Life Extension Magazine®

The viruses that cause colds and flus might be fought with vitamin D

Vitamin D and Immunity

About 40% of Americans have insufficient vitamin D levels. Recent studies demonstrate that vitamin D boosts cold weather immunity.

Scientifically reviewed by: Dr. Gary Gonzalez, MD, in March 2023. Written by: Laurie Mathena.

Vitamin D plays a critical role in supporting the immune system.1-4

Low vitamin D levels have been associated with an increased risk of communicable diseases, including viral and bacterial infections.1

Approximately 40% of Americans have insufficient blood levels of vitamin D, and close to 30% have deficient vitamin D. This represents a major health risk, especially for older individuals.5

Vitamin D supplementation has been shown to help protect against acute respiratory infections.1

The following studies, published in the past few years, have added support to vitamin D’s role in boosting immunity and protecting against various infections:

  • Vitamin D deficiency increases risk of respiratory tract infections.2 In elderly, institutionalized individuals, vitamin D deficiency was associated with an increased incidence of respiratory tract infections. The researchers suggested supplementation with vitamin D as a method for preventing respiratory tract infections.
  • Low vitamin D status is associated with increased risk of chronic rhinosinusitis.6 Researchers found a significant association between lower serum vitamin D status and having chronic rhinosinusitis, which is persistent inflammation of the upper respiratory tract caused by immune dysfunction.
  • Vitamin D supplementation reduces the risk of acute respiratory tract infections.3 After reviewing evidence from randomized, controlled trials, researchers found that vitamin D supplementation is modestly effective at reducing the risk of acute respiratory tract infections, as well as shortening the duration of their symptoms.

Life Extension recommends maintaining vitamin D blood levels (25-hydroxyvitamin D) between 50-80 ng/mL with yearly blood testing to ensure optimal status.

If you have any questions on the scientific content of this article, please call a Life Extension Wellness Specialist at 1-866-864-3027.


  1. Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017 Feb 15;356:i6583.
  2. Kuwabara A, Tsugawa N, Ao M, et al. Vitamin D deficiency as the risk of respiratory tract infections in the institutionalized elderly: A prospective 1-year cohort study. Clin Nutr ESPEN. 2020 Dec;40:309-13.
  3. Abioye AI, Bromage S, Fawzi W. Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic review and meta-analysis. BMJ Glob Health. 2021 Jan;6(1).
  4. Zdrenghea MT, Makrinioti H, Bagacean C, et al. Vitamin D modulation of innate immune responses to respiratory viral infections. Rev Med Virol. 2017 Jan;27(1).
  5. Liu X, Baylin A, Levy PD. Vitamin D deficiency and insufficiency among US adults: prevalence, predictors and clinical implications. Br J Nutr. 2018 Apr;119(8):928-36.
  6. Li B, Wang M, Zhou L, et al. Association between serum vitamin D and chronic rhinosinusitis: a meta-analysis. Braz J Otorhinolaryngol. 2021 Mar-Apr;87(2):178-87.