Question: I just saw an email from Matt Stone referring to the overly deified nutrient vitamin A. Also, a few Weston A. Price Foundation bloggers are starting to spread the word about being sick on a high vitamin A diet. Any thoughts about this and comments about Vitamin A being toxic?
You shouldn't deify any nutrient, right? Any point of view that breaks down the world into good and bad molecules, is a doomed-to-failure point of view because molecules don't have virtues.
Everything is about context. Too much vitamin A cannot be defined outside of context. Not just what your needs are, not just what your genetics are, not just what your turnover rate is, not just whether you are getting pregnant, but also the presence of other things in the diet. For example, vitamins D, E, and K, which will affect the vitamin A requirement because they all regulate each other's breakdown.
Some people have too much Vitamin A. Some people take more vitamin A then they should. There's dozens of case reports of vitamin A toxicity, but there's no evidence that people at normal intakes who are not supplementing are getting inflammation from consuming dietary levels of vitamin A.
The RDA is 3,000 IU. If you're correcting deficiency, 10,000 IU is highly reasonable over a short period of time. On the other hand, if you have someone who has a very long history of taking vitamin A supplements at 30,000, 40,000, 50,000 IU over 3 years, then, yeah, they might have all kinds of problems from that because they're taking too much. Toxicity is also way more likely if they're not taking vitamin D, vitamin E, or vitamin K.
There's nothing remotely controversial about that; no reason to question it.
There are probably a lot of people in Weston A. Price who think that more of a good thing is better, and I know for a fact that many people were taking two or three tablespoons of high-vitamin cod liver oil for many years. That was nuts then and it's nuts now; they’re getting too many fat-soluble vitamins and too many polyunsaturated fatty acids from high levels of cod liver oil like that.
But again, 3 to 10,000 IU, even long-term, there's no evidence of toxicity. Some people are going to be intolerant. I know anecdotes of people who take vitamin A at very low doses and it causes some hypersensitivity reaction. I don't know what causes it. So there will be stories of people who improve when they take the vitamin A out of their diets. It will happen, it makes sense.
And on top of that there are epidemic proportions of people with fatty liver. What happens when fatty liver gets bad? The cells that store vitamin A in the liver dump their vitamin A into the bloodstream so they can transform into cells that lay scar tissue down in the liver. So people with fatty liver, which is about three-quarters of people who are obese, right, so about 70 million Americans, maybe more now, have fatty liver disease. Some proportion of them are laying down scar tissue in their livers and they are losing the ability to properly store and metabolize vitamin A.
Could taking vitamin A out of the diet for them help? Probably, but it's a very tough place to be in because those people are going to have cellular vitamin A deficiency. So it's like, do you save the liver or do you save everything else? It makes sense to temporarily withdraw vitamin A, but really you need to just fix the obesity and fatty liver disease, then restore vitamin A that is needed.
I have no problem saying that some people take too much vitamin A and that it can be toxic, but there are people going around right now saying that vitamin A is intrinsically toxic, and those people are absolutely nuts. That's flat-Earth level thinking that it's just intrinsically toxic and not a vitamin.
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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