Three Nutrition Tips for a Stronger Immune System

Viruses are in the air and all around us, from the common cold to COVID-19. Eating a healthy, balanced diet primes and activates your immune system to fight these pathogens, even before you get sick.

In this Q&A, Taylor Stein, Associate Researcher and Registered Dietitian at The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, discusses what foods you should eat to support your immune system this cold and flu season.

How does nutrition affect my immune system?

If your diet contains a lot of saturated fatty acids, sugar, and refined carbohydrates, you will not have as strong of an immune response compared to someone consuming diets rich in micronutrients, antioxidants, and fiber. Certain nutrients—specifically vitamins A, D, E, and K—are fat-soluble, meaning they are stored in your fat and take time to accumulate, especially vitamin D. These vitamins support different functions of the immune system and are readily available to fight disease in advance.

Does this mean I need to consume these nutrients before I get sick?

Yes. When you are sick, your immune system is scavenging the body for nutrients, and if you don’t have enough fat-soluble vitamins stored, it can take you longer to get better. Additionally, being sick can affect your ability to eat and drink, so it is very important to have a balanced diet at all times to keep up your stores of these vitamins. Alternatively, vitamins that are water soluble, such as vitamin C and those in the B-complex group, cannot be stored, so you should strive to eat lots of these while you are sick. You also need to eat plenty of macronutrients—carbohydrates, proteins, fiber, and fats.

Taylor Stein, RD

What foods are good for my immune system, and why?

Immune system health largely depends on five food groups:

• Animal meats, fish, dairy products, legumes, nuts, and whole grains. Proteins are the building blocks of cytokines, small proteins that send signals to the immune system telling it where to send white blood cells to fight infections. Since cytokines require different amino acids, you need to eat a variety of protein both from animal and plant-based products. High protein foods contain B-complex vitamins, which are necessary for cell proliferation, which plays an important role in immunity.
• Brightly colored fruits and vegetables. Apricots, kiwi, blueberries, avocados, carrots, strawberries, Swiss chard, bell peppers, raspberries, red onions and other brightly colored produce are filled with both fat-soluble and water-soluble vitamins and are also a great source of fiber.
• Fortified dairy products, eggs, and salmon. These are a great source of vitamin D, which helps activate T cells and has other important functions that affect your immune system. You can also get vitamin D in smaller amounts from nuts and mushrooms. Sunlight is also a great source of vitamin D.
• Nuts, seeds, eggs, legumes, and fish. These all contain disease-fighting minerals, such as zinc, magnesium, and selenium. Pumpkin seeds, almonds, cashews, shellfish, tuna, chickpeas, and lentils are all good sources of these minerals.
• High-fiber, pre-and-probiotic, and fermented foods. These foods are good for your gut, where more than 70 percent of your immune cells live. High-fiber foods include legumes, fruits, and vegetables. Pre-and-probiotic and fermented foods include yogurt, kefir, and buttermilk. These gut-healthy foods are important in maintaining lymphoid tissue in the gastrointestinal tract that helps fight disease.

What are some easy ways to incorporate these foods into my daily diet?

A great way to get more of these foods is to eat them as snacks. For example, snacking on nuts and seeds, bean or guacamole dip, whole grain toast with avocado, and fruit and cheese are all easy ways to get more of the nutrients that prime the immune system. You also need to include them in your main meals. Each dish should include a good source of lean protein—meats, poultry, or fish—and plant-based proteins such as beans, as well as non-starchy vegetables. A simple rule is to fill one quarter of your plate with protein, one quarter with a whole grain or starchy vegetable, and the other half with brightly colored vegetables.

How do these foods compare to taking supplements?

When it comes to immune system health, it is good to have a food-first mentality. Whereas supplements typically provide only one nutrient, a balanced diet filled with whole foods contains all the micro and macronutrients you need. These nutrients work most optimally when they are paired together and are easier to digest than supplements. However, supplements can be a great tool for someone who struggles to eat a variety of foods or has a condition that reduces their ability to consume or prepare healthy food. Keep in mind that supplements are not regulated by the Food and Drug Administration, so it is important to get a doctor or dietitian’s advice on what supplements you should use.

What else is important for my immune system?

Getting plenty of sleep and exercise will also strengthen your immune system. Sleep plays a vital role in hormone production, regulation, and function, which strengthens the immune system, and plays a role in building cytokines. Exercise creates stress in your body and activates the same pathways that are triggered when you’re sick, and gets your body primed and ready for when it needs to fight a pathogen. Lastly, recent studies have found that mental health disorders are associated with decreased immune function, which leads back to sleep hygiene and physical activity. However, mental health can be the cause and effect of not getting enough sleep or exercise. In any case, physical activity, sleep hygiene, and managing mental health are all important to maintaining a healthy immune system.