Podcast episode 60 (in German)
Collagen peptides & glycine: the structural duo fact-checked
August 30, 2026
Almost a third of our body protein is a single protein: collagen. The episode checks what Europe’s biggest supplement trend can really do — and brings out of the shadows the building block that gets lost in every collagen discussion.
What it is about
From the mid-20s, collagen production falls by about 1 percent per year; the result is not only thinner skin and wrinkles, but also stiffer tendons, more sensitive joints and more brittle bones. The episode first explains why hydrolyzed collagen peptides can work despite digestion: certain two-unit building blocks survive the gut, appear in the blood and, in effect, report scaffold damage to the fibroblasts. Then it goes through the study data, first skin, then tendons, joints, muscles and bones. The second part belongs to glycine, the smallest amino acid, with 3 stories: collagen building block, sleep aid and raw material for glutathione. At the end comes how to combine both powders in practice.
Key points
- Almost a third of all body protein is collagen, and from the mid-20s production falls by about 1 percent per year; in women, menopause additionally accelerates the breakdown.
- Proksch and colleagues showed in 2014 in women aged 35 to 55 that 2.5 to 5 grams of collagen hydrolysate over 8 weeks measurably reduced eye wrinkles and stimulated procollagen formation.
- Bolke tested this in 2019 in a cleanly randomized trial with 72 women and found better moisture, elasticity and skin density after 12 weeks.
- The stronger card lies in sport: in 2008 Clark reduced athletes’ joint complaints with 10 grams daily, and in 2015 Zdzieblik combined 15 grams with strength training in older men — with more fat-free mass and strength.
- In 2018 König gave postmenopausal women 5 grams of specific collagen peptides for 1 year: bone density at the spine and femoral neck rose significantly compared with placebo.
- Every third position in the collagen helix must be a glycine, and in Japanese studies 3 grams of glycine before bedtime improved sleep quality and daytime freshness — via a faster drop in core temperature.
- The everyday arithmetic: 10 grams of collagen peptides provide roughly 3 grams of glycine, while a cup of bone broth rarely gets beyond 2 to 3 grams.
Where the data stop
Caution is warranted with skin. Many of these studies are manufacturer-funded, and a recent analysis found clearly smaller effects in the independently funded work. In addition, what is measured are surface variables such as moisture and elasticity, not younger skin. The fair summary is real but moderate — sun protection and sleep remain the bigger levers. Anyone who judges after 2 weeks judges too early: collagen remodeling is slow and needs 8 to 12 weeks.
There is no vegan collagen; what is sold as such are building-block packages without the decisive signal peptides. Without vitamin C the body cannot cross-link collagen at all, and without a training stimulus there is no reason to build — the tendon researcher Keith Baar therefore places intake 30 to 60 minutes before exercise. Joint complaints of clinical significance should be checked by a doctor.
Listen (in German)
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Published on August 30, 2026.
The topic in the database
- Amino acid, main building block of collagen. Three small sleep studies with 3 grams before bedtime show a shorter time to fall asleep …Glycine
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-19.