Vitamin A is the collective term that is used to refer to a group of fat-soluble vitamins. When vitamin A is in its useful and most active form in the body, it is then referred as RETINOL or PREFORMED VITAMIN A. Retinol as literally defined refers to a pale yellow solid chemical crystal. The two most solid forms of Vitamin A that are used as nutritional supplements are Retinyl Palmitate and Retinyl Acetate. Retinyl Palmitate is a more stable version compared to Retinyl Acetate since it requires higher concentrations just to break it down. The two only differs with how the body absorbs them but both provide the same benefits. Vitamin A’s precursors are carotenoids and more on beta-carotene. This vitamin has related compounds that are very useful to the body as well, these are, retinol, retinal, retinoic acid and they are called retinoids. When retinal is converted to retinoic acid, it can affect the gene transcription. The other related compounds like beta-carotene and other carotenoids are referred to as provitamin A carotenoids.
There are some who manually manufacture Vitamin A through fish liver oil extraction and through beta-ionone synthesis. The human body is capable of obtaining Vitamin A in two ways, one is through carotene manufacture. Carotene is a vitamin A precursor that is usually present in vegetables like carrots, broccoli, squash, spinach, kale and sweet potatoes. Carotene is one of the safest sources of Vitamin A since carotene can be converted to vitamin A in the liver. Another way is through ready-made Vitamin A absorption from plant-eating organisms. During the process of absorption that occurs in the intestines, retinols are combined with chylomicrons which then make an ester form. This ester form is the particle that transports this vitamin to the liver. Vitamin A is stored in the hepatocytes or the liver cells for future use. But when the body calls that it needs vitamin A, it is then released into the blood as a form of alcohol.
FUNCTIONS OF VITAMIN A
- Vitamin A plays an important role in the transformation of light’s reception in the retina to be noted by the brain order to convey a picture
- Helps in giving a person full and clear eyesight or vision
- Boosts the immune system by increasing the activity of antibodies thus preventing a person from obtaining infections
- It helps protect the skin and tissues or mucous membranes inside and outside of the body.
- Aids in a healthy bone and body growth
- Acts in the reproduction and development of normal cells
- Helps keep teeth healthy including the bones, the soft tissue and the mucous membranes
- Prevents a person from suffering health conditions that are caused by oxidative stress like aging, air pollution, arthritis, cancer, cardiovascular diseases, cataracts, diabetes mellitus and infection
- Vitamin A together with other retinoids inhibits the development of tumor especially those with epithelial origin, therefore decreasing the risk of developing cancer
- Helps pregnant women during postpartum repair after birth, maintains their normal vision and fights them off against infections.
According to the US National Institute of Chile Health and Human Development the RDA of Vitamin A is 2,670 IU. According to the US RDA, males who are 11 years and above needs 1,000 RE while for the females who are 11 years and above it is, 800 RE.
BEST FOOD SOURCES OF VITAMIN A
There are two forms of natural vitamin A, preformed Vitamin A and Provitamin A or carotene. The best animal sources of vitamin A are eggs, meat, beef, calf, chicken liver, fish liver oils and also dairy products such as whole milk, whole milk yogurt, cottage cheese, butter and cheese. The best vegetable sources of Vitamin A are carrots, pumpkin, sweet potatoes, winter squashes, cantaloupe, pink grapefruit, apricots, broccoli, spinach and dark green leafy vegetables.
