The Healthspan Map · Nutrient

Niacin (B3)

Linked to getting too little

Where a shortfall of Niacin (B3) is linked — 6 sources.In the order the Map holds them: strongest evidence first. That is a statement about the evidence, not about what matters most.
Nutrient or lever	Direction	Strength	Evidence type	What was found	Source
Niacin (B3)	Eat enough of	Strong	Established clinical	Pellagra's neuropsychiatric 'D' includes dementia, cognitive impairment, delirium and encephalopathy (reversible if treated early).	Pellagra case literature (Cureus/PMC) (opens in a new tab)
Niacin (B3)	Eat enough of	Emerging	Review / narrative	Niacin (NAD/NADP) is essential to cellular energy metabolism.	Micronutrients for energy/fatigue review (Tardy 2020) (opens in a new tab)
Niacin (B3)	Eat enough of	Moderate	Established clinical	Niacin deficiency causes neuropsychiatric symptoms including depression and apathy.	Pellagra case literature (opens in a new tab)
Niacin (B3)	Eat enough of	Emerging	Cohort / observational	Adequate niacin spares tryptophan for serotonin/melatonin; low niacin is associated with short sleep.	NHANES 2005-2016 (opens in a new tab)
Niacin (B3)	Eat enough of	Emerging	Review / narrative	Niacin deficiency (pellagra) can include peripheral neuropathy alongside dermatitis and cognitive change.	Nutritional & toxic neuropathy (opens in a new tab)
Niacin (B3)	Eat enough of	Moderate	Review / narrative	Niacin deficiency causes pellagra: photosensitive dermatitis (plus diarrhoea and dementia).	Niacin & pellagra (opens in a new tab)

Where an excess of Niacin (B3) is linked — 2 sources.In the order the Map holds them: strongest evidence first. That is a statement about the evidence, not about what matters most.
Nutrient or lever	Direction	Strength	Evidence type	What was found	Source
Niacin (B3)	Don't overdo	Emerging	Review / narrative	High-dose niacin causes flushing with nausea and loose stools.	Niacin flushing & GI (opens in a new tab)
Niacin (B3)	Don't overdo	Moderate	Established clinical	High-dose niacin, especially sustained-release, causes dose-dependent liver injury that can progress to acute liver failure.	Niacin (NIH LiverTox) (opens in a new tab)