For Part 1 in our series on Supporting a Healthy Immune System, we will be focusing on vital nutrients and what foods they come from. Vitamins A, C, and D, zinc, and selenium are all important for proper immune system function. It may be tempting to pop a pill or add some powder to your water, but the best sources of most nutrients are from food.
Vitamin A is a fat-soluble vitamin, meaning that it is absorbed and stored long-term in the body along with fats. Eggs, whole milk, liver, and vitamin A fortified foods like reduced fat milk are all good sources of what is called “preformed” vitamin A, or retinol. This is a good one to get from foods, as high dose vitamin A (retinol) supplements can potentially be toxic. We can also get vitamin A from plant foods, usually in the form of beta-carotene. Think about adding leafy greens and orange fruits and veggies to your diet like sweet potato, pumpkin, carrots, butternut squash, mango, spinach, and kale.
Vitamin C is a water-soluble vitamin, which means that it’s easily absorbed into your body, but also doesn’t stay long. To keep your levels topped up, be sure to eat good sources of vitamin C daily. Good sources of vitamin C to include with your meals and snacks are berries, kiwi, bell peppers, broccoli, and citrus fruits. Be sure to check with your doctor or pharmacy before eating grapefruit or drinking grapefruit juice as it can interfere with some medications. For these fruits and veggies, it’s best to eat them raw, baked, or steamed as water-soluble vitamins will be lost in the water when boiled.
Selenium is a micronutrient that does a lot of different things in the body, including helping with immune function. Brazil nuts have the highest amount of selenium found in food, but those aren’t always on hand or easy to find. Limit Brazil nuts to just one or two a day so you don’t overdo it on selenium! Seafood and meat are also good sources. If you don’t eat animal products, you can get selenium from making sure you have brown rice and sunflower seeds in your diet.
Vitamin D is also a fat-soluble vitamin, and isn’t found in high amounts in many foods except for fatty fish like salmon, mackerel, and sardines, eggs (yolks) and mushrooms. Vitamin D is a vitamin we can actually make ourselves by exposing our skin to some sun. Keep in mind, if you live at a more northern latitude you won’t be able to make enough (or any!) during the winter. If you are concerned about your vitamin D level, be sure to reach out to your doctor about whether or not you should supplement.
Zinc is a trace mineral that is essential for a healthy immune system. Zinc found in animal products is more bioavailable than plants, which means that the zinc is easier to absorb. Some good sources are beef, dark meat poultry, nuts, seeds, and beans. Oysters are also a great source, if you happen to have them available or enjoy eating them canned.
In general, if you use the Brook Healthy Plate to plan your meals, you should be getting the variety of vitamins and minerals you need to keep your immune system in top form.
In Part 2 of our series for Supporting a Healthy Immune System, we’ll be going over functional foods – what they are and which ones are good to include in your diet.
Reviewed by Kelsea Hoover, MS, RDN
on March 20, 2020. Kelsea is a Registered Dietitian with her Master's degree in Nutrition from Bastyr University in Kenmore, WA, and is one of our Brook Experts.