A company that charged patients thousands of dollars for infusions of blood plasma from younger donors said Tuesday that it had stopped treating patients after the Food and Drug Administration warned consumers against such treatments, purported to prevent aging and memory loss.

The company, Ambrosia, said on its website that it had “ceased patient treatments.” The announcement came hours after the FDA issued a statement saying there is no proof that plasma from young donors can be used as a treatment for dementia, Parkinson’s disease, multiple sclerosis, Alzheimer’s disease or post-traumatic stress disorder, as some companies have claimed.

The plasma infusions can also be dangerous, the agency added, because they are associated with infectious, allergic, respiratory and cardiovascular risks.

Be cautious about establishments in several states offering infusions of plasma from young donors as a treatment for a variety of conditions including normal aging and heart disease. https://t.co/VGxmrLuR1F pic.twitter.com/thPehOiwfj — U.S. FDA (@US_FDA) February 19, 2019

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

“We’re alerting consumers and health care providers that treatments using plasma from young donors have not gone through the rigorous testing that the FDA normally requires in order to confirm the therapeutic benefit of a product and to ensure its safety,” Dr. Scott Gottlieb, food and drug commissioner, and Dr. Peter Marks, director of the agency’s Center for Biologics Evaluation and Research, said in a statement.

The federal agency noted that several businesses offer infusions of plasma costing thousands of dollars per infusion for a variety of conditions. Such companies can often avoid FDA drug approval processes because plasma transfusions are a well-established procedure. Ambrosia, for example, had been charging $8,000 for one liter of blood and $12,000 for two as part of a clinical trial. The blood was donated by 16- to 25-year-olds to consumers ages 35 and older.

Ambrosia’s founder, Jesse Karmazin, 34, a Stanford Medical School graduate, launched the startup three years ago. In 2017, he began a clinical trial and touted impressive results, claiming that young plasma could prevent Alzheimer’s and lower blood cholesterol. But he never made the results of his study public.

Ambrosia isn’t the only company that aggressively marketed scientifically dubious potions to those desperate to preserve their youth.

Other medical establishments, such as the Maharaj Institute in Florida, have started expensive clinical trials and openly discussed plans to charge patients for transfusions of plasma from young donors. In fact, people considering enrolling said they had been told they would have to pay $285,000, STAT reported last March.

“Though the use of young plasma is promising and hopeful, there needs to be rigorous trials to ensure therapeutic benefits and safety standards for each indication of use,” said Dr. Sharon Sha, a neurologist at the Stanford Neuroscience Health Center in Palo Alto, California. “I also have concerns about 'for pay' sites that encourage participation by patients who are not aware of the risks and can be desperate for a cure.”

Plasma is the liquid part of blood that contains clotting factors, antibodies and other important proteins. Plasma infusions from young donors have been shown to have mildly positive results in Alzheimer's patients, according to a small Stanford University study.

Plasma transfusions are normally given to correct for blood-clotting deficiencies in patients who are bleeding. Plasma is not FDA-approved to treat other conditions, such as normal aging or memory loss.

“The administration of plasma for indications other than those recognized or approved by the FDA should be performed by a qualified investigator or sponsor who has an active investigational new drug application with the FDA,” the FDA said.