How well is the link between Vit B12 and diarrhoea understood? Does it just amount to observation that people with Vit B12 deficiency can have diarrhoea.
This link: nhlbi.nih.gov/health-topics....
"Other symptoms of vitamin B12 deficiency involve the digestive tract. These symptoms include nausea (feeling sick to your stomach) and vomiting, heartburn, abdominal bloating and gas, constipation or diarrhea, loss of appetite, and weight loss. An enlarged liver is another symptom."
It doesn't seem to be suggest that vitamin B12 deficiency itself can cause diarrhoea. I guess the underlying factors (intrinsic factor enzyme and parietal cell issues) are the underlying causes but it's not understood very well?