You’ve probably been giving a lot of thought to your physical well-being and immunity in the past few months. For sure, most of us are willing to dedicate a lot of time and effort to stay well. I want to say something cheerful like, “I’ll show you how a simple fruit salad can guarantee you’ll stay healthy forever,” but that would be a promise that I can’t keep. The truth is that many lifestyle factors, including how much you exercise, how much sleep you get, and how much stress you’re under help to predict your chances of getting sick. And as scary as it is, there are some things that no amount of thoughtful preparation can prevent. However, it seems that a diet rich in the right foods can play a small part in keeping you illness-free.
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Spinach and Sweet Potatoes Instead of Pills
Those carrots do more than keep your eyes healthy! Beta carotene is converted into active vitamin A and works as a powerful antioxidant to protect the cells from damaging free radicals. Vitamin A is vital for the production, development, and protection of all cells, including immune cells, and keeps all of the tissues in the body healthy. Get your fill of vitamin A-rich foods, but don’t worry about taking supplements of this vitamin. Some research shows that supplementation may worsen lower respiratory infections (such as pneumonia). Too much supplemental vitamin A might also increase the risk of bone fractures. The carotenoids in food are believed to work together, which is why getting them from food is more beneficial than taking supplements of either beta-carotene or vitamin A.
The B Team
Vitamins B6 appears to be especially crucial for older individuals’ immunity, and more might be needed by people with certain diseases, including heart disease and cancer. Intakes higher than the RDA will not necessarily help to prevent or reverse problems with the immune system, though. People diagnosed with vitamin B12 deficiency are known to have suppressed immunity, but researchers aren’t confident that correcting the anemia will reverse the problem.
Vitamin C – Not Quite the Miracle We Need
Perhaps the most popular vitamin among people wishing to prevent illness – vitamin C appears to stimulate the production of antibodies and white blood cells and may reduce the common cold in people with severe physical or emotional stress. However, at best, it only slightly reduces the duration of the cold. The jury is still out on whether the vitamin has any effect on the immunity of people under normal conditions. Studies are conflicting, and research has been riddled with errors and bias. The research generally doesn’t bear out vitamin c supplementation for the prevention of illnesses such as pneumonia at this time. Instead, eat plenty of vitamin C-rich foods such as citrus fruit and bell peppers.
Milk Does the Body Good
Vitamin D aids in the production and development of all cells, including immune cells. Our bodies use vitamin D in the creation of the antimicrobial proteins that kill viruses and bacteria. Low vitamin D status has been linked to an increased risk of upper respiratory infection and some autoimmune disorders, such as multiple sclerosis and rheumatoid arthritis. Most people benefit from 10-30 minutes of unprotected sun exposure every day. After that time, apply plenty of sunscreen.
Vitamin E works as an antioxidant and might positively influence immunity. In one study, daily supplementation with 200 IU of synthetic a-tocopherol for one year significantly reduced the risk of upper respiratory infections. Still, it did not affect lower respiratory infections in older adults. Other studies have shown no effect.
Leafy Greens for Everyone
Folate deficiency has been associated with an increased risk of infection in some human observational studies and animal studies. The type of clinical anemia that develops when someone is deficient in folate, referred to as megaloblastic anemia, causes an impaired immune response that is improved with correction of the deficiency.
Don’t Forget the Minerals
Poor selenium status is associated with a higher risk for many diseases, including cancer and heart disease, and is essential for the immune system to battle infection. It seems that very ill individuals with weak immunity might benefit from additional selenium, but it doesn’t seem to help people who are already healthy.
Even a mild deficiency in zinc has been correlated with a damaged immune response because this mineral is critically essential for the production and activation of specific white blood cells. Perhaps you’ve sucked on some horrible-tasting zinc lozenges in the hopes of dodging illness, but the reviews on the effectiveness of supplementation are mixed and inconsistent. What we do know is that massive doses can damage immune function. Consuming too much zinc also causes copper deficiency, which is not good because copper is another mineral that boosts immunity. Likewise, copper deficiency leads to malabsorption of iron, which you’ll read about below. This is why we eat foods instead of nutrients, and why popping many supplements won’t get you where you’re trying to go in terms of well-being.
Iron status impacts immune function, but the results of studies have been conflicting. For example, some research has shown that iron supplementation, especially in the tropics, may increase the risk of contracting illnesses, including malaria and tuberculosis. Some people are genetically programmed to suffer iron overload and are also more susceptible to infection than other people. Yet, iron is essential for a robust immune system, and people with iron-deficiency anemia are also more vulnerable to infection. Obviously, a healthy balance is needed when it comes to this mineral.
Worrying about specific nutrients is probably not important in the war against illness for most people. However, if choosing foods rich in particular nutrients encourages you to clean up your diet overall, it’s a win. Use the attached grocery list to plan your next food order. As you’ll see, the nutrients are found in many of the same foods – colorful fruits and vegetables, seafood, whole grains, beans, nuts, and lean protein.
Academy of Nutrition and Dietetics. Support your health with nutrition. Updated December 9, 2019.
Cherayil BJ. Iron and immunity: Immunological consequences of iron deficiency and overload. Arch Immunol Ther Exp (Warsz). 2010; 58(6):407-415. DOI: 10.1007/S00005-010-0095-9.
Hassan TH, Badr MA, Karam NA, et al. Impact of iron deficiency anemia on the function of the immune system in children. Medicine (Baltimore). 2016;95(47):E5395. DOI:10.1097/MD.0000000000005395.
Huang Z, Liu Y, Qi G, Brand D, Zheng SG. Role of vitamin A in the immune system. J Clin Med. 2018.7(9):258. Published 2018 Sep 6. DOI:10.3390/JCM700258.
Oregon State University Linus Pauling Institute. Immunity in depth. Updated 2020.