Jens Nielsen is the CEO of BioInnovation Institute,[1] Copenhagen, Denmark, and professor of systems biology[2] at Chalmers University of Technology, Gothenburg, Sweden.

[citation needed] Following his studies, he established an independent research group at DTU and was appointed full professor there in 1998.

[citation needed] In 2008, he was recruited as professor and director at Chalmers University of Technology, Sweden, where he built a research group of more than sixty people.

[citation needed] In 2019, Nielsen was recruited as CEO of BioInnovation Institute (BII), an initiative by the Novo Nordisk Foundation to support innovation and translation of science for use in society.

[citation needed] Using his systems biology toolbox developed for microorganisms, Nielsen initiated work on human metabolism.

[25] His work on human metabolism has involved studies of different diseases, such as obesity,[26] NAFLD and NASH,[27] and hepatocellular carcinoma.

He was involved in early studies on using metagenome sequencing for characterization of the gut microbiota and demonstrating that variations are associated with cardiovascular disease[30] and type 2 diabetes.

[31] He also used his advanced metabolic modelling skills to gain further functional insight into how the gut microbiota impacts changes in plasma metabolomics in response to dietary changes.