The Healthspan Map · Nutrient

Niacin (B3)

Compiled by Aamir Malik, PhD, Professor of Neuroengineering at Brno University of Technology, from published studies. He is a researcher, not a physician. Last updated 21 August 2026.

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.
Condition or system	Direction	Strength	Evidence type	What was found	Source
Brain fog & memory	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)
Chronic fatigue / low energy	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)
Depression / low mood	Eat enough of	Moderate	Established clinical	Niacin deficiency causes neuropsychiatric symptoms including depression and apathy.	Pellagra case literature (opens in a new tab)
Insomnia / poor sleep	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)
Peripheral neuropathy	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)
Skin, hair, nails & wound healing	Eat enough of	Moderate	Review / narrative	Niacin deficiency causes pellagra: photosensitive dermatitis (plus diarrhoea and dementia).	Niacin & pellagra (opens in a new tab)

Linked to getting too much

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.
Condition or system	Direction	Strength	Evidence type	What was found	Source
Digestive discomfort	Don't overdo	Emerging	Review / narrative	High-dose niacin causes flushing with nausea and loose stools.	Niacin flushing & GI (opens in a new tab)
Liver, Kidney & Urinary	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)

The Healthspan Map is part of Fix the Floor, a book by Aamir Malik. About the book