Some patients on GLP-1s are getting scurvy

In a new review, researchers from the University of Newcastle analyzed findings from 41 clinical trials on GLP-1 and GIP receptor agonist medications over the last 17 years. In total, the clinical trials included 50,000 participants.

Of these trials, researchers found all but two focused on body weight rather than nutrition. They also found that the appetite-suppressing properties of GLP-1s and other weight-loss medications can lead to vitamin deficiencies.

"These medications work, there's no question about that," said Clare Collins, laureate professor of nutrition and dietetics at the University of Newcastle and a nutrition and metabolic health researcher at the Hunter Medical Research Institute. "But a reduction in body weight does not automatically mean the person is well nourished or healthy. Nutrition plays a critical role in health, and right now it's largely missing from the evidence. With case reports of thiamine deficiency and protein malnutrition, we need to ensure we are not throwing the baby out with the bath water."

Collins also noted that there have been anecdotal reports of patients on GLP-1s developing scurvy, something that has historically been known as a "pirate disease."

For example, British pop singer Robbie Williams reported in 2025 that he had experienced symptoms of the "17th-century pirate disease" after taking "something like Ozempic." While taking the medication, Williams said that he had "stopped eating and […] wasn't getting nutrients."

According to Collins, future clinical trials on GLP-1s should include "validated dietary assessment tools" and "transparent reporting of food and nutrient intakes" to help patients currently taking the medications avoid the risk of malnutrition.

"While this mechanism drives weight loss, it also increases the risk of inadequate protein, fiber, vitamin and mineral intakes if diet quality and nutritional adequacy are not carefully monitored," Collins added.

Collins also encouraged patients on GLP-1s to seek professional help from an accredited dietitian to ensure they're getting proper nutrition. "It is challenging to assess whether your nutrient intake is adequate by yourself," she said. "People may also require a specific multivitamin or mineral supplement, along with medical nutrition therapy support."

There have also been reports of unintended muscle mass loss, a potential for increased risk of miscarriage or birth defects, and severe mental health issues like depression and suicidal thoughts while taking GLP-1s.

Because GLP-1s are still so new, more research is needed to understand both the benefits and potential risks of the drugs.

"The story of GLP-1s is really being written every day," said Ziyad Al-Aly, chief of research and education service at the VA Saint Louis Health Care System. "Our group and others have several more years — decades, even — to really flesh out [that story] completely."

To reduce the risk of negative side effects from GLP-1s, Ilana Muhlstein, a registered dietitian nutritionist based in Los Angeles, recommends patients regularly meet with their doctors to check their progress and assess their health.

"If you're on these medications, you should be seeing your doctor at least once a year and getting labs drawn to check your vitamin and mineral levels, not just your weight," Muhlstein said.