- Cancer treatment can affect your appetite, eating habits, and weight, but it is important for people with cancer to maintain a healthy weight, get essential nutrients, and remain as physically active as possible.
- If you have difficulty eating due to side effects from cancer treatment, there are ways to make eating more comfortable.
- Working with a registered dietitian/nutritionist (RDN) can help make sure you are getting the nutrition you need.
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  for some patients.
Nutrition recommendations during cancer treatment
Here are some general nutrition recommendations for people receiving 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. For most people with cancer, weight loss should be moderate, meaning only about a pound a week.
- Get essential nutrients the body needs, such as protein, carbohydrates, fiber, vitamins, minerals, phytonutrients, such as carotenoids, 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
Nutrition counseling may help people with cancer get essential nutrients, such as protein, vitamins, and minerals into their diet and maintain a healthy body weight. Ask your health care team for a referral to a registered dietitian or nutritionist. 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 very underweight and not getting enough nutrition before cancer surgery, or for those whose digestive tracts do not work well because they have had parts of the stomach, pancreas, or colon removed with 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, tea, milk or milk substitutes such as almond milk, 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, dill, 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, beans, or high protein smoothies.
- Suck on mints, chew on gum, or try fresh citrus fruits if you have a metallic taste in your mouth. Brushing your teeth before eating, using plastic utensils, and cooking in glassware can also help.
- If you have mouth sores or a gum infection, use a blender to make vegetables and meats smooth. Try juicing or making smoothies.
Some side effects are often treated with medication, so talk with your doctor or another member of your 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?
- 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 receiving cancer treatment need to be aware of food safety, because some treatments 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 your hands before and during the handling and preparing of food.
- Wash 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 weakening of the bones, called osteoporosis.
To reduce the risk of other diseases, doctors generally recommend that cancer 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  and Eating Hints for Patients Before, During, and After Treatment 
Academy of Nutrition and Dietetics: Food Safety