Collagen powder improves skin, hair and joints
Some signal for skin elasticity and joint pain at 10g+/day. But your body breaks collagen into amino acids — protein-adequate diets get 90% of the same benefit cheaper.
What the evidence says
The studies, decoded
Multiple RCTs (Proksch 2014, Genovese 2017, Choi 2019) show statistically significant improvements in skin elasticity and dermal collagen density at 2.5-10g/day over 8-12 weeks. Effect size is small-to-moderate. Joint pain studies (Clark 2008) show modest benefit in athletes. Crucially: oral collagen is hydrolyzed in the gut to amino acids; the same building blocks come from any high-protein diet at a fraction of the cost.
How it actually works
Mechanism
Hypothesized: specific dipeptides (Pro-Hyp, Hyp-Gly) survive digestion and signal fibroblasts to upregulate collagen synthesis. The signaling mechanism is plausible but the dose-response is unclear.
What to actually expect
Realistic outcome
If you're already eating 1.5g/kg/day of varied protein, collagen powder adds 10-20% on top — marginal. If you're protein-deficient, fixing protein intake will outperform any collagen supplement.
If this is overhyped — what is not
Better alternatives
Eat 1.5g/kg protein daily from varied sources (Greek yogurt, eggs, meat, fish, legumes). Vitamin C supports endogenous collagen synthesis. Topical retinoid does more for skin than any oral supplement.
Sources
Citations
- Oral supplementation of specific collagen peptides improves skin elasticityProksch et al., 2014, Skin Pharmacol Physiol
- Collagen hydrolysate for joint pain in athletesClark et al., 2008, Curr Med Res Opin
Biotin gummies / 'hair vitamins' regrow hair
Biotin deficiency is real — almost nobody has it. For deficient users, supplementation restores hair growth; for everyone else, it's a $20/month placebo with a real risk of interfering with lab tests.
WorksVitamin D supplementation improves health and looks
Real benefit IF you are deficient. Most populations are. Aim for serum 25-OH-D 40-60 ng/mL. Test, don't guess. No incremental benefit past sufficient.