This lipoic acid / heartburn issue comes up now and then.
The old form people would be taking in almost gram amounts and since it doesn't dissolve quickly, might be an issue for a very sensitive person.

I have had reflux with ginger extract, and dark chocolate at times. I simply cannot drink coffee anymore! It wrecks my GI tract. But I do drink black tea (Bigelow brand) once a day in the morning, strongly steeped.

But the 100mg of NaRALA does not seem to bother me.

Factors in reflux are bending over after a potential culprit, too full of a stomach, too much gas coming up from below., and poor integrity of the stomach lining.

Coffee and tea have more acid than that a R-lipoic capsule (100mg). The stomach itself is more acidic than that capsule.

So there might be some factor that makes lipoic acid products other than the acid, be the culprit.

Back a decade ago, I had alot of GERD. I had many tests, and they found my twisted stomach and hiatal hernia. At one point I was on Prilosec daily. At that time, I found, Dr. Sears' book, Enter the Zone, and I began Omega-3 fatty acids daily. Fish oil, primrose oil, and Flax oil. Within 3 months, my GERD was gone, and never really returned, except for the foods I mentioned now and then. It was a wake up call illustrating that the maintenance of the lining of the GI tract is dependent on
these essential fats.

If you lie down after eating at any time, or bend at the waist alot doing some activity after eating you can push acidic stomach contents into the unprotected esophagus. I think this factor alone is responsible for many GERD episodes.

One little Fosamax if taken and then the patient lies down or doesn't use enough fluid to move it along...will erode the esophagus in some patients. 10mg
Actonel is just as bad. And they are not acidic.

So I would take this "heartburn" as a sign that something is wrong. Please do check that out.