A new treatment for smell loss?
Reviewed by Joanna Stephens

It has been well established that smell training can be effective in the recovery of smell function post Covid-19 infection, and many other treatment modalities have been assessed. There have been limited studies to date evaluating the effects of dietary supplementation with Omega 3 (O3FA) in recovery from anomia or hyposmia, and the authors address this with a double-blind, placebo-controlled RCT. A total of 117 patients with self-reported symptoms were randomised to either a treatment (two Nature Made Ultra Omega-3 fish oil capsules) or a placebo group, and their outcomes measured with olfactory testing and quality of life questionnaires. Interestingly, they found initially an improved rate of recovery of objective smell function in the treatment group vs. the control group, but this did not meet statistical significance. The improvement in olfactory function was more marked in those with laboratory proven Covid-19 infection. Both groups showed an improvement in their SNOT-22 scores through the duration of the trial, but there was no significant difference between the two groups. Again, when assessing long-term follow-up, the O3FA group showed better recovery, but the recovery did not meet statistical significance. Whilst the authors accept that they did not find a benefit to using O3FA to treat smell loss, they acknowledge that had they used a different smell test, perhaps they might have had a different result. Also, the inclusion of patients both with and without laboratory confirmed Covid-19 infection may have had an impact on results. Ultimately, they found no benefit in treating with O3FA, but more research will be valuable without doubt, as this is not in harmony with previous work available in the literature.

Omega-3 fatty acid supplementation for the treatment of persistent COVID-related olfactory dysfunction.
DK Lerner, Garvey KL, Arrighi-Allisan A, et al.
AM J RHINOL ALLERGY
2023;37(5):531–40.