Transcriptomics, Proteomics and Metabolomics

Three ways of looking at what cells are doing

DNA is the instruction set. These three "omics" fields look downstream, at what cells actually make and use. All three are research tools that are increasingly used to study disease. None of them is a treatment, and a measurement from any of them is a biomarker or laboratory signal, not a health outcome.

Evidence label used on this page: established (the method or finding is described in peer-reviewed reviews or by national bodies), plus insufficient evidence and marketing claim for consumer uses. See How We Label Evidence in Specialty Topics.

Transcriptomics: the RNA readout

Gene expression is the process by which information in a gene is turned into a function, mostly through making RNA. [1] The transcriptome is the set of RNA transcripts in a sample. RNA sequencing (RNA-Seq) is an approach to transcriptome profiling that uses deep-sequencing technologies. [2] Because gene expression changes substantially under different conditions and cell types, [3] a result depends on which tissue was sampled and when. A blood sample may not reflect what is happening in an organ.

Proteomics: the protein readout

Proteins do most of the work in cells. Mass-spectrometry-based technologies now give insights into the composition, structure, function and control of the proteome, the proteins in a system. [4] A key point for readers: transcript levels by themselves are not sufficient to predict protein levels in many scenarios. [5] A change in RNA therefore cannot be assumed to mean a change in protein, and a protein change cannot be assumed to mean a change in health.

Metabolomics: the chemistry readout

Metabolomics is the comprehensive characterization of metabolites and metabolism in biological systems. [6] A Nature Reviews Drug Discovery review states it is increasingly used to diagnose disease, understand mechanisms and monitor therapeutic outcomes. [6] A single reading is a snapshot of one sample. How metabolite patterns relate to diet is discussed in the precision nutrition guides, for example Blood Biomarkers as a Nutrition Input.

What these tools can and cannot do

• They can describe. They show which molecules are present and how they differ between groups, such as people with and without a disease. Label: established as research methods.
• They can generate hypotheses. A pattern found in one group becomes a candidate biomarker, which needs testing in new groups. See Biomarker Discovery Research.
• They cannot show cause on their own. A molecule that differs between groups may be a cause, a consequence or a bystander. Consider Mechanism vs Demonstrated Benefit.
• They do not validate a product. A supplement or device that "changes the metabolome" or "improves protein markers" has shown a biomarker change, not a clinical benefit. See Biomarkers vs Clinical Outcomes.

Combining layers

Studies now combine several layers, which is called multi-omics. A review of integrative omics describes how genomics, transcriptomics, proteomics and metabolomics together can give a more complete view than any one alone. [7] See Multi-Omics Explained. For DNA-level fields, see Genomics Explained.

Consumer tests

Some companies sell wellness panels that report RNA, protein or metabolite results. This page does not rate specific products. Proper evidence not found, in the sources read for this page, that routine consumer omics panels in healthy people improve health outcomes. What was checked: national genome bodies, FDA pages and peer-reviewed reviews on omics methods, which describe the methods and research uses but not outcome trials of consumer panels. See Multi-Omics Test Panels.