Nick Norwitz's thread on aged garlic's S1PC compound boosting eNAMPT — an enzyme that circulates in blood and feeds NAD+ production in distant tissues — surprised biohacking circles. Here's what the research actually shows.
Nick Norwitz's thread on X went viral in longevity circles: aged garlic extract, specifically a compound called S1PC, appears to boost levels of eNAMPT — extracellular NAMPT — a circulating enzyme that drives NAD+ production in tissues throughout the body. The mechanism is indirect, the evidence is early-stage, and garlic is an unlikely longevity supplement for most people to consider seriously. But the underlying biology of eNAMPT is genuinely fascinating, and the research is more substantial than the "garlic goes viral" framing suggests.
Here is what eNAMPT is, why it matters, what the garlic research actually shows, and where this fits in the broader NAD+ supplementation picture.
NAMPT (nicotinamide phosphoribosyltransferase) is the rate-limiting enzyme in the biosynthesis of NAD+ from nicotinamide, the most common pathway for NAD+ production in most mammalian tissues. It exists in two forms:
iNAMPT (intracellular NAMPT): Present inside cells, where it catalyzes NAD+ synthesis from nicotinamide locally.
eNAMPT (extracellular NAMPT): Secreted into the bloodstream, where it circulates and can enter cells in distant tissues, boosting NAD+ synthesis systemically. It is particularly concentrated in adipose tissue and muscle, and appears to function as a kind of NAD+ "hormone" — an endocrine signal that coordinates metabolic state across tissues.
Shin-ichiro Imai at Washington University in St. Louis discovered eNAMPT and has published extensively on its role in aging. The key finding: blood eNAMPT levels fall with age, and this fall correlates with declining systemic NAD+ and the physiological changes associated with aging. In mouse experiments, boosting eNAMPT — either by injecting it or by genetic overexpression — extends healthspan and preserves physical function in older animals.
The compound Norwitz highlighted is 1-(1-alkenyl)-2-acyl-sn-glycero-3-phosphocholine, abbreviated S1PC. Aged garlic extract contains a specific pool of S1PC compounds formed during the aging process of garlic (distinct from the allicin in raw garlic).
Research from Toshiharu Nincheri and colleagues in Japan, and subsequent work published in *Nutrients* (2024), showed that S1PC compounds from aged garlic extract stimulate eNAMPT secretion from adipocytes in cell culture. The effect is mediated via a lysophosphatidylcholine receptor (LPC receptor) on the cell surface. When S1PC binds this receptor, it activates a signaling cascade that promotes eNAMPT secretion into the extracellular space and bloodstream.
The numbers: S1PC concentrations found in aged garlic extract (commercial Kyolic preparations) stimulated eNAMPT secretion by 30–60% in the in vitro experiments. A small human study found measurable changes in eNAMPT-related markers following aged garlic supplementation, though the human data is preliminary.
The mechanism is biologically plausible and connects two independently interesting areas — the eNAMPT longevity research (published in top journals, mechanistically clear) and the well-established bioavailability of S1PC from aged garlic extract (confirmed in human pharmacokinetic studies).
But it is important to calibrate the excitement:
1. In vitro ≠ in vivo. Cell culture results frequently don't translate to physiological effects in whole organisms. The 30–60% secretion increase in adipocyte cultures may not produce meaningful blood eNAMPT elevation in humans.
2. The human data is preliminary. The human eNAMPT marker study is small and has not yet been replicated. Blood eNAMPT measurement is not yet standardized.
3. The dose-response is unknown in humans. Commercial aged garlic extract (Kyolic) is standardized by a different marker (S-allylcysteine content, not S1PC). The S1PC content varies across preparations.
4. The longevity endpoint is extremely distal. Even if aged garlic raises eNAMPT, and even if eNAMPT raises tissue NAD+, and even if higher tissue NAD+ slows aging, demonstrating that garlic supplementation extends human healthspan requires trials that have not been run.
Beyond the eNAMPT story, aged garlic extract (Kyolic) has one of the better-characterized cardiovascular evidence bases among supplements:
Blood pressure: A 2016 *Maturitas* meta-analysis of 7 RCTs (649 participants) found aged garlic extract reduced systolic blood pressure by 5.1 mmHg and diastolic by 2.5 mmHg in hypertensive patients.
LDL cholesterol: Meta-analyses show modest reductions in LDL cholesterol and total cholesterol; effects are smaller than statins but consistent.
Coronary artery calcium (CAC): A 2016 JACC Cardiovascular Imaging trial showed aged garlic extract slowed plaque progression (measured by CT) in patients with elevated CAC scores versus placebo. This is the most compelling cardiovascular RCT: a hard structural endpoint, not just biomarkers.
Immune function: Multiple small trials show reduced duration and severity of cold and flu. Aged garlic's S-allylcysteine appears to modulate NK cell and T-cell activity.
Aged garlic extract is a supplement with genuine cardiovascular evidence (blood pressure, CAC) that now has an intriguing — if early-stage — NAD+ mechanism attached to it. The cardiovascular case alone makes it worth considering for people with elevated blood pressure, atherosclerosis risk, or elevated CAC scores.
The eNAMPT story is genuinely novel and mechanistically coherent. It does not yet justify taking aged garlic extract specifically for NAD+ reasons over established precursors like NMN or NR. But if you're already taking aged garlic for cardiovascular reasons, the S1PC/eNAMPT biology gives you a second reason to be interested in the science.
The viral response to Norwitz's thread reflects something real: the longevity community is hungry for mechanisms that connect familiar, accessible compounds to established aging biology. Aged garlic and eNAMPT is a thread worth following.