is that true? Not in my experience. ‘the gut is impaired by a...

is that true? 
Not in my experience. 
‘the gut is impaired by a number of things..mainly gluten but also by a1 dairy protein, stress and chemicals
once the gut is impaired the gut lining becomes permeable...causing leaky gut.  The gut lining is inflamed and then becomes sensitive to such things as lactose.....this does not mean you are lactose intolerant...more that the gut has been impaired by gluten etc to cause the gut to become sensitive to lactose etc.
we now know that what we originally believed was la toes intolerance is in fact not lactose intolerance at all.