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The #1 Way to Build Immunity, Say Experts

Give your immune system a serious boost.

If Google searches held their weight in gold, "How to strengthen your immune system" would be the equivalent of the great California rush—particularly since the beginning of the COVID-19 pandemic. Although there's no magic bullet for improving your immunity, you can take one easy step to seriously shore up your body's defenses against disease. Here's what experts say is the #1 way to build immunity. Read on to find out more—and to ensure your health and the health of others, don't miss these Sure Signs You May Have Already Had COVID.


How to Bolster Your Immune System

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Experts say you can do several things to support your immune system, including:

  • Exercise regularly
  • Keep your weight in a healthy range
  • Get good quality sleep
  • Reduce stress
  • Don't smoke or use tobacco
  • Drink alcohol only in moderation

But there's one habit that's probably the best to add to your routine.


The #1 Way to Build Immunity

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The #1 thing you can do to aid your immune system is to eat a healthy diet—one that's rich in a variety of fruits and vegetables, and low in processed foods, added sugar, and sodium.

Fruits and vegetables contain nutrients that directly support the immune system, including two of the most important: vitamin D and vitamin C. Look to whole foods, not supplements, first. "While vitamins and supplements can help fill in the gaps in your diet, the best way to load up on essential nutrients is to get them straight from food," says the Cleveland Clinic. "Your body absorbs and uses vitamins and nutrients better when they come from a dietary source." Additionally, fruits and vegetables contain many micronutrients and natural plant chemicals that may work together synergistically to produce benefits in the body.

Diets high in processed foods, added sugar and sodium increase your risk for overweight or obesity, diabetes, heart disease, high cholesterol, and high blood pressure—all conditions that tax the immune system.

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How Vitamin C Builds Immunity

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There's strong evidence that Vitamin C supports immunity. "Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system," wrote researchers behind a 2017 study published in the journal Nutrients. "Vitamin C deficiency results in impaired immunity and higher susceptibility to infections … supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections." 

Good food sources of vitamin C include citrus fruits, peppers, berries, and cruciferous vegetables like broccoli and brussels sprouts.

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How Vitamin D Boosts Immunity

vitamin d foods

The National Institutes of Health notes that vitamin D helps regulate immune function, while the Harvard T.H. Chan School of Public Health says that lab studies indicate vitamin D can help control infections, reduce inflammation, and slow cancer cell growth.

Good sources for vitamin D include fatty fish like salmon, herring and mackerel; egg yolks; liver; and fortified milk. That said, it can be difficult to get enough vitamin D from food alone, so taking a vitamin D supplement (after consulting your doctor) can be beneficial. 

Vitamin D has a fan in Dr. Anthony Fauci, the nation's top infectious disease expert. "There is good evidence that if you have a low vitamin D level, that you have more of a propensity to get infected when there are infections around," he said last fall. "Those data are pretty good data." And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael