A December 2014 study found that noise induced hearing loss in mice could be prevented with nicotinamide riboside, which is a precursor to NAD+ (nicotinamide adenine dinucleotide) and a precursor to vitamin B3. The researchers found that nicotinamide riboside activated a protein called SIRT3. [ref] Another study from 2013 showed that calorie restriction slows age-related hearing loss through increasing SIRT3 “by promoting the glutathione-mediated mitochondrial antioxidant defense system…” [ref]
SIRT3 is a mitochondrial protein and has also been studied in regards to longevity and metabolic syndrome. It is involved in controlling reactive oxygen species in the cell. Higher levels of SIRT3 are connected to longevity. SIRT3 is also involved in metabolism, and a study with mice lacking SIRT3 had greater obesity and insulin resistance on a high fat diet. Reduction of SIRT3 function was found to lead to mitochondrial dysfunction and metabolic syndrome.[ref]
Here are two polymorphisms of SIRT3 that you can find in your 23andMe results:
|Check your 23andMe results for rs11555236:
|Check your 23andMe results for rs11246020:|
Note: Nicotinamide and Nicotinamide Riboside are different. Nicotinamide regulates and suppresses SIRT3 [ref], where nicotinamide riboside supports NAD+ synthesis.[ref] Nicotinamide riboside can be bought as a supplement and is also found in small amounts in cow’s milk.
More to read:
Nice summary of SIRT1 and SIRT3: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3746174/