These values, which vary by age and sex, include:
Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.
Dietary reference intakes for vitamin A:
Infants (AI)
0 to 6 months: 400 micrograms per day (mcg/day)
7 to 12 months: 500 mcg/day
The Recommended Dietary Allowance (RDA) for vitamins is how much of each vitamin most people should get each day.
Contents
A, also known as retinol, has several important functions. These include: helping your body’s natural defence against illness and infection (the immune system) work properly
helping vision in dim light
keeping skin and the lining of some parts of the body, such as the nose, healthy.
Function
Dations for vitamin A, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine.
Children (RDA)
1 to 3 years: 300 mcg/day
4 to 8 years: 400 mcg/day
9 to 13 years: 600 mcg/day
Adolescents and adults (RDA)
Males age 14 and older: 900 mcg/day
Females age 14 and older: 700 mcg/day (for females aged 19 to 50, 770 mcg/day during pregnancy and 1,300 mcg/day during breastfeeding)
The best way to get the daily requirement of important vitamins is to eat a wide variety of fruits, vegetables, fortified dairy foods, legumes (dried beans), lentils, and whole grain.
What Is Vitamin A?
Our bodies absorb vitamin A from animal products better than vitamin A from plant-based foods.
Top Health Categories
Some of the most important functions of Vitamin A are described below.
Vision
Vitamin A is required for the maintenance of normal vision. A deficiency in vitamin A can lead to visual disturbances. In the eyes, a form of vitamin A called retinal is combined with a protein called opsin to give rhodopsin, an essential light absorbing molecule needed for color vision and seeing in dim light.
Immune system
Vitamin A is essential for maintaining healthy immune function and deficiency can lead to an impaired response to infection. Retinol is taken up by the cell where it is oxidized to retinaldehyde (by retinol dehydrogenases), which is then oxidized to give retinoic acid. Retinoic acid binds to these nuclear receptors called in order to regulate gene transcription.
Skin health
Retinoic acid also maintains skin health by activating genes that cause immature skin cells to develop into mature epidermal cells. Currently, the retinoic drug isotretinoin is the most commonly prescribed agent in the treatment of acne.