Abstract An elderly man in his 80s receiving home medical care presented with recurrent loss of appetite. Although the physical examination was normal, thiamine deficiency was suspected based on his history of chronic alcohol use, prior unexplained anorexia, and ongoing cancer treatment. Oral thiamine supplementation resulted in marked improvement within days. Subsequent testing confirmed thiamine deficiency, leading to the diagnosis of gastrointestinal beriberi. This case underscores the importance of considering gastrointestinal beriberi in patients with nonspecific gastrointestinal symptoms in the home medical care setting, particularly when risk factors for thiamine deficiency are present.