NAD+ vs ss-31

updated October 25, 2026

NAD+ (tier B) vs ss-31 (tier A): what each is, why each got its grade, half-life and source counts side by side.

NAD+ · tier B

not a peptide. the cofactor your mitochondria run on. IV drips are the longevity-clinic staple despite thin clinical evidence.

tier rationale

B-tier because NAD+ and its precursors sit in a commercially mature but clinically ambiguous zone. The biology is real and well-established, NAD+ declines with age, precursor supplementation elevates levels, and some metabolic improvements are documented. The gap is between basic biology (strong) and clinical outcome evidence in humans (modest). B-tier also reflects that NAD+ itself isn't strictly a peptide, though it lives in the same clinical and commercial ecosystem. Could move to A-tier if the current wave of oral precursor trials delivers clear healthspan outcomes. Could drop to C-tier if the longevity hypothesis continues to fail to translate.

ss-31 · tier A

the first mitochondria-targeted peptide drug. FDA-approved september 2025. for Barth syndrome, studied for heart failure.

tier rationale

A-tier because SS-31 now has FDA approval (September 2025) for a specific rare disease, plus substantial phase 2/3 clinical trial data across multiple indications. Not S-tier because the approved indication is extremely narrow (Barth syndrome, <1,000 US patients) and the broader phase 3 programs in more common conditions (heart failure, mitochondrial myopathy) have been mixed. Comparable in structure to sermorelin's tier placement: FDA approval for a narrow indication with widespread off-label interest. If heart failure or aging trials read out positively in future years, moves to S.

at a glance

reptides grades the research record and cites the literature behind every call. research reference only; not medical advice.