The power of nutrition to strengthen the immune system is not yet fully understood. Researchers are studying nutrition as a means of reducing cancer risk, extending survival, and increasing quality of life.
You may worry about what happens to your immune system during breast cancer treatment. Will removing lymph nodes or receiving chemotherapy damage its ability to function? Your immune system is very resilient and flexible, but certain breast cancer treatments, such as chemotherapy, can weaken it. Eating a healthy diet during and after treatment can help your immune system get back into top form quickly after you're done with treatment.
How to eat when your immune system is weak
If your immune system is weak, you want to stay away from bacteria and other organisms that could make you sick. For important steps you can take when buying and preparing food, visit the page on Food Production and Safety.
Getting enough protein is important to helping your immune system stay strong. Here are some good sources of protein for people with weakened immune systems:
- lean meat, fish, eggs, or pasteurized tofu, all well cooked; check the internal temperature of the food with a thermometer to make sure it's at the proper temperature to kill any bacteria. For a complete list of proper cooking temperatures for foods, see the United States Department of Agriculture's food safety fact sheet.
- pasteurized low-fat milk
- low-fat cottage cheese or low-fat pasteurized yogurt
- canned or dehydrated soup
- a multivitamin. Rather than take supplements, which may interact with your treatment, talk to your doctor about taking a daily multivitamin with minerals
Foods to avoid
Certain foods can have high levels of bacteria. The U.S. Food and Drug Administration (FDA) recommends that children, older adults, and those with weakened immune systems avoid the following foods:
- raw vegetable sprouts (alfalfa, radish, broccoli, mung bean, etc.), because of a high risk of Salmonella and E. coli contamination
- raw eggs, including unpasteurized eggnog, uncooked Caesar salad dressing, and unbaked meringues, because of possible Salmonella contamination
- unpasteurized fruit and vegetable juice, including cider, unless you prepare it at home with thoroughly washed produce
- raw or undercooked ground meat and poultry
- tofu packed in water
As a general rule, most registered dietitians recommend avoiding the following foods during chemotherapy because they can have levels of bacteria high enough to make a person with a weakened immune system sick:
- foods that are raw or undercooked, which can include meat, fish, shellfish, lox, sushi, sashimi, poultry, eggs, hot dogs, deli meats, tofu, sausage, and bacon
- foods containing raw eggs, such as hollandaise sauce, raw cookie dough, or homemade mayonnaise
- unpasteurized (raw) milk and dairy products made from unpasteurized milk
- soft cheeses, such as feta, Brie, Camembert, blue-veined (Roquefort, Stilton, Gorgonzola, and blue) and Mexican-style cheeses, such as those used to make queso sauce
- unwashed raw fruits and vegetables and those with mold on them
- raw honey
- sun tea
- unpasteurized beer
- uncooked brewer's yeast
Also avoid salad bars, delis, buffets, sidewalk vendors, and potluck gatherings. All have a higher risk of improperly stored or refrigerated food and of poor hygiene by the people handling and cooking the food.
You also may want to have your tap water tested, especially if you get your water from a private or small community well. City water supplies and municipal wells that serve large numbers of people are regularly tested for contamination. Private and small community wells are not. If you find a problem, visit the Breast Cancer Risk Factors: Exposure to Chemicals in Water page for tips on how to make sure your water is safe.
You may also want to check with your cancer center or a registered dietitian for other recommendations.