Vitamin-A :-

Vitamin A helps maintain healthy vision. Without vitamin A, a person could experience vision problems and possibly vision loss. 

Types :-

Vitamin A is not a single vitamin but a collection of compounds known as retinoids. Retinoids occur naturally in the human body, and they are present in some dietary sources.

Some foods provide retinols, which the body can use directly as vitamin A. Others provide provitamin A, compounds that the body converts into vitamin A.

Functions:-

Vitamin A is an essential vitamin needed for growth and development, cell recognition, vision, immune function, and reproduction.

It is a powerful antioxidant and acts as a hormone in the body, affecting the expression of genes and thereby influencing phenotype.

It also helps the heart, lungs, kidneys, and other organs to function correctly.

Retinoic acid, a derivative of vitamin A, has been found to normalizes blood sugar in mice with diabetes.

Vitamin A is important in the growth of all bodily tissues, including skin and hair.

It contributes to the production of sebum, the oil that helps maintain levels of moisture in the skin and hair.

One meta-analysis suggests that some forms of vitamin A may help protect against prostate cancer.

Sources :-

Ready-made retinol, the active form of vitamin A, only comes from animal sources.

The richest sources of retinol are:

• organ meats, such as liver
• fatty fish, such herring and salmon, and fish oils butter, milk, and cheese
• eggs

Plant-based foods contain carotenoids, antioxidant forms of vitamin A. These are converted to retinol in the body.

Carotenoid is an orange pigment that contributes to the color of certain fruits and vegetables.

Vegetable sources that are rich in carotenoids are:

• pumpkin, carrots, squash and other orange-colored vegetables
• sweet potatoes
• orange-colored fruits, such as cantaloupes, papayas, and mangos

Plant foods rich in beta-carotene include:

• broccoli, spinach, turnip greens, and other dark, leafy green vegetables
• zucchini
• peppers

Daily requirements of Vitamin-A:-

The recommended intake of vitamin A varies according to age and sex.

• From 1 to 3 years, the requirement is 300 mcg per day
• From 4 to 8 years, it is 400 mcg per day
• From 9 to 13 years, it is 600 mcg per day
• From 14 years, the requirement for males is 900 mcg per day, and for females, 700 mcg per day
• For women aged 19 to 50 years, the requirement is 770 mcg per day during pregnancy and 1,300 mcg per day while breastfeeding