Vitamin B3 is an interesting molecule but I am not an expert of the field, please do not get irritated by the following if you are an expert, and your criticisms are mostly welcome:
1. TB (tuberculosis) was prevalent in eras and areas of poverty. Mycobacterium tuberculosis was hypothesized as meat for the poor people because it can provide this essential ingredient to the infected, malnourished host and prevent problems such as pellagra et al., which can be much more serious and urgent than normally mild TB. Interestingly, Pyrazinamide, the indispensable antibiotic among different combination TB therapies, is an Nicotinamide derivative. Is Pyrazinamide mimicking Vitamin B3 hence help the host to get rid of TB/Vitamin B3 addiction? Interestingly, all TB therapies so far are quite time-consuming and it seems to me that, on the host side instead of the bacteria side, it is difficult to persuade the host to give up a beneficiary cohabitant. Indeed, consumption of meat is inversely correlated with TB incidence and pellagra patients were craving for tabacco which provides Vitamin B3 (niacin). No wonder that leaders of the old generations love smoking. When they do not get enough Vitamin B3 from diet (such as meat), it is better to smoke it and keep the brain in a better shape for mental challenges. A clinical case reported that an alcoholic man suffered from Vitamin B3 deficiency but was given Vitamin B complex without B3. The man lost consciousness, almost died instantly and finally rescued by Vitamin B3. This clinical accident somehow demonstrated the urgent and specific effect of Vitamin B3 deficiency in human beings. Alcoholism is known to cause Vitamin B3 deficiency for reasons I do not understand yet and to supplement the diet with meat, dairy product, or various "energy" drinks rich in Vitamin B3 are popular solutions.
2. Vitamin B3 is essential and continuous supply is required. "High energy requirements (brain) or high turnover rate (gut, skin) organs are usually the most susceptible to their deficiency."(from Wikipedia). But why exactly? Vitamin B3 can derive from amino acid such as tryptophan and be converted into NAD+, which is essential for the function of NAD dependent deacetylase SIR2 that is critical in the regulation of chromosome. I once read that SIR2 consumed Vitamin B3 but I did not understand how. If I took it wrong, then how is Vitamin B3 consumed?
Here is the reaction of SIR2 mediated deacetylation(from SIR2 uniprot):
NAD+ + an acetylprotein = nicotinamide + O-acetyl-ADP-ribose + a protein.
It seems that nicotinamide is a product hence nicotinamide is a well-established inhibitor of SIR2 activity, at least in unicellular yeast. Well, where does the vitamin B3 go in the end? Has any classic tracing experiment been carried out with Vitamin B3 labelled with isotope? Where would Vitamin B3 accumulate in the body, skin, gut, brain?
3. The story of SIR2
http://web.mit.edu/biology/guarente/yeast/sir2.html
"Caloric restriction is likely to reduce the carbon flow through glycolysis and result in more free cytoplasmic NAD. SIR2 could act as a sensor of NAD levels within the nucleus. Under conditions of caloric restriction, NAD levels are high, SIR2 is activated, and the rate of aging is decreased."
Hence addition of vitamin B3, if converts into NAD, could activate SIR2; if converts into nicotinamide, could inhibit SIR2?
4. It seems that cholera toxin also catalyzes a similar reaction on the critical Arginine residue of an important GTPase, Gα (Attached image).
NAD+ + Arg of Gα = nicotinamide + O-acetyl-ADP-ribosed Arg of Gα.
Again, NAD+ is consumed and converted into nicotinamide, where would nicotinamide go next? If nicotinamide can be recycled, there is no need for new Vitamin B3.
From "Alfred Wittinghofer (MPI) Part 2: GTPase Reactions and Diseases
https://www.youtube.com/watch?v=Ek4Y7EunfQQ"
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Sorry for the lack of organization and apology for the missing citations. Just eager to know the answers. Thanks!
Vitamin B3 is found in foods like Tuna, chicken , turkey, lamb, beef, salmon, brown rice bpeanuts shrimps. Vitamin B3 is water-soluble, meaning that the body does not store them, however one can meet all of thebody's needs for B3 through diet. It is rare for anyone especially in the developed world to have a B3 deficiency. In the U.S., alcoholism is the main cause of vitamin B3 deficiency.
Vitamin B3 is available in several different supplement forms:
Niacinamide
Niacin
Inositol hexaniacinate.
Niacin is available as a tablet or capsule in both regular and timed-release forms. The timed-release tablets and capsules may have fewer side effects than regular niacin. However, the timed-release versions are more likely to cause liver damage. Regardless of which form of niacin you are using, doctors recommend periodic liver function tests when using high doses (above 100 mg per day) of niacin.
you may find this article helpfl
Niacinamide - Alternative Medicine Review
www.altmedrev.com/publications/7/6/525.pdf
Vitamin B3, also called niacin, is a water-soluble B vitamin. This means that niacin is not stored in the body. You need to eat foods rich in niacin every day. Sources of Vitamin B3 include: meat, liver, Fortified bread, Carrot leaves, turnips, Tuna, chicken breast, beef, halibut, and salmon.
Thanks for the helpful information, Adejoke Yetunde Onaolapo! Considering the risk of liver damage, maybe smoking can somehow deliver Vitamin B3 to the brain faster. And Snus (tabacco extract absorbed through mouth instead of lung) may deliver Vitamin B3 to the brain even more conveniently. Well, I do not smoke or sell tabacco. But the connection between Vitamin B3 and the brain caught my interest.
Well, more details can be found in the following review, which explains that in non-redox reactions, such as the ART, Sir2, PARP reactions, NAD was "split" hence consumed. But every such reaction accompanies the production of NAM(Nicotinamide) that can be used for the synthesis of new NAD. Hence as long as Nicotinamide is recycled, there should be no need for new Vitamin B3. What reaction really kills the Vitamin B3 we constantly consumed?
The review:
Diversification of NAD biological role : the importance of location
by M Di Stefano - 2013 - Cited by 27
if you google, you will find the foods that provide vitamin B 3 such as Liver, pork, groundnuts, beef pork etc.