Vitamin D may stop you getting colds…
This study looked at the relationship/association between levels of Vitamin D in the blood and incidence of respiratory tract infections… or more commonly known as ‘cold’ symptoms. There seemed to be an association between higher levels of Vitamin D and lower incidence of cold symptoms. As we always say, association does not mean causation; in this instance we can demonstrate this quite well. Good researchers will create hypotheses from observational studies such as these. Two such hypotheses are a) Higher Vitamin D levels improve immune function and reduce the incidence of cold symptoms or b) that the higher Vitamin D levels in those that had a lower incidence of cold symptoms are indicative of individuals who take more exercise (outside) and that these individuals have stronger immune systems due to being fit and healthy….
It is interesting to note that a huge number of people in this study were actually ‘deficient ‘ in Vitamin D! There is much controversy over the optimal or even appropriate level of Vitamin D but a general consensus is that people should be between 32 – 80 ng/ml. It is a shame that another ‘group’ was not investigated with levels above ~50ng/ml.
METHODS: 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)
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
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.