Apigenin's popularity comes from splicing together two separate literatures. One is a genuine mechanistic finding: apigenin inhibits the NADase CD38 and raises NAD+ — in cells and in mice. The other is a randomized trial in generalized anxiety disorder using apigenin-standardized chamomile extract. Neither is a trial of apigenin capsules for sleep, NAD+ or aging, and none exists. The awkward part is pharmacokinetic: a human study found free apigenin — the form in capsules — was poorly absorbed at about 0.5% of intake recovered as urinary metabolites, while chamomile-type glycosides were absorbed up to about 34%.
Apigenin (4',5,7-trihydroxyflavone) is a naturally occurring flavone abundant in chamomile, parsley, celery, and other plants. It is a pharmacological inhibitor of CD38, the principal NAD+-consuming (NADase) enzyme in mammalian tissues, and this activity underlies its ability to raise intracellular NAD+ levels. By preserving NAD+, apigenin supports the activity of NAD+-dependent sirtuins such as SIRT1 and the mitochondrial deacetylase SIRT3. It also modulates additional targets, including GABA-A receptors and NF-kappaB-driven inflammatory pathways. Human pharmacokinetic studies show the free aglycone is poorly absorbed—only about 0.5% of an oral dose is recovered in urine as metabolites—whereas the glycoside forms found in chamomile are absorbed far better.
Claims below are supported by the primary sources linked under each line — the same sources we cite on the product page.
Each line pairs a claim that circulates in marketing and forums with the trial result that contradicts or narrows it.
Quotations are verbatim from the cited paper. Negative and inconclusive trials are listed alongside the positive ones because that is the whole point of this page.
“Human pharmacokinetic study: free apigenin was poorly absorbed (about 0.5% of intake recovered in urine as metabolites), while chamomile-type glycoside forms were absorbed far better (up to about 34%).”
“In 57 adults with mild-to-moderate generalized anxiety disorder, 8 weeks of apigenin-standardized chamomile extract reduced anxiety scores significantly more than placebo (p = 0.047)—the main human efficacy signal for apigenin, at far lower doses than capsules provide.”
“apigenin increases NAD+ levels by inhibiting CD38”
Result: CD38 regulates global protein acetylation through changes in NAD+ levels and sirtuin activity. Pharmacological inhibition of CD38 by apigenin resulted in higher intracellular NAD+ levels in cell cultures. Treatment of cell cultures with apigenin decreased global acetylation, as well as the acetylation of p53 and RelA-p65. Apigenin…
“Here we demonstrate that expression and activity of the NADase CD38 increase with aging and that CD38 is required for the age-related NAD decline and mitochondrial dysfunction via a pathway mediated at least in part by regulation of SIRT3 activity.”
“Cumulatively, a large body of evidence positions apigenin as a unique molecule capable of influencing both aging and sleep.”
CD38 activity rises with age and drives the tissue decline of NAD+ that is linked to mitochondrial dysfunction, inflammation, and cellular senescence, so inhibiting CD38 is a plausible strategy to preserve NAD+ during aging. In animal and cell studies, apigenin lowers CD38 activity, raises the NAD+/NADH ratio, restores SIRT3-dependent mitochondrial antioxidant defenses, and improves metabolic, vascular, senescence, and neuroinflammatory endpoints. Human data, however, come largely from chamomile extracts standardized to apigenin: a randomized trial in mild-to-moderate generalized anxiety disorder found chamomile modestly outperformed placebo, but such extracts deliver far less apigenin than dedicated capsules, and no published trial has tested isolated apigenin at typical supplement doses for sleep, NAD+, or aging outcomes. Whether apigenin supplements raise NAD+ or slow aging in people remains unproven; most mechanistic evidence is preclinical. This evidence describes the compound apigenin and the CD38/NAD+ mechanism itself, not this specific commercial product.
A grade that cannot be falsified is a marketing claim. These are the specific results that would move this one up.
Apigenin is cheap and well tolerated, and the CD38 mechanism is one of the more interesting stories in NAD+ biology. If you are taking it, take it knowing the human record is a chamomile anxiety trial and a pharmacokinetic study suggesting the capsule form is the badly absorbed one. If your actual goal is sleep, the interventions with human evidence are behavioural and light-based, and they are free or close to it.
Graded Strong. Morning bright light is the best-supported intervention for sleep timing in this catalogue.
Graded Moderate, inexpensive, and with a more direct human literature for sleep-adjacent complaints.
What is actually supported for sleep, ordered by strength of evidence.
The NAD+ story with actual human trials attached — and the limits of what those trials show.
Apigenin molecule page · NAD+ pathway · SIRT1 · CD38 · Apigenin capsules — the graded product page · Nutraceuticals and cellular energizers · The full evidence record
Sibling pages in this record: NMN (nicotinamide mononucleotide) · Resveratrol · Vitamin D · Omega-3 fish oil
Yes, in cells and in animal models — that finding is solid and it is why the compound is interesting. The unresolved question is whether an oral capsule achieves the exposure needed to do that in a human, and a human pharmacokinetic study found free apigenin was poorly absorbed at about 0.5% of intake recovered as urinary metabolites.
No trial has tested isolated apigenin for sleep. The human evidence is a randomized trial of apigenin-standardized chamomile extract in generalized anxiety disorder, which is a different compound preparation, a different dose scale, and a different outcome. We say this on the product page too.
On absorption grounds the glycoside forms found in chamomile preparations were absorbed far better than free apigenin in the human pharmacokinetic study — up to about 34% versus about 0.5%. That does not make tea a therapy, but it does undercut the assumption that a higher-milligram capsule delivers more.
Because the mechanism is well characterised and there is some human data, even though it is for a different preparation and a different outcome. Emerging is our label for a plausible mechanism with early human evidence that is small, short or not yet replicated — which describes apigenin exactly.