Braggs Apple Cider Vinegar is a health food store staple and my preferred brand. It's unfiltered, containing what is referred to as the "Mother" that contains healthy bacteria, enzymes and living food. Always look for the "Mother" in any Apple Cider Vinegar that you purchase and preferably buy an Organic variety. Among other benefits it is a fermented beverage which supports healthy bacteria in the intestines, supporting digestion.
Many people use it with success to combat acid reflux. Acid reflux isn't a condition of too much acid; it occurs when the stomach doesn't have enough acid when food enters the stomach.
The food sits in the stomach for too long without adequately produced acid. It then passes partially digested into the small intestine. Finally, the stomach gets around to producing acids but it's too late, the food has moved on! Too much acid produced in the stomach when there is no food in it, causes stomach upset, erosion of the lining of the stomach, and acids launching up into the esophagus (acid reflux). Food passing partially digested into the small intestine creates malabsorption of nutrients. The small intestine should only be receiving digested food or "chyme" from the stomach.