Immunity During the Holidays

 Written By: Chloe Raben; SLU Dietetic Intern

        Have you ever gotten sick during the holiday season because of changing weather or being around others who are unwell?

        Almost all nutrients in the diet play a crucial role in maintaining an "optimal" immune response, and both insufficient and excessive intakes can have negative consequences on the immune status. Ferencik’s article summarizes the importance of two micronutrients, selenium, and zinc, and describes the mechanisms through which they affect the immune status and other physiological functions (Ferencik et al., 2003). This article claims that selenium is needed for the proper functioning of neutrophils, macrophages, NK cells, T lymphocytes and some other immune mechanisms.

        A 2024 study demonstrated that zinc cannot be stored in significant amounts, so regular dietary intake is essential (Stiles et al., 2024). Adequate nutrition is crucial during the holiday season due to the season often bringing colder temperatures and increased indoor activity, both of which can raise the risk of illnesses like colds and flu. Strengthening the immune system through proper nutrition is vital during this time. Several key nutrients support immune health, including beta-carotene, vitamin C, vitamin D, zinc, and probiotics. Beta-carotene, an antioxidant found in foods like sweet potatoes, carrots, and spinach, supports skin health and mucous membranes. Vitamin C, abundant in citrus fruits and bell peppers, helps maintain immune function, while vitamin D, from sources like fortified milk and fatty fish, plays a critical role in immune regulation.

        Zinc is essential for the proper function of white blood cells, can be found in beef, nuts, and beans, and probiotics in yogurt and fermented foods support gut health, a cornerstone of immunity. Zinc is indispensable for the proper functioning of all immune cells. It helps mount a balanced immune response to bacteria, viruses, and parasites, as noted in a 2021 study by Wessels et al. Meanwhile, selenium and beta-carotene supplementation can increase total T cells, which play a critical role in fighting infection, as detailed in the Integrative Medicine book by Wood et al. T cells work by destroying infected cells and signaling other immune cells to join the fight. It stated the selenium and beta-carotene supplementation caused an increase in total T cells by 27% and 31%. T cells are a type of white blood cell called lymphocytes. They help your immune system fight germs and protect you from disease. The T cells do this by destroying infected cells and send signals that direct other immune cells to fight infection. This demonstrates the importance of having adequate nutrition during these holiday times to strengthen our immune system. Foods that are high in selenium include, Brazil nuts, fish, poultry, eggs, etc. Foods high in beta-carotene are yellow, orange, and green leafy fruits and vegetables, such as carrots, spinach, lettuce, tomatoes, sweet potatoes, broccoli, cantaloupe, and winter squash. Luckily these foods are seasonal in the winter months as well.

Immune-Boosting Foods to Add to Your Holiday Meals

        The good news? Many foods rich in these immune-supporting nutrients are also delicious and perfect for the winter season! Here are some highlights:

- Selenium: Found in Brazil nuts, fish, poultry, and eggs.

- Beta-Carotene: Abundant in yellow, orange, and green vegetables like carrots, sweet potatoes, spinach, and winter squash.

- Zinc: Found in beef, nuts, beans, and seeds.

- Vitamin C: Found in citrus fruits, bell peppers, and tomatoes.

- Vitamin D: Found in fortified milk, fatty fish, and egg yolks.

- Probiotics: Found in yogurt, kefir, and fermented foods like sauerkraut.

        Incorporating colorful and nutrient-dense foods into holiday meals is an excellent strategy to support health. Eating a variety of colors—such as red tomatoes, orange carrots, green kale, and purple cabbage—ensures a broad intake of vitamins and antioxidants. For example, a rainbow-inspired salad can include spinach, red cabbage, orange slices, and nuts. Additionally, making thoughtful substitutions can reduce sugar and sodium while boosting nutrient content. For example, replace marshmallows on sweet potatoes with apples and walnuts, or use fresh green beans sautéed with mushrooms and garlic instead of traditional creamy casseroles. These swaps not only enhance flavor but also provide critical nutrients like zinc and vitamin C.

Flavorful and Healthy Substitutions

        Flavoring meals with herbs and spices rather than salt is another way to prioritize health without sacrificing taste. Spices like garlic powder, sage, and bay leaves not only reduce sodium intake but also offer additional antioxidants. Homemade dishes, such as roasted vegetable stuffing, can replace processed options to limit additives and maximize nutrient density. By making these adjustments, holiday meals can be both delicious and immune boosting, ensuring a season of joy and wellness.

Green Bean Casserole → Holiday Green Beans

    Holiday Green Beans Ingredients:

· 1 tbsp olive oil

· 2 bulbs finely chopped shallots

· 4 cloves minced garlic.

· 1 lb. fresh green beans, blanched in water for 2 minutes.

· salt and pepper

· 1 can Anchovy oil

· 2-3 chopped anchovy fillets.

    Holiday Green Beans Instructions:

· Blanch green beans for 2 minutes in boiling water.

· Add garlic, shallots, anchovy oil and chopped fillets to a skillet over medium high heat.

· Add green beans to the skillet and cook for 30-40 minutes.

· Serve and enjoy!

 

References:

Wessels, I., Fischer, H. J., & Rink, L. (2021, July 13). Dietary and physiological effects of zinc on the immune system. PubMed. https://pubmed.ncbi.nlm.nih.gov/34255547/

Ferencik, M., & Ebringer, L. (2003). Modulatory effects of selenium and zinc on the immune system. Folia microbiologica. https://pubmed.ncbi.nlm.nih.gov/12879758/

Stiles , L., Ferrao , K., & Mehta , K. (2024, February 17). Role of zinc in health and disease. Clinical and experimental medicine. https://pubmed.ncbi.nlm.nih.gov/38367035/

Wood , steven, beckham , C., yosioka , A., Darban, H., & Watson , R. (2000, September 14). Β-carotene and selenium supplementation enhances immune response in aged humans. Integrative Medicine. https://www.sciencedirect.com/science/article/pii/S1096219000000093?casa_token=2azn6esnGnIAAAAA%3AwKGktzO1nw6FxtWyYMe7DuwQ5owLdcle5N4pPw69oqpdQ-MxNWJ7Eb2z0Lc-kJqll-aaiONpJMYqQQ

Wong, C. (2024b, July 11). 5 food nutrients to enhance immunity. Verywell Health. https://www.verywellhealth.com/types-of-foods-to-boost-your-immune-system-8902