The Effect of Fish Oil Fatty Acid Supplementation on Two-Step Tuberculin Skin Test: A Randomized Controlled Clinical Trial

Background: A two-step tuberculin skin test (TST) should be performed if the subsequent TSTs are to be conducted at regular intervals, especially among health care professionals, and its interpretation of serial TST is particularly complex. Methods: In this randomized controlled clinical trial, the effect of fish oil fatty acid (FA) supplementation on two-step TST was investigated. The outcome was considered a change in 2 sequential TST induration sizes; 6 mm or more were considered as a criterion to distinguish the increase in reaction size. The study protocol was approved in the ethic committee of Qazvin University of Medical Sciences. In the present study, 213 healthy participants (medical and nursing students of Qazvin University of Medical Sciences in 2014) were randomly assigned into a normal diet (control) or fish oil supplementation (treatment) group. One gram of fish oil supplement was given to the treatment group daily for 5 consecutive days. Results: The mean secondary induration and the difference between the primary and secondary induration sizes were significantly higher in the fish oil users (P < 0.001). Noticeable increase in TST size in the treatment group was significantly higher than in the control (16.3% vs. 1.2%). Conclusions: Short-term supplementation with fish oil FAs seems to increase the accuracy of two-step TST.