For many Americans, wintertime means fewer 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.
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
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:
|Vitamin D Recommendations||FDA||Endocrine Society|
|Infants (0-12 months)||400 IU||400-1000 IU|
|Children (1-18 years)||600-800 IU||600-1000 IU|
|Adults (19+ years)||800 IU||1500-2000 IU|
|Pregnancy and Lactation||600 IU||1500-2000 IU|
*4000–6000 IU/day is the mother’s required intake if the 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
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 flu1,9
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”.
Denise John, PhD is a Science Researcher and Writer for Nordic Naturals. A published author, Denise holds a Doctorate in Neuroscience from Florida State University, and is passionate about sharing science to help others make informed choices and live better lives.