There does not appear to be any danger of nerve damage from a single night's usage of 1 g of Vitamin B6.
See this document generated by the UK Food Standards Agency for a summary of all tests on B6-induced side effects.
Here are some relevant excerpts from a few studies:
Berger et al, 1992 (p. 86)
Doses of 1000 or 3000 mg/day pyridoxine were administered to three and two healthy volunteers respectively, until the development of symptoms of neuropathy in an experimental study. Symptoms occurred within 1.5 and 3.5 months in high-dose subjects.[/b]
Schaumburg et al., 1983 (p. 87)
This paper describes case reports of seven patients who had ataxia and severe sensory nervous system dysfunction after vitamin B6 consumption. Patients self-prescribed a maximum of 2 – 6 g vitamin B6 daily. Only two of the seven patients started taking the vitamin at such high doses, while others began with doses of 50 to 100 mg/day. None experienced symptoms at doses below 2 g per day.[/b]
Parry and Bredesen, 1985 (p. 87)
The paper describes 16 patients who developed neuropathy after taking high doses of pyridoxine (200-5000 mg/day) for several months or more. The patients developed unstable gait, perioral numbness and a ‘stocking-glove’ sensory loss followed. Discontinuation of pyridoxine was followed by improvement in symptoms. The authors believed that the toxicity of pyridoxine was manifest through an effect on the dorsal root ganglion. Most patients took 2000 mg/day or more pyridoxine (many of these had started at lower doses) and symptoms became apparent within a year of taking 2000 mg/day or more.[/b]
So no, it doesn't look like one night with one gram should have a significant effect. It takes at least a month for neuropathy to start at that dosage.
Vitamin B6-induced neuropathy is most likely a temporary effect caused by a build up of the un-phosphorylated form of pyridoxal, which acts as an antagonist to pyridoxal 5 phosphate (the metabolized form of Vitamin B6). Thus, both deficient and excess amounts Vitamin B6 have the same effects on the body. Since short-term B6 deficiency doesn't cause permanent neuropathy, there's no reason short-term B6 excess should.
On the other hand, it does look like Vitamin B6 excess has some very interesting effects on the central nervous system, as reported in Molimard et al., 1980 (p. 86).
In a second experiment, a group of 30 patients were randomised to receive placebo, 20 mg or 1000 mg/day pyridoxine for 15 days with subjects given a variety of tests before and after treatment. At the high dose, an adverse effect was reported for word recognition, but not for word or visual memorisation. Performance in the visual retention test was worse in the high dose pyridoxine group after treatment.[/b]
This effect is temporary, but it's something to keep in mind if you're dosing up on B6 the night before a big test.
|
|
Bookmarks