Vitamin D was named the “Vitamin of the year” a couple of years ago by the nutrition journals. There are new articles coming out every month about the impact this vitamin/hormone and its amazing amount of physiological functions. There have been several studies that show Vitamin D’s role in modulating the immune system including this one just published last week. What this study tells us is that if you often gets upper respiratory infections then you may have low vitamin D levels. So do ask your PCP to order you a Vitamin D panel. You need to get a 25-Hydroxyvitamin D or 25(OH)D test. It should be at least 50ng/ml although you’ll see on lab reports that 30ng/ml is considered low normal. Don’t go by the ranges as research is showing that 30ng/ml is inadequate – your levels should be between 40-60 ng/ml year round!
It is most important to supplement from September to March in the Northeast. Some people need as high as 10,000IU/day during winter in order to keep their levels in the 40-60ng/ml range! But most are around 2000-5000IU/day during the winter months. During the summer many people will not need supplementation, but some still do. Those that may are darker skinned folks and of course ones that always wear sunscreen.
Here is the abstract of the article mentioned above:
Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey
Adit A. Ginde, MD, MPH; Jonathan M. Mansbach, MD; Carlos A. Camargo Jr, MD, DrPH
Arch Intern Med. 2009;169(4):384-390.
Background Recent studies suggest a role for vitamin D in innate immunity, including the prevention of respiratory tract infections (RTIs). We hypothesize that serum 25-hydroxyvitamin D (25[OH]D) levels are inversely associated with self-reported recent upper RTI (URTI).
Methods We performed a secondary analysis of the Third National Health and Nutrition Examination Survey, a probability survey of the US population conducted between 1988 and 1994. We examined the association between 25(OH)D level and recent URTI in 18 883 participants 12 years and older. The analysis adjusted for demographics and clinical factors (season, body mass index, smoking history, asthma, and chronic obstructive pulmonary disease).
Results The median serum 25(OH)D level was 29 ng/mL (to convert to nanomoles per liter, multiply by 2.496) (interquartile range, 21-37 ng/mL), and 19% (95% confidence interval [CI], 18%-20%) of participants reported a recent URTI. Recent URTI was reported by 24% of participants with 25(OH)D levels less than 10 ng/mL, by 20% with levels of 10 to less than 30 ng/mL, and by 17% with levels of 30 ng/mL or more (P < .001). Even after adjusting for demographic and clinical characteristics, lower 25(OH)D levels were independently associated with recent URTI (compared with 25[OH]D levels of 30 ng/mL: odds ratio [OR], 1.36; 95% CI, 1.01-1.84 for <10 ng/mL and 1.24; 1.07-1.43 for 10 to <30 ng/mL). The association between 25(OH)D level and URTI seemed to be stronger in individuals with asthma and chronic obstructive pulmonary disease (OR, 5.67 and 2.26, respectively).
Conclusions Serum 25(OH)D levels are inversely associated with recent URTI. This association may be stronger in those with respiratory tract diseases. Randomized controlled trials are warranted to explore the effects of vitamin D supplementation on RTI.