I'm making the assumption that like me, most of you eat a vast amount of vitamin A rich foods. So I'm wondering if anyone else has had this thought about too much Vitamin A in our diets?
I for one eat loads of oily fish, red meat, eggs, butter, carrots, sweet potatoes and spinach - all of which are high in retinol or beta-carotene which converts to Vitamin A. I don't eat liver (still can't stomach it) but can only image that if I did, that would be total overkill. Can't imagine what people are doing if they also have Cod Liver Oil on top of all this! My daily averages are already +500-1000% the RDI. Is there potential for liver toxicity and I have also read that large doses of retinol can increase one's risk of osteoporosis? Or will maintaining sufficient levels of calcium and Vitamin D offset this risk? Or is this all just void because the body doesn't even convert half the retinol/beta-carotene and hence, doesn't absorb as much Vitamin A as you may think you're consuming?
asked byCoconutBliss (1930)
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on January 09, 2013
at 12:06 PM
The plant forms of vitamin A can't cause retinol overdose.
You're not going to get anywhere near overdose from oily fish (2000kcal mackerel: 30% RDA), butter (2000kcal: 130% RDA) or eggs (2000kcal: 154% RDA). But even eating nothing but eggs and getting 150% of the RDA, you're still only getting 7000IU per day, which is significantly less than the TUI for a 25 year old male, which is 10000IU. But the TUI itself is very conservative and chronic toxicity is more likely to require 4000IU/kg over long periods of time. Obviously you're not going to be anywhere near approaching this from a diet of the above foods or, realistically, from cod liver oil.
Eating liver it is at least physically possible to achieve chronic toxicity. But the risk of vitamin A toxicity is significantly reduced if you have adequate vitamin D. You can still safely at liver once a week without problems (and all the butter you like).
on January 09, 2013
at 02:20 PM
I agree with David Moss' answer and would add that with the amount of A and D we typically get its very important to get enough K2. After reading the book Vitamin K2 and the Calcium Paradox, I added K2 supplementation.
A and D work together to produce all kinds of K2-activated proteins, some of which, when properly activated by K2, direct calcium into bones and teeth and away from soft tissues like arteries and heart valves.
Think about it. The government tells us to stop eating eggs, butter, and animal fats in the 70s and what happens? People start seeing artheriosclerosis on the rise, which is calcification of arteries. Whats in eggs, butter, and animal fats - K2.
There have been studies where women supplemented massive amounts of D and calcium to prevent bone breakage. For every bone they kept from breaking they caused 3 storkes or heart attacks. Turns out the participants were K2 deficient. Add K2 and everything is great. In some cases the K2 actually removed calcium from arteries and heart valves.
Given theres no know toxicity to K2, I load up on it.