The two sites below show studies on the treatment of low stomach acid with niacin.
Long term hypochlorhydria results in protein maldigestion which can result in niacin deficiency (primarily due to unvailability of tryptophan).
Niacin is critical for the release of histamine, a key player behind stomach acid secretion. One study shows that a 3 week therapeutic supplementation with niacin completely eliminated hypochlorhydria and symptoms tied in with it.
Supplementation with betaine HCl may be beneficial as well (specially if H pylori is evident), however it requires a more long term dosage to provide the same results (up to year as per Judy Kitchen).
There's a clear relationship between dysbiosis like candida as well as nutritional deficiencies stemming from protein maldigestion and limited carb/fat metabolism.
I urge everyone to take a deeper look at this and evaluate if this route can be beneficial.
I'm currently increasing my niacin dosage (as non flush version, however pure niacin may be best to get the desired histamine release).
I will monitor my necessity of supplementing with betaine HCl as I start making my own stomach acid.
I have more energy since starting niacin two days ago and bowel movements are better so far.