Every claim on this site is tied to a published human trial. This page lists them.

Where the evidence is strong, we say so. Where it is limited or absent, we say that too.

These studies tested the ingredients at their studied doses. They did not test Happy Cells products.

NAD+ is a coenzyme present in every living cell, where it participates in energy metabolism, enzyme function, and DNA repair processes.

Published studies have measured lower NAD+ in some human tissues in older versus younger adults, including skin (Massudi H, et al. PLoS One 2012;7(7):e42357), brain (Zhu XH, et al. PNAS 2015;112(9):2876-2881), and skeletal muscle (Janssens GE, et al. Nat Aging 2022;2:254-263).

The magnitude varies by tissue and by measurement method. Recent work indicates NAD+ in whole blood does not clearly change with age, so tissue and blood NAD+ should not be treated as the same thing.

Found in SIGNAL at 500 mg per capsule.

NMN is a precursor in the salvage pathway, the route cells use to synthesize NAD+.

A 2024 meta-analysis of 12 randomized controlled trials covering 513 participants found a significant overall effect of oral NMN supplementation on blood NAD+ levels. (Zhang J, Poon ETC, Wong SHS. Crit Rev Food Sci Nutr 2025;65(22):4382-4400. PMID 39116016)

In a randomized, double-blind, placebo-controlled trial, 250 mg/day for 12 weeks in older adults produced significantly higher blood NAD+ and a significantly shorter 4-metre walking time versus placebo. (Morifuji M, Higashi S, Ebihara S, Nagata M. GeroScience 2024;46(5):4671-4688. PMID 38789831)

A multicenter dose-ranging trial in 80 healthy middle-aged adults tested 300, 600, and 900 mg daily for 60 days. All doses raised blood NAD+. (Yi L, Maier AB, Tao R, et al. GeroScience 2023. DOI 10.1007/s11357-022-00705-1)

Found in REWIND at 250 mg per serving, from Sophora japonica flower bud.

Quercetin is a plant flavonoid also present in onions, apples, and capers, studied for antioxidant activity.

A meta-analysis of 7 randomized trials in 587 participants found quercetin significantly reduced systolic and diastolic blood pressure at doses of 500 mg per day and above. (Serban MC, Sahebkar A, Zanchetti A, et al. J Am Heart Assoc 2016;5(7):e002713. PMID 27405810)

REWIND contains 250 mg, below the dose at which that effect reached significance.

Found in REWIND at 150 mg per serving, from Japanese knotweed root standardized to 98%.

A 26-week randomized, double-blind, placebo-controlled trial in 46 healthy adults aged 50 to 75 studied resveratrol at 200 mg/day combined with quercetin at 320 mg/day, and reported improved memory retention and glucose metabolism. (Witte AV, Kerti L, Margulies DS, Floel A. J Neurosci 2014;34(23):7862-7870. PMID 24899709)

A later trial in adults with mild cognitive impairment did not reproduce the memory finding.

Found in HAPPY GUTS at 2,300 mg per scoop, standardized to 25% immunoglobulin G.

Colostrum is the first milk produced after calving, containing immunoglobulins, growth factors, and antimicrobial peptides.

A systematic review and meta-analysis of 10 randomized controlled trials found bovine colostrum significantly reduced the urinary lactulose/rhamnose ratio, a validated marker of intestinal permeability. (Dig Dis Sci 2024;69(4):1345-1360. PMID 38361147)

A meta-analysis of 5 randomized controlled trials in 152 adults over 8 to 12 weeks found bovine colostrum significantly reduced upper respiratory symptom days versus placebo. (Jones AW, March DS, Curtis F, Bridle C. BMC Sports Sci Med Rehabil 2016;8:21)

Heterogeneity between trials was high in the permeability analysis.

Cosmetic ingredients are regulated differently from supplements and are described here by what they are, not by clinical outcome.

Copper lysinate/prolinate is a copper peptide complex used in skincare since the 1990s. Found in THE OPTIMIST.

Methylglucoside phosphate is a stabilised vitamin C derivative. Found in THE OPTIMIST.

Acetyl octapeptide-3 and tripeptide-29 are peptides used for the appearance of smoother expression lines. Found in THE UNBOTHERED.

Retinol is the most studied ingredient in cosmetic skincare, used for the appearance of refined texture and tone. Found in THE UNBOTHERED.

Ceramide NP and phospholipids are barrier lipids. Found in THE UNBOTHERED.

Full ingredient lists are published on every product page.

Meta-analyses of NMN trials found no significant effect on fasting glucose, insulin, HbA1c, HOMA-IR, or lipid profile. Happy Cells makes no claims in those areas.

There is no published human trial demonstrating that orally administered NAD+ raises NAD+ levels. REWIND's NAD+ content is listed as an ingredient, not as a mechanism claim.

Human pharmacokinetic data indicate quercetin does not increase resveratrol absorption, contrary to a common industry claim.

Early findings that resveratrol directly activates SIRT1 were shown to be an assay artifact. (Pacholec M, et al. J Biol Chem 2010;285:8340-8351) We make no sirtuin activation claims.

Every dose is printed on the label. No proprietary blends.

Where a trial used a different dose than our formula contains, we say so.

Where a finding failed to replicate, we say so.