Cancer treatment often affects a person's eating habits and nutritional needs. Although it is important for people with cancer to maintain a healthy body weight and eat nutritious foods, the side effects of surgery, radiation therapy, and chemotherapy may cause a person to eat less and lose weight. On the other hand, some treatments may cause weight gain  in some patients.
Nutrition recommendations during cancer treatment
Here are some general nutrition recommendations for people undergoing cancer treatment.
- Maintain a healthy weight. For many people, this means avoiding weight loss by getting enough calories on a daily basis. In people who are obese, this may mean losing some weight (moderately, only about a pound a week).
- Get essential nutrients the body needs, such as protein, carbohydrates, vitamins, minerals, and water.
- Be as active as you can, such as taking a daily walk. If you sit or sleep too much, you may lose muscle mass and increase your body fat, even if you are not gaining weight.
Ways to get essential nutrients and manage a healthy weight
Dietary counseling may help people with cancer get the appropriate nutrients into their diet and maintain a healthy body weight. Ask your health care team for a referral to a registered dietitian (RD). You can also find a dietitian  through the Academy of Nutrition and Dietetics.
Dietitians and other members of the health care team work with people to meet their nutritional needs. In addition to dietary counseling, they may recommend the following:
- Dietary supplements, such as multivitamins and calcium
- Liquid meal replacements and nutrient-dense beverages and snacks
- Feeding tubes
- Parenteral nutrition, which means getting nutrients into the body in a manner other than through the digestive tract; for example, intravenous (IV) injection. This strategy is for those who are exceptionally underweight and not getting enough nutrition before cancer surgery, or for those whose digestive tracts are not functioning (as in people who have had parts of the stomach, pancreas, or colon removed by surgery).
Side effects and nutrition
Cancer treatment often causes side effects , such as nausea, mouth sores, and taste changes that may make it difficult to eat or drink. Follow these tips to help you get the nutrition you need:
- If water tastes unpleasant to you, take in more liquid though items such as soup or a sports drink. Or, flavor your water by adding fresh cut fruit.
- If food tastes bland, try seasoning it with flavorful spices such as garlic, cayenne, and rosemary.
- Eat several small meals throughout the day instead of trying to eat large amounts of food at one time.
- If meat is no longer appealing, get protein from foods such as fish, egg whites, cheese, and beans.
- Suck on mints, chew on gum, or try fresh citrus fruits if you have a metallic taste in your mouth.
- If you have mouth sores or a gum infection, use a blender to make vegetables and meats smooth. Try juicing.
- Use plastic utensils instead of metal ones if the metal ones taste unpleasant to you. Cook in glassware.
Some side effects can be treated with medication, so talk with your doctor or other member of the health care team for more information.
The use of dietary supplements
Low-dose dietary supplements (such as multivitamins) may be appropriate for people with cancer who are not able to get all of their nutrients through foods. Multivitamins are dietary supplements that contain generally all of the required daily vitamins, minerals, and trace elements; they may also contain some minerals such as calcium, magnesium, or iron. They are typically taken orally (by mouth) as a pill, capsule, tablet, liquid, or powder. Because high doses of specific individual nutrient supplements can be harmful, it is important to talk with your doctor if you plan to take individual supplements.
Questions to ask your doctor before taking any dietary supplement include:
- What are the benefits of taking this dietary supplement?
- What are the possible side effects of taking this dietary supplement?
- Are there risks to taking this dietary supplement?
- Can taking dietary supplements interfere with my cancer treatment (surgery, chemotherapy, radiation therapy)?
- How much should I take and for how long?
- Where can I learn more about dietary supplements?
Read more about dietary and herbal supplements .
People undergoing cancer treatment need to be aware of food safety, because cancer treatment may weaken the immune system and lead to an infection. An infection  occurs when harmful bacteria, viruses, or fungi (such as yeast) invade the body and the immune system is not able to destroy them quickly enough. Here are some basic food safety tips to reduce the risk of infection.
- Wash hands before and during the handling and preparing of food.
- Wash your vegetables and fruit thoroughly before eating them.
- Handle and store food appropriately. For example, keep raw meat away from other foods when cooking.
- Eat thoroughly cooked foods. For example, do not eat eggs that are not cooked solid, and do not eat raw fish, oysters, or shellfish.
- Avoid drinking unpasteurized beverages, such as unpasteurized cider, raw milk, and fruit juices.
- Make sure food you purchase is not past its “sell-by” or expiration date.
Read more about food safety during and after cancer treatment .
Diet and nutrition after treatment
Although most nutrition recommendations include eating fruits, vegetables, and whole grains, the effect of specific dietary factors on cancer survival rates is not as well understood and is actively being studied. However, a healthy diet is important for cancer survivors because they may be at increased risk for other health conditions, such as heart disease, type 2 diabetes, and osteoporosis (weakening of the bones).
To reduce the risk of other diseases, doctors generally recommend that survivors follow common recommendations for good health, such as eating a nutrient-dense diet, quitting smoking , maintaining a healthy weight, and staying physically active.
National Cancer Institute: Overview of Nutrition in Cancer Care 
National Cancer Institute: Eating Hints for Patients Before, During, and After Treatment 
Academy of Nutrition and Dietetics: Home Food Safety 
Last Updated: February 15, 2012