Can someone explain this contradiction about B vitamins?

[hedgehog]

We are told that taking excess water soluble vitamins only means that we will make exspensive urine, since the body eliminates the excess,

http://www.guardian.co.uk/science/blog/2009/sep/10/optimum-vitamin-dose-supplements

http://www.huffdevdesign.com/index.php/learning-center/health-articles/78-multivitamins/309-creating-expensive-urine

yet elsewhere, we are warned that we can overdose on these vitamins:

http://www.vitaminstohealth.com/vitamin-overdose.html

http://en.wikipedia.org/wiki/Vitamin_B6

http://www.buzzle.com/articles/folic-acid-overdose-symptoms.html



:shrug:

[jobycom]

1. The body always eliminates toxins, but you can still take more than your body can eliminate.

That would be my guess. Your body still processes them before it eliminates them. It just stops absorbing them and processing them where they are needed. Niacin, for instance, can cause your liver to overproduce certain chemicals, so it isn't the vitamin killing you, it's the reaction of the body to the vitamin.

Just a guess. I'm a bookkeeper, not a doctor. Jim. Dammit. :)

[louis-t]

5. Hmm, I have been taking niacin every day for 35 years.

I have 0 plaque in my arteries, even though my cholesterol is high, I have a family history of severely blocked arteries in men of my age, and I SMOKE! I will look into this further. Thanks.

[jobycom]

6. You have to take a lot before it becomes an issue.

Like 3000 mgs before they even warn you to worry about your liver (1500 mg if it's the slow release kind). After that you get only a small risk until you get much higher. And since it's water soluble, it doesn't store in fat so you don't have to worry about buildup. Basically, if it's not hurting you now, it's probably never going to.

I take niacin, too. :) This was all research I did on it when I started. If your doctor tells you something different, by all means don't take my word over hers. :)

[louis-t]

10. Only taking 100 mg.

I like to think it has helped me dodge the genetic bullet.

[Warpy]

2. Both are true, silly

because there is a limit to what our kidneys can push out of our bodies on any given day.

People who take a B-50 stresstab once a day will have expensive urine.

People who take a handful of B-200 tabs a day will run into overdose problems eventually.

[Zoeisright]

3. Well, first of all, there's a difference between excess vitamin intake and

a megadose. It's never wise to take megadoses of anything.

Secondly, Vitamins A, K, D, and E are fat-soluble vitamins and it's fairly easy to overdose on them.

And the RDA for vitamin intake is not intended to prevent disease - it's really the minimum needed for good health. You can take more of the water-soluble vitamins, but your body will, as the first two articles say, only use as much as YOU PERSONALLY need then flush the rest.

It's the megadosing where you get into trouble.

[hlthe2b]

4. The B vitamins work in concert....

very high doses sustained over time can create a feedback loop that impacts the other B vitamins (whether through decreased absorption or other mechanisms).... The main issue is with very very high levels of folic acid (B6) over a long period of time creating some temporary neurological effects... Yes, excess is excreted in the urine, but I think the effects of high dose over time are more one of imbalance of the other important B vitamins than pure toxicity. And yes, as has already been mentioned, we are talking mega doses, not just excess.

[hedgehog]

7. So, an excess dose would be...? and a mega dose would be..?

[hlthe2b]

8. There could be some individual variation... but...

the current RDA for B6 (pyrodoxine )is 25 miligrams (mg) and is generally considered safe below 200 mg/day; folic acid RDA is 400 micrograms(mcg) but can become problematic over 15 miligrams (mg). So there is really a pretty wide margin of safety between RDA levels, those that might be seen in supplements, and those mega doses that could become harmful. The other b vitamins are probably not as concerning, but should probably be taken together as a b-complex supplement, rather than individual large doses unless recommended by your health provider for a specific purpose (e.g., B12 for those taking high doses of stomach acid inhibitors, for example).


SInce some vitamins/minerals are measured in miligrams, others in micrograms (1/1000th of a miligram), and others in international units, supplementing at higher doses requires considerable attention to what you are taking and how it is measured. Confusion over the measuring unit might be one way that people get themselves in trouble.

Generally, though, the principle still applies: water soluble vitamins are far safer than fat-soluble (e.g., A, E, D, and K) because healthy people will excrete the excess water soluble vitamins through urine.

[hedgehog]

9. My thanks to everyone who replied - since most articles are either

pushing vitamins or pooh-poohing the need for supplements, I was having trouble seperating the wheat from the chaff.