Let’s talk a little about vitamin A. Vitamin A is important stuff, but it’s a bit complex. Vitamin A is essential for your health, but because it’s a fat soluble vitamin and can be stored in your body, it’s possible to get too much. It also comes in a couple of forms, both with their virtues and their drawbacks.
Vitamin A is essential for a strong immune system; if you’re short you’ll be susceptible to infections, especially respiratory infections. Vitamin A is important for healthy epithelial cells – these are the cells that line all the surfaces of your body, inside and out: your skin, the inside of your mouth and other orifices, your lungs, the lining of your digestive tract, even the corneas of your eyes. If you’re deficient in vitamin A, you may have dry, thick skin, or even little bumps around your hair follicles. You could have digestive problems, or dry eyes.
Vitamin A plays a role in creating thyroid hormones. This is important to us because a thyroid deficiency makes it near-impossible to lose weight, while also making you sluggish and depressed.
You know how when headlights flash in your eyes at night, your vision takes a little while to recover? That’s because a substance in your retinas called “visual purple,” essential for night vision, is destroyed by light, and takes a little time to regenerate. Vitamin A is an essential component of visual purple. If you see poorly at night, you may need more vitamin A.
Vitamin A is measured in retinol equivalents (REs) or international units (IUs). The RDA is 800 RE for women and 1000 for men, or 4000 IU for women, 5000 for men. There are two sources of vitamin A: preformed vitamin A, and pro-vitamin A. In other words, some food contains actual vitamin A, while other foods contain substances your body can, under ideal circumstances, convert into vitamin A. Preformed vitamin A is found in animal foods, especially fish liver oil, liver, eggs, whole milk, cream, and butter. It is an interesting historical note that when low fat/low cholesterol diets were first proposed in the mid-twentieth century, many doctors objected because they feared the result would be vitamin A deficiency.
Pro-vitamin A, or carotene, is found in deep green and yellow or orange vegetables and fruits. Spinach and broccoli are excellent sources, and very low carb; eat them often. Carrots have a bit more carbohydrate, but are so high in carotenes that just five or six baby carrots will supply your RDA with just 3 grams of usable carb. Cantaloupe and apricots are good sources, and quite low in sugar.
You can easily consume twice the RDA of vitamin A without any problem, and many people may benefit. It is possible to get too much vitamin A, but acute poisoning is rare. It’s mostly limited to children who accidentally overdose on vitamin pills that contain pre-formed vitamin A. This is a very good reason to keep supplements out of the reach of small children. Doses of pre-formed vitamin A over 3000 IU taken daily during pregnancy have been known to cause birth defects; many authorities recommend that pregnant women only take supplements containing pro-vitamin A. There is also some feeling that very high doses of vitamin A, taken over the long haul, may weaken bones.
There’s little risk of vitamin A toxicity from foods, unless you eat liver every day. Since your body only converts carotenes to vitamin A as it is needed – and may not even do that — overdose from pro-vitamin A is unknown. The flipside is that preformed vitamin A is far easier for your body to absorb and use. The degree to which bodies convert carotenes to actual vitamin A varies widely. The solution, it seems, is to eat sources of both forms.
Because our low carb diets include butter, cream, eggs, and cheese, we get more preformed vitamin A than we would on a low fat diet. And since vitamin A made in your body from carotene is better absorbed if you have enough fat in your diet, we’ll use it better than we would on a low fat diet. This question of absorption also makes it clear the folk wisdom behind the tradition of eating vegetables with a source of fat – oil on salads, oil or butter or cream sauces on cooked vegetables: It rendered the vitamins available.
Here’s a great slow cooker side dish that provides both preformed vitamin A from cream and cheese, and plenty of carotenes from spinach.
Spinach Parmesan Casserole
- 2 10-ounce packages frozen chopped spinach, thawed and drained
- 1/3 cup heavy cream
- 1/2 cup shredded Parmesan cheese
- 1 clove garlic, crushed
- 2 tablespoons minced onion
- 1 egg
- 1/2 teaspoon salt
Make sure your spinach is very well drained – it’s best to put it in a colander and press it as hard as you can, turning it several times. Put it in a mixing bowl.
Add everything else, and stir it to blend very well. Spray a 1-quart Pyrex casserole with non-stick cooking spray, and put the spinach mixture in the casserole, smoothing the top. Place the casserole in your slow cooker, and carefully pour water around it up to 1″ of the rim. Cover the pot, set to low, and let cook for 4 hours. Uncover and turn off pot at least 30 minutes before serving time, so the water cools enough that you can remove the dish without scalding yourself.
6 servings, each with: 109 Calories; 8g Fat; 7g Protein; 5g Carbohydrate; 3g Dietary Fiber; 2 g usable carb. 815 RE of vitamin A – roughly 80% of a day’s requirement!
© 2010 by Dana Carpender. Used by permission of the author. What do you think? Please send Dana your comments to Dana Carpender.