David K. Lerner, Katherine L. Garvey, Annie Arrighi-Allisan, Evan Kominsky, Andrey Filimonov, Abdurrahman Al-Awady, Peter Filip, Katherine Liu, Sen Ninan, Todd Spock, Benjamin Tweel, Maaike van Gerwen, Madeleine Schaberg, Patrick Colley, Anthony Del Signore, Satish Govindaraj, Alfred Marc Iloreta

To evaluate the efficacy of omega-3 fatty acid (O3FA) supplementation in the treatment of COVID-related olfactory dysfunction (OD). Patients with laboratory-confirmed or clinically-suspected COVID-19 infection and new-onset OD from August 2020 to November 2021 were prospectively recruited. Patients with quantitative OD, defined as a brief smell identification test (BSIT) score of 9 or less, were eligible for study inclusion. The experimental group received 2 g of O3FA supplementation, while the control group received an identical placebo to be taken daily for 6 weeks. The primary outcome was a change in BSIT score between the initial and 6-week follow-up tests. One hundred and seventeen patients were included in the analysis, including 57 patients in the O3FA group and 60 in the placebo group. O3FA group patients demonstrated a mean BSIT improvement of 1.12 ± 1.99 compared to 0.68 ± 1.86 in the placebo group (p = 0.221). Seventy-seven patients, 42 within the O3FA group and 35 in the placebo group, completed a follow-up BSIT survey at an average of 717.8 days from study onset. At long-term follow-up, there was an average BSIT score improvement of 1.72 within the O3FA group compared to 1.76 within the placebo group (p = 0.948). Among patients with persistent COVID-related OD, our study showed no clear evidence of relative short-term or long-term olfactory recovery among patients receiving high doses of O3FA supplementation.