Vitamin A is in eggs, dairy (butter, milk, cream), in meat fats like pork and grain-fed beef, in salmon, in liver, in cod liver oil. Vitamin-A precursors (carotenes) get converted into Vitamin A in the body, they are in red and orangey fruits and vegetables such as carrot, tomato, chili, chili-powder spice, bell pepper, sweet potato, apricot, mango, butternut squash, grapefruit, watermelon, papaya, passion fruit, cantaloupe, pumpkin, also in dark greens like kale, collard greens, spinach.
Carotenoids are used as a natural food colouring, beta-carotene is E160a, e.g. I've seen it in Red Leicester cheese, yellow custard powder, red jelly, in glace cherries. American law requires vitamin A fortification in reduced-fat dairy. Companies optionally fortify it in things like wheat flour, or breakfast cereal. Retinoids are in beauty and moisturising skin creams and sun tan lotions, and sometimes used as extreme acne medication.
Things that have been promoted for "good health" for decades, such that someone who wants to avoid it needs to deliberately choose an awkward diet of non-colourful foods like potato, rice, onion, parsnip, coconut, apple, pear, cucumber, zucchini, black beans, white beans, lean meats or carefully chosen meat fats, breads made from un-fortified flour, avoiding many restaurant, take-away, or processed foods and "eat the rainbow" variety of fruit and veg.
Grant Genereux has proposed that overflowing the liver's ability to store and process Vitamin A / retinoids leads to them circulating in the blood, that they can enter cells bypassing the normal methods, can cause damage which makes cells denature and burst, which triggers an immune system response to try and find an attacker, which gets misdiagnosed as the immune system causing the damage. And has proposed this as a mechanism which explains some of the 25 - 50 million Americans having unexplained auto-immune diseases.
Proposing that retinoic acid builds up inside body cells over years and decades even whan taken ordinary 'safe' levels, not enough to trigger hypervitaminosis A or acute symptoms but chronically accumulating until the body has so much of it stored that cell damages releases retinoids into the bloodstream which enter nearby cells, denature some of them, releasing their stored retinoids, causing a domino effect which we know as an auto-immune flare-up. And that it's a matter of luck where the concentration is higher whether that makes a skin rash or a kidney or joint or thyroid inflammation, or just generally high "inflammation".
It's an interesting hypothesis with a lot of specific testable claims and specific proposed mechanisms, mixed with quite a lot of conspiracy theorising and less-testable claims.
I'm past the comment edit window, but incidentally these two Harvard pages[1,2] say that:
- the recommended daily vitamin C is 90mcg for men and 75 for women, the upper limit is 2000mcg. That's a safety margin of 22x, and exceeding the upper limit may cause diarrhoea and gastrointestinal distress.
- the recommended vitamin A is 900mcg for men and 700 for women, and the upper limit is 3000mcg. That's a safety margin of 3.3x, and even that upper limit has "some evidence that this much preformed vitamin A might increase the risk of bone loss, hip fracture, or some birth defects".
- "Sometimes people take cod liver oil for vitamin D but may not be aware it is also very high in vitamin A, beyond the RDA at 192%"
That is, even without any alternative views on it, it's much easier to go above the safe levels, easier to do accidentally, and the risks are more serious.
Carotenoids are used as a natural food colouring, beta-carotene is E160a, e.g. I've seen it in Red Leicester cheese, yellow custard powder, red jelly, in glace cherries. American law requires vitamin A fortification in reduced-fat dairy. Companies optionally fortify it in things like wheat flour, or breakfast cereal. Retinoids are in beauty and moisturising skin creams and sun tan lotions, and sometimes used as extreme acne medication.
Things that have been promoted for "good health" for decades, such that someone who wants to avoid it needs to deliberately choose an awkward diet of non-colourful foods like potato, rice, onion, parsnip, coconut, apple, pear, cucumber, zucchini, black beans, white beans, lean meats or carefully chosen meat fats, breads made from un-fortified flour, avoiding many restaurant, take-away, or processed foods and "eat the rainbow" variety of fruit and veg.
Grant Genereux has proposed that overflowing the liver's ability to store and process Vitamin A / retinoids leads to them circulating in the blood, that they can enter cells bypassing the normal methods, can cause damage which makes cells denature and burst, which triggers an immune system response to try and find an attacker, which gets misdiagnosed as the immune system causing the damage. And has proposed this as a mechanism which explains some of the 25 - 50 million Americans having unexplained auto-immune diseases.
Proposing that retinoic acid builds up inside body cells over years and decades even whan taken ordinary 'safe' levels, not enough to trigger hypervitaminosis A or acute symptoms but chronically accumulating until the body has so much of it stored that cell damages releases retinoids into the bloodstream which enter nearby cells, denature some of them, releasing their stored retinoids, causing a domino effect which we know as an auto-immune flare-up. And that it's a matter of luck where the concentration is higher whether that makes a skin rash or a kidney or joint or thyroid inflammation, or just generally high "inflammation".
It's an interesting hypothesis with a lot of specific testable claims and specific proposed mechanisms, mixed with quite a lot of conspiracy theorising and less-testable claims.