Biological Function of Vitamin A
Vitamin A is not a single vitamin , but a collective name for a group of structurally related molecules, including retinol, retinal, and retinoic acid . In food it occurs in two main forms: preformed vitamin A (retinoids) from animal products and provitamin A (carotenoids, such as beta-carotene) from plant sources .
Once these nutrients are absorbed by the body, they are stored in the liver and transported to the tissues as needed Here, vitamin A plays several crucial roles:
- Vision Support: Vitamin A is an essential component of rhodopsin, a protein in the retina that absorbs light. This plays a key role in the eyes' ability to adapt in dim light .
- Maintaining healthy skin: It contributes to maintaining the normal structure and function of the skin and mucous membranes, which act as the body's first barrier. .
- Role in the immune system: Vitamin A is involved in the normal functioning of the body's natural defenses by supporting the production and activity of white blood cells. .
- Cell renewal: It plays a role in the process of cell differentiation and the normal growth of cells and tissues .
Nutritional Context: Sources and Intake
A varied diet is the basis for an adequate vitamin A status. Because vitamin A is fat soluble, the body needs fats in meals to efficiently absorb the vitamin in the intestines .
- Liver and liver products (very rich sources) .
- Eggs and dairy products such as milk, butter and cheese .
- Fatty fish such as salmon and mackerel .
Plant sources (Provitamin A):
- Orange and yellow vegetables such as carrots and sweet potatoes .
- Dark green leafy vegetables such as spinach and kale .
- Fruits such as mango, papaya and apricots .
The body converts carotenoids from plants into retinol, although this process is less efficient than the direct absorption of preformed vitamin A from animal sources .
Balance in Status: Deficits and Surpluses
Although vitamin A deficiency is less common in Western countries, it can occur with specific absorption problems or a one-sided diet. . One of the first signs of low status is reduced vision in the dark, also known as night blindness .
On the other hand, vigilance is advised in case of excessive intake. Because vitamin A is stored in the body (especially in the liver), a structurally too high intake through supplements or excessive consumption of liver can lead to hypervitaminosis A . This can manifest itself in complaints such as dizziness, nausea or, in the case of prolonged excess, reduced bone density. .
Quality and Formulation
When selecting supporting nutrients, purity and dosage are of great importance. For adults, the recommended daily amount is usually between 700 and 900 micrograms of retinol equivalents (RE) A supplement should be specifically formulated to meet daily needs without exceeding safe upper limits.
For those seeking targeted support, a high-quality formulation offers a reliable way to ensure vitamin A status, in line with a conscious and healthy lifestyle.
Summary
Vitamin A is an indispensable ally for healthy eyes, skin, and natural defenses. An optimal balance can be achieved through a combination of vegetable carotenoids and animal-based retinol, or targeted supplementation. It's essential to strive for a controlled intake that supports the body's natural processes without burdening them.
FAQ
How much vitamin A do I need per day? The average requirement for adult men is approximately 700 µg and for women 600 µg per day .
Can I get too much vitamin A? Yes, a structural intake of more than 1.5 mg per day from food and supplements may entail risks in the long term. . It is advisable not to eat liver more than once a week if you are also taking vitamin A supplements. .
Is Vitamin A Safe During Pregnancy? Pregnant women are advised to be careful with high doses of vitamin A and avoid eating liver, as an excess can affect fetal development .
What is the role of vitamin A for the skin? Vitamin A plays a role in the maintenance of normal mucous membranes and contributes to the maintenance of healthy skin by being involved in cell renewal .
