Question: Why did the FDA have a vitamin A requirement during pregnancy at 8,000 IU, which is much higher than the IOM recommendations in the past?
I have no idea. I do know that the concerns around vitamin A during pregnancy are that in the first weeks of pregnancy, 10,000 IU and higher has been associated with birth defects. That was one prospective study in 1995, which is higher quality than retrospective studies, but still contradicted all the retrospective studies that came to the opposite conclusion.
So, there's no good consensus on the data, there's just moderately justifiable paranoia about the possibility that you could could cause birth defects. Also, there were like seven or eight letters to the editor about why that study had a bunch of problems with it, like the data just doesn't make sense.
So the basis for restricting A in pregnancy is a theoretical concern that doesn't have a lot of data to support it. That said, I see no reason why someone needs 10,000 IU or more going into the first eight weeks of pregnancy.
If you eat liver once or twice per week, you're not getting more than that. If you took a half a teaspoon of cod liver oil every day, you're not getting more than that. If you eat eggs and dairy every day, you're not getting more than that.
So, I would not supplement with 10,000 IU and higher vitamin A going into pregnancy, not because I'm super paranoid and there is good data justifying the restriction, but because the theoretical concern outweighs the lack of theoretical benefit in most cases for most women.
Now if that woman is trying to get pregnant, but her serum retinol is low and her eyes are dry and her night vision is bad and she has hyperkeratosis, then you bend the rules a little bit because you have an obvious justification to get her vitamin A levels up.
It's just speculation versus speculation, so why not pave the middle ground of what you would reasonably get from food?
This Q&A can also be found as part of a much longer episode, here: https://chrismasterjohnphd.com/podcast/2019/02/24/ask-anything-nutrition-feb-17-2019/
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