This all important vitamin is a catalyst on which innumerable biochemical processes depend. Vit A acts as an antioxidant, protecting the body against pollutants and free radicals. Vit A stimulates the secretion of gastric juices needed for protein digestion, plays a vital role in building strong bones and rich blood, contributes to the production of RNA and is needed for the formation of visual purple.
Vitamin A is involved in the modulation of skin health, vision, the immune system, and gene transcription. Different forms of vitamin A will serve different functions. For example, it is retinoic acid that is involved in gene transcription and the maintenance of skin health; it is retinaldehyde that binds certain proteins to the cones and rods of the eye, allowing the eye to function in low-light environments.
Sources of preformed Vit A (called retinol) include butterfat, egg yolks, liver and other organ meats, seafood and fish liver oils.
Provitamin A or carotene is also a powerful antioxidant. It is found in yellow, red, orange and dark green fruits and vegetables. Carotenes are converted to vitamin A in the upper intestine. Studies show that our bodies cannot convert carotenes into Vit A without the presence of fat in the diet.
It is best to obtain Vit A from natural sources like grass-fed butte, egg yolks, organ meats, fish, shellfish and cod liver oil as high amounts of synthetic Vit A from supplements can be toxic, especially to those with impaired liver function and to those whose diets are otherwise poor.
Antibiotics, laxatives, fat substitutes and cholesterol-lowering drugs interfere with Vit A absorption.
The Human Effect Matrix provided by Examine.com summarises human studies to tell you what effects Vitamin A has on your body, how much evidence there is, and how strong these effects are.
Wrinkles: 3 studies show a NOTABLE effect on wrinkles: The appearance of fine (small) wrinkles appears to be reliably reduced with topical application of a nightly vitamin A cream, with efficacy in all ages assuming fine wrinkles are present.
Skin Dryness: 3 studies show a MINOR effect on skin dryness: Skin dryness is a side-effect of topical application in some persons, increasing in frequency with higher doses; it is mild in severity and, while it may be associated with flaking, rarely causes dropouts.