The universe of the study is heart patients.  The advice should logically apply only to heart patietnts. I'm not seeing what the hazard ratios of heart patients outside of the study were, as compared to those taking niacin.  In naming the metabolites as a cause, are there other metabolites not mentioned like NMN? What happens when NMN is no longer present in patients that have reduced niacin levels?  What are the hazards of low niacin as compared to high niacin? What is considered the correct dose of niacin in this study? There's so much that's not studied or understood that it's difficult to see anyone taking action on half baked science... until you realized that the beneficiary of not taking niacin to lower cholesterol is actually the pharmaceutical companies that sell cholesterol lowering drugs...whose side effects are never part of a published study...because to do such research essentially ruins your career.  But frankly we all know of the negative side effects of statins but we won't study those.