Can Vitamin D Protect Against Upper Respiratory Infections?

Can Vitamin D Protect Against Upper Respiratory Infections?

By Eric Madrid MD

If there is one vitamin in the world that may help optimize a person’s health and well-being, it’s vitamin D (also known as vitamin D3 or cholecalciferol). Recent research indicates that vitamin D may play a crucial role in preventing the common cold, also known as an Upper Respiratory Infection (URI). 

How is Vitamin D Made?

Vitamin D can be made and absorbed into the body for free when time is spent in the sun—ultraviolet B (UV-B) light waves from the sun react with a form of cholesterol in our skin to create the vitamin D hormone. However, during less sunny months, less vitamin D is generated.

The Health Benefits of Vitamin D

Thousands of studies over the last decade show health benefits when one optimizes vitamin D intake. These studies tell us that those with higher levels of vitaminin their blood have a lower risk for heart attacks, breast cancer, colon cancer, multiple sclerosis, type 1 and type 2 diabetes, high blood pressure and other health complications. 

In my Southern California Practice, 80 percent of patients are vitamin D deficient. The incidence is higher in less sunny climates. I routinely recommend my patients supplement with vitamin D.

Vitamin D and Respiratory Infections

A 2019 study in the International Journal of Environmental Research and Public Health concluded that those with higher blood levels of vitamin D were at lower risk for Upper Respiratory Infections compared to those with lower vitamin D blood levels. 

Two additional studies have supported these findings. First, there was a 2017 study in the British Medical Journal where researchers evaluated 25 randomized controlled trials which included 11,321 participants, whose ages ranged from babies to 95 years of age. 

In total, vitamin D supplementation reduced the risk of an upper respiratory infection by 12 percent. Those who had vitamin D blood levels less than 25 nmol/L (10 ng/dl) noticed the biggest benefit and saw a 70% decrease in infection rate when they were supplemented. In those patients who had a vitamin D level greater than 25 nmol/L (10 ng/dl), a 25% reduction in respiratory infections was noted after supplementation.

Lastly, a 2017 study in the Journal of the American Geriatric Society compared a standard dose vs. high dose of vitamin D in the elderly. The high dose group of 55 people received 100,000 IU of vitamin D3 per month (~3300 IU daily) while the other group of 52 people received either a monthly placebo or 12,000 IU per month (~400 IU/day). The study took place over a 4 year period. Those who took the high dose vitamin D were 40 percent less likely to have an Upper Respiratory Infection compared to the others.

Overall, vitamin D’s safety profile has been widely established. Consult with your physician prior to supplementing if any concerns.

Suggested dose: Most children can safely take around 1,000 IU daily while many adults take between 2,000 to 5,000 IU daily. 


  1. Pham H, Rahman A, Majidi A, Waterhouse M, Neale RE. Acute Respiratory Tract Infection and 25-Hydroxyvitamin D Concentration: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2019;16(17):3020. Published 2019 Aug 21. doi:10.3390/ijerph16173020
  2. Martineau Adrian R, Jolliffe David A, Hooper Richard L, Greenberg Lauren, Aloia John F, Bergman Peter et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data BMJ 2017; 356 :i6583
  3. Ginde AA, Blatchford P, Breese K, et al. High-Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long-Term Care Residents: A Randomized Clinical Trial. J Am Geriatr Soc. 2017;65(3):496–503. doi:10.1111/jgs.14679

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