VITAMIN B3

Niacin is the most foundational and universal B vitamin in all of energy metabolism. It is a nutritional precursor of the bioactive molecules nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). NAD and NADP are important cofactors for most cellular redox reactions, and as such are essential to maintain cellular metabolism and respiration. They are involved in over 400 biochemical reactions in your body — mainly related to obtaining energy from the food you eat.

Functions:
- It helps you use your neurotransmitters, those little chemicals that allow your brain cells to communicate with one another, and allow your nerves to control your muscles and to sense your environment.
- It release prostaglandins, or chemicals that help your blood vessels widen — improving blood flow and reducing blood pressure. For this reason, niacin may play a role in the prevention or treatment of high blood pressure.
- It repairs your DNA whenever it gets damaged.
- It lengthens your telomeres. These are little caps on the ends of your chromosomes, the bundles of DNA that house all of your genes. This helps them keep your cells dividing and staying strong as you age, allowing you to live longer.

Deficiency:
Severe niacin deficiency is called pellagra which is characterized by 4 Ds in clinical manifestations - diarrhea, dermatitis, dementia, and death.

Recommended daily allowance of niacin is as follows:
- Infants: 5 to 6 mg
- Children: 9 to 13 mg
- Adults: 13 to 20 mg
- Pregnant and lactating mothers: 17 mg and 20 mg, respectively

Source:
We can actually MAKE niacin from protein!
BUT making niacin from protein ain't easy.
It requires iron, riboflavin, and vitamin B6. Deficient in these? You're out of luck.
Niacin is freely available in animal foods.
- Liver
- Nutritional yeast
- Salmon
- Mushrooms
- Cod
- Organ meat
- Coffee (Dark roast)

Supplementation:
Unlike thiamin and riboflavin, niacin can be toxic.
1. NICOTINIC ACID:
This is often just called "niacin." Using this form in this way has NOTHING to do with using niacin as a nutrient. It works as a drug that alters how you handle fats and carbohydrates. This is also the form that causes flushing (redness, heat, and itching).
2. SLOW-RELEASE AND INOSITOL HEXANICOTINATE:
These are forms of nicotinic acid that reduce the flushing, but increase the risk of liver toxicity at high doses. Although small doses of inositol hexanicotinate in multivitamins and B complexes are probably perfectly safe, I'd rather avoid them.
3. NICOTINAMIDE RIBOSIDE (NR)
This is the best form to use for anti-aging, but it's expensive. It's superior to all other forms at nourishing your niacin status, and it doesn't cause flushing or mess with your cholesterol. Reasonable doses to experiment with range from 75 to 2000 mg/d.
4. NICOTINAMIDE MONONUCLEOTIDE (NMN)
This is probably digested into nicotinamide riboside before you absorb it. So it probably works just like NR.