When to take NMN: afternoon doses showed the largest gains in a morning-vs-afternoon trial

Doses used in trials

We copied each trial’s dose and schedule as its abstract states it. One trial made time of day its main question: Kim and colleagues gave 108 older Japanese adults 250 mg of NMN or placebo once a day, either in the morning or in the afternoon, for 12 weeks (Kim 2022). Of the others, Yi 2023 and Fukamizu 2022 gave NMN once a day, Katayoshi 2023 split it into two doses, and the rest report a daily total.

Study	Design	People	Dose	Duration	Result	Grade
Kim 2022	RCT	108 older Japanese adults, four groups	250 mg once a day, morning or afternoon	12 weeks	Afternoon NMN group had the largest effect sizes for 5-times sit-to-stand (d = 0.72) and drowsiness (d = 0.64)	A
Morifuji 2024	RCT	60 older adults	250 mg a day	12 weeks	Higher blood NAD+ and its metabolites and a shorter 4-m walking time than placebo at 12 weeks; better sleep-questionnaire scores	A
Katayoshi 2023	RCT	36 healthy middle-aged adults	125 mg capsule twice a day (250 mg a day)	12 weeks	Serum nicotinamide, an NAD+ metabolite, higher than placebo	A
Yi 2023	RCT	80 healthy middle-aged adults	300, 600 or 900 mg once a day	60 days	Blood NAD higher than placebo and baseline at day 30 and day 60 in every NMN group; longer 6-minute walk	A
Liao 2021	RCT	48 trained amateur runners	300, 600 or 1200 mg a day	6 weeks	Oxygen uptake (VO2) and power at the first and second ventilatory thresholds rose more at 600 and 1200 mg than placebo	A
Fukamizu 2022	RCT	31 healthy adults aged 20 to 65	1250 mg once a day	Up to 4 weeks	No changes beyond physiological variation; no severe adverse events	A

NMN Pure Powder. Renue’s NMN Pure Powder is NMN with no other ingredients, at 500 mg per scoop. Renue says it “supports NAD+ levels that help power your cells.” Renue’s suggested use is half a scoop twice daily for the first week for people new to NMN, then one full scoop (500 mg) twice daily, or 1,000 mg a day. That sits inside the 250 to 1,250 mg a day the trials above gave, with the top amount coming from a 4-week safety trial. Renue’s two doses a day match the split schedule Katayoshi 2023 used, at a higher amount. See NMN Pure Powder at Renue By Science

Timeline

Here is when the human trials saw their measured markers move, from the shortest check to the longest.

Day 30. In the 80-adult trial, blood NAD was higher than placebo and baseline by day 30 at 300, 600 and 900 mg once a day, and stayed higher at day 60, highest at 600 and 900 mg (Yi 2023). The 6-minute walk also rose more than placebo.

Week 6. Runners training 5 to 6 times a week gained more in oxygen uptake and in power at their first and second ventilatory thresholds on 600 or 1200 mg a day than on placebo (Liao 2021).

Mid-trial to week 12. In the morning-versus-afternoon trial, drowsiness in both afternoon groups had improved by the mid-intervention check and stayed improved after 12 weeks. The afternoon NMN group showed the largest effect sizes, d = 0.72 for the 5-times sit-to-stand and d = 0.64 for drowsiness. The authors concluded that NMN taken in the afternoon improved lower-limb function and reduced drowsiness in older adults (Kim 2022).

Week 12. At 250 mg a day, older adults had higher blood NAD+ and its metabolites and a shorter 4-m walking time than placebo after 12 weeks, and better scores for daytime dysfunction and overall sleep quality on the Pittsburgh questionnaire (Morifuji 2024). With 125 mg taken twice a day, serum nicotinamide was higher than placebo at 12 weeks, and the authors concluded that NMN raised NAD+ metabolism in healthy middle-aged adults (Katayoshi 2023).

What did not change. In the timing trial, chair-stand times improved in all four groups, placebo included, and drowsiness improved in the afternoon placebo group too, so the afternoon result is one early signal rather than a settled rule. The 12-week trial at 250 mg found no difference in its main stepping test (Morifuji 2024), the runners’ VO2max did not change in any group (Liao 2021), and a meta-analysis of trials in adults with a mean age over 60 found no significant NMN effect on grip strength, gait speed or the 5-time chair stand (Prokopidis 2025).

Safety

Four of the trials in the table report safety results, and none found a serious problem at the amounts they gave.

• Up to 900 mg once a day for 60 days: no safety issues in adverse events, lab tests or clinical measures, and NMN was well tolerated (Yi 2023).
• 1250 mg once a day for up to 4 weeks: no changes beyond physiological variation in body measurements, blood, urine or body composition, and no severe adverse events (Fukamizu 2022).
• 250 mg a day for 12 weeks: no adverse effects related to NMN (Morifuji 2024), and the twice-daily 125 mg schedule was well tolerated with no adverse events (Katayoshi 2023).
• Across 33 human studies: a 2026 systematic review found oral NR and NMN generally well tolerated over weeks to months (Gallagher 2026).