Vitamin A is fat soluble vitamin that is crucial to many processes in the body. Fat soluble means just that, it needs a certain amount of fat in order to be utilized.
Vitamin A is also called retinol or preformed vitamin A, and it's found in animal sources, like egg yolks, liver and organ meats, butterfat, seafood, and fish liver oils.
This vitamin doesn't play around. It helps in vision, stimulates several immune system activities, acts as anti-oxidant (protecting the body against pollutants and free radicals, hence cancer). It stimulates the secretion of gastric juices needed for protein digestion, plays a crucial role in building strong bones and rich blood.
And there's more.
It helps with cell growth and development and is essential to reproductive processes in both men and women.
Deficiency in vit A affects skin, hair, eyes, and the immune system. It's also been linked with growth retardation and bone abnormalities.
What I recently learned was that when I'm munching and crunching on a, say carrot. I'm getting provitamin A aka carotene. Carotenes are powerful anti-oxidants and are found in yellow, red, orange or dark green fruits and vegetables.
Think spinach, sweet potatoes, kale, collard greens, carrots, and tomatoes.
Once in the body, carotenes are converted to vitaminA in the intestine. That's news to me!
At times, some diabetics, and folks with poor thyroid function cannot make this conversion. Children convert them poorly, and infants not at all. (Thus, getting it from animal sources is good)
Sally Fallon, author of Nourishing Traditions, writes that high amounts of synthetic vitamin A from supplements can be toxic, esp. to those with impaired liver function and whose diets are poor. However, high levels of natural vitamin A have no toxic effects.
(That makes me a bit nervous, and I'll tend to fall back on my momma's advice of everyting being in moderation!! Hmm, but what is moderate? There are the RDA values, but some claim that in reality they are too low! Animals foods are quite potent vs. vegetable sources. And perhaps, as always, variety is best. That includes having a variety of the veggies that we eat...)
Whfoods.com reports that there are no toxic side effects of carotenes(you might get some discoloration in hands/feet, but it's considered harmless and reversible). In fact, Institute of Medicine at the National Academy of Sciences did not establish a Tolerable Upper Intake Level (UL) for carotenoids when it reviewed these compounds in 2000.
There are certain veggies, like carrots that are high in carotenes. And know, when carrots are lightly steamed/cooked, the tough cell walls are broken down and release the beta carotene, making it more available for the body to use. (Aw, shucks, whether, they're raw, cooked, or in bowl of soup, they're just a versatile bunch of folks...)
In any case, all the power to both preformed and provitamin A. They're both important, and for me, it's nice to be aware of what form I'm eating when I'm eating it.
Check it out:
Sally Fallon, Nourishing Traditions