★★★★☆
I make sure to keep it below 1000 mg/day. Undecylenic acid was recommended along with niacin, but I cannot find it at the stores. My mouth had geographic tongue, and sores all everywhere and especially after eating certain sugary foods things got tender, but now that I'm eating these niacinamide supplements, I can eat whatever I want again, and the big sores are gone and my tongue is back to normal. If I feel it starting to flare up, I chew up a pill and rub the niacinamide all over my tongue and lips and I can feel the fungus dying, and everything returning to normal. After months of suffering, I'm so glad to have it so much better, not perfect, but I just started 2 days ago, so what can we expect.