Research review
Nicotinamide riboside (NR): what the research does and doesn't show
Nicotinamide riboside's core NAD+, dosage and safety research is covered in depth elsewhere on this site. This page rounds up what the same trials do and don't say about diarrhea, headaches, fertility and pregnancy.
Nicotinamide riboside's core NAD+, dosage and safety research is covered in depth elsewhere on this site. This page rounds up what the same trial literature does and doesn't say about a few narrower questions: diarrhea, headaches, fertility and pregnancy.
What the evidence doesn't support
It doesn't support nicotinamide riboside as a documented cause of diarrhea or headaches — neither shows up as an NR-specific side effect in the trials reviewed on this site. It doesn't support any claim about fertility, because no human trial has tested nicotinamide riboside for that outcome. And it doesn't support any guidance on pregnancy, because the largest safety trial specifically excluded pregnant and breastfeeding women.
What the trials found
The largest safety trial (140 adults, doses up to 1,000 mg/day for 8 weeks) recorded the mild, possibly-related side effects of nicotinamide riboside as nausea, muscle soreness, leg pain and a sore back — diarrhea wasn't among them, in either the NR groups or placebo. A separate 6-week crossover trial in 30 older adults recorded headache as a symptom during the placebo phase, not during nicotinamide riboside treatment, suggesting NR itself wasn't the cause in that trial. See nicotinamide riboside side effects for the full side-effect picture across all the trials reviewed.
On fertility, no human trial has tested nicotinamide riboside for that outcome — the research that touches on reproduction is in animals, not people, and isn't reviewed here. On pregnancy, the largest safety trial required that women of childbearing potential be non-pregnant, non-breastfeeding, and using contraception to enroll, which is why there's no human pregnancy safety data to report either way; see who should not take nicotinamide riboside for the fuller picture of who the trials excluded.
Questions people ask
Can nicotinamide riboside cause diarrhea?
No trial reviewed on this site has reported it as a side effect, in the NR group or the placebo group.
Can nicotinamide riboside cause headaches?
In the one trial that recorded it, headache showed up during the placebo phase, not during nicotinamide riboside treatment — evidence against NR being the cause in that trial, not proof it can't happen to a given person.
Does nicotinamide riboside help with fertility?
No human trial has tested it for that outcome, so there's no evidence either way from the research reviewed on this site.
Is nicotinamide riboside safe during pregnancy?
There's no human safety data either way — the largest safety trial specifically excluded pregnant and breastfeeding women. Ask a doctor before taking any supplement during pregnancy.
When to talk to a doctor
Nicotinamide riboside is not a treatment for any condition discussed here. If you're pregnant, breastfeeding, or trying to conceive, or you take medication for any condition, talk to a doctor before adding a supplement — see nicotinamide riboside and medications: what to check.
Related reading: nicotinamide riboside benefits: what the research does and doesn't show, nicotinamide riboside side effects, and who should not take nicotinamide riboside.
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.
*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.