Vitamin A, or retinol, is one of the most important fat-soluble vitamins , which plays an indispensable role in maintaining vision, supporting healthy skin and strengthening the immune system. Since the body cannot produce vitamin A itself, we must obtain it from food or high-quality supplements. In this guide, we will explain what vitamin A is, how it works in the body, which foods contain it, what the daily requirements are, and how to avoid deficiency and the risk of overdose.
Last updated: May 2026
What is vitamin A and its two forms?
Vitamin A is not a single chemical compound, but a group of fat-soluble substances belonging to the retinoid and carotenoid families. It occurs in food in two main forms:
- Active Vitamin A (retinol and retinyl esters): Found only in animal foods. The body can use it immediately and efficiently.
- Vitamin A precursors (provitamin A or carotenoids): The best known of these is beta-carotene, which is found in plant foods (especially orange and yellow vegetables). The body must first convert beta-carotene into active vitamin A in the liver.
Main functions of vitamin A in the body
1. An indispensable role for eyes and vision
Vitamin A is needed to produce rhodopsin, a protein that helps the eyes see in the dark and dim light. The first and most well-known sign of vitamin A deficiency is night blindness, or the inability to see in the dark. It also protects the cornea from drying out and damage.
2. Healthy skin and retinol in beauty products
Retinol (active vitamin A) stimulates cell renewal and collagen production. It keeps the skin elastic, reduces wrinkles and helps treat acne. Vitamin A deficiency can cause the skin to become dry, flaky and rough (keratosis).
3. Strengthening the immune system
Vitamin A is often called the "anti-infective vitamin." It supports the integrity of mucous membranes (eyes, lungs, intestines), which are the body's first line of defense against bacteria and viruses. It also helps produce white blood cells.
The best natural sources of vitamin A
To obtain vitamin A, both animal sources of active retinol and plant sources of beta-carotene should be included in the menu:
| Foodstuff | Vitamin A form | Content (per 100g) |
|---|---|---|
| Beef liver (cooked) | Active retinol | ~9400 µg (super rich source) |
| Cod liver oil | Active retinol | ~30,000 µg (highest concentration) |
| Sweet potato | Beta-carotene | ~960 µg |
| Carrot | Beta-carotene | ~830 µg |
| Butter and cheese | Active retinol | ~300–600 µg |
| Egg (yellow) | Active retinol | ~140 µg |
Daily requirement and dangers (overdose)
The recommended daily allowance for adult men is **900 µg RE** (retinol equivalents) and for women **700 µg RE**. The requirement increases during pregnancy and lactation, but pregnant women should be very careful with synthetic vitamin A supplements, as an overdose can cause fetal damage.
Since it is a fat-soluble vitamin, excess is stored in the liver. **Excessive consumption of plant-based beta-carotene is safe** (skin may turn yellow, but this is harmless), but **excessive consumption of synthetic retinol (>3000 µg per day for a long time) can be toxic**, causing hair loss, dry skin, joint pain and liver damage.
Recommended products and internal links
If your diet is low in liver or orange vegetables, supplements can help optimize levels. In the Omegafit.ee selection you will find high-quality and safe products that contain vitamin A in a natural or balanced form:
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