Metabolomics is a powerful approach because metabolites and their concentrations, unlike other “omics” measures, directly reflect the underlying biochemical activity and state of cells / tissues. Thus metabolomics best represents the molecular phenotype.
代谢组学研究的是小分子：
A small molecule (or metabolite) is a low molecular weight organic compound, typically involved in a biological process as a substrate or product. Metabolomics usually studies small molecules within a mass range of 50 – 1500 daltons (Da).
例如：
sugars
lipids
amino acids
fatty acids
phenolic compounds
alkaloids
应用场景：
Agricultural
The development of new pesticides is critical to meet the growing demands on farming. Metabolomics enables us to improve genetically modified plants, and helps us to estimate associated risks by allowing us to get a glimpse of their complex biochemistry viainformative snapshots acquired at different time points during plant development.

Plant metabolomics is particularly interesting because of the range and functions of primary and secondary metabolites in plants. About 300 distinct metabolites could be routinely identified per sample a decade ago, and the number is gradually increasing over time.

Biomarker discovery
Biomarker discovery is another area where metabolomics informs decision making. Biomarkers are “objective indications of medical state observed from outside the patient – which can be measured accurately and reproducibly” (4). In metabolomics, biomarkers are small molecules (metabolites) that can be used to distinguish two groups of samples, typically a disease and control group. For example, a metabolite reliably present in disease samples, but not in healthy individuals would be classed as a biomarker. Samples of urine, saliva, bile, or seminal fluid contain highly informative metabolites, and can be readily analysed through metabolomics fingerprinting or profiling, for the purpose of biomarker discovery.

Personalised medicine
Personalised medicine, the ultimate customisation of healthcare, requires metabolomics for quick medical diagnosis to identify disease. In healthcare, we currently use classical biochemical tests to measure individual metabolite concentrations to identify disease states (e.g. the blood-glucose level in the case of diabetes). Metabolomics offers the potential for the rapid indentification of hundreds of metabolites, enabling us to identify these disease states much earlier.
实验方法：
Untargeted (global) approach:
This method measures as many metabolites as possible from a range of biological samples without any (intended) bias.
Targeted approach:
This method is used when you want to measure sets of metabolites and have a specific biochemical question that you want to answer.

技术手段：
1.核磁
2.质谱
数据处理：

principal component analysis (PCA, Figure 10a) and partial least squares (PLS)

参考：
1.https://www.ebi.ac.uk/training/online/courses/metabolomics-introduction/what-is/