The human organism requires a variety of small molecules, such as sugars or fats, in order to function properly. The composition of these so-called metabolites and their interaction—the metabolism—varies from person to person and is dependent not only on external influences, such as nutrition, but also to a significant extent on natural variations in our genetic make-up. In an international study, scientists from the Berlin Institute of Health (BIH) and Charité-Universitätsmedizin Berlin joined forces with colleagues from the United Kingdom, Australia and the United States and discovered hundreds of previously unknown variations in genes that have a sometimes drastic impact on the concentration of these small molecules in the blood. The researchers have now published their findings in the journal Nature Genetics.