Guide
When is the best time to take nicotinamide riboside (NR)?
No trial has directly compared morning and evening dosing for nicotinamide riboside. Chronic trials split daily doses into two servings roughly 12 hours apart, mainly to keep blood levels steady — not because a specific time of day was tested and found better.
No trial has directly compared taking nicotinamide riboside in the morning against the evening. What the research shows instead is that trials at higher doses split the daily amount into two servings, roughly 12 hours apart — a study-design choice aimed at keeping blood levels steady, not evidence that any particular time of day works better.
What the trials actually did
At 100-1,000 mg a day, an 8-week trial of 140 adults dosed once daily, without the published methods specifying a particular time of day (PMID 31278280). At higher chronic doses — 1,000 mg/day and 2,000 mg/day — two separate trials split the total into two servings, taken roughly 12 hours apart, for 6 and 12 weeks respectively (PMID 29599478, PMID 29992272). None of these trials tested once-daily against twice-daily dosing, or morning against evening, as their own variable — the schedules were chosen for practical dosing reasons, not tested against alternatives.
With or without food
None of the trials we reviewed tested nicotinamide riboside with versus without food as its own variable. The 8-week, 140-person trial did ask participants to limit other dietary sources of niacin and tryptophan for the study's duration, so the NAD+ measurements weren't confounded by diet — but that's a study-control measure, not a with-food-vs-without-food comparison (PMID 31278280). If it upsets your stomach taken on an empty stomach, taking it with food is a reasonable, common-sense adjustment.
Morning, evening, or split — what the choice comes down to
Because no trial isolated timing as a variable, there's no research-backed reason to prefer morning over evening, or evening over morning. Unlike a sleep-focused supplement, nicotinamide riboside has no evening-specific research to time a dose around — see nicotinamide riboside (NR) benefits: what the research does and doesn't show for what it has and hasn't been shown to do. Splitting a higher daily amount into two doses, as the chronic trials did, is a reasonable approach if a product's label recommends it; taking a lower daily amount once is equally supported by what's been tested at that dose.
Questions people ask
When should I take nicotinamide riboside?
No trial has tested one time of day against another. Trials taking it once daily didn't specify a preferred time; trials splitting the dose spaced the two servings about 12 hours apart.
Should I take nicotinamide riboside in the morning or at night?
Neither has been shown to work better — that comparison hasn't been tested. Pick whichever time you're more likely to take it consistently, since the trials reviewed here all used daily, fixed schedules over weeks, not occasional use.
Should I take nicotinamide riboside with food?
No trial tested this directly. If it causes stomach upset on an empty stomach, taking it with a meal is a reasonable adjustment; nothing in the research says it must be taken either way.
Can I take nicotinamide riboside twice a day?
Yes — two of the chronic-dosing trials reviewed here split a higher daily total (1,000 mg or 2,000 mg) into two servings roughly 12 hours apart, and both schedules were well tolerated (PMID 29599478, PMID 29992272).
Related reading: how much nicotinamide riboside (NR) should you take a day?, nicotinamide riboside (NR) side effects, and nicotinamide riboside (NR) benefits: what the research does and doesn't show.
Sources
- Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults A 2019 randomized, placebo-controlled trial of 140 adults found nicotinamide riboside raised blood NAD+ dose-dependently at 100-1,000 mg/day over 8 weeks with no reports of flushing and no rise in LDL cholesterol or homocysteine, unlike the other forms of vitamin B3.
- Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD(+) in healthy middle-aged and older adults A 2018 crossover trial's discussion explains that niacin's flushing reaction comes from binding a specific skin receptor (GPR109A) that nicotinamide riboside isn't expected to activate, and found flushing reports were, if anything, more common on placebo than on NR.
- A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects A 2018 trial of 40 obese men given 2,000 mg/day of NR for 12 weeks found no improvement in insulin sensitivity, glucose metabolism, or body composition compared with placebo, though it was safe and well tolerated.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.