How Can I Make My Immune System More Resilient? 10 MD-Approved Strategies

The occasional (or seasonal) cold or flu is a natural part of life. But if you notice you're spending way more time laid up on the couch, taken out by yet another bout of sickness, it may be a sign that your immune system support and resilience aren't optimized.

Chronic stress (coupled with inadequate sleep) is the No. 1 reason people get sick, according to Heather Moday, M.D., an allergist and immunologist.

"When we are run down and cortisol soars, our virus surveillance cells dip and we get sick more easily," she explains. "Cortisol itself interferes with the ability of specific white blood cells called T-cells to proliferate and get signals from the body. In addition, cortisol also lowers an important antibody called secretory IgA, which lines the respiratory tract and gut and is our first line of defense against invading pathogens."

Stress is a normal part of life, so you're never going to be able to eliminate it completely, but it's vital to find ways to manage it.

Moday explains, lack of sleep makes you more likely to get sick because your body can't fight off pathogens as easily.

Moday says if you're feeling under the weather, the best thing to do is give in and let your body rest.

And when you're feeling better, make sure you're getting at least eight to 10 hours of quality sleep every night to support recovery.

There are several essential macro- and micronutrients (i.e., our body can't make them, so we must consume them daily!) that keep your immune system healthy, but vitamin D, vitamin C, and zinc are Moday's top picks.

Vitamin C and zinc are antioxidant powerhouses,* but "humans cannot produce vitamin C [which is chewed up with stress], so we need a constant intake of it," she previously told mbg. "Zinc insufficiency is [also] rampant, and it's such an integral player in immunity."

Vitamin D is a potent immunomodulator, which means it helps regulate and control your immune system and the complex immune cell functions working so hard to keep us healthy.*

Unfortunately many people have poor vitamin D status (low levels of vitamin D) since it's only found in small amounts in a few foods we eat.

Moday recommends consuming this immune-essential trio of micronutrients (C, D, zinc) daily through two strategies. First, by eating a well-balanced, nutrient-dense diet (see tips below), and then complementing this approach with a targeted, high-quality nutrition supplement.*

To up your intake of vitamin C-dense foods, focus on fruits and vegetables. To incorporate more zinc-rich foods, Moday recommends oysters, crab, pumpkin seeds, and dark chicken meat.

Vitamin D is found in a limited number of foods (fatty fish, egg yolk, liver, and certain types of UV-irradiated mushrooms), plus fortified sources like cereal, milk, and orange juice. The issue here is dose, since these foods contribute a small amount of vitamin D.

If 2020-2021 taught us anything, it's that dirty hands are one of the fastest ways we can spread germs and make ourselves sick.

Studies show that people touch their face around 23 times per hour3, which means over the course of a regular day, you've presented 368 opportunities for germs to enter your body through your eyes, nose, and/or mouth.

Wash your hands often with soap and warm water, making sure to scrub them for at least 20 seconds.

While hand sanitizer is a temporary solution when soap and water aren't available, it doesn't take the place of regular hand-washing—and some hand sanitizers aren't the best choice.

Many contain triclosan, an ingredient that's been connected to various health issues and gut imbalance5.

While high-intensity exercises are OK sometimes, most of your exercise routine should consist of moderate-intensity exercise and aerobic activity 30 to 60 minutes per day. The effort should mimic brisk walking.

As you become more physically fit, your personal definition of "moderate intensity" will change, but pay attention to how you're feeling. Exercise should leave you recharged and energized (albeit a little sweaty), not drained and dragging.

Alcohol negatively affects both your innate and adaptive immune systems7, damaging T-cells, the natural killer cells that find and destroy pathogens.

Alcohol also kills good bacteria in your gut, weakening your defenses and your gut barrier function. What's more, it can trigger inflammation. 

Limit your alcohol intake as much as possible. While the Dietary Guidelines for Americans recommends no more than two drinks a day for men and one drink a day for women, a meta-analysis published in The Lancet found that an upper limit of 100 grams per week9 is necessary to prevent negative effects.

Sugar affects your immune system in two ways.

"When your blood sugar spikes, the function of white blood cells [part of the innate immune system10] is reduced, and this affects our immune system's ability to battle pathogens," Ali Miller, R.D., L.D., CDE, registered dietitian and certified diabetes educator, previously told mbg. "T-cells, which are the cells that regulate the acquired or learned immune system10, are also hindered when insulin levels are elevated in excess11." 

But you don't have to take her word for it. An older, yet still relevant, study published in the American Journal of Clinical Nutrition reported that the efficiency of white blood cells drops by 50% one to two hours after eating sugar12, and that immune response lasts up to five hours.

You may not think of hydration status as a major player in whether or not you get sick, but it's an important piece of the puzzle.

Water keeps your mucus membranes lubricated and protected, so viruses, bacteria, and other potentially harmful pathogens can't latch on to the tissue, explains Catherine Waldrop, M.D.

On the other hand, when you're dehydrated, your nasal passages dry out and can crack, making it easier for these minuscule microbes to enter your body and make you sick.

Drink more water! The exact amount you need depends on various factors, like your body weight, activity level, and current climate, but as a general rule, you should aim to drink half your body weight in ounces. That means if you weigh 150 pounds, you'll want to drink at least 75 ounces of water per day.

And don't forget that sometimes dehydration occurs from a lack of minerals.

It's a good idea to talk to a health care professional about this, but there are electrolyte supplements or natural "sports" drinks (try to limit sugary sports drinks with artificial colors) that can help replenish the minerals in your body.

Antibiotics certainly have their place, but if you're prescribed them too often, they can wreak havoc on your gut.

Antibiotics kill all bacteria, not just bad bacteria, so if you're constantly taking them, it's likely that your ratio of good bacteria to bad is off. The diversity of your gut and optimal gut health is a key factor in optimal immune health, explains Moday.

Don't take antibiotics unnecessarily. While antibiotics can be lifesaving against bacterial infections, they're useless for viruses.

If you do have to occasionally take antibiotics, work with your doctor to optimize a concurrent probiotic regimen and do all you can to support your gut.

Functional medicine expert Will Cole, IFMCP, DNM, D.C., who believes that the root of all disease begins in your gut, also recommends drinking bone broth.

If you have a compromised immune system, the best course of action is to work closely with a doctor or a health care professional who can guide you through your condition and develop the right care plan.