VitaminClinical dose · 100–1,000mg/day raised blood NAD+ (+22% at 100mg, +51% at 300mg, +142% at 1,000mg after 8 weeks); cognition and fatigue trials used 1,000–2,000mg/day in patient groups and found no benefitOnset · Blood NAD+ rose within 2 weeks and stayed higher to week 8; no trial has shown an effect on cognition or energy

Nicotinamide Riboside (NR)

Name: Nicotinamide Riboside (NR) — Human Clinical Effect Matrix
Creator: The Nootropic Lab
License: https://creativecommons.org/licenses/by/4.0/

NR raises NAD+ in human blood: in an 8-week trial in 140 healthy overweight adults, whole-blood NAD+ rose 22%, 51% and 142% at 100, 300 and 1,000mg/day (Conze et al., 2019, funded by ChromaDex), and the rise has been reproduced by other groups, including Nestlé researchers. That is a biomarker, not a health outcome. No randomized cognition trial in healthy adults was found. Three placebo-controlled trials in mild cognitive impairment or subjective cognitive decline (1,000mg/day for 8–12 weeks) and a long-COVID trial (2,000mg/day) found no cognitive benefit, even though blood NAD+ rose 2- to 3-fold. In the largest trial, NOPARK (410 people with early Parkinson's disease, 1,000mg/day for 52 weeks, published in JAMA in 2026), symptom scores worsened more on NR than on placebo. A 2023 review of 25 human studies concluded that oral NR has shown few clinically relevant effects. Most NR trials are funded, supplied or co-authored by ChromaDex/Niagen Bioscience or Elysium Health.

By The Nootropic Lab editorial teamUpdated Oct 19, 20268 min read✓ Fact-checked

Evidence reviewed: Oct 19, 2026

Mechanism of action

Nicotinamide riboside (NR) is a form of vitamin B3 and a precursor of NAD+. Supplements usually contain the salt nicotinamide riboside chloride, sold as NIAGEN by Niagen Bioscience (formerly ChromaDex). Taking NR reliably raises NAD+ in human blood; the authors of a 2026 trial propose that it works partly through gut bacteria converting it to nicotinic acid. Blood NAD+ is a surrogate marker: no trial has shown that raising it improves thinking, memory or energy.

Clinical evidence summary

Human effect matrix

Based on human clinical trials only. Animal and in-vitro data excluded.

Effect	Evidence	Magnitude	Studies	Notes
Blood NAD+ (Biomarker)	strong	Large	5	Single 100–1,000mg doses raised blood NAD+ metabolites in proportion to dose (Trammell 2016). Over 8 weeks, whole-blood NAD+ rose 22%, 51% and 142% at 100, 300 and 1,000mg/day (Conze 2019); 1,000mg/day raised it about 60% in blood cells (Martens 2018); 250mg NR with 50mg pterostilbene raised it about 40% (Dellinger 2017, a combination product). A Nestlé trial reproduced the rise (Christen 2026). This is a marker, not a health outcome.
Memory & Thinking (Healthy Adults)	preliminary	Negligible	—	No randomized trial with a cognitive outcome in healthy adults was found; the healthy-adult trials measured NAD+ metabolites, blood pressure, muscle or vascular outcomes. Evidence of benefit is absent, not negative.
Cognition (MCI & Subjective Decline)	preliminary	Negligible	3	1,000mg/day for 8–12 weeks did not change MoCA scores (Orr 2024, n=20), the primary cognitive outcome (Martens 2026, 42 completers) or RBANS scores (Wu 2025, n=46), although blood NAD+ rose 2- to 2.6-fold. Lower plasma pTau217 in the Wu trial is a biomarker finding, not a cognitive benefit.
Fatigue & Energy	preliminary	Negligible	2	In 58 adults with long-COVID, 2,000mg/day did not change fatigue or cognition versus placebo (Wu 2025, a separate trial). A meta-analysis found no support for NR or NMN for muscle mass and function in adults over 60 (Prokopidis 2025). No trial in healthy adults.
Parkinson's Disease	moderate	Negligible	3	Two small early trials leaned positive (NADPARK 2022, n=30; NR-SAFE 2023, n=20, where symptom scores were confounded by levodopa timing). The phase 3 NOPARK trial (Brakedal 2026, n=410, 1,000mg/day, 52 weeks) found symptom scores worse on NR than on placebo. The evidence is against benefit.
Healthy Ageing	preliminary	Negligible	2	A critical review of 25 human studies found few clinically relevant effects (Damgaard 2023); a systematic review of 33 human studies (Gallagher 2026) found consistent NAD+ increases but functional and healthspan effects that were heterogeneous and often null.

Evidence key: Strong = multiple consistent RCTs · Moderate = smaller/fewer RCTs · Preliminary = early trials or small n · Mixed = conflicting results

Documented benefits

Raises NAD+ in blood, more at higher doses (biomarker only; replicated in several trials)
No more adverse events than placebo at 100–1,000mg/day over 8 weeks in healthy overweight adults (one trial)

Side effects & cautions

In the NOPARK phase 3 trial (early Parkinson's disease, 1,000mg/day for 52 weeks, n=410), Parkinson's symptom scores worsened more on NR than on placebo (+2.72 points, p=.02) and non-motor symptoms worsened more; serious adverse events were less common on NR (8.3% vs 14.1%). The authors say the results do not support NR as a disease-modifying treatment
EFSA judged nicotinamide riboside chloride safe at up to 300mg/day for healthy adults, but only up to 230mg/day in pregnancy and breastfeeding
In a 2021 opinion, EFSA noted experimental data indicating several ways in which intakes of nicotinamide or its precursors well above physiological needs might cause adverse effects
Healthy-adult safety data stop at 8 weeks: in that trial there was no flushing, no LDL-cholesterol rise and no difference in adverse events between NR and placebo
At 3,000mg/day for 4 weeks in Parkinson's disease there were no moderate or severe adverse events, but serum homocysteine rose slightly at first
In a long-COVID trial at 2,000mg/day, 51% of the group that took NR for 20 weeks dropped out, versus 14% in the group that took placebo first; the abstract gives no reasons

How to take

DosageFor raising blood NAD+, 100–1,000mg/day of nicotinamide riboside chloride was tested (300mg/day: +51% after 8 weeks). EFSA judged up to 300mg/day safe for healthy adults (230mg/day in pregnancy and breastfeeding). No dose has been shown to improve cognition or energy

TimingOnce daily after breakfast in the dose-ranging trial; blood NAD+ rose within 2 weeks.

With foodThe dose-ranging trial gave it after breakfast; the trials reviewed set no other rule.

FormsCapsule. Supplements usually contain nicotinamide riboside chloride (NIAGEN or TRU NIAGEN), and most trial product was supplied by ChromaDex, now Niagen Bioscience. Trials that name the form (Trammell 2016, Conze 2019) give doses as mg of nicotinamide riboside chloride, so a label stating mg of the chloride compares directly. NMN, niacin and nicotinamide are different compounds whose trials are not evidence for NR.

Frequently asked questions

Does raising NAD+ improve memory or focus?

Not in the trials so far. No randomized cognition trial in healthy adults was found, and trials in mild cognitive impairment, subjective cognitive decline and long-COVID (1,000–2,000mg/day) found no cognitive benefit even though blood NAD+ rose 2- to 3-fold.

What dose raises NAD+?

In an 8-week trial, whole-blood NAD+ rose 22% at 100mg/day, 51% at 300mg/day and 142% at 1,000mg/day. No trial of 250mg of NR alone with NAD+ as the outcome was found; a combination of 250mg NR with 50mg pterostilbene raised it about 40%.

Is NR safe?

Trials of 100–1,000mg/day for up to 8 weeks found no more adverse events than placebo. EFSA judged up to 300mg/day safe for healthy adults but only up to 230mg/day in pregnancy and breastfeeding. In early Parkinson's disease, a year of 1,000mg/day was followed by worse symptom scores than placebo. Long-term safety in healthy people has not been established.

Who funds NR research?

Most trials were funded, supplied or co-authored by Niagen Bioscience (formerly ChromaDex), which sells NIAGEN, or by Elysium Health. The NAD+ rise has been reproduced by Nestlé researchers, and the trials that found no cognitive benefit come from academic groups, some using vendor-supplied product.

Nicotinamide Riboside (NR) in Japan

Products in Japan

None of the stacks we have audited are listed in our catalogue in Japan yet.

Consumer Affairs Agency (FFC)

Prefecture guides

Regulatory note

本ページは教育目的の編集コンテンツであり、医学的助言を構成するものではありません。日本国内で販売される機能性表示食品（FFC）および特定保健用食品（FOSHU）は、消費者庁への届出または許可を必要とします。届出のない輸入品については、日本の薬機法（旧薬事法）の下で疾病治療を示唆する表現は規制されます。サプリメントを開始する前に、必ず資格のある医療専門家にご相談ください。This page is editorial and not medical advice. Foods with Function Claims (FFC) and Foods for Specified Health Uses (FOSHU) sold in Japan require notification or approval from the Consumer Affairs Agency. Imported products without notification cannot make disease-treatment claims under the Pharmaceuticals and Medical Devices (PMD) Act. Consult a qualified healthcare professional before starting any supplement.

Sources (17)expand

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