A Waste of Money: Gastrointestinal Beriberi and Vitamin B1

I distinctly remember going to my doctor and asking whether I should take vitamins as part of my diet. They said to me that it is just "expensive pee". While some of this is true, we do absorb most of our vitamins and minerals from our diet, but the changing food environment in the US can make it harder to get enough. This could be due to a variety of situations, such as individuals' diets, sex, or just some people needing more of certain vitamins. 

A syndrome called Gastrointestinal Beriberi was discovered in 2004; it is a vitamin B1 deficiency. This syndrome has been forgotten for some time. Some symptoms of Gastrointestinal Beriberi include nausea, vomiting, and abdominal pain. Scans in the ER will turn out normal, but if it is left untreated, it can cause serious issues, even death. 

A 31-year-old male comes into the ER with these symptoms after having one night of heavy drinking. He went to the ER eleven times and even had surgery, and no one found anything. Two months later, his eyes stopped tracking correctly, and doctors thought it might be due to vitamin B1. They gave him vitamin B1, and his symptoms disappeared within hours. 

Vitamin B1 is vital as it converts carbohydrates into energy and supports proper function of the brain, heart, and nervous system. 

Many thought that vitamin B1 (thiamine) deficiencies were related to individuals who are heavy drinkers. Since our bodies do not naturally produce thiamine, we must get it from our diets. People who drink heavily obtain most of their calories from alcohol rather than nutrient-dense foods, and alcohol actively prevents the body from using or taking up thiamine. New studies found that thiamine deficiency is not only in heavy drinkers, but in those who have a normal diet as well. 

Your body stores enough B1 for only two weeks, and even less if you don't eat; when you're sick, it depletes even faster. Vitamin B1 deficiency paralyzes gut motility, worsening gastrointestinal symptoms. 

New data show that 25% of people who don't drink heavily and don't already take a B vitamin are vitamin B1 deficient. What does that mean going forward? Why does this matter?

Millions are being prescribed GLP-1 as an appetite suppressant on their weight-loss journey. As an appetite suppressant, it can lead to fewer thiamine-rich foods being consumed. Two separate reviews this year have come out with patients who are taking GLP-1 agonists developing Wernicke's encephalopathy-like symptoms of Gastrointestinal Beriberi. 

Screening for thiamine deficiency should be number one for someone who has been vomiting for a week straight, and especially someone who is taking GLP-1's. Making sure everyone eats thiamine-rich foods as part of a healthy diet; it may not be just "expensive pee." 

Sources:

Day, B. D., Lever, J. E. P., Vickers, K., & Centor, R. (2026). Gastrointestinal Beriberi Secondary to Intermittent Hemodialysis With Rapid Improvement Following Thiamine Administration. Case Reports in Gastrointestinal Medicine, 2026(1), 3195006.

Donnino, M. (2004). Gastrointestinal beriberi: a previously unrecognized syndrome. Annals of internal medicine, 141(11), 898-899.

Lev, D., Leibowitz, A., Lang, A., Shlomai, G., Twig, G., Eden-Friedman, Y., ... & Goldman, A. (2026). Glucagon-like peptide-1 receptor agonists and Wernicke encephalopathy: a pharmacovigilance study and literature review. Clinical Nutrition, 106571

Nisar, S., Tanvir, M., Ganie, M. A., Kareem, O., Muzaffer, U., & Wani, I. A. (2022). Clinical profile of patients presenting with thiamine-responsive upper-gastrointestinal upset: a pointer toward gastric beriberi. Nutrition, 102, 111730.

Overton, E., Emelyanova, A., & Bunik, V. I. (2025). Thiamine, gastrointestinal beriberi and acetylcholine signaling. Frontiers in Nutrition, 12, 1541054.

Pereira, A. G., Cunha, L. N. D. P., Paiva, S. A. R., Azevedo, P. S., Zornoff, L. A. M., Polegato, B. F., ... & Minicucci, M. F. (2026). An overview of beriberi. Medical Principles and Practice, 35(1), 18-24. Urbina, J., Salinas‐Ruiz, L. E., Valenciano, C., & Clapp, B. (2026). Micronutrient and nutritional deficiencies associated with GLP‐1 receptor agonist therapy: a narrative review. Clinical obesity, 16(1), e70070.

Xie, X., Deng, L., Zhao, J., Sun, X., Liu, L., Pan, X., & Zhang, Y. (2026). Fulminant cardiovascular collapse after acute pancreatitis: a case report of non-alcoholic Shoshin beriberi and literature review. AME Case Reports, 10, 88.