Few diets warn against the inclusion of raw vegetables, but if you’re wondering what foods to avoid while on chemotherapy, unwashed raw veggies, some egg products, and select cheeses make the list.

Chemotherapy is a type of treatment that uses potent chemicals to disrupt the life cycle of fast-growing cancer cells. As a systemic, or whole-body therapy, it can also affect your overall health in ways beyond cancer treatment.

Immune suppression is a common concern when it comes to chemotherapy side effects. Chemotherapy can change how well your bone marrow produces white blood cells — the cells that help you ward off infections.

If you’re in an immune-compromised phase of treatment, monitoring what you eat can help reduce your risk of dangerous foodborne infections.

Foods to avoid while on chemotherapy are those that may increase your risk of foodborne illnesses.

Catalina Ruz Gatica, a registered dietitian who specializes in chronic illness at Top Nutrition Coaching in Chicago, explained, “For those undergoing chemotherapy, it’s particularly important to avoid foods such as undercooked or raw meats, raw fish, food past its expiration date, or unwashed produce.”

Knowing which foods may be high risk can be tricky. Some products that may seem safe — such as Caesar salad dressing — can contain items like uncooked eggs.

Dry-cured or smoked meats

Products like dry-cured raw salami or smoked fish are preserved through drying, salting, and exposure to heat and smoke. While these processes can inhibit bacteria growth, they may not be as effective as high temperatures in killing all potentially harmful pathogens.

According to the National Center for Home Food Preservation, for example, certain molds are resistant to salt and can grow inside cured meats after they’re sliced.

Unpasteurized milk products

Pasteurization is the heat-based sterilization process used for many commercially packaged, sealed foods, including:

  • dairy products
  • juices
  • sandwich meats
  • egg products
  • nut butters

You may want to avoid raw milk products, such as unpasteurized yogurt, during chemotherapy because they haven’t undergone sterilization. These products include soft or blue-veined cheeses made with unpasteurized milk, such as:

  • blue cheese
  • brie
  • stilton
  • Roquefort
  • Gorgonzola
  • queso blanco fresco

Open-case products and bulk-bin items

Salads and meats stored in deli coolers for the day may be kept cold, but they’re potentially exposed to pathogens every time the door opens for an employee.

The same goes for bulk-bin items, such as cereal, that you can dish out yourself. You may not know what these foods were exposed to when the last person opened the bin.

Unwashed fruits, sprouts, and vegetables

Fruits and vegetables can be an important part of getting nutrients during chemotherapy, but they should always be washed or cooked before consumption to avoid surface contaminants that may make you ill.

This precaution includes packaged products made from fresh produce, such as salsas and unpasteurized “fresh squeezed” juices. Sprouts also need to be cooked because they have a higher risk of bacterial growth.

Undercooked meats

Cooking meat to the appropriate temperature is one of the safest food habits to perform during chemotherapy. High temperatures kill pathogens on the outside of the meat as well as internally.

You may want to avoid any undercooked meat, including those deliberately left raw, such as sushi, sashimi, and lox.

Raw egg

Raw eggs, including cooked eggs with runny yolks, are notorious for possibly carrying Salmonella bacteria, but products containing raw eggs can be challenging to spot.

Items that may contain raw egg include:

  • smoothies
  • homemade eggnog
  • homemade mayonnaise
  • uncooked cookie dough
  • hollandaise sauce
  • Caesar salad dressing

Raw nuts or fresh nut butters

Raw nuts may seem safe because of their low moisture content and long shelf life, but certain pathogens such as Salmonella don’t need much moisture to thrive.

Avoiding raw nuts and their products, such as fresh nut butters, can help lower your risk of a foodborne illness in the same way as it does for raw vegetables.

The Center for Foodborne Illness Research and Prevention notes that long storage times for nut products may also increase the risk of illness related to fungi growth.

Cream-filled baked goods

Baked goods that contain cream fillings often have a milk base, which can be an ideal medium in which foodborne pathogens may grow.

Raw honey or honeycomb

The use of raw honey during cancer treatment is controversial.

Some evidence suggests honey may have a variety of anticancer properties, but at the same time, it can potentially carry dangerous pathogens such as those that may cause botulism.

Certain water

Using water directly from wells, springs, or streams may expose you to microorganisms and pathogens that cause illness, such as:

With the rules of washing, cooking, and sourcing in mind, there are plenty of helpful foods to eat during chemotherapy.

According to Ruz Gatica, some foods may even boost your immunity.

“There are certain foods that can support the body’s immune function during chemotherapy. Foods rich in vitamins A, C, and E, selenium, and zinc are particularly beneficial for the immune system,” she said.

Vitamin-rich sources can be found in foods such as:

  • sweet potatoes
  • broccoli
  • squash
  • pumpkin seeds
  • lentils
  • salmon
  • eggs

Remember, it’s not that you can’t eat eggs or vegetables while undergoing chemotherapy. As long as they’re properly prepared, they can be a part of maintaining overall health.

Ruz Gatica suggested, “If symptoms like poor appetite occur while undergoing chemotherapy, consuming these immune-supportive foods as small, frequent meals can help meet energy needs without exacerbating symptoms.”

Diet management during chemotherapy is important as a means of warding off infection, but it’s also how you can keep your body as healthy as possible to aid in cancer treatment and minimize the side effects of chemotherapy.

“When it comes to going through chemotherapy, what’s on your plate really matters,” indicated Ruz Gatica. “Eating the right foods helps keep your body’s engine running smoothly, supporting metabolic and functional health while warding off any chance of malnutrition.”

She added that by ensuring you get enough protein, calories, vitamins, and minerals, you’re helping your body stay strong and resilient throughout treatment.

Foods to avoid while on chemotherapy are those that may increase your chances of food-related illness.

While anyone can become sick from eating a contaminated product, chemotherapy knocks your immune system down and can make you more vulnerable to infections.

Focusing on thoroughly cooked foods and washed produce, as well as skipping bin-style and deli cooler items, are simple rules that can help you eat the right foods during cancer treatment.