Researchers are warning that popular GLP-1 weight loss medications may be linked to a rare and potentially life threatening brain condition.

However, the study behind the warning does not establish that the drugs caused the disorder.

The new study, published in Clinical Nutrition, identified 15 reported cases of Wernicke encephalopathy among people taking GLP-1 receptor agonists.

The neurological disorder is caused by a severe deficiency of vitamin B1.

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Most of the reported cases involved semaglutide, which is sold under the brand names Ozempic and Wegovy, or tirzepatide, sold as Mounjaro and Zepbound.

Researchers found the cases through the FDA's Adverse Event Reporting System, published medical literature and their own medical center.

Most patients experienced gastrointestinal symptoms or nutritional issues, according to the study. Those problems included weight loss, vomiting, loss of appetite or malnutrition.

Reports of Wernicke encephalopathy appeared more often among people taking GLP-1 medications than among those using other drugs, the researchers found.

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At the same time, they emphasized that their findings cannot prove the medications caused the condition.

Vitamin B1 has an important role in brain function, the researchers said. A severe deficiency can cause confusion, difficulty walking, balance problems and changes in vision.

If Wernicke encephalopathy is not treated, it can result in permanent neurological damage or death.

The study nevertheless focused on a small number of reported cases among the millions of people taking the medications.

Karthik Achari, a Chicago based clinician and founder of PepMD who was not involved in the study, said the results need to be kept in perspective. He noted that researchers identified only 15 cases after reviewing adverse event reports and medical literature.

"That's out of millions of people on these medications. So this is rare," Achari said. He added, "But it's real, it's serious, and the mechanism makes sense."

Achari said the medications can reduce appetite while also causing nausea and vomiting. Those effects can make it easier for some people to become deficient in vitamin B1.

"The drug shrinks your appetite. It doesn't shrink your body's requirements," Achari said. He explained that people can eat very little without feeling it, even though their need for protein, vitamins and fluids remains.

According to Achari, some people may face a higher risk, including those with persistent nausea and vomiting.

He also pointed to people losing weight very quickly while eating little, those with a history of bariatric surgery and people who use alcohol heavily.

Erin Palinski Wade, a New Jersey based nutritionist and author of "The Sleepdemic Solution," said nutrition and hydration should be considered part of treatment for people taking the medications.

She said dramatically reduced appetite may lead some people to unintentionally consume too little protein, fiber and fluids.

Palinski Wade also said ongoing vomiting or diarrhea can raise the risk of dehydration and kidney problems. She urged patients to seek medical guidance when those symptoms continue for roughly 24 hours.

"Severe or persistent symptoms deserve attention," Palinski Wade said. Her warning reflected concern that patients may dismiss every side effect as a routine part of taking the medication.

The researchers acknowledged that their study relied largely on reports submitted to the FDA.

They called for more research, while experts said patients should not stop taking prescribed GLP-1 medications based on these findings alone.