The 25(OH)D assay used may have overestimated levels for smokers William B. Grant, Sunlight, Nutrition and Health Research Center 13 January 2011 Interesting results. However, there may be an error in the findings. As noted in the paper: "About 78% of men with TB were smokers, and this prevalence was significantly higher than in controls (61%, P = 0.007)." A recent paper reported that the serum 25(OH)D assay used, ELICA, found higher values for smokers than nonsmokers: "In the population-based study, the serum levels of 25(OH)D using the ECLIA method were 51.9, 53.2 and 72.0 nmol/l in never, former and current smokers (P<0.01). In the validation study, the serum concentration of 25(OH)D was 10.3 nmol/l higher in smokers than in non-smokers (P<0.01) using the ECLIA (Roche), while non-significantly lower serum levels of 25(OH)D were found in smokers using the other five methods." [Grimnes et al., 2010]. Thus, the values of 25(OH)D for smokers should be rechecked to see whether this problem affected the findings. Grimnes G, Almaas B, Eggen AE, Emaus N, Figenschau Y, Hopstock LA, Hutchinson MS, Methlie P, Mihailova A, Sneve M, Torjesen P, Wilsgaard T, Jorde R. Effect of smoking on the serum levels of 25-hydroxyvitamin D depends on the assay employed. Eur J Endocrinol. 2010 Aug;163(2):339-48. Competing interests I receive or have received funding from the UV Foundation (McLean, VA), the Sunlight Research Forum (Veldhoven), Bio-Tech-Pharmacal (Fayetteville, AR), the Vitamin D Council (San Luis Obispo, CA), and the Danish Sunbed Federation (Middelfart).