancer patients. Eating in a calm, comfortable place and getting regular exercise may improve appetite. The following may help cancer patients who have a loss of appetite:
See the NCI website for Eating Hints: Before, During, and After Cancer Treatment, which has recipes such as Lactose-Free Double Chocolate Pudding, Banana Milkshake, and Fruit and Cream. For a free copy of this booklet, call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).
Changes in how foods taste may be caused by radiation treatment, dental problems, mouth sores and infections, or some medicines. Many cancer patients who receive chemotherapy notice a bitter taste or other changes in their sense of taste. A sudden dislike for certain foods may occur. This can cause a loss of appetite, weight loss, and a decreased quality of life. Some or all of a normal sense of taste may return, but it may take up to a year after treatment ends. The following may help cancer patients who have taste changes:
Taking zinc sulfate tablets during radiation therapy to the head and neck may help a normal sense of taste come back faster after treatment.
Dry mouth is often caused by radiation therapy to the head and neck and by certain medicines. Dry mouth may affect speech, taste, and the ability to swallow or to use dentures or braces. There is also an increased risk of cavities and gum disease because less saliva is made to wash the teeth and gums.
The main treatment for dry mouth is drinking plenty of liquids. Other ways to help relieve dry mouth include the following:
See the Dry Mouth section of the PDQ summary on Oral Complications of Chemotherapy and Head/Neck Radiation for more information.
Mouth Sores and Infections
Mouth sores can be caused by chemotherapy and radiation therapy. These treatments affect fast-growing cells, such as cancer cells. Normal cells inside the mouth also grow quickly and may be damaged by these cancer treatments. Mouth sores can be painful and become infected or bleed and make it hard to eat. By choosing certain foods and taking good care of their mouths, patients can usually make eating easier. The following can help patients who have mouth sores and infections:
See the Oral Mucositis and Infection sections of the PDQ summary on Oral Complications of Chemotherapy and Head/Neck Radiation for more information on mouth sores and infections.
Nausea caused by cancer treatment can affect the amount and kinds of food eaten. The following may help cancer patients control nausea:
See the PDQ summary on Nausea and Vomiting for more information.
Diarrhea may be caused by cancer treatments, surgery on the stomach or intestines, or by emotional stress. Long-term diarrhea may lead to dehydration (lack of water in the body) or low levels of salt and potassium, which are important minerals needed by the body.
The following may help cancer patients control diarrhea:
See the Dehydration (Lack of Fluid) section for more information.
Low White Blood Cell Counts and Infections
A low white blood cell count may be caused by radiation therapy, chemotherapy, or the cancer itself. Patients who have a low white blood cell count have an increased risk of infection. The following may help cancer patients prevent infections when white blood cell counts are low:
Dehydration (Lack of Fluid)
The body needs plenty of water to replace the fluids lost every day. Nausea, vomiting, and pain may keep the patient from drinking and eating enough to get the amount of water the body needs. Long-term diarrhea causes a loss of fluid from the body. One of the first signs of dehydration (lack of water in the body) is feeling very tired. The following may help cancer patients prevent dehydration:
It is very common for cancer patients to have constipation (fewer than three bowel movements a week). Constipation may be caused by the following:
Preventing and treating constipation is a part of cancer care.
To prevent constipation:
To treat constipation:
Good food sources of fiber include the following:
See the Constipation section of the PDQ summary on Gastrointestinal Complications for more information.
Palliative care helps relieve symptoms that bother the patient and helps improve the patient's quality of life.
The goal of palliative care is to improve the quality of life of patients who have a serious or life-threatening disease. Palliative care is meant to prevent or treat symptoms, side effects, and psychological, social, and spiritual problems caused by a disease or its treatment.
Palliative care for patients with advanced cancer includes nutrition therapy (see the Treatment of Symptoms section) and/or drug therapy.
Nutrition needs are different for patients with advanced cancer.
It is common for patients with advanced cancer to want less food. Patients usually prefer soft foods and clear liquids. Those who have problems swallowing may do better with thick liquids than with thin liquids. Patients often do not feel much hunger at all and may need very little food.
In patients with advanced cancer, most foods are allowed. During this time, eating can be focused on pleasure rather than getting enough nutrients. Patients usually cannot eat enough of any food that might cause a problem. However, some patients may need to stay on a special diet. For example, patients with cancer that affects the abdomen may need a soft diet to keep the bowel from getting blocked.
The benefits and harms of nutrition support are different for each patient.
Answering the following questions may help to make decisions about using nutrition support:
Cancer patients and their caregivers have the right to make informed decisions. The healthcare team and a registered dietitian can explain the benefits and risks of using nutrition support for patients with advanced cancer. In most cases, there are more harms than benefits, especially with parenteral nutrition support. However, for someone who still has good quality of life but is unable to get enough food and water by mouth, enteral feedings may be best. The benefits and risks of enteral nutrition during advanced cancer include the following:
Some foods do not mix safely with certain drugs.
Cancer patients may be treated with a number of drugs. Taking certain foods and drugs together may decrease or change how well the drugs work or cause life-threatening side effects. The following table lists some of the food and drug interactions that may occur with certain anticancer drugs:
Talk with your doctor about possible food and drug interactions.
Some herbal supplements do not mix safely with certain drugs or foods.
Taking some herbal supplements with certain foods and drugs may change how well cancer treatment works or cause life-threatening side effects. Talk with your doctor about how herbal supplements may affect your cancer treatment.
Cancer survivors have special nutrition needs.
Everyone needs a healthy diet and exercise for good health and to help prevent disease. Cancer survivors have special health needs, especially because of the risks of late effects and the cancer coming back. Studies have shown that a healthy diet helps to prevent late effects such as obesity, heart disease, and metabolic syndrome. Researchers are also studying whether certain diet and exercise habits in cancer survivors can keep cancer from coming back or keep new cancers from forming.
Healthy diet and lifestyle habits can improve the quality of life for cancer survivors.
Surveys show that many cancer survivors do not follow cancer prevention guidelines and have lifestyle behaviors that may increase their risk for late effects or make late effects worse. Education programs can help cancer survivors learn how to make behavior changes that keep them healthier. Programs that cover diet, exercise, and stress management are more likely to help cancer survivors make lasting changes.
The effects of diet and lifestyle on cancer continue to be studied.
Following certain dietary guidelines may help prevent cancer.
The American Cancer Society and the American Institute for Cancer Research both have dietary guidelines that may help prevent cancer. Their guidelines are a lot alike and include the following:
The effect of soy on breast cancer and breast cancer prevention is being studied.
Study results include the following:
Soy has substances in it that act like estrogen in the body. Studies were done to find out how soy affects breast cancer in patients who have tumors that need estrogen to grow. Some studies have shown that soy foods are safe for women with breast cancer when eaten in moderate amounts as part of a healthy diet.
If you are a breast cancer survivor be sure to check the most up-to-date information when deciding whether to include soy in your diet.
National Cancer Institute
For information from the National Cancer Institute (NCI) about nutrition and cancer treatment, see Side Effects.
For information from NCI about nutrition and cancer prevention, see the following PDQ summaries:
For general nutrition information and other resources, see the following:
Check the list of NCI-supported cancer clinical trials for supportive and palliative care trials about malnutrition, nutritional support and nutritional therapy that are now accepting participants. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug.
General information about clinical trials is also available from the NCI website.
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government's center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
Purpose of This Summary
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.
Reviewers and Updates
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Date Last Modified") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Supportive and Palliative Care Editorial Board.
Clinical Trial Information
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials are listed in PDQ and can be found online at NCI's website. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237).
Permission to Use This Summary
PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as "NCI's PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary]."
The best way to cite this PDQ summary is:
National Cancer Institute: PDQ® Nutrition in Cancer Care. Bethesda, MD: National Cancer Institute. Date last modified <MM/DD/YYYY>. Available at: http://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-pdq. Accessed <MM/DD/YYYY>.
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Last Revised: 2016-01-08
If you want to know more about cancer and how it is treated, or if you wish to know about clinical trials for your type of cancer, you can call the NCI's Cancer Information Service at 1-800-422-6237, toll free. A trained information specialist can talk with you and answer your questions.
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