The Preiss-Handler pathway starts with nicotinic acid. Usually, nicotinic acid is located in meals but will also be eaten via a dietary health supplement. This NAD+ precursor molecule is also made by the bacterial microflora within the intestines or saliva. Focusing on NAD+ metabolism is usually a functional nutritional intervention https://nad-plus89000.thechapblog.com/13739873/the-nad-diaries