A couple of years ago my father-in-law had an operation to remove a rather large gallstone, & with it his gall bladder. It had caused him a couple of urgent hospital admissions, through blocking the bile duct & causing a back-up of bile. He was quite seriously ill for a bit but is now fully recovered, although he has to watch his diet.
Anyway, he'd have been intrigued by an item I've just listened to on the Skeptics Guide podcast - a listener had written in asking about something that one of her relatives was trying to get rid of gallstones. Basically it involved drinking large quantities of apple cider for a couple of days, after which time the gallstones would be passed into the gut & come out with all the other undigested gunk. The person (website?) giving the advice had noted that these 'stones' would be greenish & 'soft to the touch'. Eewww - who goes around touching these things?
So, here's a question for you - based on your knowledge of the human digestive tract & maybe some chemistry, just how likely is it that drinking apple cider would soften gallstones to the point where you could pass them in your faeces?
Gallstones, by the way, are formed from bile that's sat around in the gall bladder for a while. Among other things, they contain cholesterols, bile pigments, & calcium, and have a crystalline structure that is both hard & sharp-edged (the latter is what causes pain when the gall bladder contracts). In my father-in-law's case, they were periodically blocking his bile duct, which meant that the gall bladder became distended with bile & was extremely painful.
Anyway, the premise of this treatment seems to be that in some way drinking apple cider (or apple juice, it depends who's giving the advice), usually combined with olive oil, will 'emulsify' or otherwise change the nature of gallstones so that they can pass through the bile duct & into the gut. Frankly, it's hard to see how this would work - there's a sphincter on the bile duct that ensures that fluid flow is very definitely one-way, out of the bile duct. So the mayonnaise mix you've drunk - & that's essentially what it is - isn't going to move up & into the gall bladder. Nor is it in some strange way going to change your blood pH: that's controlled within fairly strict limits by your body's own homeostatic mechanisms. (Apparently there are things you can take - under medical supervision - that can act to dissolve gallstones, but they're blood-borne & take months rather than days to have their effect.)
Despite this, promoters of this 'cure' will tell you that yes, it works, & you can see & feel squishy 'gallstones' in your faeces... Amazingly large numbers of them - more than you'd expect a gall bladder to contain. So what are they actually seeing? (Let's not think about the feeling part!) The outcome of a chemical reaction, in the gut, between lipases (the enzymes that digest fats & oils) and the olive oil component of the 'cure'. We know this because doctors have done the necessary experimental work on a patient's self-provided 'gallstones', produced after she'd followed the mayonnaise regimen (trust Orac to find the details of these things!)
Microscopic examination of our patient's stones revealed that they lacked any crystalline structure, melted to an oily green liquid after 10 min at 40°C, and contained no cholesterol, bilirubin, or calcium by established wet chemical methods. Traditional faecal fat extraction techniques indicated that the stones contained fatty acids that required acid hydrolysis to give free fatty acids before extraction into ether. These fatty acids accounted for 75% of the original material.
Experimentation revealed that mixing equal volumes of oleic acid (the major component of olive oil) and lemon juice produced several semi solid white balls after the addition of a small volume of a potassium hydroxide solution. On air drying at room temperature, these balls became quite solid and hard.
They concluded that
... these green "stones" resulted from the action of gastric lipases on the simple and mixed triacylglycerols that make up olive oil, yielding long chain carboxylic acids (mainly oleic acid). This process was followed by saponification into large insoluble micelles of potassium carboxylates (lemon juice contains a high concentration of potassium) or "soap stones".
In other words, the apple juice/cider & olive oil combination, plus the body's own lipases, is forming little gobs of oily soap...
A little biology knowledge goes a long way in this context :-)