Read "it works" and "there is evidence" separately.
For supplements like NMN, the marketing language always arrives before the research language. This site puts, for each ingredient, what it is claimed to do (the benefit) and what has actually been measured in published human trials (the numbers) on the same page.
The grade at the top of each page is this site's own rating based on the quality and quantity of published human trials (A: several large meta-analyses agree / B: meta-analyses exist, direction consistent / C: a few small RCTs / D: weak or inconsistent evidence / E: mostly animal or in-vitro). It is not medical advice.
Ingredient guides
NMN (β-nicotinamide mononucleotide)
An NAD+ precursor. Dramatic in animal studies; human trials are small and the results are split. Before "rejuvenation": what has been shown, and what has not.
Collagen peptides
Meta-analyses agree on "statistically significant" for joint pain, skin elasticity and bone density. The ingredient with the most consistent numbers in this field, including a meta-analysis of 35 RCTs.
Lactoferrin
Meta-analyses point the same way for iron deficiency and childhood infections. Milk-derived, so allergy caution applies.
Curcumin (turmeric)
A meta-analysis of 103 RCTs. Significant changes in blood glucose and inflammation markers, but poor bioavailability and trial quality are the weak points.
Magnesium (sleep)
Popular, but the sleep evidence is rated low to very low. Included as an example of a D grade.
Before you read
- How to read evidence (RCTs, meta-analyses, GRADE, SMD) — once you can read the numbers, most supplement ads disqualify themselves.
- Dietary supplements are not medicines. They are not for treating or preventing disease; if you notice changes while taking them, consult a physician.
- This site may earn income from links (disclosure). Grades and rankings are independent of compensation.