Other

A lab-made copy of a natural thymus-gland peptide that fine-tunes the immune system. It is a licensed prescription medicine in many countries (as Zadaxin) but not in the UK, where it is sold only as an unlicensed research chemical.

Grade B · Human trials exist but are incomplete.

A brain peptide discovered in sleeping rabbits in the 1970s and tested as a sleep aid in humans, but development stalled and it never became a licensed medicine.

Grade C · Some human data, far from settled.

An experimental peptide that kills the blood vessels feeding fat tissue, with striking results in mice and a few monkeys.

Grade D · No meaningful human evidence yet.

A lab-made four-amino-acid peptide from the Russian 'bioregulator' family, sold for lung and airway health, with rat and cell-dish results but no human trials we could find.

Grade D · No meaningful human evidence yet.

A lab-made four-amino-acid peptide from the Russian 'bioregulator' family, sold to support the heart, but every result so far is from rat hearts, cell dishes and the developers' own patent, with no human trials.

Grade D · No meaningful human evidence yet.

A lab-made four-amino-acid peptide from the Russian 'bioregulator' family, sold for the liver and anti-ageing, whose evidence is rat livers, cells in dishes and one group's papers, with no human trials.

Grade D · No meaningful human evidence yet.

A lab-made three-amino-acid peptide claimed to protect brain cells. The evidence is almost entirely from cell dishes and rodents, produced by one research group, with no proper human trials.

Grade D · No meaningful human evidence yet.

A natural zinc-dependent thymus hormone that helps immune cells mature, sold as a research peptide despite almost no convincing human trial evidence as a treatment.

Grade D · No meaningful human evidence yet.