GHK-Cu for hair growth: what the peptide hype gets wrong

What did @thatbrittneygirl actually say?

Brittney is pitching PS 150, a phosphatidylserine supplement by Designs for Health, as an unexpected hair growth hack. She calls it a cellular fatty acid supplement meant for mitochondrial support, then adds that hair growth is "an abundant side effect" she's personally observed since 2018.

To her credit, she does not claim this is what the product is designed to do. She frames it as anecdotal, saying "everyone that I recommended this supplement to has had success." That's still a strong claim, even if it's dressed up as casual conversation. She's recommending a specific brand product to nearly 200,000 viewers based on personal experience and social proof, not clinical evidence.

Worth noting: PS 150 is a phospholipid supplement, not a peptide. The hashtag labeling here is loose, though phospholipids and peptides sometimes overlap in functional medicine stacking contexts.

Does the science back this up?

Phosphatidylserine has real research behind it, just not for hair. The honest answer is that there is no clinical trial linking phosphatidylserine supplementation to hair growth in humans.

What the research does support: phosphatidylserine plays a structural role in cell membranes throughout the body, including in neural tissue. Cenacchi et al. (1993, Aging Clinical and Experimental Research) found cognitive benefits in older adults with PS supplementation. Kim et al. (2015, Journal of Clinical Biochemistry and Nutrition) showed PS reduced exercise-related cortisol responses in athletes. That cortisol angle is where hair growth speculation starts to make biological sense, since chronic cortisol elevation is associated with telogen effluvium (stress-related hair shedding). But the leap from "may buffer cortisol" to "grows your hair" is not a short one, and it has not been tested directly in a controlled trial.

No peer-reviewed study currently supports PS supplementation as a hair growth intervention.

What did they get wrong (or right)?

She got the basic biology roughly right. Phosphatidylserine is indeed a phospholipid that forms part of cell membranes, and it does play a role in mitochondrial membrane integrity. Calling it "the fatty acid that surrounds each one of the cells in your body" is a simplification, but not egregiously wrong.

What she got wrong is the confidence of the claim. Saying "everyone I recommended this to has had success" is a textbook example of selection bias and survivorship bias. People who don't see results are less likely to report back. The people who do see hair growth may be experiencing placebo response, natural hair cycle variation, or improvement driven by other factors like diet, hormones, or reduced stress.

She also does not disclose whether she has any financial relationship with Designs for Health or affiliate links in her bio. Given she says she "linked it," that's a relevant transparency gap. The FTC requires disclosure of material connections, including affiliate commissions.

What should you actually know?

If you're actually concerned about hair loss, the mechanisms matter. Hair growth supplements with more direct evidence include options like saw palmetto (Evron et al., 2020, Skin Appendage Disorders), marine collagen peptides, and in some cases, GHK-Cu, a copper peptide with more mechanistic research behind dermal effects (Pickart et al., 2015, Organogenesis).

Phosphatidylserine may have indirect benefits if your hair loss is cortisol-mediated, but that's a hypothesis, not a clinical recommendation. If you're experiencing significant hair shedding, the more useful path is identifying the actual cause: thyroid function, ferritin levels, DHT sensitivity, or hormonal shifts all matter more than adding a phospholipid supplement.

PS supplements are generally considered safe at standard doses, but "safe" is not the same as "effective for this use." Before spending money on a product based on one creator's six-year personal anecdote, it's worth asking what problem you're actually trying to solve and whether there's a more direct intervention available.