Can I Boost My Immune System?

Why would vitamin D lower risk for respiratory illness? Our bodies need adequate vitamin D to produce the antimicrobial proteins that kill viruses and bacteria. “If you don’t have adequate vitamin D circulating, you are less effective at producing these proteins and more susceptible to infection,” says Dr. Adit Ginde, professor of emergency medicine at the University of Colorado School of Medicine and the study’s lead author. “These proteins are particularly active in the respiratory tract.”

It’s important to note that there are no clinical recommendations to take vitamin D for immune health, although the standard recommendation for bone health is for 600 to 800 international units per day. (That is the level found in most multivitamins.) In the study of respiratory illness and vitamin D, the dose was equivalent to about 3,330 international units daily.

Vitamin D can be found in fatty fish, such as salmon, and in milk or foods fortified with vitamin D. In general, our vitamin D levels tend to be influenced by sun exposure, skin tone and latitude — people in northern areas who get less sun exposure in the winter typically have lower vitamin D. A blood test is required to check vitamin D levels. Less than 20 nanograms per milliliter is considered deficient. Above 30 is optimal.

The bottom line: If you are concerned about immune health, you may consider having your vitamin D level checked and talking to your doctor about whether to take a supplement.

Avoid excessive alcohol consumption. Numerous studies have found a link between excessive alcohol consumption and immune function. Research shows people who drink in excess are more susceptible to respiratory illness and pneumonia and recover from infection and wounds more slowly. Alcohol alters the number of microbes in the gut microbiome, a community of microorganisms that affect the immune system. Excessive alcohol can damage the lungs, and impair the mucosal immune system, which is essential in helping the body recognize pathogens and fight infection. And it’s not just chronic drinking that does damage. Binge drinking can also impair the immune system.

The bottom line: A cocktail or glass of wine while you are sheltering in place during coronavirus is fine. But avoid drinking to excess. The current U.S. Dietary Guidelines for Americans recommend that alcohol should be consumed only in moderation — up to one drink per day for women and two drinks per day for men.

Eat a balanced diet and skip unproven supplements. A healthful diet and exercise are important to maintaining a strong immune system. However, no single food or natural remedy has been proven to bolster a person’s immune system or ward off disease. But that hasn’t stopped people from making specious claims. A recipe circulating on social media claims boiled garlic water helps. Other common foods touted for their immune-boosting properties are ginger, citrus fruits, turmeric, oregano oil and bone broth. There are small studies that suggest a benefit to some of these foods, but strong evidence is lacking. For instance, the bone broth claim has been fueled by a study published in 2000 that showed eating chicken soup seemed to reduce symptoms of an upper respiratory tract infection. A number of small studies have suggested garlic may enhance immune system function. Claims that elderberry products can prevent viral illness also are making the rounds on social media, but evidence is lacking.