In my case the coated tongue is due to food intolerance. I've literally seen it happen right before my eyes after eating something that triggers a reaction. At the same time the little bumps on the back of my tongue swell up and when I looked this up I found out they are my taste buds swelling up due to an allergic response. If it was due to my intestines not functioning properly It seems odd that it would happen within a few bites of eating something I'm intolerant to and then go away after a few days. Its actually been a helpful indicator for me in figuring out which foods bother me since sometimes my reactions are delayed. I always check my tongue after I eat. When I have reflux symptoms the coating is always present.
I've just had a colonoscopy and a barium CT. I've had a few of these and also an Endoscopy. I got thoroughly cleaned out for the colonoscopy. Everything looked good on the tests....I saw the pictures myself...a perfectly healthy clean and pink colon. I have food intolerances caused by leaky gut most likely caused by gluten intolerance. I got tested for candida in the stool twice. Once was negative and once was a mild overgrowth. Either way my symptoms were the same both times I was tested.
I could go all week eating pancakes and muffins and cookies (made with sugar) but believe me....if I get one tiny amount of some Mono-Sodium-Glutamat (Natrium Glutamat)
or corn in me...like from some typical vanilla extract (or any extract)....I'll be completely wiped out. My tongue will be white, massive brainfog to the point that I cant function, depression, major head pressure, blurred vision, chemical sensitivities, aches and pains, etc... I could score of the charts on a yeast questionairre on these days. This is how I used to feel everyday until I went on the candida diet. It took me awhile to learn that it wasnt candida though....although I probably have a more than desireable amount of it at times....I'm quite sure its not the cause of my symptoms or white tongue. If I manage to avoid stuff that causes reactions my mind is clear from brainfog and I feel normal....it can change in an instant though.
Also acid reflux is most commonly caused by food intolerance. When I get it...it sucks. Its painful but it goes away in about a day and it only happens to me about once a month....if I really mess up good as far as what I eat.
I think it has alot to do with digestion. The foods I react to are likely foods I dont digest well and these are the foods that will continue to keep the cycle going and prevent healing of the intestinal lining (leaky gut). Diet is crucial.
Also when you have a food intolerance that particular food *is* a toxin and yes, your body can become overwhelmed as well as your liver....especially if you are constantly exposing yourself to the food or "antigen". It will put a strain on your immune system as well as your organs.