Healthy Ways to Strengthen Your Immune System

By Marisa Sweeney RDN, RYT

How can you strengthen your immune system? First, it is worth noting that your immune system does an excellent job fighting off colds, germs, viruses, and invasive bacteria on its own. However, we can help ourselves. A significant amount of research shows that diet and lifestyle factors can greatly impact your immune function. Here are three evidence-based tips that support an optimally functioning immune system!

1: Balance is key: The idea of “boosting your immunity” is enticing, but the ability to do so has proved elusive for several reasons. The immune system is precisely that — a system, not a single entity. To function well, it requires balance and harmony.¹  To help with a balanced diet, use the MyPlate method, created by the USDA. It’s a great tool to guide you in creating healthful, balanced meals. Some key takeaways from MyPlate – allow fruits and vegetables to make up most of your meal (~ 50%); aim to include foods with lots of color and variety; opt for whole grains (~25% of your plate) and lean proteins (~25%); and have monounsaturated and polyunsaturated fats in moderation, such as olive oil, avocados, nuts and seeds. 

2: Get adequate micronutrients: There is some evidence that various micronutrient (vitamin and mineral) deficiencies. — for example, deficiencies of zinc, selenium, iron, copper, folate, and vitamins A, B6, C, and E — alter immune responses.¹ For example, researchers from Ohio State University determined that zinc is lured into key cells that are first-responders against infection. Zinc interacts with a process that is vital to the fight against infection and by doing so helps balance the immune response.² Another example, The National Library of Science reports that Vitamin C supports epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin, thereby potentially protecting against environmental oxidative stress. Vitamin C accumulates in phagocytic cells, such as neutrophils, ultimately killing unwanted microbes.³ Below is a list of food sources for these micronutrients:

Zinc: Whole grains, dairy products, some breakfast cereals, oysters, red meat, and poultry, almonds and chickpeas.

Selenium: Brazil nuts (just 2 a day give you all you need!), whole grains, dairy products, eggs, fish, and chicken.

Iron: Heme (blood) sources – beef, chicken, fish, turkey, eggs; Non-heme (plant) sources – spinach, lentils, beans, fortified cereals, dark chocolate.

Copper:  shellfish, seeds and nuts, organ meats, wheat-bran cereals, whole-grain products, and chocolate.

Folate: bananas, strawberries, whole grains, beans, all the dark leafy green vegetables.

Vitamin A: dairy products, liver, fish, and fortified cereals, carrots, broccoli, cantaloupe, and squash.

Vitamin B6: beef, liver, tuna, chickpeas, salmon, dark leafy greens, bananas, papayas, oranges, and cantaloupe.

Vitamin C: oranges, tomatoes, citrus fruits, red and green peppers, kiwi fruit, broccoli, strawberries, Brussels sprouts, and cantaloupe.

Vitamin E: pumpkin, red bell pepper, sunflower seeds, almonds, peanuts, Sunflower, safflower, and soybean oil.

With a balanced diet, you may find that getting adequate amounts of these vitamins and minerals through food is not very difficult! The USDA has created a Dietary References Intake (DRI) table that estimates average requirements for various nutrients based on age and gender. This is a great place to start in determining if you’re getting enough valuable immune-supporting micronutrients:

3: Consider if supplemental vitamins could be beneficial for you: What you struggle getting enough of in your diet, supplements may help! For those who eat a healthful diet, a multivitamin may have little or no benefit. A diet that includes plenty of fruits, vegetables, whole grains, high quality proteins, healthful fats and the foods listed above should provide most of the nutrients needed for good health.⁴ That being said, not everyone eats or has access to foods that allow for a healthful and balanced diet. When it comes to specific vitamins and minerals, some Americans get less than adequate amounts. For example, more than 90% of Americans get less than the Estimated Average Requirement (ERA) for vitamin D.⁵ Certain conditions and groups are at higher risk for a nutrient deficiency. These include older age, pregnancy, malabsorption conditions, particular medications that deplete stores of certain vitamins and minerals, following diets that limit certain foods groups, and poor appetite.⁴  Work with an RDN or healthcare provider to assess if supplemental vitamins and minerals may be beneficial before starting a regimen on your own.

References

1. How to boost your immune system. Harvard Health. https://www.health.harvard.edu/staying-healthy/how-to-boost-your-immune-system. Published February 15, 2021. 
2. Kloubert V, Rink L. Zinc regulation of the immune response. Nutrition, Immunity, and Infection. 2017:245-278. doi:10.1201/9781315118901-15 
3. Ang A, Vissers MCM, Pullar JM. Vitamin C in immune cell function. Vitamin C. 2020:137-159. doi:10.1201/9780429442025-8 
4. Harvard T.H. Chan School of Public Health. Should I take a daily multivitamin? The Nutrition Source. (2021, November 12). Retrieved November 15, 2021, from https://www.hsph.harvard.edu/nutritionsource/multivitamin/.
5. Fulgoni III VL, Keast DR, Bailey RL, Dwyer J. Foods, fortificants, and supplements: where do Americans get their nutrients?. Journal of Nutrition 2011 Oct 1;141(10):1847-54.