Collagen, growth hormone, NAD+ and DHEA all decline as we get older. Here is the shape of that decline, and why it drives so much peptide interest.
By the pru team · Updated July 9, 2026 · 5-minute read
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Much of the interest in peptides and longevity traces back to one plain fact: several of the body's own signaling molecules fall steadily with age. Collagen drops about 1% a year after 25. Growth hormone falls roughly 14% a decade. These curves are modeled from published decline rates, and they explain the questions people bring to peptides.
The decline, charted
Each line shows the level of a molecule as a share of its young-adult peak, from age 20 to 80. Different molecules fall at different speeds, but the direction is shared.
Relative level as a share of young-adult peak, by age. Modeled from published decline rates.
about 1%/yr
collagen decline after age 25
about 14%
growth hormone drop per decade after 30
about half
less NAD+ in skin by mid-life (varies by tissue)
about 2%/yr
DHEA decline from its mid-20s peak
Biomarker
Age 20
Age 50
Age 80 (percent of peak)
Collagen
100
75
45
Growth hormone
100
65
40
NAD+
100
70
34
DHEA
100
50
15
Relative level as a percent of young-adult peak. Modeled from published decline rates.
Why this drives peptide interest
These declines are why so many peptide questions cluster around recovery, energy, skin, and healthy aging. A peptide is studied as a signal the body already uses, and interest rises where a natural signal is known to fade. This report describes the biology, not a treatment claim.
Yes. Many studies find NAD+ levels roughly half of youthful levels by mid-life, which is part of why NAD+ draws longevity interest. The exact figures vary by tissue and study.
How fast does collagen decline?
Skin collagen falls by roughly 1% per year after about age 25, a widely cited rate, which is why collagen and copper-peptide interest is common in skin care.
Why do peptides get associated with aging?
Several of the body's own signaling molecules, from growth hormone to NAD+, decline steadily with age. Peptide interest tends to rise around those fading signals.
How does pru keep peptides affordable?
pru runs on an at-cost model. You pay one flat membership, and the medication is passed through at the pharmacy's price with no member markup. Because pru never marks the medication up, we have every reason to push its price down, not up. As pru grows and orders more, we negotiate lower pricing with our partner pharmacies, and those savings go straight to you. Healthcare pricing is usually hidden and inflated; pru is built to sit on your side of it: transparent, at cost, and fighting to make peptides more affordable as we scale.
Do the savings add up if I take more than one peptide?
Yes, and this is where pru's at-cost pricing saves you the most. Because pru never marks the medication up, every vial is priced at cost, so each peptide you add avoids the markup a typical provider builds in. If a physician has you on more than one peptide, or on a stack, that saving repeats on every vial, all under one flat $50 membership instead of a marked-up price on each. The more your protocol includes, the more the difference adds up, which makes doing it the right way a financially responsible choice, not an expensive one.
Sources & further reading
Modeled from published age-decline rates (collagen, growth hormone, NAD+, DHEA).
Compiled by pru; values are approximate and pending a full citation pass.
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