Posted by Larry Hoover on November 5, 2002, at 13:44:59
In reply to B vitamins, posted by Kari on November 5, 2002, at 13:21:19
> It is claimed that any excess in B intake results in the vitamins being flushed out. If this is true, why is B6 known to cause neurological damage in excess?
Yes, you'll excrete the excess in your urine, but first the vitamins are in your blood. Your body can be thought of as various compartments. There are membranes separating the compartments, and on each side of the membrane, there are different concentrations of all kinds of different chemicals. Taking B vitamins results in a transient increase in blood concentrations, which permits the various compartments to take up some of them before the kidneys have a chance to waste it all.
There are a number of theories to explain the apparent neurotoxicity of excess B6, but the most compelling is that taking B6, or any of the Bs, in huge doses can cause deficiency in other of the B vitamins. B6 overdose depletes B12, and neurological sequelae are the major sign of B12 deficiency. I've checked medline, and the only reports of B6 neurotoxicity involved taking grams per day for years. There is a myth about B6 toxicity, and it stems from misreporting of this factoid. If you research this issue, I bet you that you'll only find secondary or tertiary references. In other words, the sort like "So-and-so says that...."
> Another strange thing- I once took niacin (25 or 50 mg-I forgot) for two days and ended up practically knocked out with clouded consciousness and unable to feel my arms and legs. Has anyone experienced anything similar?
It depends on the form of the niacin, but nicotinic acid causes vasodilation, and resulting loss of blood pressure. Was the effect transient?
You can avoid it altogether with niacinamide, or inositol nicotinate.B vitamins should always be taken in combination. That's why B-complex formulations exist, and Stress-vitamins all have B-complex in them.
Yes, you'll excrete a lot of it. But, during the time it's coursing through your veins and arteries, your various organs and tissues have a chance to take it up. Once it's gone, they don't get another chance, until you ingest some more.
Lar
poster:Larry Hoover
thread:126299
URL: http://www.dr-bob.org/babble/20021101/msgs/126532.html