Vitamin B6

Vitamin B6 is a required cofactor for the synthesis of dopamine, serotonin, and GABA, and its active form, pyridoxal-5-phosphate (P5P), simultaneously lowers the excitatory neurotransmitter glutamate by converting it into GABA. 2 Peat observed that vitamin B6 is effective for many problems related to the distribution of salts and water, recounting how a single 10 mg dose of pyridoxine hydrochloride stopped intractable diarrhea in a dying child within an hour when a hospital’s intravenous treatments had failed. 2 Roddy notes that high amounts of tryptophan and estrogen suppress vitamin B6, disabling its pro-dopamine, anti-prolactin effects, while adequate B6 facilitates amino acid utilization, supports the liver, and helps regulate glycogen. 4

A central practical distinction exists between the inexpensive precursor pyridoxine hydrochloride and the active coenzyme P5P. Peat warned that it is possible to overdose with either form, but people are finding the active form easier to overdose with; he saw 10 to 20 mg as almost always all a person needs therapeutically, far beyond the normal daily requirement. 1 Dinkov has written that the neuropathy side effect associated with high-dose B6 stems specifically from the failure to convert pyridoxine hydrochloride into P5P, and that P5P itself does not carry this neurotoxic risk. 2 He estimates that P5P has roughly ten times the potency of the standard form, making 5–10 mg of P5P a practical daily dose for most people. 2

Mechanistically, Dinkov positions vitamin B6 as the most potent endogenous, non-steroidal glucocorticoid antagonist, which explains its anticatabolic and muscle-protective actions. 3 By reducing cortisol signaling, B6 shifts the balance from muscle breakdown toward repair and regeneration, and it has been shown to inhibit myostatin expression by about 25–30% while increasing proteins responsible for muscle growth and differentiation. 2 This anabolic profile makes it relevant for counteracting the sarcopenic effects of drugs like metformin and GLP-1 agonists. 3 Dinkov also highlights that a simple deficiency of activated B6 is sufficient to cause full-blown type II diabetes in animals by suppressing mitochondrial function, and that restoring P5P levels may reverse some cases, lending mechanistic support to Peat’s story of his father curing diabetes with Brewer’s yeast. 6

Peat generally did not recommend supplements because foods can provide the vitamins and supplements are always contaminated to some extent in manufacturing, though in extreme cases he recommended small doses of pyridoxine hydrochloride which worked immediately and very well. 5 He dismissed claims that pyridoxine hydrochloride inhibits or depletes P5P activity as marketing rhetoric. 5 Dinkov, while agreeing on the superiority of food sources, has formulated supplements with P5P at doses consistent with Peat’s therapeutic range, noting that some B vitamins including B6 are stored long-term in tissues. 9 Both caution that forum discussions often amplify corporate slander and poorly supported claims about nutrient depletion, and that the purity of individual supplements remains a real issue. 2