Good nutrition is especially important if you have cancer because both the illness and its treatments can change the way you eat. Cancer treatments can also affect the way your body tolerates certain foods and uses nutrients.
The nutrient needs of people with cancer vary from person to person. Your doctor, nurses, and/or a registered dietitian can help you identify your nutrition goals and plan ways to help you meet them. Eating well while you are being treated for cancer might help you:
- Feel better.
- Keep up your strength and energy.
- Maintain your weight and your body’s store of nutrients.
- Better tolerate treatment related side effects.
- Lower your risk of infection.
- Heal and recover faster.
Eating well means eating a variety of foods that will give your body the nutrients needed to help fight cancer. These nutrients include protein, carbohydrates, fat, water, vitamins, and minerals.
We need protein for growth, to repair body tissue, and to keep our immune systems healthy. When your body doesn’t get enough protein, it might break down muscle for the fuel it needs. This makes it take longer to recover from illness and can lower resistance to infection. People with cancer often need more protein than usual. After surgery, chemotherapy or radiation therapy, extra protein is usually needed to heal tissues and help fight infection. Good sources of protein include fish, poultry, lean red meat, eggs, low-fat dairy products, nuts and nut butters, dried beans, peas and lentils, and soy foods.
Fats play an important role in nutrition. Fats and oils are made of fatty acids and serve as a rich source of energy for the body. The body breaks down fats and uses them to store energy, insulate body tissues, and transport some types of vitamins through the blood.
You may have heard that some fats are better for you than others. When considering the effects of fats on your heart and cholesterol level, choose monounsaturated and polyunsaturated fats more often than saturated fats or trans fats.
Monounsaturated fats are found mainly in vegetable oils like olive, canola, and peanut oils.
Polyunsaturated fats are found mainly in vegetable oils like safflower, sunflower, corn, and flaxseed. They are also the main fats found in seafood.
Saturated fats are mainly found in animal sources like meat and poultry, whole or reduced-fat milk, cheese, and butter. Some vegetable oils like coconut, palm kernel oil, and palm oil are saturated. Saturated fats can raise cholesterol and increase your risk for heart disease. Less than 10% of your calories should come from saturated fat.
Trans-fatty acids are formed when vegetable oils are processed into margarine or shortening. Sources of trans fats include snack foods and baked goods made with partially hydrogenated vegetable oil or vegetable shortening. Trans fats also are found naturally in some animal products, like dairy products. Trans fats can raise bad cholesterol and lower good cholesterol; try to eliminate them from your diet.
Carbohydrates are the body’s major source of energy. Carbohydrates give the body the fuel it needs for physical activity and proper organ function. The best sources of carbohydrates – fruits, vegetables, and whole grains – also supply needed vitamins and minerals, fiber, and phytonutrients to the body’s cells.
Whole grains or foods made from them contain all the essential parts and naturally occurring nutrients of the entire grain seed. Whole grains are found in cereals, breads, flours, and crackers. Some whole grains, such as quinoa, brown rice, or barley, can be used as side dishes or part of an entree. When choosing a whole-grain product, look for the words “whole grain,” “stone ground,” “whole ground,” “whole-wheat flour,” “whole-oat flour,” or “whole-rye flour.”
Fiber is the part of plant foods that the body cannot digest. There are 2 types of fiber. Insoluble fiber helps to move food waste out of the body quickly, and soluble fiber binds with water in the stool to help keep stool soft.
Other sources of carbohydrates include bread, potatoes, rice, spaghetti, pasta, cereals, corn, peas, and beans. Sweets (desserts, candy, and drinks with sugar) can supply carbohydrates, but provide very little in the way of vitamins, minerals, or phytonutrients.
Water and liquids or fluids are vital to health. All body cells need water to function. If you do not take in enough fluids or if you lose fluids through vomiting or diarrhea, you can become dehydrated (your body doesn’t have as much fluid as it should). If this happens, the fluids and minerals that help keep your body working can become dangerously out of balance. You do get some water from the foods you eat, but a person should drink about eight 8-ounce glasses of liquid each day to be sure that all the body cells get the fluid they need. You may need extra fluids if you are vomiting or have diarrhea. Keep in mind that all liquids (soups, milk, even ice cream and gelatin) count toward your fluid goals.
Vitamins and Minerals
The body needs small amounts of vitamins and minerals to help it function properly. Most are found naturally in foods. They are also sold as supplements in pill and liquid form. They help the body use the energy (calories) found in foods. A person who eats a balanced diet with enough calories and protein usually gets plenty of vitamins and minerals. But it can be hard to eat a balanced diet when you are being treated for cancer, especially if you have treatment side effects that last for a long time. In this case, your doctor or dietitian may suggest a daily multivitamin and mineral supplement.
If you are thinking of taking a vitamin or supplement, be sure to discuss this with your doctor first. Some people with cancer take large amounts of vitamins, minerals, and other dietary supplements to try to boost their immune system or even destroy cancer cells. But some of these substances can be harmful, especially when taken in large doses. In fact, large doses of some vitamins and minerals may make chemotherapy and radiation therapy less effective.
If your oncologist says it’s OK for you to take a vitamin during treatment, it may be best to choose a supplement with no more than 100% of the Daily Value (DV) of vitamins and minerals and one without iron (unless your doctor thinks you need iron).
Antioxidants include vitamins A, C, and E; selenium, and zinc; and some enzymes that absorb and attach to free radicals, preventing them from attacking normal cells.
If you want to take in more antioxidants, health experts recommend eating a variety of fruits and vegetables, which are good sources of antioxidants. Taking large doses of antioxidant supplements or vitamin-enhanced foods or liquids is usually not recommended while getting chemo or radiation therapy. Talk with your doctor to find out the best time to take antioxidant supplements.
Phytonutrients or phytochemicals are plant compounds like carotenoids, lycopene, resveratrol, and phytosterols that are thought to have health-protecting qualities. They are found in plant products such as fruits, vegetables, and teas. Pill or supplement forms of phytochemicals have not been shown to be as helpful as eating the foods that contain them.
Herbs have been used to treat disease for hundreds of years, with mixed results. Today, herbs are found in many products, like pills, liquid extracts, teas, and ointments. Many of these products are harmless and safe to use, but others can cause severe and harmful side effects. Some may even interfere with proven cancer treatments, including chemo, radiation therapy, and recovery from surgery. If you are interested in using products containing herbs, talk about it with your oncologist or nurse first.
Many people believe that if they find a pill or supplement in stores, it’s safe and it works. The Food and Drug Administration (FDA) has rules to help ensure that supplements contain what their labels claim they do, but the supplement’s safety and its effects on the body are not addressed by any FDA rules. The FDA does not make manufacturers of these products print possible side effects on their labels. And the FDA cannot pull a dietary supplement or herbal product from the market unless they have proof that the product is unsafe.
This means there’s no sure way to know if a supplement is safe or how it will affect you. Tell your health care team about any over-the-counter products or supplements you are using or are thinking about using. Take the bottle(s) to your doctor to talk about the dose and be sure that the ingredients do not interfere with your health or cancer treatments. Some other safety tips:
- Ask your doctor or nurses for reliable information on dietary supplements.
- Check the product labels for both the quantity and concentration of active ingredients in each product. Stop taking the product and call your doctor right away if you have side effects, like wheezing, itching, numbness, or tingling in your limbs.
Information Source: American Cancer Society