ammonia crosses the blood brain barrier,and settles inside the brain,,thats the key....ammonia is nuro toxin,,unregulated suger control in diebetics, causes nerve damage,including tn,,,,,food does cause pain,,,or at least its by products do,,,to say,two blood vessels are pressing on two nerves at exactly the same time,,on opposite side of the head,,for me,,thats improblable,if not impossible,,,but amonnia could do that,,,an irritating agent would olso progress over the years as the ammonia stripps away the outer nerve sheath,,think its called demyalisation, humans are not desinged to eat huge amounts of animal protiene