Cell studies answer narrow questions
In-vitro experiments can show whether a peptide affects a pathway, receptor or cell type under controlled conditions. They do not establish how a whole human body will respond.
Animal studies add complexity
Animal models can reveal pharmacology, tissue responses and safety signals, but species differences in metabolism, receptors and disease biology can make results fail to translate.
Human pharmacology is not the same as clinical benefit
A study showing that a peptide changes a hormone or biomarker proves biological activity, not necessarily that people feel better or experience fewer health problems.
Controlled outcome trials carry more weight
Randomized trials with clinically meaningful endpoints, adequate sample sizes and independent replication provide much stronger evidence than anecdotes or mechanistic studies alone.