How to eat right to stave off infectious disease

An ounce of prevention is worth a pound of cure, right? That couldn’t be more true in the COVID-19 era, and while we’re sure you’re wiping surfaces, avoiding indoor spaces, and wearing a mask, why not also turn your immune system into the robust machine it wants to be? Make sure you’re getting enough of the following four vitamins and minerals to stay healthy now and in all flu seasons to come.

Vitamin C

Vitamin C is certainly the most widely known vitamin for treating illness or infection. This vitamin’s power is the source behind every mom-passed glass of OJ when she hears you sniffle. It also may come as a surprise that Vitamin C is an essential vitamin, meaning your body needs it but doesn’t produce it. Luckily it is found in many fruits and vegetables, making it easy to meet the recommended daily intake of 75mg for women and 90mg for men.

So how does it work? Vitamin C supports white blood cell function. These less-lauded blood cells make up only about 1% of your blood supply, but without them your immune system ceases to function. Vitamin C is an antioxidant, keeping your white cells healthy and numerous, protected from those hilariously named “free radicals.” Your white blood cells, in turn, return the favor!

While Vitamin C plays an important role in your immune cell function, let’s not confuse causation with correlation. There are still mixed reviews on just how much of a role it can play in directly preventing or curing the common cold. The majority of studies show that while Vitamin C plays no active role in preventing colds or infections, taking a higher dose at the onset of illness may aid in shortening a cold by one day.

Vitamin D

Ah, the sunshine vitamin. Most people know that exposure to the sun promotes Vitamin D production in your body, supporting bone health, but more recently studies boast of its impressive efforts within your immune system as well. A 2010 study by the American Journal of Clinical Nutrition showed a 7.8% reduction in influenza A in schoolchildren given vitamin D(3) supplements during the winter versus children given a placebo. It’s also important to be aware of the flip side and the adverse effects on your immune system from a Vitamin D deficiency. Many recent studies show a close correlation between lower Vitamin D levels and increased infection.

So how does it work? Vitamin D helps enhance the pathogen-fighting attributes in certain white blood cells. As we pointed out above, those cells boost your immune system. In addition, Vitamin D reduces inflammation in your body, which improves immune response. Adults with Vitamin D deficiency exhibit higher rates of respiratory disease, an obvious danger this particular summer. So be sure you’re taking advantage of these beautiful months by getting ample time in the sun (while practicing proper sun safety of course!). You can also boost levels of Vitamin D by eating fatty fishes or taking a cod liver oil supplement (your grandma was a trendsetter, it turns out). Other sources include mushrooms, eggs, livers, and soy, almond, and oat milks.


Zinc is another essential mineral that might surprise you by the plethora of functions it enables in the body. This mighty mineral provides aid to over 300 enzymes in your body boosting everything from metabolism, digestion, nerve function and more. Zinc also helps support skin health which can ward off infections and speed up the healing of wounds. On the other hand, much like Vitamin D, a zinc deficiency can lead to a weakened immune system.

Since zinc is essential and you should strive to get the recommended daily dose (8mg for women and 11mg for men), many studies suggest that taking an over the counter zinc supplement at the onset of symptoms has the ability to shorten the life of a cold. Make sure you’ve got the right kind, though, since many types of zinc are not bioavailable over the counter. Aim for something with zinc acetate or zinc gluconate, and try to consume the supplement with a meal containing protein, but one that doesn’t include corn, rice, or other cereals. What’s this “bioavailable” thing? When you take a drug or a supplement, only a portion of the dose survives to circulate throughout your system. That percentage is the bioavailability of the substance. Several factors affect bioavailability, such dosage, route of administration, and other substances in your system.

Vitamins B6

B6 has been linked to supporting your immune system, and if you have a regular diet that includes poultry, fish, chickpeas, potatoes, or bananas, you’re probably getting enough to keep this level high enough. If you’ve experienced any kidney disease, however, or have issues absorbing nutrients into your system, you can run low on B6, possibly leading to a compromised immune system.

Risks of Supplementation

For many vitamins and minerals, there are few risks with supplementation, as many of them are water soluble and easily dissolve into your waste system. If you’ve ever taken a lot of Vitamin C and wondered about the—ahem—lurid color of your urine, it’s because you’re excreting most of the vitamin. No risks are associated with water soluble vitamins, but you do need to be careful with fat soluble vitamins, such as Vitamin D. Since we don’t excrete body fat, these vitamins reside in your adipose (fat) tissue, and if you ingest too much their levels can become toxic. How much is enough? If you’re under 70, then 4-600 IUs is enough, and if you are over 70, 6-800 IUs.


If your immune system is weak because of a particular vitamin or mineral deficiency, then supplementing with that nutrient may lead to positive outcomes, but remember that taking supplements should not and can not be used as a replacement for a healthy lifestyle. Maintaining a balanced diet, getting enough sleep, exercising regularly, and avoiding smoking are some of the important ways you can keep your immune system healthy and reduce your chance of infection and disease.


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