Niacin or niacinamide supplementation – good or bad idea?
"It was disturbing to some readers when I characterized niacinamide as a pro-aging substance in the March 24 blog post SIRT1, mTOR, NF-kappaB and resveratrol, as it was disturbing to me when I first came to that realization years ago. In response to several blog comments I promised some readers to further research niacinamide and niacin for both health benefits and possible pro-aging hazards, and this blog post reports on that research. I will report on a number of research studies and finally I will give my opinions on how it all comes together and I will even disclose my past secret affair with niacin."
"Niacin or niacinamide supplementation – good or bad idea?" source
"Niacin and Niacinimide
“Nicotinamide, also known as niacinamide and nicotinic acid amide, is the amideof nicotinic acid (vitamin B3/ niacin). Nicotinamide is a water-soluble vitamin and is part of the vitamin B group. Nicotinic acid, also known as niacin, is converted to nicotinamide in vivo, and though the two are identical in their vitamin functions, nicotinamide does not have the same pharmacologic and toxic effects of niacin, which occur incidental to niacin’s conversion. Thus nicotinamide does not reduce cholesterol or cause flushing,[1] although nicotinamide may be toxic to the liver at doses exceeding 3 g/day for adults.[2] In cells, niacin is incorporated into nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), although the pathways for nicotinamide and nicotinic acid are very similar. NAD+ and NADP+ are coenzymes in a wide variety of enzymatic oxidation-reduction reactions.[3] (ref)”
Continuing, “Nicotinamide adenine dinucleotide (NAD) and its relative nicotinamide adenine dinucleotide phosphate (NADP) are two of the most important coenzymes in the cell. NADP is simply NAD with a third phosphate group attached – (ref). — NAD plays several key roles in metabolism. It “participates in many redox reactions in cells, including in glycolysis and most of those in the citric acid cycle of cellular respiration(ref).” And, as I have discussed previously, SIRT1 requires NAD for its actions(ref)(ref).
General information on dietary sources of niacin/niacinamide and problems associated with deficiency of vitamin B3 can be found here and here. “Niacin can be found in nuts, dairy products, lean meats, poultry, fish, and eggs. Some niacin is also supplied by legumes and enriched breads and cereals. The best dietary sources of vitamin B3 are found in beets, brewer’s yeast, beef liver, beef kidney, pork, turkey, chicken, veal, fish, salmon, swordfish, tuna, sunflower seeds, and peanuts. The body can synthesize niacin from the essential amino acid tryptophan, but the synthesis is extremely slow; 60 mg of tryptophan are required to make one milligram of niacin. For this reason, eating lots of tryptophan is not an adequate substitute for consuming niacin. As serotonin synthesis is reliant on tryptophan availability, inadequate dietary intake of vitamin B3 may also therefore lead to depression. The liver is the main storage area for this vitamin and absorption of vitamin B3 takes place in the intestines(ref).”
Further, “Niacin works closely with vitamin B1, vitamin B2, vitamin B6, pantothenic acid, and biotin to break the carbohydrates, fats, and proteins in food . — Vitamin B3 is essential in the metabolism of carbohydrates (to produce energy), fats, and proteins. It also aids in the production of hydrochloric acid, needed for proper digestion. Additionally, vitamin B3 facilitates the body’s ability to eliminate toxins.” — Vitamin B3 is required by the body for digestive processes, activating enzymes which nourish the brain, regulating blood pressure and regulating cholesterol levels.” “Niacin is a water-soluble vitamin that participates in more than 50 metabolic functions, all of which are important in the release of energy from carbohydrates. Because of its pivotal role in so many metabolic functions, niacin is vital in supplying energy to, and maintaining the integrity of, all body cells. Niacin also assists in antioxidant and detoxification functions, and the production of sex and adrenal hormones. Vitamin B3 (niacin, niacinamide, nicotinic acid) lowers cholesterol by preventing its buildup in the liver and arteries. Niacin moves fat from tissues for fat metabolism, burning it for energy. It promotes healthy skin, the health of the myelin sheath (the protective covering of the spinal nerves), and good digestion, where it is also vital for the production of hydrochloric (stomach) acid. It is an aid in protecting the pancreas, and is necessary for the health of all tissue cells(ref).”
The government-recommended daily allowance (RDA) for niacin/niacinamide is 16 mg a day for men, 14 mg for women. The 95th percentile intake for both food and supplements is estimated to be 40-70 mg for both food and supplements(ref). Pharmacological doses of either form of B3 can range from 500mg to 2gm daily. There is a possibility of liver endangerment at the level of 3gms or more daily." click to read more
"Niacin or niacinamide supplementation – good or bad idea?" source