How Nutrition Plays a Role in Immune Health
The foods we eat can contribute to maintaining a healthy immune system by supplying our bodies with the essential nutrients to nourish and support the many functions of our immune system.
There is growing research connecting the gut’s microbiota’s effect on our immune system and overall health. Our gut is home to trillions of microorganisms dedicated to protecting and maintaining balance in our body. (1)
Plant-based diets, rich in fruits, vegetables, whole grains, legumes, nuts, and seeds, may facilitate the growth of more diverse, beneficial gut bacteria, likely attributed to the high dietary fiber content, which can positively impact gut health and overall health and wellness. (1)
Dietary fiber, an undigestable carbohydrate found in plant foods, has been associated with many health-promoting roles, including reducing inflammatory markers in the body, improving digestive health, lowering blood cholesterol, and stabilizing blood sugar levels. (2)
Prebiotics are another notable component found in various plant foods, including garlic, onions, bananas, whole grains, and legumes, which act as food for beneficial gut bacteria.
Plant foods also provide many other immune-protective nutrients, such as vitamins A, C, and D, iron, protein, and zinc.
Immune-Protective Nutrients
Vitamin A
Vitamin A is a fat-soluble vitamin that supports eye and immune health. The plant-based source of vitamin A, known as beta-carotene, is a type of phytonutrient that gives fruits and vegetables their vibrant colors and converts to vitamin A in the body.
Vitamin A-rich plant foods include winter squash, carrots, mangoes, sweet potatoes, and leafy green vegetables.
The other form of vitamin A, called preformed vitamin A, in the form of retinol, is found in animal-based sources such as liver, eggs, and dairy products. Although, dairy milk is typically fortified with vitamin A.
There is a Tolerable Upper Intake Level set for the animal-based preformed vitamin A only, which is 3,000 micrograms for adults, as excessive amounts of preformed vitamin A can lead to vitamin A toxicity.
The nutritional highlights of plant-based vitamin A beta-carotene are its health-promoting antioxidant properties, dietary fiber, and other vitamins and minerals, and eating plenty of vitamin A-rich fruits and vegetables is encouraged!
Vitamin C
Vitamin C contributes to a healthy immune system and skin health, such as collagen production (the protein in connective tissue) and wound healing.
Severe vitamin C deficiency, also known as scurvy, is a historically significant nutritional deficiency documented as early as the 1500s. This nutritional deficiency is linked to a lack of fruits and vegetables, with symptoms of swollen and bleeding gums and impaired wound healing.
This led to the discovery of vitamin C, or its chemical name, ascorbic acid, in the 1930s, and was recognized for preventing scurvy. (3)
Vitamin C deficiency in developed countries is rare, and we can get all the vitamin C we need by including fruits and vegetables in our diet, such as citrus fruits and fruit juice, broccoli, bell peppers, and potatoes.
Vitamin C also helps increase the absorption of non-heme iron, or the iron found in plant-based foods when vitamin C-rich foods are combined with iron-rich plant foods in the same meal.
Vitamin D
Vitamin D supports bone health and the growth and development of immune cells.
Plant-based sources of vitamin D include vitamin D-fortified plant milk and juice, and cereals, and vitamin D dietary supplements.
The Recommended Dietary Allowance, or RDA, for vitamin D for adults is 15 micrograms or 600 International Units and increases to 20 micrograms or 800 International Units over 70 years of age.
Iron
Iron supports immune cell function and is essential for hemoglobin production, a protein in red blood cells that transports oxygen throughout the body.
Iron-rich plant food sources include legumes, whole grains, leafy green vegetables, nuts, and seeds.
Protein
Protein is a macronutrient with many roles in the body, including growth, repair, and maintenance of the muscles, bones, and cells and supporting a healthy immune system.
Plant proteins include legumes, whole grains, nuts, seeds, vegetables, and plant-based meats.
Plant proteins offer the nutritional benefits of dietary fiber, vitamins, minerals, antioxidants, lower saturated fat content, and no dietary cholesterol.
Zinc
Zinc is essential for immune health, cellular function, wound healing, and sense of taste and smell.
Zinc-rich plant foods include whole grains, legumes, nuts, and seeds.
Zinc dietary supplementation is commonly associated with alleviating common cold symptoms. However, more research is needed in this area. It’s also important to note that the Tolerable Upper Intake Level for zinc for adults is 40 milligrams.
If starting a zinc dietary supplement recommended by a healthcare provider, always check the supplement label to avoid taking excessive amounts.
There are also food preparation techniques that can help increase the absorption of zinc in plant foods. For more information, check out my blog article, “Boosting Nutrient Absorption in a Vegan Diet.”
A Note on Dietary Supplements for Immune Health
It can be a common idea to support our immune system during wintertime by taking more vitamins and minerals in dietary supplement form.
However, it’s more nutritionally optimal to meet our daily recommended dietary needs rather than consuming extra dietary supplements, as taking excessive amounts of vitamin and mineral dietary supplements can have adverse health effects.
Getting most of our nutrients from various nutrient-dense plant foods, such as vitamin C-rich fruits and vegetables, offers the nutritional benefits of dietary fiber, phytonutrients, antioxidants, and other health-protective vitamins and minerals in these plant foods.
Practical Tips for Winter Meal Planning
Incorporating winter seasonal produce into recipes
For example, winter squash, potatoes, parsnips, cabbage, and leeks can make a nutritious and comforting base for a plant-rich soup. Roasted beets and Brussels sprouts make for a nutrient-dense and savory side dish.
Planning recipes around the ingredients you already have at home
Checking the pantry and freezer for staples, such as whole grains and frozen vegetables, and researching recipes that include these ingredients can help save time when planning meals for the week.
Choosing a preferred cooking method for more convenient cooking and clean-up
For example, one-pot or sheet-pan recipes, such as a lentil stew or baked tofu and vegetables.
Switching up whole grains and other starchy foods
Whole grains, such as brown rice, quinoa, barley, and whole-wheat pasta, are packed with dietary fiber, making a more filling meal.
Bean-based pasta is a nutritious pasta alternative packed with plant protein and dietary fiber. Potatoes are a nutrient-dense, starchy vegetable with potassium, vitamin C, and even some protein!
Choosing a combination of fresh, frozen, and canned produce can help further winter meal planning
Rotating fresh produce that lasts a little longer, such as onions, garlic, potatoes, carrots, cabbage, apples, and oranges, can help save time between grocery shopping trips.
Keeping frozen fruit and vegetables on hand can also make cooking more convenient while retaining comparable nutritional value to fresh produce. Having no-salt-added canned vegetables in the pantry can also make quick additions to soups, stews, and pasta.
Boosting the Plant-Richness of Winter Meals
Go for legumes
Legumes include beans, peas, lentils, and soy foods. Legumes are especially rich in protein, dietary fiber, and other nutrients like iron, zinc, and folate.
Legumes offer versatility in meals – for example, adding a bean of choice to pasta and rice dishes, tofu scrambles and curries, veggie burgers, and other plant-based meat alternatives, such as ‘beefless’ crumbles in chili.
Trying various ways to eat vegetables
Adding frozen vegetables to jarred pasta sauce can be an easy way to add more nutrients to pasta dishes. Leafy green vegetables can also be incorporated into soups, stews, plant-based mac n’ cheese, or lasagna.
Including healthy fats in meals
Adding a moderate amount of plant-based dietary fat to meals helps increase the absorption of fat-soluble vitamins D, E, K, and A – for example, avocado, nuts, seeds, olives, or a plant oil-based dressing. Healthy dietary fats can also help promote satiety and meal satisfaction.
Savory with less salt
Comforting meals tend to have a higher sodium content. When making recipes at home, using salt-free herbs, spices, and low-sodium vegetable broth can reduce the overall amount of sodium while experimenting with various flavor profiles. Many herbs and spices are also rich in health-promoting antioxidants.
Take-Home Message
We can make delicious and comforting plant-rich meals over the winter season while maximizing the nutritional content for our overall health and well-being and incorporating meal-planning approaches to simplify and make food preparation more convenient!
For more educational content on various plant-based and vegan nutrition topics, check out my YouTube Channel here!
If you’re interested in personalized nutritional guidance and support for your plant-based goals, please reach out to schedule a free 20-minute discovery call here!
References
1. Tomova, A., Bukovsky, I., Rembert, E., Yonas, W., Alwarith, J., Barnard, N. D., & Kahleova, H. (2019). The Effects of Vegetarian and Vegan Diets on Gut Microbiota. Frontiers in Nutrition, 6. https://doi.org/10.3389/fnut.2019.00047
Nutrition and Immunity. (n.d.). The Nutrition Source. https://nutritionsource.hsph.harvard.edu/nutrition-and-immunity/
2. Fiber. (2022, April). The Nutrition Source. https://nutritionsource.hsph.harvard.edu/carbohydrates/fiber/
Office of Dietary Supplements – Vitamin A and Carotenoids. (2023, December 15). https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
3. Office of Dietary Supplements – Vitamin C. (2021, March 26). https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
Office of Dietary Supplements – Vitamin D. (2024, July 26). https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
Office of Dietary Supplements – Zinc. (2022, September 28). https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
Academy of Nutrition and Dietetics – Vegetarian Nutrition Dietetics Practice Group Downloadable PDF Handout: Vegetarian Nutrition and Immune Health
Disclaimer: This blog post is provided for informational and educational purposes only and should never be relied upon in any way as medical or mental health advice. Always consult your physician or other qualified healthcare provider for any health-related questions and concerns or before implementing anything you may learn through this blog post.
