What is Vitamin A & D?
Vitamin A was the first vitamin to be discovered. It is a family of fat-soluble vitamins. Retinol is one of the most active, or usable, forms of vitamin A, and is found in animal foods such as liver and eggs and in some fortified food products.
Vitamin A is a generic term for a large number of related compounds. Retinol (an alcohol) and retinal (an aldehyde) are often referred to as preformed vitamin A. Retinal can be converted by the body to retinoic acid, the form of vitamin A known to affect gene transcription. Retinol, retinal, retinoic acid, and related compounds are known as retinoids.
Beta-carotene and other carotenoids that can be converted by the body into retinol are referred to as provitamin A carotenoids. Hundreds of different carotenoids are synthesized by plants, but only about 10% of them are provitamin A carotenoids (1). The following discussion will focus mainly on preformed vitamin A and retinoic acid.
Vitamin A is essential for lactation, reproduction and the formation of steroid hormones. It is used to form the cells lining the digestive, respiratory, reproductive and urinary tracts and in all tissue linings of the body. It is also vital for healthy skin and is a famous antioxidant.
It is best absorbed by the body when taken with oil or fat. Individuals with low thyroid function may have a reduced ability to change beta-carotene into vitamin A. For them, vitamin A from animal sources may be better. Each capsule contains 10,000 IU of vitamin A derived from fish oils, 200 percent of the Daily Value
is important in helping the body absorb and use calcium from food and supplements. It aids in bone and tooth formation and supports muscle and nerve function, and studies have shown that vitamin D helps to prevent osteoporosis.
Vitamin D deficiency is the latest of many abnormalities that are being implicated in numerous common maladies from heart disease and strokes to depression and diabetes.
Vitamin D is in fact the only vitamin that humans can produce on their own, rather than having to eat it. Technically, that makes it not a vitamin at all, but it's extremely important for healthy bones. It allows us to absorb calcium and use it to grown and strengthen bones throughout our lives.
As we age, we tend to lose some of our muscle strength. It has been found that this tendency goes hand in hand with a reduction of the vitamin D levels in our blood. By taking a supplement, studies showed that elderly people could increase their muscle strength. So making sure that you get enough of it may keep your muscles healthier for longer along with your bones.
We have learned a great deal more in recent years about Vitamin D and its different forms. We are learning that it may play a more important role than the traditional musculoskeletal health for which it has been known. Vitamin D has long been important for calcium metabolism. An association of low vitamin D levels with a number of other conditions has recently been recognized.
Combination of Vitamin A & D:
Vitamin D works synergistically with vitamin A, we recommend a 7:2 ratio. It plays a role in absorbing and regulating calcium and phosphorus. It also helps build strong bones, teeth and skin. It is vital to the health of the nervous system and kidneys.
Source Naturals Vitamin A & D
Carlson's Vit A+D