Metabolomics

Our bodies are always busy. Tiny parts in our cells change all the time. These small parts leave a mark like a fingerprint.

Scientists study these marks to see how we work. This tells them what is happening right now. They can look at things like sweat or spit. It helps them learn how to keep us healthy. It is a very big job!

Inside every living thing, tiny chemical changes are always happening. These small molecules are called metabolites. They are the end products of how a cell works. Scientists study these molecules using a field called metabolomics.

Metabolomics is like looking at a chemical fingerprint. Each cell or organ leaves a unique pattern behind. By looking at these patterns, scientists can see a snapshot of health. While genes tell us what might happen, metabolites show what is actually happening right now.

Scientists can find these molecules in many places. They look at blood, urine, saliva, and even sweat.

To keep track of all this data, experts use large databases. One big project is the Human Metabolome Project. In 2007, it finished a first draft of the human metabolome. This list included about 2,500 metabolites, 1,200 drugs, and 3,500 food parts. This helps scientists understand how food and medicine change our bodies.

Metabolomics is the study of small molecules called metabolites. These molecules are the end products of chemical processes inside a cell. Every living thing has a metabolome, which is the full set of these molecules. You can think of the metabolome as a chemical fingerprint. Each tissue or organ leaves behind a unique pattern. While genes show what might happen, metabolites show what is actually happening. They provide a direct readout of the physiological state of an organism.

This science works by looking at how molecules move through a system. Metabolites act as substrates, intermediates, and products in a large network. This network is often called a hypercycle because the output of one reaction becomes the input for another. Scientists collect samples like blood, urine, saliva, or even sweat to find them. These samples are always in balance with the body. This makes it easy to get a quick snapshot of health. By studying these patterns, researchers can see how a body responds to change.

People have been studying these patterns for a long time. Roger Williams introduced the idea of a metabolic profile in the late 1940s. He used paper chromatography to look at urine and saliva. In 1971, a group led by Horning used gas chromatography-mass spectrometry to measure compounds. This tool is called GC-MS. Other scientists like Linus Pauling and Arthur B. Robinson also helped develop these methods. Later, in 1974, Seeley and others used NMR spectroscopy to find metabolites in muscle. They found that 90% of cellular ATP is linked with magnesium.

Today, scientists use huge databases to organize what they learn. The METLIN database was started in 2005 at the Scripps Research Institute. By December 2023, it held data on over 960,000 molecular standards. Another major effort is the Human Metabolome Project. Led by David S. Wishart, it finished its first draft in January 2007. This draft included 2,500 metabolites, 1,200 drugs, and 3,500 food components. The Human Metabolome Database also contains over 220,945 metabolite entries. It even links to 8,610 protein sequences.

Metabolomics helps us connect many different parts of biology. It links to genomics, which studies DNA, and proteomics, which studies proteins. Scientists use tools like the XCMS algorithm to align data. This tool has over 30,000 registered users as of 2019. We can see how food and medicine affect our bodies through this work. For example, researchers once found a molecule called oleamide in animals. This molecule was shown to have sleep-inducing properties. By studying these tiny parts, we understand the whole living system better.

Metabolomics is the scientific study of chemical processes involving metabolites. These metabolites are small molecules that act as substrates, intermediates, and products of cell metabolism. The complete set of these molecules in a cell, tissue, or organism is called the metabolome. While other sciences look at the blueprints of life, metabolomics looks at the actual results.

To understand how this works, we must look at the flow of biological information. Genomics studies DNA to see what could happen in a cell. Transcriptomics looks at messenger RNA to see what appears to be happening. Proteomics examines proteins to see what makes processes happen. Finally, metabolomics shows what has happened and what is currently happening. It provides a direct functional readout of the physiological state of an organism. This makes it an instantaneous snapshot of how a cell is actually working.

Metabolites function within a complex, interconnected network of chemical reactions. This network is often described as a hypercycle. In a hypercycle, the output of one enzymatic reaction becomes the input for another. This creates a continuous loop of chemical activity. Scientists often study these molecules by collecting bio-specimens. Common samples include plasma, serum, urine, saliva, feces, muscle, sweat, and even exhaled breath. Because these samples are in dynamic equilibrium with the body, they can describe the host as a whole.

There are different ways to categorize these molecules depending on the organism. In plant-based studies, scientists distinguish between primary and secondary metabolites. Primary metabolites are directly involved in growth, development, and reproduction. Secondary metabolites are not essential for growth but serve important ecological functions, such as pigments or antibiotics. In human studies, metabolites are often described as endogenous or exogenous. Endogenous metabolites are produced by the host organism itself. Exogenous substances, such as drugs, are called xenometabolites.

The history of this field began in the late 1940s with Roger Williams. He suggested that individuals might have a unique metabolic profile in their biological fluids. He used paper chromatography to find patterns in urine and saliva. In 1971, the term "metabolic profile" was officially introduced by Horning and his team. They used gas chromatography-mass spectrometry, or GC-MS, to measure compounds in human tissue and urine. Other researchers, including Linus Pauling and Arthur B. Robinson, helped develop GC-MS methods throughout the 1970s.

Another vital tool is NMR spectroscopy, which was discovered in the 1940s. In 1974, Seeley and colleagues used NMR to detect metabolites in unmodified muscle samples. They discovered that 90% of cellular ATP is complexed with magnesium. Later, Jeremy K. Nicholson pioneered the use of pattern recognition with NMR data. In the 1990s, Gary Siuzdak and his colleagues used liquid chromatography mass spectrometry to study sleep-deprived animals. They identified a molecule called oleamide, which was later shown to have sleep-inducing properties.

Today, massive databases help scientists organize this complex information. The METLIN database was developed in 2005 at the Scripps Research Institute. As of December 2023, METLIN contains data on over 960,000 molecular standards. Another major effort is the Human Metabolome Project, led by David S. Wishart. In January 2007, they completed the first draft of the human metabolome. This draft included 2,500 metabolites, 1,200 drugs, and 3,500 food components.

The Human Metabolome Database (HMDB) is one of the most extensive public resources available. It contains 220,945 metabolite entries, including both lipid-soluble and water-soluble types. The database also links to 8,610 protein sequences, such as enzymes and transporters. Each entry can contain up to 130 data fields. This helps researchers in clinical chemistry and biomarker discovery. By integrating metabolomics with other "-omics" fields, scientists hope to achieve a complete understanding of cellular biology.