Supplements: Needed or Not?
WebMD Live Events Transcript
A trip down the vitamin and supplement aisle can confuse even the smartest health consumer. How do you narrow down the choices? Which ones have been proven to work, and how do you know if you need them? We sorted through the supplements with WebMD nutrition expert Kelly Dorfman.
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I am considering purchasing some dietary supplements for daily use. The vitamins and minerals, in many cases, are listed as having up to 225% of the RDA (although in most cases it is about 100% or a little more). Is there a danger in taking more than the RDA (such as kidney or liver damage), or is this actually a recommended thing to do? Also, if there is documented medical evidence or other studies to back this up, I would love to see it.
It depends if you're talking about vitamins or minerals. Minerals are a separate case because you can excrete them easily. So for minerals, you want to stick to approximately the recommended dietary allowances.
For the vitamins, except for vitamin A, that's not as important. If you are a man, you want to make sure your multivitamin does not contain iron at all, because men cannot excrete it and it can tend to cause medical problems. B vitamins, if you take more than the recommended allowance, you urinate out the extra and this is generally not a problem, except with certain medical conditions.
There was a book written a number of years ago called The Right Dose , by Patricia Hausman, and this took several thousand medical studies and distilled them down to determine the safe dosing for supplements. This might be a good resource for you.
This reminds me of the trend of 'mega-doses' of vitamin C that was touted for a while. Are people still doing that? Or was it shown to be unhelpful, dangerous or both?
Some people are still doing it, and vitamin C has a unique situation, in that it will be actively absorbed until you don't need it anymore. At that point, it becomes passively absorbed and causes loose stool. Therefore, it is very difficult to become toxic in vitamin C, because you just get diarrhea and cannot absorb any more.
In an old study they found that up to about 3 grams of vitamin C in the blood improved immune parameters. So I think there still is some evidence that higher doses of vitamin C can be useful.
Many people, including myself, feel the recommended allowances for vitamin C are way too low. Humans are one of the few mammals that don't make vitamin C. (Guinea pigs are another!) So we need a lot more vitamin C. If you actually took as much vitamin C as you would make if you were a mammal of your weight that made it, it would be several thousand milligrams, which is one of the reasons higher levels are recommended.
Does green tea really have any effect on weight loss? It's added to my multivitamin and claims to speed the process.
I am not aware of any components of green tea, other than caffeine, that could shift metabolism. As a weight loss device, I'm dubious. There is, however, an antioxidant in green tea that has been found to help prevent cancer.
|"Many people, including myself, feel the recommended allowances for vitamin C are way too low. Humans are one of the few mammals that don't make vitamin C. (Guinea pigs are another!) So we need a lot more vitamin C."|