NMN Converts to Nicotinamide Riboside Before Entering Cells: Preclinical Findings

Synopsis

NAD+ is an essential molecule that helps enzymes like sirtuins and poly(ADP-ribose) polymerases work properly. Supplements like nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) can protect against metabolic diseases, brain disorders, and age-related decline in mammals. Researchers found that the enzyme nicotinamide riboside kinase 1 (NRK1) is crucial and limits how cells use NR and NMN to make NAD+. They showed that NRK1 is not necessary for using other NAD+ precursors like nicotinamide or nicotinic acid. Using labeled compounds, they confirmed that NMN is first broken down outside the cell into NR, which then enters the cell and is converted into NAD+. This means cells depend on converting NMN to NR before taking it up to produce NAD+, explaining why NMN and NR have similar effects. Increasing NAD+ levels helps reverse some signs of aging, and NRK1 plays a key role in controlling how cells process these NAD+ precursors.

Journal

Nature Communications