GLP-1 weight-loss drugs linked to vitamin B12, protein and fiber deficiencies

An August review of research from Harvard T.H. Chan School of Public Health and the University of Copenhagen identified significant nutrient gaps among GLP-1 drug users, including low vitamin B12, protein and fiber intake. With roughly 30 million Americans on these medications, the shortfall could impair nerve health, muscle repair and digestive function.

Ohio State University researchers estimate 10 million Americans lack adequate B12, a risk heightened for those on plant-based diets. The review also noted that 43 percent of patients do not meet protein recommendations, while inadequate fiber can trigger gastrointestinal discomfort. Separate studies found that one in six adolescents using GLP-1s for a year develop vitamin D deficiency, and a January review reported a 13.6 percent deficiency rate in adults over 480,000 patients, raising concerns for bone health across age groups.