Evidence & Research Status
Longevity research spans dozens of compounds and several biological systems, and much of the material written about multi-compound combinations does not explain how the underlying research is…
Evidence Level reflects the general state of published research for this compound category and is not a claim about the safety, efficacy, or approval status of any product sold on this site. All compounds are offered strictly for research use.
Longevity research spans dozens of compounds and several biological systems, and much of the material written about multi-compound combinations does not explain how the underlying research is organized.
This article describes how aging research groups compounds by the biological system they act on — cellular energy, hormonal signaling, inflammation and repair, and cognition — which compound classes are studied in each, and where the evidence cited here stops.
Key Takeaways
- Aging research is organized around biological systems rather than single compounds.
- Cellular energy (mitochondrial function and NAD+ metabolism) is treated in this framework as a foundational system.
- Hormonal signaling is examined as the environment that shapes downstream cellular response.
- This article cites no human trial showing that any compound discussed, alone or in combination, extends healthspan or lifespan.
- This article is a starting framework for organizing PTW’s broader longevity research content.
The Framework: Systems Rather Than Single Compounds
Rather than treating each compound in isolation, longevity research is usually organized by the biological system a compound is studied in. Grouping compounds this way makes it clearer what each one is thought to act on and how findings in one system relate to another.
This article uses four groupings, referred to below as pillars:
- Cellular Energy: Mitochondrial function and NAD+ metabolism
- Hormonal: The GH/IGF-1 signaling axis
- Anti-Inflammatory / Regenerative: Chronic inflammatory signaling and tissue repair
- Cognitive: Neuroplasticity, neuroprotection, and neurotransmitter signaling
Unless a finding below is described as clinical, it should be read as mechanistic or as coming from research models. This article does not cite a human trial of any compound for a longevity outcome.
Pillar 1: Cellular Energy — Mitochondrial Function
Mitochondrial function is a central topic in aging biology. Beyond producing ATP, mitochondria are involved in cell death signaling, generate reactive oxygen species (ROS) that accumulate as biological damage, and take part in regulating inflammation.
Mitochondrial function declines with age. NAD+ — a substrate for mitochondrial electron transport and a cofactor for sirtuins — is also reported to decline with age.
Compound classes studied in this system:
- NAD+ precursors (NMN or NR): Both are studied as ways of raising NAD+ levels; they differ in their conversion pathway to NAD+. Often studied alongside TMG (trimethylglycine) as a methyl donor. Portal to Wellness does not publish amounts or schedules for any compound.
- MOTS-c: A mitochondria-derived peptide (encoded by mitochondrial DNA) that activates AMPK. Research has examined its relationship to metabolic flexibility, insulin sensitivity, fat oxidation, and physical performance; this article cites no human trial of MOTS-c.
- SS-31 (Elamipretide): A mitochondria-targeted peptide that acts on the inner mitochondrial membrane and electron transport chain. The findings referred to here come from models of age-related mitochondrial dysfunction, not from human longevity studies.
NAD+ metabolism is among the most studied topics in this system, because NAD+ is a cofactor in many downstream processes and its decline is widely reported across aging populations. Whether raising NAD+ levels changes healthspan or lifespan in people is not established by anything cited in this article.
📚 Part of our Energy & Longevity research guide.
MOTS-c and NAD+ Support — Shop the Longevity Category
Pillar 2: Hormonal — The GH/IGF-1 Axis
In longevity research, hormonal signaling is studied mainly through the GH (Growth Hormone) / IGF-1 axis rather than through testosterone or estrogen. The GH/IGF-1 axis is studied for its roles in tissue repair, body composition, sleep, and age-related decline across many tissues.
GH secretion peaks in early adulthood and declines progressively with age. This decline is described as a normal aging trajectory rather than a disease state.
GH secretagogues are compounds that act on the pituitary to stimulate release of the body’s own GH, which is secreted in a pulsatile pattern. They are studied as a separate category from exogenous GH, which carries its own risk and regulatory considerations. This article does not compare secretagogues with approved GH therapy.
Compound classes studied in this system:
- Ipamorelin: A selective GH secretagogue (GHS) and ghrelin receptor agonist that stimulates GH release, described as having minimal effect on cortisol or prolactin.
- CJC-1295 (no DAC): A GHRH analogue that acts on the pituitary directly. It is often discussed alongside ipamorelin because the two act on complementary receptor systems (the GHRH receptor and the ghrelin receptor).
- Epitalon: A tetrapeptide reported to activate telomerase and to influence the pineal gland’s melatonin output. Research has examined telomere maintenance and circadian rhythm.
CJC-1295 and ipamorelin are frequently discussed as a pair because of their complementary mechanisms. This article cites no controlled human data on the combination, and none of the compounds in this pillar is FDA-approved for human use.
Pillar 3: Anti-Inflammatory and Regenerative — Inflammation and Tissue Repair
Chronic low-grade inflammation — “inflammaging” — is one of the most consistent findings across aging biology. It is associated with tissue degradation, impaired mitochondrial function, and cognitive decline.
Research in this pillar examines two areas: systemic inflammatory signaling and the repair of structural tissue damage.
Compound classes studied in this system:
- BPC-157: Studied for connective-tissue repair, the nitric oxide (NO) system, and inflammatory signaling at injury sites. These findings come from preclinical research; see the full BPC-157 guide for detail.
- TB-500: A peptide studied for actin regulation and stem cell homing, with research interest in cardiac and neural tissue as well as musculoskeletal tissue. This article cites no human trial of TB-500.
- Thymosin Alpha-1 (Tα1): An immune-regulatory peptide that modulates T-cell activity. It has been studied in several clinical indications involving immune function; this article cites no human study of Tα1 for an aging or longevity outcome.
Pillar 4: Cognitive — Neuroplasticity and Neuroprotection
Research on cognitive aging describes structural brain changes associated with cognitive decline as beginning in the 40s, often before any symptoms are present.
Research in this pillar focuses on neuroplasticity, neuroprotection, and the neurotransmitter signaling involved in mood, motivation, and executive function.
Compound classes studied in this system:
- Semax: A synthetic ACTH analogue studied for its effects on BDNF (Brain-Derived Neurotrophic Factor) expression and on dopaminergic and serotonergic signaling, in the context of neuroprotection and cognitive function.
- Selank: A peptide derived from tuftsin, studied for anxiolytic activity, immune modulation, and serotonergic signaling. Selank and Semax are often discussed together because their reported mechanisms differ — Semax on the stimulatory side, Selank on anxiety-related and immune signaling.
- Pinealon: A tripeptide derived from the pineal gland, studied for neuroprotective effects and circadian regulation.
- Dihexa: A compound studied for its action on HGF (Hepatocyte Growth Factor) signaling and synaptogenesis — the formation of new synaptic connections.
This article cites no human trial showing that any compound in this pillar slows cognitive aging.
Semax, Selank, and Cognitive Support Compounds
How Studies Group These Compound Classes
By pillar: Research in this space is generally organized around a single pillar’s compounds — structural/regenerative work, hormonal-pillar work, cognitive-pillar work, and cellular-energy work each tend to be studied and evaluated on their own terms, by mechanism. Portal to Wellness does not recommend which pillar, compound, or combination fits any individual’s situation.
Across pillars: Where more than one pillar is studied together, the literature this guide draws on generally tracks each pillar’s markers independently rather than changing several variables at once. Portal to Wellness does not publish amounts, schedules, or administration routes for any compound, and nothing in this guide is a stacking protocol.
Markers such as hsCRP, HbA1c, and IGF-1 are measurements, not clinical outcomes. A change in a marker reported in a study does not by itself establish an effect on healthspan or lifespan.
What This Research Does Not Establish
The compound findings described in this article are mechanistic, come from research models, or — in the case of Tα1 — come from clinical study in immune-related indications rather than aging. This article cites no human trial showing that any of these compounds, alone or in combination, extends healthspan or lifespan, and it does not establish the safety or tolerability of any compound or combination in people.
Sleep, structured resistance training, metabolic flexibility (through diet and fasting), and stress management are also studied as variables in aging biology. Nothing in this article suggests that any compound discussed here substitutes for them.
Further Reading
Related articles on NAD+ and on the difference between biomarkers and clinical outcomes are listed below.
Browse the PTW Catalog by Research Area