Vitamin B6 (pyridoxine)
A water-soluble vitamin that acts as a cofactor for more than 100 enzymes, essential for protein metabolism, the synthesis of neurotransmitters and the formation of red blood cells.
Vitamin B6 is an enzymatic « Swiss army knife »: a cofactor in more than 100 reactions, mainly in the metabolism of amino acids (protein). It is also crucial for making neurotransmitters (serotonin, dopamine, GABA) and haemoglobin, and for regulating homocysteine.
The original angle (the mood and sleep vitamin): B6 is essential for converting tryptophan into serotonin and then melatonin, and for producing dopamine and GABA. A deficiency can therefore affect mood, sleep and stress management. For this reason it is often combined with magnesium in « anti-stress/sleep » supplements: the B6 + magnesium duo supports the synthesis of calming neurotransmitters.
It is also studied for premenstrual syndrome (PMS): some studies suggest a benefit of B6 on symptoms (mood, irritability), through its role in neurotransmitters.
The toxicity paradox (rare for a water-soluble vitamin): most water-soluble vitamins are eliminated if taken in excess (without toxicity). B6 is an exception: very high-dose, prolonged supplementation can cause neuropathy (nerve problems, tingling). It is one of the few water-soluble vitamins for which overdose (through supplements, never through food) is a real risk. Do not take mega-doses without a reason.
Homocysteine and the heart: together with B9 and B12, B6 regulates homocysteine (an amino acid whose excess is a cardiovascular risk factor). The B6-B9-B12 trio works together on this.
Sources: meat, fish, poultry, banana, potato, chickpeas, pistachios, sunflower seeds, wholegrain cereals.