Vitamin B6 (pyridoxine / pyridoxal-5-phosphate)

A primary role of vitamin B6 is in production of the neurotransmitter serotonin: it is a co-factor in the pathway for synthesis of serotonin from tryptophan. Because of this role, low levels of vitamin B6 in the blood can be linked to depression[88] (often a symptom of low serotonin). Giving vitamin B6 supplements was found in an early study to increase serotonin levels in the blood in hyperactive children[89]; and a later observational study – also on children – found that higher intake of vitamin B6 and tryptophan at breakfast promoted the synthesis of serotonin when the children were exposed to sunlight for at least 10 minutes.[90]

Vitamin B6 can also be said to have a role in sleep, through its part in serotonin production. Serotonin is of course converted to melatonin, the hormone that regulates the circadian rhythm and sleep cycles. However, there don’t seem to be any clinical trials directly examining the effects of vitamin B6 supplements on sleep.

There is also some evidence that vitamin B6 may have antioxidant effects. A lab study on different forms of B6 including pyridoxine and pyridoxal-5-phosphate found that they could reduce the formation of free radicals and damage to cell membrane lipids (fats).[91]



88. Hvas, AM et al. Vitamin b(6) level is associated with symptoms of depression. Psychother Psychosom. 73(6):340-343, 2004.

89. Bhagavan, H. N., et al. The effect of pyridoxine hydrochloride on blood serotonin and pyridoxal phosphate contents in hyperactive children. Pediatrics. 55(3):437-441, 1975.

90. Nakade M et al. Can breakfast tryptophan and vitamin B6 intake and morning exposure to sunlight promote morning-typology in young children aged 2 to 6 years? J Physiol Anthropol. 2012 May 22;31:11.

91. Kannan, K., et al. Effect of vitamin B(6) on oxygen radicals, mitochondrial membrane potential, and lipid peroxidation in h(2)o(2)-treated U937 monocytes. Free Radic Biol Med. 36(4):423-428, 2004.




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