Hype about peptides: The molecular promise

Peptides for health, that's what a hype can be called. They are touted by influencers as all-rounders in the sense of self-optimization, and even the US Secretary of Health Robert F. Kennedy Jr. wants to promote it.

Starting with products like collagen, which have long been heralded as a miracle cure for rejuvenation, new peptides with sometimes obscure names are now being added. They are called BPC-157 or TB-500. The general promise: looking younger, healing faster, bigger muscles - all of this can sound tempting. There is often little scientific behind it. But from the beginning.

Peptides are small snippets of amino acids - these are the building blocks that proteins are made of. What exactly “small” means is not clearly defined. A review paper from 2023 speaks of typically 2 to 50 amino acids, which are arranged either as a chain or as a circle. Larger amino acid arrangements are then called proteins.

“In general usage, however, these terms are often used more vaguely,” says Mario Thevis, professor and head of the Institute of Biochemistry at the Center for Preventive Doping Research at the German Sport University Cologne. “Basically, we can understand peptides as a variety of active ingredients.”

In the body, they act primarily as signaling molecules for communication between cells, through which important processes are controlled. A well-known example: insulin, which is a so-called peptide hormone and is responsible for regulating blood sugar. Others have an effect on blood pressure or the feeling of satiety.

The body naturally produces peptides itself. In some cases, individual amino acids are completely reassembled, in other cases they are specifically split off from larger proteins or are created as a by-product of protein metabolism.

We can produce some of the amino acids we need ourselves or get them by breaking down the body's own proteins. However, intake from your diet is also important, especially essential amino acids that the body cannot produce.

However, supplying peptides as a whole artificially is not that easy. “Most peptide active ingredients do not remain intact when I absorb them through my stomach,” says Mario Thevis. Rather, they would also be broken down into smaller fragments or individual amino acids in the gastrointestinal tract. Substances such as insulin are therefore usually injected so that the body can actually use them as a whole.

Various peptides have already been approved as drugs. Insulin is probably the best-known example. In addition, the peptide hormone oxytocin is used to induce labor in difficult births. So-called weight loss injections have been in the headlines a lot lately. They contain the peptide hormones semaglutide or tirzepatide. With their help, type 2 diabetes can be treated, especially due to their supporting effect on weight loss.

An essential point of all approved medicines: their effectiveness has been proven in clinical studies and the quality is carefully controlled.

The peptide collagen is primarily touted in skin care. According to the promises of manufacturers, it is supposed to make the skin look younger, sometimes also make the hair more lush and the nails stronger. Collagen is actually a structural protein that is produced less by the body as we age. The industry's idea: Anyone who takes it as a dietary supplement, for example as a powder in coffee, will stay visually younger.

In fact, various human studies show how collagen reduces wrinkles. The catch, however, is that such studies are usually financed by industry and are therefore not independent. In addition, often only a few test subjects are examined and the overall quality is questionable. In addition, just because a study sees significant effects does not mean that there are visible effects. In real life, no one stands with a ruler to measure the depth of wrinkles - would a change of a few percent really be noticeable, even if the study calls it "significant"?

Independent experts assume that collagen does not have a visible effect as a dietary supplement and that a balanced, protein-rich diet is completely sufficient. The consumer advice center also emphasizes that other measures such as sun protection, avoiding nicotine and a healthy lifestyle would have a greater effect.

Newer than collagen are peptides with less catchy names such as BPC-157, TB-500, CJC-1295 and MOTS-c. They are primarily intended to arouse the interest of amateur athletes - especially because they are banned as doping substances in professional sports.

“There are different promises behind the names,” says Mario Thevis. “BPC-157 and TB-500, for example, are primarily intended to support wound healing and regeneration.” However, the scientific evidence for this is comparatively sparse. Previous reviews and studies refer to animal models and clearly emphasize the lack of studies with human test subjects.

According to Thevis, CJC-1295 and MOTS-c can be classified somewhat more clearly because at least the respective mechanism of action has been proven there. The former increases the blood concentration of growth hormones, which in turn supports muscle growth and increases fat burning. MOTS-c affects the energy production in the cells and could thus increase performance. But even here, convincing clinical studies are lacking, as scientific reviews show.

Thevis emphasizes that one can only speculate about the effects of products advertised on the Internet on people: “Especially because there is rarely any quality control for products that are sold via Internet-based platforms.” So no one can be sure whether it actually contains what it says. In order to build or maintain muscles, exercise is also essential. Even if the peptides actually work, they could only support training, not replace it. It is questionable whether the smallest changes caused by the active ingredients would be relevant for amateur athletes.

It is currently difficult to say how the respective active ingredients affect people, even in a negative sense, because there are no meaningful studies. This means that effects and side effects are equally unknown.

The lack of quality controls for products from the Internet not only means that you may not get what is promised - they may instead contain other substances with potential dangers. Injecting the peptides can also be critical: For example, infections can occur at the injection sites if the needles are not sterile or even contaminated. Depending on the active ingredient, allergic reactions are also possible.

Basically, it can be said: Injecting unapproved peptides or taking them as dietary supplements has no proven benefits, but does have possible undesirable consequences. Certain peptides have an important role as medications, but they must also be taken in a controlled context, as high-quality preparations and in a defined dose. It is therefore unlikely that people will encounter something that brings them noticeable benefits, even with untested products of dubious quality and effectiveness.