High vitamin B6 doses over a long period could cause irreversible nerve damage

And this is hard do to if you weren't intentionally controlling or at least logging your water intake among other factors.

Do you realise that sweating is the body's way of thermoregulating? Your body has partially lost the ability to thermoregulate as much as it used to.

Your conclusion of staying away from vit supplements (as opposed to energy drinks who are not health at all) is a very curious one. If you are anything like the average citizen, you are likely vitamin deficient in some form or another. Staying away from supplements while keeping energy drinks is not a great choice health wise.

Had an experience with a missed type 1 diabetes diagnosis causing neuropathy in a loved one. There is a surprising amount of actionable scientific literature out on neuropathy and all sorts of other issues commonly discussed as best-you-can-do-is-wait-and-see. Once you happen to dig in and start reading.

I remember reading papers on acetyl-L-carnitine helping with diabetic neuropathy, and it was our clear experience that it did help.

There were other supplements which helped with various similar repercussions of a severe and prolonged state of elevated blood sugar, which causes oxidation and tissue damage, and isn’t dissimilar to B6 toxicity as it seems. I don’t remember exactly which nutrients/OTC medications seemed to help neuropathy, but I’d suggest looking into alpha lipoic acid (ALA; more specifically Na-R-ALA), argine, maybe BCAAs in the context of mitochondrial function. Probably some other stuff that has results out on it too.

I’d also suggest reading the molecular biology and neuroimmunobiology on NMDA receptor antagonists and 5-HT2A receptor agonists, classes both of which are shown to be “profoundly immunomodulating” as one paper put it – reducing inflammation, including neuroinflammation – as well as encouraging neuroplasticity, which is also useful in peripheral nerves. The discussion of these known molecular-biological results and implication is unfortunately swamped by various social effects; the best-known NMDA receptor antagonist is called “Ketamine”, haha, and 5-HT2A agonists are usually known as psychedelics and, uh, yeah… molly. The partying and the “wheeee” factor isn’t interesting to me; the neuroimmunobiology of it is!! And I, yeah, I emphatically recommend reading the scientific literature on that.

And generally looking for recent papers on nutrients/supplements/OTC medications in the context of all kinds of similar issues. There are often results in one sub-specialization which are applicable to other things. You don’t need to limit yourself to randomized controlled trials, especially if considering supplementation of compounds known to be safe, rather than medication; Molecular biology is molecular biology, and it’s implausible to me that the placebo effect will reliably improve things like chronic neuropathy. Or insulin sensitivity. I’ve seen direct results on continuous glucose meters and all manner of labwork that confirm this view. —Don’t believe me; I deeply and emphatically recommend reading academic literature.

To paraphrase a nice-seeming guy,

Read papers. Mostly published. Not too slowly.

ps., Claude is unusually good at navigating the scientific landscape!

I drink a zero-calorie energy drink every morning for the past 10 years and I've never had any issues.

Edit: read it again and that's based on 2 tablets per day (I take one) so I guess I get 20mg. Might cut it to every other day though.

That's very hard to believe. In my "normal" vitamin B-Complex supplement there is 20mg of B6 in the daily dose. If 21mg per day would cause nerve damage, that we'd know (and it would be an epidemic).

In pregnant adult women, vitamin B6 is likely safe at a dose of up to 100 mg per day. In adolescent pregnancy, vitamin B6 is likely safe at a dose of up to 80 mg per day.

In lactating adult women, vitamin B6 is likely safe at a dose of up to 100 mg per day. In adolescents who are lactating, vitamin B6 is likely safe at a dose of up to 80 mg per day.

In children, vitamin B6 is likely safe at a daily dose of 30 mg (1-3 yrs), 40 mg (4-8 yrs), 60 mg (9-13 yrs) and 80 mg (14-18 yrs).

The likelihood of side effects increases at doses higher than 200 mg per day.

In 2023, the European Food Safety Authority set an upper limit of vitamin B6 of 12 mg per day for adults, and 2.2 to 10.7 mg per day for infants and children.

Source: https://inspectsupplement.com/vitamin-b6 (Edited Note: My Website)

Interesting that they ostensibly make a version with the P-5-P form. I've read that the P-5-P form is less associated with neuropathy. As a personal anecdote, 50mg of pyridoxine hydrochloride daily for a couple of weeks gave me nothing except numb fingers (which resolved after a few weeks). However, 12mg of P-5-P with my magnesium supplement has been life-changing so far. Been taking 350mg of magnesium daily for a year or more but only when adding the P-5-P with it, do I have relief from cramps.

Anyone in the know: is there some condition that would explain this?

You can take quite an amount of Vitamin D safely, an example: "Results of daily oral dosing with up to 60,000iu of vitamin D3 for 2 to 6 years in 3 adult males"

https://pubmed.ncbi.nlm.nih.gov/28012936/

So, be careful about assuming one economies variant of a pill is the same as another. Same container, same branding.

Without a multi-vitamin I'd likely get some sort of vitamin/nutrient deficiency, I imagine.