Thanks for the new information. I stumbled upon a controversial declaration.
Point 5 of the following analysis indicates that Nicotinamide accelerates aging?
http://www.anti-agin...life-extension/
QUOTE:
5. Nicotinamide (Nam)
Nicotinamide is a direct inhibitor of both the SIRT enzymes and the PARP enzymes.
The accumulation of excess nicotinamide in cells is probably a major cause of aging. Whereas we typically associate “NAD deficiency” with aging, “Nam excess” may have a similar effect. To no one’s surprise, the levels of the two compounds are inversely related in aging.
Nam plays a role in both aging and in disease. In hypertension and in aging individuals with normal blood pressure, Nam inhibits the methylation-mediated degradation of catecholamines. Thus Nam excess plays a role in hypertension (see references below).
Nicotinamide also has an epigenetic effect. When SIRT1 is inhibited, cells age and cancer oncogenes are re-activated. SIRT1 silences these genes by histone deacetylation of H3K9 and H4K16 residues on the histones of these oncogenes.
A recent article showed that in rats, nicotinamide supplementation during pregnancy causes global DNA hypomethylation in rat fetuses. Nicotinamide has detrimental effects in development, detrimental metabolic effects, and detrimental epigenetic effects when given to young rats. Low dose nicotinamide increased weight gain in developing rats. High dose nicotinamide did not, however. The livers of nicotinamide-fed young rats had more DNA damage (8oxoG), impaired glucose tolerance, and increased insulin resistance. Nicotinamide increased the levels of N-methylnicotinamide in the blood and decreased betaine levels in the blood. This resulted in a global hypomethylation of DNA in the rat genome. Nicotinamide also had “gene-specific effects” on CpG islands within the promoters of the following genes:
- NNMT gene – this was down-regulated
- DNMT genes – these were down-regulated
- Homocysteine metabolism genes – these were down-regulated
- Antioxidant genes and oxidative stress protection genes – these were down-regulated
Since niacin is converted into nicotinamide in human tissues, high dose niacin probably produces all of the above effects. A recent paper called niacin and nicotinic acid “methyl consumers” and strongly suggested that high niacin/nicotinic acid intake is bad.
Excess nicotinamide has also been shown to increase plasma serotonin and histamine levels in humans, due to disrupting the metabolism of these neurotransmitters. This is probably due to the fact that methyl donors and methylation enzymes are needed for serotonin/histamine metabolism. Most importantly, nicotinamide is a direct inhibitor of the Sirtuin enzymes (SIRT1-7) and the PARP enzymes (all 17 of the PARPs).
The molecular mechanism by which Nam works is very straightforward. Nam acts as a direct inhibitor of the SIRT1 enzyme pocket where NAD binds. Thus Nam is a “competitive inhibitor” of NAD and is “bad” when it comes to most cancers, aging, and most diseases.