A Beginner's Guide To Peptides

Peptides are gaining attention for their potential in health, skincare and performance. This article explores how they work, where they are used and what beginners should know. 

The insights in this article are provided by Vivere's Head of Nutrition, Yusra Serdaroglu Aydin, a registered dietitian with a background in nutrition, food engineering and culinary arts. Her scientific approach and understanding of personalised nutrition and the human microbiome help explain how peptides may support different aspects of wellbeing.

Peptides are short chains of amino acids that influence many functions in the body, from appetite regulation to skin repair.

Here are the five biggest takeaways from this beginner’s guide to peptides:

• What is a peptide? It is a short chain of amino acids that acts as a signalling molecule in the body.

• How do GLP-1 peptides support weight loss? They help regulate appetite, slow stomach emptying and support healthier metabolic responses.

• Are skincare peptides effective? Certain peptides promote collagen production and support skin repair, which may improve firmness and hydration.

• Why are muscle-related peptides considered a grey area? Research is ongoing and some popular peptides sit outside regulated medical use.

• Are peptides legal in the UK? It depends on the peptide type and how it is sold, with strict regulation of medicines and looser rules for cosmetics and supplements.

A peptide is a short chain of amino acids that forms the building blocks of proteins.

Peptides sit between amino acids and full proteins in size and act as messengers that influence many biological processes. Amino acids combine to create peptides, which then join to form proteins, giving structure to tissues and supporting functions such as hormone signalling and immune activity. 

Because peptides are smaller, they can interact more easily with receptors in the body, which is why they are used in medicines, supplements and skincare products.

GLP-1 is a naturally occurring peptide hormone that helps regulate appetite and blood sugar [1] [2].

GLP-1 medicines, such as Mounjaro and Wegovy, mimic this hormone and work by slowing stomach emptying, improving insulin response and reducing hunger signals. Clinical research has shown significant weight loss outcomes when GLP-1 medicines are paired with diet and lifestyle improvements. These medicines are available only with a prescription.

Retatrutide is an investigational multi-receptor agonist peptide being studied for its potential to produce better weight loss results than current GLP-1 medicines [3].

Early findings suggest it may target several metabolic pathways at once, which could provide stronger effects on appetite regulation and energy use. Although results are promising, Retatrutide is still under clinical evaluation and any future use in the UK would depend on regulatory approval, long-term safety data and availability through specialist healthcare providers.

Collagen peptides are short chains derived from collagen proteins and may support skin elasticity and hydration when consumed or applied topically [4] [5].

Research shows they can stimulate the body's own collagen production, helping counter age-related decline in firmness, and smoothing the skin's appearance. Collagen powders and drinks are widely available in the UK and often used alongside moisturisers that include peptide complexes to enhance the skin barrier.

GHK-Cu is a naturally occurring copper-binding peptide that plays a role in tissue repair and skin regeneration [6].

It supports collagen and elastin production, has antioxidant properties and may improve skin texture when used regularly. It is commonly found in serums marketed for anti-ageing and post-procedure recovery and is considered safe when used as an ingredient in cosmetic products.

Peptide lip treatments use specific peptides that aim to hydrate, smooth and plump the lips.

These formulas usually contain signal peptides that encourage natural moisture retention and can help soften fine lines around the lip area. They are sold as cosmetic products in the UK and are suitable for daily use alongside standard lip balms.

BPC-157 is a synthetic peptide studied mainly in animals for its potential effects on tissue repair and inflammation [7].

Although early findings are interesting, there is no robust evidence in humans, and it is not approved as a medicine in the UK. Many products claiming to contain BPC-157 are sold as unregulated research chemicals not intended for human or veterinary use.

Epitalon and similar peptides are sometimes promoted for their influence on ageing pathways or growth hormone release, but evidence in humans is limited [8].

These peptides are not available as licensed medicines in the UK. Products sold online sit outside regulated healthcare and are usually listed for research purposes only.

PT-141 is a prescription-only peptide used in some countries for sexual dysfunction and works by activating pathways linked to arousal [9].

It is not licensed for medical use in the UK, and products marketed online as medical PT-141 are typically unregulated, making them unsafe. People seeking support for libido should speak to a GP or specialist service for evidence-based treatment.

Antimicrobial peptides are part of the body's defence system and help protect against bacteria, viruses and fungi [10].

They are being studied for their potential in new antibiotics and skincare formulations, particularly as antimicrobial resistance grows. Although research is promising, AMPs are not yet widely used in health products.

The legal status of peptides in the UK depends entirely on the specific peptide and how it is sold or used.

Licensed medicines containing peptides are legal only with a prescription, cosmetic peptides are allowed in skincare and supplements, and research peptides sold online are strictly not for human or veterinary use.

Prescription peptides such as insulin, tirzepatide (Mounjaro) and semaglutide (Wegovy) are legal in the UK when prescribed by qualified healthcare professionals.

They undergo strict safety checks and monitoring. These products should only be sourced through recognised medical providers to ensure you remain safe whilst using them.

Cosmetic peptides found in moisturisers, serums and collagen supplements are legal and widely sold in the UK.

These products are designed for surface-level benefits and must comply with cosmetic safety standards.

Research peptides sold online are not approved for human use and are unregulated in the UK.

Products not listed as research-only may contain unknown ingredients, inconsistent dosing, unknown interactions and decreased effectiveness due to mixed formulas, which makes them risky. Their safety cannot be assured, so they should be avoided.

“Peptides cover a wide range of compounds that support essential functions in the body, from appetite control and metabolic health to skin repair and immune defence. Some are well studied and regulated, and others remain experimental or unapproved. Understanding the differences helps you make informed decisions and avoid unregulated products that may put your health at risk.”

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[1] Press releases - Novo Nordisk

[2] Tirzepatide Once Weekly for the Treatment of Obesity | New England Journal of Medicine

[3] Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial | New England Journal of Medicine

[4] Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis - PubMed

[5] Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis - PubMed

[6] Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data - PMC

[7] The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration - PubMed

[8] Epithalon peptide induces telomerase activity and telomere elongation in human somatic cells - PubMed

[9] Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder - PMC

[10] Antimicrobial Peptide Combination Can Hinder Resistance Evolution - PMC