The claim: Melatonin can prevent COVID-19
Can a natural sleep aid be useful against the novel coronavirus? Apparently so, according to a claim floating around social media.
"The Cleveland Clinic was able to show that the ancient molecule melatonin has the greatest potential out of 34 drugs used to prevent and treat C 19," Facebook user Doris Loh posted Nov. 17, referring to a study published by the medical center.
Melatonin received much attention in October after President Donald Trump's COVID-19 diagnosis and hospitalization at Walter Reed National Military Medical Center. The president took the supplement as part of a medical regimen that included Gilead's remdesivir, Regeneron's antibody cocktail and over-the-counter zinc, antacids and aspirin, the latter three of which have not demonstrated compelling therapeutic value.
Loh suggested ascorbic acid, or vitamin C, may have a role in COVID-19 treatment and detailed an upcoming Cleveland Clinic clinical trial comparing the effectiveness of zinc, ascorbic acid or a combination for coronavirus treatment.
"Which arm do you think will have the best outcomes? But more importantly, have you had your AA and MEL today?" she wrote.
USA TODAY could not reach Loh for further comment.
What is melatonin?
Deep within the brain lies the pea-sized pineal gland, which primarily produces the hormone melatonin. It does this in response to changes in light, slowly releasing the slumber-inducing molecule as the sun goes down and easing off as it rises.
Aside from governing sleep, melatonin is linked to many other biological processes, such as reproductive development, and may underlie cancer and mental health problems such as major depressive or bipolar disorder.
When it comes to immune function, melatonin may be critical in keeping the body's inflammatory response at bay, as observed in a study in 2019 published on the ScienceDirect website. This study found the hormone appeared to work synergistically with an antiviral drug to keep influenza A-infected mice from dying.
What did the Cleveland Clinic study find?
On the hunt to find a coronavirus treatment, the Cleveland Clinic study published Nov. 6 looked at 34 different drugs used to treat a variety of respiratory, cardiovascular, neurological and immunologic diseases, as well as cancer. Anti-hypertensive drugs targeting the angiotensin receptor, a protein found on the surface of many cell types and used by the coronavirus as a point of entry, were included.
Melatonin usage was observed to lower the chance of a positive coronavirus test, after adjusting for age, sex, race, smoking history and various disease comorbidities, by about 28%. Even compared with drugs targeting the angiotensin receptor, melatonin usage seemed to significantly reduce the likelihood of a positive test.
The study looked at different patient subgroups and found melatonin usage associated with a 52% reduced likelihood of a positive result for Black patients. Melatonin usage was likewise observed to lower the probability of a positive test result for diabetics, less so for asthmatic and hypertensive patients.
Though these discoveries sound promising, there is a caveat.
Because this was an observational study examining nearly 27,000 patients who underwent coronavirus testing with the Cleveland Clinic Health System, its findings only suggest a possible association between melatonin usage and COVID-19. Randomized controlled trials, the gold standard for clinical research, are needed to establish whether there is an actual clinical benefit to the hormone, something the study's authors acknowledged.
"It is very important to note these findings do not suggest people should start to take melatonin without consulting their physician," said Dr. Feixiong Cheng, the study's lead author, in a news release in November. "Large-scale observational studies and randomized controlled trials are critical to validate the clinical benefit of melatonin for patients with COVID-19, but we are excited about the associations put forth in this study and the opportunity to further explore them."
Our rating: Missing context
We rate this claim MISSING CONTEXT, because without additional context it might be misleading. A Cleveland Clinic study did find melatonin usage associated with a reduced likelihood of a positive coronavirus laboratory test; however, because the study was observational, it does not prove benefits. Randomized controlled trials are needed to establish a link between melatonin usage and preventing COVID-19.
Our fact check sources:
USA TODAY, Oct. 5, "Trump is receiving lots of medical care, and some doctors wonder if it's too much"
LiveScience, Dec. 18, 2013, "What Is Melatonin?"
Frontiers in Endocrinology, March 6, "Melatonin and Female Reproduction: An Expanding Universe"
Memorial Sloan Kettering Cancer Center, May 4, "Melatonin"
Frontiers in Psychiatry, May 20, "Pineal Gland Volume in Major Depressive and Bipolar Disorders"
Journal of Functional Foods, Feb. 25, 2019, "Melatonin possesses an anti-influenza potential through its immune modulatory effect"
Consult QD Cleveland Clinic, Nov. 13, "Melatonin a Promising Candidate for Prevention and Treatment of COVID-19"
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This article originally appeared on USA TODAY: Fact check: Melatonin could help against COVID-19, more studies needed