This might be more of a GQ type question, but I’m thinking that I might need my facts to be supplemented with advice in order for me to allay my confusion.
I’ve been trying to improve my diet and nutrition lately, and to that end I’'m planning on doing the green smoothie thing. I’ve even got a spreadsheet where I’m keeping track of what nutrients each ingredient provides.
But I’m completely stumped when it comes to vitamin A. Nutrition labels sometimes list units in mg, sometimes mcg, sometimes IU. Daily recommendation sources list in mcg RAE, or IU. The conversion rate is not entirely clear. Mcg to mg is straightforward, of course, but when I try to switch from or to RAE or IU, I’m somehow supposed to know if I’m dealing with retinol or beta carotine or some other thing. I’m like, it’s a fucking carrot.
So, with a carrot and some kale and some spinach and whatnot, I’m fairly certain I’ll have more than enough vitamin a in my diet, but my math is so confused on this that I’m afraid I might actually be looking forward to ingesting toxic levels. That can be very likely, can it?
IIRC vitamin A toxicity is mostly a risk if you consume it directly as retinol/retinal/etc. for example by eating liver.* Getting it from plant sources as a “pro-vitamin” (e.g. beta carotene) is much less of a worry since your body converts what it needs to Vitamin A and you just excrete the excess.
the usual example is polar bears; they store so much vitamin A in their livers that eating even a very small piece can be extremely dangerous.
I don’t know if I can trust the numbers I’m getting, at all.
The source I’m using (nutritiondata.self.com) has kale at over 10k IU per cup all by itself, and it says it’s 206% of DV. That’s by far the largest number from the veggies I’m looking to include, but spinach, carrot, and chard all have a lot, and the other veggies have a bit, bringing my total, just for the smoothie, to about 30k IU.
Then, I’m thinking of adding a tsp. of spirulina powder, which has 11.5k IU of vitamin A according to one label I saw on Amazon.
I don’t take any vitamin A supplements, aside from what might be in the 2400mg fish oil recommended by my doctor. Except the fish oil label doesn’t mention vitamin A at all.
And of course, there’s no indication as to how any of that vitamin A breaks down in terms of retinol or beta carotene.
And even after looking over those websites, I have no idea if that amount of Vitamin A (42k IU, maybe) in my diet is perfectly fine and reasonable - if a bit more than needed, or absofuckinglutely madhouse suicidal liver poison.
Keep in mind that in the US and other resource-rich countries, clinically significant vitamin A deficiency is almost never seen outside of certain disease states and folks on nutritionally compromising diet regimens. As such, meticulously trying to track your vitamin A consumption (which is best consumed via natural foods, NOT pills/supplements) won’t lead to better health.
I wasn’t worried about not getting enough vitamin A, it’s just that I was doing up a spreadsheet to cover everything I was putting in the smoothie and the vitamin A numbers were high enough to have me worried that I might end up with toxic levels.
As you may know, and as I finally figured out, “Although excess preformed vitamin A can have significant toxicity (known as hypervitaminosis A), large amounts of beta-carotene and other provitamin A carotenoids are not associated with major adverse effects.” from Vitamin A and Carotenoids - Health Professional Fact Sheet
Which is more or less what **jz **was getting at, but more definitively. And I also didn’t fully grok that jz meant to say that plant sources specifically are not preformed, but are pro-vitamin instead.
To be clear, I’m in the clear, as almost all of my vitamin A intake will be from plant sources, and none will be from medication or vitamin A supplements.
You can still have problems if you ingest too much beta-carotene however. Like this guy who was eating about a pound of carrots per day. Which seems like a moderately large, but not ridiculously large amount.