Usually at night, stomach ache, acid reflux, or feeling full as though my food is not digesting properly, I use one teaspoon of apple cider vinegar in a glass of water. Instantly the burning ,nausea, stomach fullness feels lessened, as thought it is helping increase stomach acid aiding the digestion process. The burning that my Mom felt when she laid down was diagnosed as acid reflux or GURD she was prescribed acid reducers that took weeks to work, and she had to use constantly. That is when I first tryed apple cider vinegar in water. I read that increasing the acid, NOT reducing the acid, will help digest food that is sitting in the stomach undigested, it made sense to me, I tried it and it has always worked for me, any time I feel full, burp or nausea, I try the vinegar in water. It only happens to me if I overeat late at night or when I have to take a lot of oral medication all at one time, that is hard to digest (hard caplets). I have been using grocery store liquid, any brand, I did not know about any of the below listed kinds! I did like the natural trader joe brand or any health food store kind, that is cloudy. Cheap store brands are very acidic and hard to swallow, but that is what I'm looking for, to increase the acid level in my gut. If you think about it it really makes sense. If food is backing up into the esophagus, it needs to digest faster. One time 35 years ago (age 17 yrs) I was very, very obviously constipated (stomach sticking out in a bikini, hadn't moved bowels for 2 weeks due to out house situation) and a friend had me eat a bowl of vegetables, broccoli, cauliflower, carrots, and apple cider vinegar and sesame oil dressing, I had a smooth BM the next day and have used that recipe since then. My sister is an RN and she had tried everything to help including an enema (that never came out!) I have been a fan of apple cider vinegar for years for all kinds of digestion help.Read More Read Less