Aging and longevity expert David Sinclair, who is a researcher in the department of genetics and codirector of the Paul F. Glenn Center for Biology of Aging Research at Harvard Medical School, announced the findings on Twitter. 

The results, published in the journal Aging this month, underscore aging as a process that can be reversed versus something inevitable. It adds to the growing interest in aging medicine, as people spend upwards of $100,000 per year at longevity clinics in the quest for the fountain of youth. CEO Bryan Johnson is known for his $2-million-a-year reverse-aging protocol.  

“We’ve previously shown age reversal is possible using gene therapy to turn on embryonic genes,” Sinclair tweeted in a thread with over 1 million engagements. “Now we show it’s possible with chemical cocktails, a step towards affordable whole-body rejuvenation.” 

Grateful to share our latest publication: We’ve previously shown age reversal is possible using gene therapy to turn on embryonic genes. Now we show it’s possible with chemical cocktails, a step towards affordable whole-body rejuvenation 1/17 https://t.co/J9c01lv5FQ

— David Sinclair (@davidasinclair) July 12, 2023

In research over the course of three years, Sinclair and his team at Harvard observed mice taking six “chemical cocktails” that can reverse key hallmarks of aging by rejuvenating senescent or older, deteriorating cells “without erasing cellular identity,” according to the study. 

“Studies on the optic nerve, brain tissue, kidney, and muscle have shown promising results, with improved vision and extended lifespan in mice and, recently, in April of this year, improved vision in monkeys,” Sinclair tweeted. 

In a press release, Sinclair said, “This new [hotlink]discovery ignore=true[/hotlink] offers the potential to reverse aging with a single pill, with applications ranging from improving eyesight to effectively treating numerous age-related diseases.” 

Is a “chemical cocktail” the answer to living longer? 

So what’s in this cocktail? Even Elon Musk tweeted back, “Ok, so what exactly is it?” 

Ok, so what exactly is it?

— Elon Musk (@elonmusk) July 13, 2023

The cocktail consists of a variety of molecules, including valproic acid, which is an anti-seizure medication used for migraine and mood disorders, and a drug used for cancer with anti-aging properties.

To Sinclair, we may be close to a reverse-aging concoction to restore youthfulness, but longevity experts have their concerns. It’s too early to interpret these results for humans, Dr. Luigi Fontana, author of Manual of Healthy Longevity & Wellbeing and the director of the Healthy Longevity Research and Clinical Program at the University of Sydney, tells Fortune. 

“These are just preclinical data that must be validated in well-designed and adequately powered human randomized clinical trials,” he says. “It is essential to rely on rigorous scientific research and evidence-based studies before drawing conclusions about the effects of such molecules on human health.”

Dr. Neil Paulvin, a New York–based regenerative and functional medicine doctor, says the study does not prove there’s one pill to extend life span. Top of mind for him in the aging space is addressing inflammation and mitochondrial issues, which are integral to extending health span. 

“Some of the cocktail may have potential for aging 15, 20, 50 years from now,” Paulvin tells Fortune, although people should not assume “that there’s something coming tomorrow that’s going to help them live another 10 years.”

Additionally, all of the components of the cocktail must be rigorously tested in humans to ensure they don’t cause an increased risk of cancer, for example. 

Sinclair says the team is preparing for human cellular trials using gene therapy for reverse aging, per his Twitter account, and he responded to a question confirming human trials will be available within a decade. 

“There’s a race between many groups to show chemicals can rejuvenate cells like gene therapy can,” Sinclair tweeted. He adds, “We envision a future where age-related diseases can be effectively treated, injuries can be repaired more efficiently, and the dream of whole-body rejuvenation becomes a reality.”