1. What is Vitamin A And Where Does It Come From?
Although vitamin A doesn’t get the good press that some of the more glamorous nutrients such as coenzyme Q-10 and omega-3 fatty acids do, this yellowish, fat-soluble compound deserves respect for its seeming ability to fight respiratory infections, improve lung function in those suffering from emphysema and cystic fibrosis, reduce the sebum buildup that is associated with acne, and even stave off blindness in those with the eye disease retinitis pigmentosa.
If you have any of these conditions, work with a knowledgeable physician who understands the possible uses of vitamin A. But in most cases the amount of vitamin A that we obtain from both quality food sources such as liver and brightly colored vegetables and/or a good multivitamin should be plenty.
A major reason for the ease with which vitamin A can be obtained from diet has to with the ability of three compounds known as carotenoids, alpha-carotene, beta-carotene, beta-cryptoxanthin, to be converted by the liver into vitamin A as needed. Even if the diet lacks pre-formed vitamin A, these three compounds can usually take up the nutritional slack.
The carotenoids are some of the few nutrients you can see without a microscope, since they give many plants and even parrot feathers their distinctive colors. Beta-carotene is the best known of the carotenoids, since so many supplements contain it and because carrots and pumpkins derive their orange hue from it.
2. What Does Vitamin A Do And What Scientific Studies Give Evidence To Support This?
It wasn’t that many years ago that scientists fully expected that research involving beta carotene would show that this nutrient would have powerful cancer-fighting and cardioprotective properties. Unfortunately, studies of beta-carotene have so far yielded decidedly mixed results, and much of the excitement surrounding it has died down. But beta-carotene still shows potential as a powerful quencher of singlet oxygen, a type of free radical implicated in the aging of human skin. (So even if it doesn’t help us live longer, beta-carotene may some day at least enable us to leave better-looking corpses.)
Other carotenoids can’t be converted into vitamin A, but nonetheless so far seem to be living up to their promise as health-protecting nutrients. This is particularly the case with astaxanthin, lycopene, lutein and zeaxanthin.
Astaxanthin gives wild salmon its distinctive pink color. (Farm-raised salmon, by the way, is administered a synthetic dye to make it look wild.) Research on animals and some human clinical trials suggest that this carotenoid may help protect against cataracts and UVA damage to the skin, as well as a number of other serious conditions such as stroke. One Tokyo study involving mice fed a high-fat diet even raises the possibility that astaxanthin may play a role in the prevention of obesity and metabolic syndrome.
Lycopene gives tomatoes their reddish color. Research with this fat-soluble nutrient supports a strong link with protection from prostate cancer—a finding of particular significance, since men who live long enough seem to be destined to develop at least the early stages of this disease. Other studies also suggest the possibility that lycopene may help reduce high blood pressure, a major killer of both men and women.
Lutein and zeaxanthin can be found in leafy green vegetables such as spinach and kale, and also in eggs. These are also the only two carotenoids found in the human eye, which perhaps explains why lutein and zeaxanthin may help reduce the risk of macular degeneration (a leading cause of blindness), as well as cataract formation. Interestingly, lutein consumption also appears to be linked with a lowered risk of both artery blockage and colon cancer.
3. Who Needs Vitamin A And How Much Should Be Taken? Are There Any Side Effects Or Symptoms Of Deficiency?
Keep in mind that both vitamin A and the carotenoids are fat soluble. This means that they require a little fat or oil in your food for absorption. Butter is an okay choice, heart-healty olive oil a better one. Research suggests that carotenoids derived form supplements may be better absorbed than carotenoids from vegetables.
Too much vitamin A has been tentatively linked with certain kinds of birth defects, so pregnant women need to take this nutrient only under the supervision of a doctor. Fortunately, supplement makers have reformulated their prenatal vitamins to reflect the latest research involving vitamin A.
And remember that if you take too much beta-carotene, this can cause the skin to take on a carrot-colored look that is harmless, temporary, and somewhat comical. So follow the label directions when taking this or any other supplement.
The moral of all this research involving carotenoids and vitamin A? Your mother was right when she told you to eat your vegetables. If only she had known about supplements, too.
And remember, you can obtain the best selling vitamin A and carotenoid supplements from A1Supplements.com at the lowest prices!
Author: Kenneth Stevens,
