10 replies to this topic

[shifter]

I've been wondering what the upper threshold for safe supplementing is of certain vitamins&minerals.

I know the RDI is the minimum amount required to stave off nasty effects but some 'supplements' give 1000's times more than the RDI so was wondering what are safe upper doses for each vitamin?

I have just started taking NOWs Gamma E complex and that provides me with 400IU or 1330% of the RDI, is that fine to take every day? (natural vitamin E )
And with Vitamin B, why is so much put in when so much just goes out at once? I prefer to have lower doses but take multiple times a day. Found a pretty good one from Country life though with there 'coenzyme' formula which i'll be giving a try.

So is there an 'agreed' upper limit for these things as well?

[OutOfThyme]

Maybe I can help with the first part of your question. A good place to start would be Medline. The basic vitamins are listed under "V". See if that works for you.

I often visit CL, for that sort of info, but it requires subscription. The above is free.

[jdog]

Oh man, I can't believe all this time I haven't known about Medline's database of all these substances. Thanks for the link!

[pycnogenol]

You can try www.naturalstandard.com database on ULs.

I registered with them over a week ago and get a "Sorry, you do not have access
to this page. Please contact a system administrator."

I contacted them about the access issue and still have not heard back.

[shamus]

You should watch out for too much Vitamin A, Zinc and Selenium.


Speaking of the devil, how much Zinc is too much?

[EmbraceUnity]

I take the LEF Mix and Super Booster which together have 400mcg of Selenium. I was looking into Wolfberries since many people like them, but I decided to stay away from them since they have 50mcg of Selenium and I am already at the "tolerable upper limit" of 400mcg for Selenium.

http://ods.od.nih.go...selenium.asp#h7

I do take 6 grams of vitamin C per day though, and supposedly vitamin C inhibits selenium absorption. So are my fears unfounded?

[krillin]

I take the LEF Mix and Super Booster which together have 400mcg of Selenium. I was looking into Wolfberries since many people like them, but I decided to stay away from them since they have 50mcg of Selenium and I am already at the "tolerable upper limit" of 400mcg for Selenium.

http://ods.od.nih.go...selenium.asp#h7

The selenate and selenomethionine in LEF's products are obsolete. Join the rest of us on the AOR bandwagon. Both Multi-Basics 3 and Ortho-Core only have Se-Methylselenocysteine.

http://www.aor.ca/us...2003_Spring.pdf

I do take 6 grams of vitamin C per day though, and supposedly vitamin C inhibits selenium absorption. So are my fears unfounded?

Vitamin C only interferes with selenITE absorption.

[EmbraceUnity]

Actually the newest formulations of the LEF Mix and Booster contain Se-methylselenocysteine. Half of the selenium they use is in SeMC form, the rest is in the other forms. This seems reasonable to me, but I suppose it is arguably suboptimal

Where are you getting your information that Vitamin C only affects Selenite and not other forms of Selenium?

Edited by progressive, 11 April 2007 - 07:33 PM.

[krillin]

Where are you getting your information that Vitamin C only affects Selenite and not other forms of Selenium?

"Results showed that the protective effect of selenite in tumorigenesis was nullified by vitamin C, whereas the chemopreventive action of seleno-DL-methionine was not affected"

http://www.ncbi.nlm....2&dopt=Abstract

The following isn't peer reviewed, but is a nice summary of the different forms of selenium.

http://www.nutri.com/wn/sel.html

[xanadu]

Avoid all megadoses, just for starters. Taking about 2x the rda is a good safe place to start. A few things you might want to go to 10 or 20x like with C or folic acid. I am suspicious of huge doses of anything even resveratrol.

[donjoe]

I think with reasonable megadoses your biggest problem would be that after a while you become adapted to them and if you drop back to "normal" levels you may develop deficiency symptoms. (Basically, it just means you have to make a reserve in case something happens and you can't renew your supply for a while. Or if you really want to give up, it means you have to lower your doses gradually.)

As far as B-complex goes, like shifter said, mostly it's thought megadoses are a waste since there's an upper limit to how much your body can absorb. But some research suggests there's another absorption mechanism that enables us to actually benefit from the extra quantities:
http://www.quantium....tm#_Toc22709835