Introduction to Vitamin A
Vitamin A is a family of substances called retinoids that includes retinol, retinal, and retinoic acid. These are called preformed vitamin A because they are in a form that your body readily uses. Retinol is the most usable of the three forms and can be converted to both retinal and retinoic acid in your body. They are called preformed vitamin A because, unlike carotenoids, they do not need to be converted to become biologically active.
Benefits of Vitamin A
- Essential for vision.
- Involved in cell differentiation.
- Supports reproduction
- Helps in bone health
- supports and improves immunity
Vitamin A Deficiency Symptoms
- A chronic vitamin A deficiencycan lead to an inability to regenerate rhodopsin, causing night blindness.
- A prolonged vitamin A deficiency can also lead to dryness and permanent damage to the cornea.
- Vitamin A deficiency is the number-one cause of preventable blindness in children.
- A deficiency of vitamin A is also associated with stunting of bones.
Daily Vitamin A Requirements
- Men 19 to 50 years – 900 μg
- Women 19 to 50 years – 700 μg
Vitamin A Upper Limits
- The upper level for adults has been set to 3000 μg
Vitamin A Toxicity
Consuming more than 15,000 micrograms of preformed vitamin A at one time or over a short period of time can lead to nausea, vomiting, headaches, dizziness, and blurred vision
Food Sources of Vitamin A
- Squash, winter, cooked, 1/2 cup – 268 μg
- Spinach, raw, 2 cups – 282 μg
- Green leaf lettuce, 2 cups – 417 μg
- Carrots, baby, raw, 10 medium – 690 μg
- Kale, frozen, cooked, 1 cup – 956 μg
- Sweet potato, baked, 1 medium – 1096 μg
- Collards, frozen, cooked, 1 cup – 1146 μg
- Pumpkin, canned, 1 cup – 1906 μg
- Mango, sliced, raw, 1 cup – 62 μg
- Apricots, dried, 1/2 cup – 117 μg
- Cantaloupe, cubed, 1 cup – 270 μg
- Milk, low fat or skim, 8 oz – 145 μg
- Liver, braised, 3 oz – 8026 μg