If you're expecting to undergo chemotherapy, or currently are, you may be wondering if there's a way to build up your immune system during treatment. While eating certain foods might boost your immunity, focusing on getting enough calories and protein to keep your body well-nourished is also very important.
That's simply because good nutrition sets the stage for tolerating chemo better and staying as healthy as possible during treatment. If you've lost weight without trying, or if you have been eating a lot less than usual due to a poor appetite, your body's immune system could already be impaired. And a diet that is deficient in calories, protein and other specific nutrients can cause immune dysfunction, according to a June 2016 review in Trends in Immunology.
So what does it mean to eat well? Start by eating a variety of foods throughout your day. The U.S. 2015-2020 Dietary Guidelines recommend a healthy eating pattern that includes protein foods, grains, fruits, vegetables and calcium-rich foods such as milk, yogurt or fortified soy drinks. If you've been eating poorly or if you are underweight, increasing your calorie and protein intake — as well as incorporating healthy foods below — are all linked to bolstering your immune system before and during treatment.
Go for Protein
Protein foods are important as they help build and maintain muscles and tissues, and protein is a vital component of many body cell — including immune cells. The National Cancer Institute recommends modest amounts of meat and milk products, so opt for plant-based proteins when you can. Include protein-rich foods such as:
- Beans, peas or lentils
- Nuts or peanut butter
Reach for Quality Carbs
Breads, grains, cereals and starchy vegetables are sources of carbohydrates, which provide energy. When these foods are whole grains or minimally processed, they're considered high quality and solid sources of fiber and other nutrients. The 2015-2020 Dietary Guidelines recommend that at least half of your grain choices be whole grains, such as:
- Brown rice
- Whole-wheat pasta
- Sprouted whole-grain bread
- Whole-grain cereal
- Whole cornmeal
Refined grains, such as white rice, cream of wheat cereal, saltine crackers or white pasta aren't forbidden — but it's important that whole grains get more of an emphasis in your diet.
If you find that these low-fiber grains are easier to eat or tolerate if you have treatment side effects, such as nausea or poor appetite, don't fret: You can incorporate more of these foods during treatment if doing so helps you eat enough calories. When your treatment is completed and you're feeling better, you can work on swapping these for whole grains.
As an alternative to grains, you can choose starchy vegetables such as:
- White and sweet potatoes
- Winter squash (butternut, acorn)
Finish the meal with a fruit or a vegetable — or both if you have the appetite. Tips to include the most nutritious ones are to choose whole fruits and vegetables (instead of juices) and to eat a variety of colorful choices each day. The pigments in red, purple, orange, green and yellow fruits and vegetables are plant chemicals linked to health benefits, which may include cancer-fighting and immune-building benefits, according to the American Institute for Cancer Research.
Add Healthy Fats
If you've lost weight or muscle mass, you'll need to prioritize gaining weight and trying to eat a bit more. Being undernourished going into chemo puts you at risk for poor treatment tolerance and more side effects, according to cancer nutrition guidelines published in the February 2017 issue of Clinical Nutrition.
Ensure your meals are balanced and take steps to sneak extra calories and protein into your diet. A good way to add calories is to include healthy fats — especially sources of unsaturated fats that tend to have favorable effects on cholesterol levels and inflammation. Try these tips to get more healthy fats:
- Add slivered almonds or pine nuts to your cooked vegetables
- Toss sunflower seeds or pecans in your salad
- Spike your oatmeal with walnuts or ground flax seeds
- Dip your apple in peanut butter or almond butter
- Liberally use olive oil-based dressing on your salad
- Add avocado or hummus to your sandwich, salad or on toast
- Drizzle olive oil on your pasta, rice or veggies
Get Plenty of Immune-Boosting Nutrients
Although eating well supports immunity, there's no quality research that shows specific foods can boost immune function during chemo. However, nutrition plays a role in the development, maintenance and functioning of the immune system.
And certain nutrients — most notably vitamins A, C, E and zinc — are known to be essential to immune health, according to the Academy of Nutrition and Dietetics. To further optimize your diet, start by including foods high in the nutrients below.
Vitamin A Foods
Vitamin A helps keep the skin and tissues in the respiratory system, intestines, mouth and stomach healthy. And this helps the body keep bad bacteria and viruses out. Foods rich in vitamin A include:
- Green vegetables such as broccoli, greens, kale and spinach
- Orange fruits and vegetables including carrots, cantaloupe, apricots and yams
Vitamin C Foods
Vitamin C helps the body make antibodies which, in turn, boosts immunity. This can protect your body from infections. Foods rich in vitamin C include:
- Citrus fruit, such as oranges, grapefruit, lemon and lime
- Kiwi fruit
- Red and green peppers
Vitamin E Foods
Vitamin E is an antioxidant, which protects the body from damaging free radicals and helps immune function. Sources of vitamin E include:
- Oils made from nuts or seeds
- Spinach and broccoli
- Fortified breakfast cereals
Foods High in Zinc
Zinc is a mineral that helps the immune system work properly. According to a December 2017 review in Nutrients, both a deficiency and excess zinc impair immunity, so the right balance is important. All immune cells depend on adequate zinc for proper function, and you can get more zinc by including these foods in your diet:
- Beans, peas, lentils
- Nuts and seeds
- Whole grains
- Lean meat, poultry and fish
What About Probiotics?
Probiotics — the live microorganisms found in yogurt, kimchi, miso and other fermented foods — are associated with helping the body's immune response, according to a February 2014 review in Today's Dietitian. What's more, probiotics are linked to alleviating cancer treatment-associated side effects, according to Memorial Sloan Kettering Cancer Center. However, the safety of probiotics when undergoing chemo is not well-established, so before supplementing your diet with fermented foods or taking probiotics, discuss risks and benefits with your cancer care team.
Should You Take a Supplement?
Since many vitamins play a role in immunity, does this mean that taking dietary supplements will help? The answer is not so straightforward. There are concerns that some supplements decrease the effectiveness of chemo, while others may help improve treatment tolerance, according to a March 2016 review in Nutrients. This illustrates the importance of talking with your oncologist and cancer care team about supplements and only taking what is recommended during your chemo treatment.
What's more important appears to be the "symphony" of eating a diet that emphasizes whole, unprocessed plant-based foods like colorful fruits and vegetables. The interactions between different foods, nutrients and plant chemicals is something the supplements can't provide. And one reason a plant-based diet may be so healthy is because of its beneficial effect on the gut, an important part of the immune system.
A healthy gut acts as a barrier to protect the body from toxins, and the trillions of bacteria that line the gut also help regulate inflammation (which is related to immunity) and produce substances that help fight disease-causing microorganisms.
To keep your gut healthy, adopt a diet that is centered on whole, minimally processed plant foods. In fact, the Mediterranean diet is linked to healthier gut bacteria, according to research in the September 2015 issue of the journal Gut.
Work on Staying Well
There are other ways to improve immunity before, during and after chemo. For example, it's important to wash your hands regularly with soap and water, particularly after being around people who are sick or after touching items that can make you ill, such as garbage or animal waste. Also, limit contact with people who are sick and avoid large crowds. Ask your oncologist about other ways to protect yourself and stay current with your flu shot and other immunizations.
Seek the assistance of a dietitian, preferably one from your cancer care team, to you have a clear understanding of the amount of calories and protein you need, and to clarify any other tips to build immunity during chemo. Your dietitian can also review eating strategies to counter treatment-related side effects such as nausea, mouth sores or poor appetite.
Is This an Emergency?
- Clinical Nutrition: "ESPEN Guidelines on Nutrition in Cancer Patients"
- National Cancer Institute: "Eating Hints: Before, During and After Cancer Treatment"
- Trends in Immunology: "Immune Dysfunction as a Cause and Consequence of Malnutrition"
- Academy of Nutrition and Dietetics: "Protect Your Health with Immune-Boosting Nutrition"
- Nutrients: "Micronutrients in Oncological Intervention"
- Gut: "High-Level Adherence to a Mediterranean Diet Beneficially Impacts the Gut Microbiota and Associated Metabolome"
- Memorial Sloan Kettering Cancer Center: "Probiotics"
- Today's Dietitian: "Nutrition, Inflammation and Disease"
- Dietary Guidelines 2015-2020: "Executive Summary"
- American Institute for Cancer Research:"Phytochemicals: The Cancer Fighters in Your Foods"