Case of an unconscious vegan with severe vitamin B12 deficiency in Osaka (Yanagisawa et al. 2023)

Yanagisawa et al. (2023) reported the case of a vegan in Japan who had undiagnosed diabetes, might have been a fruitarian, and surely had not taken a vitamin B12 supplement. He was severely vitamin B12-deficient. He was also severely emaciated (underweight) and was taken to hospital in a near-coma.

"We herein report a case of Candida pneumonia in a vegan patient with type 2 diabetes mellitus (DM) and a poor nutritional status due to an unbalanced diet. Bronchoscopy helped diagnose this disease, and we successfully treated the patient."

Some background info about the patient:

  • 39 years old
  • vegan (at least dietary) - no info on how long he had been vegan
  • He had diabetes /type 2) but seemed to not have known this.
  • "He denied alcohol abuse"
  • non-smoker
  • took no medications
  • took no "illicit" drugs
  • He had no family history of diabetes.
  • "He was a vegan and had been consuming a nutritionally unbalanced diet for at least a year. He had only eaten fruit until six days before admission, when anorexia [lack of appetite] developed."
  • body height was 175 cm
  • body weight was 47 kg, i.e., his body mass index was only 15.3 kg/m2. - "He showed noticeable emaciation."


  • general malaise
  • anorexia (i.e., no appetite - it does not mean Anorexia nervosa)
  • "an altered mental status"
  • admitted to hospital with diabetic ketoacidosis
  • He was unconscious! - "On admission, he was unconscious with a Glasgow Coma Scale score of 9 [the scale goes from 3 to 15, with 15 being the best] [.], and a large amount of food residue was suctioned from his trachea."

Vital signs and blood markers:

  • blood pressure was extremely low (92/56 mmHg)
  • heart rate was was (101 beats/min)
  • body temperature was low (35.1°C)
  • metabolic acidosis 
  • blood sugar was 1054 mg/dL (!) - extremely high
  • HbA1c was 11.6% (!), i.e., diabetes
  • white blood cell count was 7040 /μL
  • and C-reactive protein (CRP; inflammatory marker) was 0.68 mg/dL - quite high but not extremely high
  • serum albumin was 3.3 g/dL - too low but not extremely low
  • vitamin B12 was below the limit of detection (i.e., <50 pg/mL) - a normal level would be >300 pg/mL 
  • zinc was 17 μg/dL - I'm assuming, this is serum zinc. A normal level would be ~60-120 µg/dL [Barman et al. 2020]

Diagnosis and treatment:

  • first diagnosed with pneumonia which did not get better after treatment with antibiotics
  • then diagnosed with Candida pneumonia (i.e., pneumonia caused by a kid of fungus) which improved rapidly after antifungal therapy

Lungs before and after:

The authors understoof what veganism is put it quite nicely: 

  • "Veganism is a lifestyle that excludes all animal products and attempts to limit animal cruelty and exploitation as much as possible. People who follow veganism, called vegans, eat foods formulated without ingredients produced by or derived from animals."


  • Atsushi Yanagisawa, Yuhei Kinehara, Masaki Tanaka, Ryusuke Ninomiya, Miho Nishioka, Susumu Ochiai, Ryu Jokoji, Shoichi Ihara, Kunihiko Hashimoto, Isao Tachibana: Candida Pneumonia in a Young Vegan Man with Diabetic Ketoacidosis. Intern Med. 2023 Dec 15;62(24):3679-3683. doi: 10.2169/internalmedicine.1520-22. Epub 2023 May 10.