Peptides and young blood: what you actually get in return

The world of interventions and supplements for healthy ageing is expanding at breakneck speed, and so are the promises. Peptides that repair tissue, young plasma that winds your cells back in time, drugs that slow ageing itself. Some of the hype is partly justified; some of it is outright premature. Below, the most popular interventions are weighed against what the evidence actually says.

Collagen peptides

Peptides are small protein fragments with a wide range of roles in the body: they signal to cells, regulate hormones and fight bacteria. As supplements, collagen peptides are the best studied. They reduce joint pain and improve joint function, particularly in people who exercise regularly. The effects are modest and not everyone benefits, but the evidence holds up. For muscle strength or general performance gains, high-quality protein sources are better supported than collagen supplements.

The problem with most other peptide supplements is more fundamental: peptides taken orally are largely broken down in the stomach and intestines before they ever reach the bloodstream. Absorption is so low that little should be expected of them. The only proven exception is oral semaglutide, which reaches the bloodstream through a special formulation. Promising delivery techniques for other peptides are in development, but as an ordinary consumer product they do not yet exist. Anyone who wants to use peptides medically is better off with injections for now – and that is a conversation to have with a doctor.

BPC-157: impressive in animals, barely studied in humans

BPC-157 is one of the most popular peptides in biohacker circles, praised for its supposed healing power in tendons, muscles and the gut. The evidence from animal studies is remarkably consistent and positive. In humans it has barely been studied: a small case series and a pilot study with two participants are not enough to know whether it works or is safe. Dosing, indication and long-term effects have not been established in humans. Self-administration is, at this point, a leap into the unknown.

Young blood works in… mice

Plasma exchange using young blood produces impressive results in mice: improved stem cell function, greater brain plasticity, better blood vessel formation. Commercial providers are eager to translate that into human applications. But in humans, there is no evidence whatsoever of efficacy or safety. Clinical studies are still running and results are not in. Until they are, young plasma as a rejuvenation treatment has not been shown to work. The mouse studies are interesting enough to keep the research going; they are not a reason to spend money on commercial infusions right now.

Rapamycin: encouraging early signals, incomplete picture of risks

Rapamycin suppresses a cellular growth signal that becomes overactive with age. In mice it consistently extends lifespan. In humans there are early positive signals for immune function and skin, but the studies are small and short-term. Side effects such as increased susceptibility to infections and unfavourable blood lipids are a real risk. Long-term safety is unknown. Most doctors do not prescribe it to healthy people, simply because the evidence for anti-ageing in humans is not yet there. Off-label use outside a clinical trial is premature, and any doctor who considers it will do so only for a handful of rare conditions, with careful weighing of risks.

Metformin: disease prevention is established, slowing ageing itself is not yet

Metformin is the drug where the hype comes closest to reality – but with an important qualification. Its best-supported effect is helping to prevent diabetes and cardiovascular disease, which can extend healthy years, indirectly. Whether metformin also slows ageing itself in people without diabetes is an open question that the ongoing TAME trial is trying to answer. Until those results are in, the signals from cell and animal research are not enough to justify practical advice for healthy people. On top of that, gastrointestinal complaints affect a substantial proportion of users: in comparative research, people taking metformin were more than three times as likely to experience side effects as those on a placebo, with diarrhoea being the most common. Gradually increasing the dose reduces the problems for many people.

What all these interventions have in common

Nearly every intervention here follows the same pattern: strong animal evidence, weak or absent human evidence, and commercial providers trying to bridge the gap. The fact that research is moving forward is not a reason to act as though it is already settled. Collagen peptides for joints and metformin for disease prevention stand on the firmest ground. For everything else: wait for solid clinical results in humans before drawing conclusions.