Vitamin B3 (niacin/niacinamide)

Niacin and niacinamide (also known as nicotinamide) are two forms of vitamin B3 that are used in the body – and can be consumed in food or supplements.

Like the other B vitamins, B3 has an important role in metabolism. It is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), coenzymes that are required for over 400 enzymatic reactions in the body, including those involved in energy production.[96]

Vitamin B3 is thought to have antioxidant activity.[97] Several studies have examined this link, including a trial that found reduced DNA damage to lymphocytes (white blood cells) after 8 weeks of supplementation with 100mg of B3 (as niacin).[98]; and a study on 127 older adults that found a link between higher dietary niacin intake and reduced oxidative stress.[99]

There is some suggestion that vitamin B3 could also encourage growth hormone production. A laboratory study using rat pituitary cells found that vitamin B3 (as niacinamide) and its derivatives increased the synthesis of growth hormone in the cells, including in response to triiodothyronine (T3 – a thyroid hormone).[100] While there seem to be few human studies on this, one double-blind trial on 42 adults tested a combination of glycine, glutamine and niacin for its effects on memory, growth hormone secretion and insulin-like growth factor-I (IGF-1), finding that those taking the supplement showed a 70% increase in serum growth hormone levels.[101]

Ensuring the body has adequate levels of vitamin B3 may also support serotonin synthesis. This is because in situations of vitamin B3 deficiency, B3 can be manufactured in the body from tryptophan, the precursor to serotonin. Hence, more of the tryptophan is being used for manufacture of B3 instead of being converted to serotonin. However, again there seems to be little in the way of studies directly examining intake of vitamin B3 in diet or supplements and its effect on serotonin levels.



96. Linus Pauling Institute / Jane Higdon, Ph.D.. 2002. Micronutrient Information Center: Niacin. [ONLINE] Available at: [Accessed 02 April 15].

97. Sahebkar A. Effect of niacin on endothelial function: a systematic review and meta-analysis of randomized controlled trials. Vasc Med. 2014 Feb;19(1):54-66.

98. Weitberg AB. Effect of nicotinic acid supplementation in vivo on oxygen radical-induced genetic damage in human lymphocytes. Mutat Res. 1989 Aug;216(4):197-201.

99. Kaplon RE et al. Vascular endothelial function and oxidative stress are related to dietary niacin intake among healthy middle-aged and older adults. J Appl Physiol (1985). 2014 Jan 15;116(2):156-63.

100. Kimura N et al. Nicotinamide and its derivatives increase growth hormone and prolactin synthesis in cultured GH3 cells: role for ADP-ribosylation in modulating specific gene expression. DNA. 1983;2(3):195-203.

101. Arwert LI et al. Effects of an oral mixture containing glycine, glutamine and niacin on memory, GH and IGF-I secretion in middle-aged and elderly subjects. Nutr Neurosci. 2003 Oct;6(5):269-75.





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