Apigenin and NAD+ Metabolism: A Supplement You've Probably Overlooked

Apigenin and NAD+ Metabolism: A Supplement You've Probably Overlooked

When longevity enthusiasts discuss raising NAD+ levels, the conversation typically focuses on NMN and NR — precursors that feed the biosynthetic pathway. But there is a complementary approach that is rarely discussed despite solid mechanistic rationale: blocking the enzyme responsible for consuming the majority of the body's NAD+.

The CD38 Problem

CD38 is an enzyme found on the surface of immune cells and in the mitochondria. Its functions include calcium signaling and immune regulation. Its problem, from a longevity perspective, is that it is extraordinarily efficient at consuming NAD+ — hydrolyzing it into nicotinamide and ADP-ribose.

Research from Johan Auwerx's group at EPFL (Swiss Federal Institute of Technology) found that CD38 activity increases dramatically with age and is the primary driver of the age-related decline in NAD+ [1]. Middle-aged mice show two to three times higher CD38 activity than young mice, correlating precisely with their lower NAD+ levels.

Notably, when CD38 is genetically deleted in mice, the expected age-related NAD+ decline largely does not occur — the animals maintain more youthful NAD+ levels throughout aging [2].

This suggests that blocking CD38 is a complementary strategy to supplementing NMN or NR: rather than simply adding more NAD+ precursors into a leaky system, you reduce the rate of loss.

Apigenin as a CD38 Inhibitor

Apigenin is a flavonoid found in parsley, chamomile tea, celery, and other plant foods. It was identified as a potent natural inhibitor of CD38 by the Auwerx laboratory and subsequently studied for its ability to raise NAD+ levels.

In animal studies, apigenin supplementation raises NAD+ levels in multiple tissues — including liver, muscle, and brain — in a manner consistent with CD38 inhibition. The effect is complementary to NMN: in mice given both apigenin and NMN, NAD+ levels rose more than with either compound alone [3].

Additional Evidence Beyond NAD+

Apigenin has a substantial evidence base independent of its NAD+ effects:

Anti-inflammatory: Apigenin inhibits NF-κB — a master transcription factor that drives inflammatory gene expression. Multiple in vitro and animal studies document anti-inflammatory effects. A randomized trial found chamomile extract (rich in apigenin) reduced inflammatory markers in patients with type 2 diabetes [4].

Anxiolytic effects: Apigenin is a partial agonist at GABA-A receptors, which is likely the mechanism behind chamomile tea's well-known calming effects. A randomized trial of chamomile extract in generalized anxiety disorder found significant reductions in anxiety scores compared to placebo [5].

Cancer research: Apigenin has been studied extensively in cancer cell lines and animal tumor models, where it demonstrates pro-apoptotic effects in multiple cancer types. Human clinical data is limited, but the mechanistic evidence — including effects on p53, BCL-2, and NF-κB — is substantial.

The NMN + Apigenin Protocol

Among longevity researchers and practitioners, the combination of NMN (raising NAD+ through precursor supplementation) with apigenin (reducing NAD+ loss through CD38 inhibition) has become a popular protocol — sometimes referred to as "the floor and the ceiling" approach:

• NMN raises NAD+ by increasing supply
• Apigenin preserves NAD+ by reducing the primary drain

David Sinclair of Harvard Medical School has discussed taking this combination in interviews, though he is careful to note that his own use does not constitute medical evidence.

Dosing

Clinical trials have not established optimal dosing for apigenin specifically as a CD38 inhibitor or NAD+ optimizer. Based on:

• The concentration of apigenin found effective in cell culture studies
• The estimated bioavailability of oral apigenin (poor, approximately 1-3%)
• Published protocols from longevity practitioners

50-500mg/day is the commonly cited range. Because bioavailability is low, some practitioners use higher doses or look for liposomal formulations that may improve absorption.

Food Sources

Chamomile tea is the richest practical dietary source — a cup of chamomile tea contains approximately 3-5mg of apigenin. Parsley and celery contain meaningful amounts, and dried parsley contains concentrated apigenin (up to 45mg/g). Regular dietary intake from these foods is generally well below supplemental doses used in research.

Disclaimer: This article is for informational purposes only. Apigenin may interact with certain medications metabolized by CYP enzymes.

References

[1] Camacho-Pereira J et al. CD38 dictates age-related NAD decline and mitochondrial dysfunction through an SIRT3-dependent mechanism. Cell Metabolism. 2016;23(6):1127-1139.

[2] Tarragó MG et al. A potent and specific CD38 inhibitor ameliorates age-related metabolic dysfunction by reversing tissue NAD+ decline. Cell Metabolism. 2018;27(5):1081-1095.

[3] Chini CCS et al. The pharmacology of CD38/NADase. Trends in Pharmacological Sciences. 2018.

[4] Rafraf M et al. Effectiveness of chamomile tea on glycemic control and serum lipid profile in patients with type 2 diabetes. Journal of Endocrinological Investigation. 2015.

[5] Amsterdam JD et al. A randomized, double-blind, placebo-controlled trial of oral Matricaria recutita (chamomile) extract therapy for generalized anxiety disorder. Journal of Clinical Psychopharmacology. 2009;29(4):378-382.