The median serum 25(OH)D level was 29 ng/mL…and 19%…of participants reported a recent URTI [recent respiratory tract infections]. 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…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).
The authors stress that the study’s results need to be confirmed in clinical trials before vitamin D can be recommended to prevent colds and flu. “We are planning clinical trials to test the effectiveness of vitamin D to boost immunity and fight respiratory infection, with a focus on individuals with asthma and COPD, as well as children and older adults – groups that are at higher risk for more severe illness,” Ginde says. “While it’s too early to make any definitive recommendations, many Americans also need more vitamin D for its bone and general health benefits. Clinicians and laypeople should stay tuned as this exciting area of research continues to expand.”
The overused chestnut that correlation imply causation is important to keep in mind here. But, causation does entail correlation, so this is a place to start. A few years ago I was diagnosed with Vitamin D deficiency (serum levels below 10 ng/mL). This is not surprising as I have dark skin and live in a region with low levels of radiation. Since that point I’ve been taking supplements and my blood serum is now within the normal range (Carlson has 360 2000 IU tablet packages, so this isn’t even a major expense). I also have had a history of nearly ubiquitous minor respiratory problems. Since I started taking the supplements I can report that these are not nearly as much of an issue, though I have had bronchitis a few times (bacterial infections). It seems likely that most dark-skinned people in northern climes have Vitamin D deficiency, so if the correlation does pan out to be a causation then micronutrient supplementation would be a quick way to increase median levels of public health.