I thought this was an interesting breakthrough - Nottingham Trent Uni scientists have found evidence of leaky gut in the form of endotoxins leaking through the gut and distruption how fat cells functions. This is relevant to obesity and diabetes, but I believe it's also relevant for B12 deficiency and for those with absorption problems.
standard.co.uk/news/uk/toxi...
"Endotoxins are toxic substances present inside bacterial cell walls and released when it ruptures or disintegrates".
There is also a recent research paper into the connection between Endotoxins and neurodegeneration. While this is specific to conditions like Alzheimers and Parkinson's disease, the evidence seems to be creeping up for the quality of gut health/permeability to determine overall quality of health.
"Increased endotoxin is associated with neurodegenerative disease, and increased endotoxin can cause neurodegeneration, but whether neurodegenerative disease is caused by increased endotoxin is not known. "