system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 49-year-old man presents to the clinic with skin lesions and chronic diarrhea. His wife also reports that he has become more irritable and forgetful in the past year. His medical history is significant for a gastroenterostomy performed 4 years ago due to gastric outlet obstruction caused by hyperplastic polyposis, which was complicated by afferent loop syndrome. He became a vegan a year ago, and currently, his diet consists of starchy foods such as potatoes, corn, and leafy vegetables. The patient’s vital signs include blood pressure 100/75 mm Hg, heart rate 55/min, respiratory rate 14/min, and temperature 36.3℃ (97.3℉). His skin is pale, dry, and thin, with areas of desquamation and redness on the sun-exposed areas. His lymph nodes are not enlarged and breath sounds are normal. The cardiac apex beat is located in the 5th left intercostal space 2 cm lateral to the midclavicular line. Heart sounds are diminished and S3 is present. His abdomen is slightly distended and nontender to palpation. The liver and spleen are not enlarged. Neurologic examination reveals symmetrical hypesthesia for all types of sensation in both upper and lower extremities in a 'gloves and socks' distribution. On a mini-mental status examination, the patient scores 25 out of 30. Production of which substance is most likely to be impaired in this patient?
assistant
NAD+