What's That About Vitamin A and Folic Acid?

One of the first things we were told when people found out we were pregnant--we heard this from no less than three people and two books--was that we needed to watch out for vitamin A. Dawn should get a prescription for pre-natal vitamins, and we should be wary of vitamin A.
  This struck me as odd. Granted, my expertise with vitamins is limited to a course I had in biochemistry back in high school; but I had an awesome teacher, and he taught us all about supplements and which ones were good and which ones you could just as easily toss over your shoulder and get the same effects as taking them. So I knew from this that vitamin A is toxic in large amounts, and that you can build up vitamin A in your system because it's fat soluble--unlike, say, vitamin C, which is not and is filtered out of your system fairly quickly.
  Nonetheless, you need to take quite a bit of vitamin A before you hit toxic levels. So what was this fear about vitamin A during pregnancy?
  We were especially concerned because my wife and I have been taking these positively enormous vitamin supplements from Twin Labs. Specifically, they're these multivitamins with time-released vitamin C and all sorts of minerals and so on and so forth, called Dual Tabs. What concerns me in vitamin supplements are these factors: Is the vitamin C time-released? Non-time-released vitamin C is a waste of money, because vitamin C is acidic and is filtered by your kidneys very quickly, and without a steady state of C, it doesn't do any good. Are the minerals chelated? Non-chelated minerals are unlikely to be processed. Is there a good balance of the various minerals? Iron requires another mineral for its uptake into the body--I forget which one, maybe it's magnesium--so a supplement containing only iron could easily leave you short on another mineral. The same is true of some other nutrients. Are the binders used in the pills such that your body will never digest them? Is the company known for its high purity, high quality ingredients?
  Well, I don't remember enough from the class to know for sure about the balance of the minerals, and I have no idea how one finds out about binders and such; however, I do recall being told by my teacher that Twin Labs had the best vitamins on the market. I take it on faith that now, eight years later, Twin Labs has not degraded its product. And my wife and I have been very happy with these vitamins, which we've both been taking since I read that large doses of vitamin C can help improve sperm counts in men with low concentrations. (So you see, I'll never know if it was the surgery or the vitamins--some scientist I turned out to be.) Dawn actually reports that when she fails to take the vitamins, she feels more tired and sluggish and weak than when she does take them. To be fair, I haven't noticed this in myself.
  But now, doubt was cast on my faith in my wonder vitamins. Have I been unknowingly poisoning my wife and unborn child with vitamin A? The books and our friends told us we should keep our dosage under 8,000 IUs of A per day--and Dawn was getting close to 18,000 IUs. We were worried.
  Naturally, while we were at the doctor's, we spoke to her about it. She was also concerned about our vitamins, although she noted that the limit of 8,000 IUs a day was not for beta carotene, but other forms of vitamin A. She suggested, however, that Dawn stop taking our vitamins and start taking these prescription pre-natal vitamins called Vitafol, which Dawn did.
  When we got home, though, I checked our bottle of Twin Labs vitamins. My faith in them was somewhat restored: Only 5,000 IUs of the Vitmain A taken by Dawn was in palmitate form--the rest was in beta carotene. I was reminded--though I should have remembered, and I'm sure my biochemistry teacher would take me to task for forgetting--that beta carotene is actually two vitamin A molecules linked, and your body only splits it apart if it needs vitamin A at the time. Thus, beta carotene isn't toxic until taken in much, much higher doses than any other form of A.
  Still, I was concerned. So I did a little research, and I found this article on the Web, from The New England Journal of Medicine. It turns out this sudden concern over vitamin A was all started by a single article in NEJM published at the end of 1995. You can read this editorial itself, but basically, the facts are these: A non-randomized non-double blind study performed and published less than a year ago concluded that certain levels of vitamin A palmitate or acetate may lead to birth defects, and that these levels were much lower than those shown in previous studies.
  This put my mind at ease. Clearly, there isn't a lot to be worried about; and I suspect too many people have been reading The New York Times and not enough have been reading The New England Journal of Medicine. Judging by this article, it would be quite difficult, taking over-the-counter supplements at regular doses, to exceed the recommended amount--assuming this new study is even close to accurate, which it may not be, as only time will tell.

And I'm concerned about these Vitafol vitamins. Why they are prescription-only vitamins is a mystery to me, as they contain just about no vitamins of any kind. There's a little iron and calcium--hardly enough to get upset over--and precious little else in these. And again, I'm worried about binders and chelation and proportions. And these Vitafol pills come with complicated instructions: You can't take them with food, should drink two full glasses of water after you take them, shouldn't have dairy products within two hours of taking them, and so on. And I've never heard of the company that makes them, either.
  I imagine that all these instructions are to ensure proper absorption of the vitamins; and yet, I've never heard of taking vitamins without food.
  I think I might just have to claim ignorance on this whole matter--but we plan to talk our doctor about this at our very next visit. I expect our doctor will go along with our way-cool Twin Labs vitamins and let Dawn take those again. The only thing missing from the Twin Labs pills, in fact, is folic acid.

Which brings us to the folic acid question. How important is folic acid? Well, apparently--according to that article cited previously--folic acid is very important for preventing certain kinds of birth defects, specifically neural tube defects. The neural tube is the structure in the developing fetus which will eventually become the baby's brain and spinal cord, so clearly its proper formation is quite important.
  So the conclusion is: Folic acid is very important, and the daily dose of it should be about 0.4mg; and vitamin A in the form of palmitate, acetate, or retinol is to be taken only in amounts of less than 8,000 IU daily. Beta carotene, on the other hand, is all right.

Of course, none of these studies are as scientific as one would like, since really performing controlled experiments would involve purposely putting babies at risk in one way or another, which isn't very nice. So it really just is a matter of accumulating evidence whenever possible and keeping on top of new information when it comes in.
  And it helps not to be afraid to ask questions and do a little primary research.
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