For many Americans, wintertime means less sun rays, more time indoors, and extra layers of clothing. Add in a crackling fireplace, and you have yourself a cozy winter night. However, these seasonal factors (minus the fireplace) also contribute to something much less pleasant: vitamin D deficiency. Because vitamin D plays such an essential role in immune health, low levels can weaken our defenses and increase susceptibility to illnesses, like colds and flu.¹ Instead of cozy winter nights, you could have days of feverish, coughing and sneezing.

Vitamin D deficiency is most prevalent during the peak of cold and flu season 

Although vitamin D deficiency is most prevalent during the during winter months (the peak of cold and flu season), supplementation can help reduce the occurrence and symptoms of colds and flu.^1–6 For example, one research study analyzed nearly 11,000 participants (that’s a lot of people!) between the ages of 0 and 95 years (that’s a big range!) and found that daily doses of vitamin D supported respiratory tract health and reduced the incidence of common seasonal infections.⁴

Supplement daily vitamin D

So that means supplementing with vitamin D can help the entire family stay well this winter. Vitamin D testing, which requires a simple blood sample, can help determine your specific vitamin D requirements. Prior to testing, here are some general daily dosing guidelines:

*4000–6000 IU/day is mother’s required intake if infant is not receiving 400 IU/day.

RDI = Recommended Dietary Intake; IU = International Units.

[Table is modified from Evaluation, Treatment, and Prevention of Vitamin D
Deficiency: an Endocrine Society Clinical Practice
Guideline.⁷

Vitamin D helps regulate the immune system 

Vitamin D supplementation helps boost your immune system by stimulating naturally occurring antimicrobial peptides, which protect the body by destroying invading microbes.⁸ These antimicrobial peptides live in immune cells throughout the body, including cells lining the upper and lower respiratory tract. There, they are able to directly fight off viruses and bacteria that cause common immune and respiratory infections like colds and flu^1,9

Take vitamin D this cold and flu season

Supplementing with vitamin D is important for immune health throughout the entire year, but especially during the peak of the cold and flu season when vitamin D levels are at their lowest. So, before cozying up by the fireplace with your hot chocolate this winter, take your daily dose of vitamin D. Your immune system will thank you. To learn more, here’s pretty much “Everything You Need to Know About Vitamin D”.