Nicotinamide, Nicotinamide Riboside, and Testosterone

Nicotinamide (NAM), which is also known as Niacinamide, and Nicotinamide Riboside (NR) both may have implications for testosterone, and testosterone metabolites such as DHT. There is evidence of enhanced DHT-induced androgen receptor expression from NAM, however, there are also grounds for caution in supplementation. Nicotinamide Riboside may be a safer option, but far more work needs to be done before we can be sure.

Cell line study: "Nicotinamide… enhanced DHT-induced AR [Androgen Receptor] expression"
http://mcb.asm.org/content/26/21/8122.full

Cell line study: The mitochondrial NADH:NAD+ ratio is related to testosterone production in rat Leydig cells
https://www.ncbi.nlm.nih.gov/pubmed/2214777
- Same study suggests glutamate may be protective against alcohol induced damage to this ratio.

Nicotinamide Riboside increases NAD+ in humans and mice
https://www.ncbi.nlm.nih.gov/pubmed/27721479
http://pure.qub.ac.uk/portal/files/120387147/ncomms12948_1_.pdf
Perhaps, and I stress the perhaps, this means that Nicotinamide, or Nicotinamide Riboside would increases testosterone in humans. However, this will only be the case if testosterone is low because of some kind of issue in the testes (which won't be true of everyone with low testosterone).

Nicotinamide Riboside is found in cow milk
https://www.ncbi.nlm.nih.gov/pubmed/27052539
"Conventional milk contained more NR than milk sold as organic"

Grounds for caution in NAM dosage
Nicotinamide overload may lead to type-2 diabetes
https://www.ncbi.nlm.nih.gov/pubmed/19960564
https://www.ncbi.nlm.nih.gov/pubmed/20179894

Also connections have been made with Parkinsons disease
https://www.ncbi.nlm.nih.gov/pubmed/22249857
https://www.ncbi.nlm.nih.gov/pubmed/15728403
- Basically NAM is converted via NNMT to N1-methylnicotinamide (MNAM), which may be toxic to neurons.
N1-methynicotinamide (MNAM) is different to nicotinamide mononucleotide (NMN)

For an interesting overview, see here:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5419340/

It may also reduce SAMe (also written as SAM)

NR better?
Nicotinamide Riboside may reduce type-2 diabetes
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4882590/
"In T2D mice, NR greatly reduced non-fasting and fasting blood glucose, weight gain and hepatic steatosis while protecting against diabetic neuropathy"

In fruit flies (!) Nicotinamide Riboside may actually protect against Parkinsons
https://www.nature.com/articles/cddis201672
And so might Nicotinamide itself (oh dear, need to do more reading!)
https://www.ncbi.nlm.nih.gov/pubmed/28011627

Very high dose Nicotinamide Riboside may reduce exercise performance https://jissn.biomedcentral.com/articles/10.1186/s12970-016-0143-x

Read: https://www.nature.com/articles/ncomms12948