Metabolites are the substrates, intermediates and products of metabolism. Within the context of metabolomics, a metabolite is usually defined as any molecule less than 1.5 kDa in size. [24] However, there are exceptions to this depending on the sample and detection method. Metabolites are the intermediate products of metabolic reactions catalyzed by various enzymes that naturally occur within cells. Metabolites are the intermediate molecules formed during the numerous metabolic reactions that occur within living cells. They are essential for maintaining life, as they participate in growth, development, energy production, and the regulation of cellular activities. Metabolites are small organic molecules produced during metabolism that play key roles in energy production, growth, and cellular signaling. They are broadly classified into primary and secondary metabolites, both vital for survival, adaptation, and biotechnology applications. Metabolites is an international, peer-reviewed, open access journal of metabolism and metabolomics, published monthly online by MDPI. Living systems are defined not only by their genes or proteins, but by the countless small molecules that constantly flow through cells, tissues, and biofluids. These molecules—collectively known as metabolites—represent the most immediate and dynamic readout of biological activity. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, catalytic activity of their own (usually as a cofactor to an enzyme), defense, and interactions with other organisms (e.g. pigments, odorants, and pheromones). A substance made or used when the body breaks down food, drugs or chemicals, or its own tissue (for example, fat or muscle tissue). This process, called metabolism, makes energy and the materials needed for growth, reproduction, and maintaining health. It also helps get rid of toxic substances. Metabolites represent the end products, intermediates, and starting materials of cellular metabolic pathways, acting as a direct functional readout of the cell’s activity. They include compounds such as sugars, amino acids, lipids, and vitamins, that are constantly cycled through the body’s systems. Metabolite - an overview | ScienceDirect Topics.