Three longevity supplements dominate the anti-aging conversation in 2026: alpha-ketoglutarate (AKG), NAD+ precursors such as NMN, and NAD+ itself. A clinical study published in May 2026 by Rejuvant added fresh momentum to AKG, while simultaneously raising questions about how it compares to the NAD+ pathway compounds that have been hyped for years. This article covers what the current science actually says about each and what it does not yet justify claiming.
The short answer: all three have genuine biological rationale and emerging human evidence. None has the long-term randomized trial data needed to call it a proven longevity intervention, and the evidence quality differs meaningfully between them.
What the Research Actually Says (2026 Update)
AKG: The New Contender With Growing Clinical Interest
Alpha-ketoglutarate is a naturally occurring compound in the body’s citric acid cycle, the metabolic pathway cells use to produce energy. AKG levels decline with age, which has led researchers to investigate whether supplementation might support healthspan.
The most-discussed recent data comes from a Rejuvant-funded clinical study announced in May 2026. Reported by PRNewswire, the study found that participants supplementing with a calcium AKG formulation showed biological age improvements as measured by epigenetic methylation clocks, and the effect appeared to outperform NAD+ precursors and several other longevity compounds on the same metrics. Times of Israel and other outlets also highlighted related research on SIRT6 activation (a longevity-associated sirtuin pathway), suggesting AKG may support mechanisms linked to DNA repair and cellular rejuvenation.
These findings are noteworthy. They are also early-stage. The study was funded by the manufacturer, the participant group was relatively small, and epigenetic clock improvements, while a meaningful biomarker, are not the same as confirmed reductions in disease risk or mortality. Independent replication at larger scale is needed before drawing firm conclusions.
Evidence quality: Small industry-funded RCT; epigenetic clock biomarker outcomes; independent replication pending.
Cautions: Who Should Be Careful With AKG
- Medication interactions: AKG may influence ammonia metabolism and could theoretically interact with medications used for liver or kidney conditions. Consult a healthcare professional if you take any prescription medications.
- Contraindicated conditions: People with kidney disease or impaired ammonia clearance should avoid AKG supplementation without medical supervision, as the compound affects nitrogen balance.
- Pregnancy and nursing: No adequate safety data exists for AKG in pregnancy or lactation. Avoid unless directed by a healthcare provider.
NAD+ Precursors (NMN and NR): More Human Data, Still Early
NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are precursors the body converts into NAD+, a coenzyme central to energy metabolism, DNA repair, and sirtuin activity. NAD+ levels decline with age, which is the biological rationale for supplementing with precursors.
Human trial data for NMN is more developed than for AKG at this point. Multiple small studies through 2025 and 2026 have confirmed that oral NMN supplementation raises blood NAD+ levels in humans. A handful of these trials have reported improvements in muscle function and aerobic capacity in older adults, as well as certain metabolic markers. Scientific American’s recent coverage of universal aging clocks noted that NAD+ pathway modulation remains one of the most-studied longevity targets in geroscience.
However, what raised NAD+ levels do at the clinical level in healthy humans remains poorly characterized. Most trials are short (8–12 weeks), involve fewer than 100 participants, and have not been independently replicated at scale. Large, long-term RCTs are absent. At least one major supplement brand received a regulatory recommendation to withdraw certain NAD+ marketing claims for insufficient substantiation. The Rejuvant study’s direct comparison of biomarker outcomes between AKG and NAD+ precursors suggested AKG may perform comparably or better on epigenetic clock metrics, though that comparison deserves independent verification.
Evidence quality: Multiple small RCTs confirming NAD+ level increases; limited and mixed evidence for clinical outcomes; no large-scale long-term trials.
Cautions: Who Should Be Careful With NMN and NR
- Medication interactions: NMN and NR may interact with medications that affect NAD+ metabolism, including certain chemotherapy agents. Some researchers have raised theoretical concerns about supplementing NAD+ in contexts of existing cancer, as NAD+ supports cell proliferation pathways. This remains an active research question; discuss with an oncologist if relevant.
- Contraindicated conditions: People with a personal or family history of hormone-sensitive cancers should approach NAD+ precursors with caution and consult a healthcare professional. Those with chronic kidney disease should also seek medical guidance.
- Pregnancy and nursing: Safety data for NMN or NR during pregnancy and lactation is insufficient. Avoid unless a healthcare provider specifically advises otherwise.
How to Think About These Comparisons
Biomarker Improvements Are Not the Same as Proven Longevity
A central challenge in interpreting all three compounds is the distinction between biomarker change and clinical outcome. Epigenetic clocks, NAD+ blood levels, and cellular aging markers are useful research tools. They are not the same as demonstrated reductions in disease incidence or mortality. Early evidence suggests these biomarkers may correlate with health outcomes, but the causal chain is not yet established in humans at the required evidence threshold.
Funding Source and Independent Replication
The most prominent AKG data comes from a manufacturer-funded study. That does not invalidate the findings, but independent replication is especially important before treating the results as settled. The same caveat applies to some NMN research, where commercial interests are significant.
Combination Use and Who This Research Applies To
AKG and NAD+ precursors work through distinct but overlapping pathways. Some researchers hypothesize that stacking them could be additive; there is no strong human evidence for or against this at current doses, and the cost is meaningful. Current longevity research is also predominantly conducted in adults over 40 with measurable age-related biomarker decline. Younger adults, those with underlying conditions, and people on multiple medications represent a different risk-benefit profile; a conversation with a healthcare provider is the right starting point.
Common Misconceptions
“These supplements reverse aging.” No supplement has evidence sufficient to claim it reverses biological aging in humans. What some compounds do is modestly shift biomarkers associated with aging, meaningful to researchers but not a guaranteed longevity benefit.
“Animal studies prove it works in humans.” Longevity interventions that extend lifespan in mice have a poor track record of translating to human aging. Human metabolism and aging mechanisms differ substantially from rodent models.
“If the biomarker improved, my health improved.” Epigenetic clock scores are research proxies. Optimizing a surrogate endpoint is not the same as improving the underlying health outcome it is meant to represent.
Related Reading and Tools That May Help
If you are researching longevity-adjacent supplementation more broadly, a few existing guides on this site may be useful context. Our Best Nootropics 2026 roundup covers cognitive support compounds, some of which (lion’s mane, phosphatidylserine) also appear in longevity-adjacent research. For foundational micronutrient support, our Best Women’s Multivitamins 2026 guide reviews formulas that include longevity-relevant nutrients such as B vitamins (relevant to NAD+ metabolism) and antioxidant cofactors. If you are evaluating overall health tracking (sleep quality, HRV, and recovery metrics that some longevity researchers use as lifestyle biomarkers), our Best Sleep Trackers 2026 wearable comparison may be worth a look. And if you are exploring whether a comprehensive greens formula might support a longevity-oriented supplement stack, see our Best Greens Powders 2026 review for evidence-based options.
Frequently Asked Questions
Is AKG better than NMN for longevity?
Based on a May 2026 clinical study, AKG supplementation appeared to outperform NMN on certain epigenetic clock biomarkers. However, that study was small, manufacturer-funded, and has not yet been independently replicated. It is premature to conclude AKG is definitively superior; both compounds have plausible mechanisms and limited but emerging human evidence.
How long does it take to see any effect from these supplements?
The Rejuvant AKG study observed biomarker changes over several months of continuous use. NMN trials have typically run 8–12 weeks. Neither compound produces noticeable short-term effects in most participants, and any subjective “energy” improvement should be interpreted cautiously given the strong placebo effect documented in supplement trials.
Can I take AKG and NMN together?
There are no well-designed human studies on combination use. The compounds work through different pathways, so synergy is theoretically plausible, but the incremental benefit is unproven and the cost is meaningful. Discuss with a healthcare provider before combining longevity supplements, especially if you take any prescription medications.
Are these supplements safe?
Both AKG and NMN/NR have reasonably clean short-term safety profiles in published trials, with mild gastrointestinal discomfort reported occasionally. Long-term safety data, particularly for NMN at the doses commonly sold commercially, is limited. Safety in pregnancy, nursing, and specific disease conditions is not established. Always consult a healthcare professional before starting any new supplement regimen.
Bottom Line
AKG has earned a genuine place in the longevity conversation based on the Rejuvant 2026 data, but it remains early-stage evidence from a small, industry-funded trial. NMN and NR have a broader base of small human studies, though clinical outcome evidence is thin and large-scale replication is still pending for both pathways.
None of these should be treated as proven longevity interventions. What they may offer is plausible early support for cellular aging mechanisms, best taken alongside strong lifestyle fundamentals and with input from a healthcare provider familiar with geroscience. The research is genuinely exciting; the caution is warranted.