"It turns out that there’s enough niacin in blood to keep the yeast’s adhesion-promoting genes turned off, we discovered," he adds. "But in urine and perhaps other host environments, there is such a limited amount of niacin that these genes are turned on, allowing the organism to stick to host cells."
2) Niacin is converted to niacinamide in the body.
3) Niacinamide appears to be directly toxic to the yeast rather than just turning off the adhesion genes.
So its not clear to me which one would be better. But niacin causes some serious fatigue.