Vitamin A

Learn what Vitamin A is, how it works, its benefits, and how to take it correctly. Expert analysis from SportZone.

What is Vitamin A?

Vitamin A — Vitamin A is a fat-soluble vitamin essential for many vital functions in the human body. It exists in several forms, the most active being retinol, retinal, and retinoic acid, and is known for its key role in vision, the immune system, and cell growth.

🔬 From SportZone's experience

In our work with over 50,000 clients, we see that a large portion of active people underestimate the role of Vitamin A, focusing primarily on Vitamins D and C. Another common mistake is excessive intake of Vitamin A in the form of supplements, which can lead to toxicity, especially when combined with a diet rich in Vitamin A. We recommend moderate and balanced intake tailored to individual needs.

⚡ Vitamin A at a glance

Type: Fat-soluble vitamin
Source: Natural (plant and animal), dietary
Best for: Maintaining vision, immune function, and skin health
Timing of intake: Any time of day, preferably with fats for better absorption
Daily dose: Approximately 700-900 mcg RAE (retinol activity equivalents) for adults
Main benefit: Supports vision in low-light conditions and strengthens the body's defenses.

Explained in simple terms: What does Vitamin A do?

Think of Vitamin A as a "master repairman" for your body, especially skilled at maintaining your eyes, skin, and immune system. It helps your eyes see well in the dark, keeps your skin healthy and smooth, and makes your immune system strong enough to fight off illnesses. Without it, these systems start to "creak" and don't work efficiently.

👉 In other words: Vitamin A is key for clear vision, healthy skin, and a strong immune system, acting as an important defender and regulator in the body.

Scientific explanation of Vitamin A

Vitamin A is a general term for a group of fat-soluble retinoids, including retinol, retinal, retinoic acid, and retinyl esters. It is an essential nutrient, meaning the body cannot synthesize it on its own and must obtain it through diet. In animal products, it is found in the form of retinol (preformed Vitamin A), while in plant products, it occurs as provitamin A carotenoids, the most well-known being beta-carotene. After intake, beta-carotene is cleaved in the intestines and liver to form retinal, which can subsequently be converted to retinol or retinoic acid.

At a molecular level, Vitamin A plays a critical role in gene transcription by binding to nuclear receptors (RAR and RXR), regulating the expression of hundreds of genes involved in cell differentiation, growth, and metabolism. Its metabolites are vital for phototransduction in the retina (retinal), maintaining epithelial tissues (retinoic acid), and modulating immune responses by influencing T-cell and B-cell development and function. Vitamin A deficiency is a leading cause of preventable blindness and increased susceptibility to infections worldwide.

How does Vitamin A work in the body and why is it effective?

The main mechanisms of Vitamin A include:

📚 Scientific sources

Ross, A. C. (2012). Vitamin A and the immune system. Journal of Nutrition, 142(8), 1629S-1633S. (DOI: 10.3945/jn.111.156372)
Dawson, M. I. (2000). Retinoids in the skin. Clinics in Dermatology, 18(5), 585-592. (PubMed ID: 11119525)
Rösch, P. & Heise, B. (2009). Biological functions of retinoids. International Journal of Vitamin and Nutrition Research Supplement, 79(1), 1-10. (PubMed ID: 20112443)
Tanumihardjo, S. A. (2011). Vitamin A and the alleviation of vitamin A deficiency in developing countries: past, present and future. Journal of Biomedical & Biotechnology, 2011, 1-13. (DOI: 10.1155/2011/985935)

Supporting vision — Retinal is a key component of rhodopsin, a pigment found in the retina of the eye. Rhodopsin converts light into electrical signals that the brain interprets as images, allowing us to see, especially in low light.
Regulating cell growth and differentiation — Retinoic acid acts like a hormone, binding to nuclear receptors that control gene expression. This is crucial for the proper development and function of epithelial cells that form the skin, and the mucous membranes of the respiratory, digestive, and genitourinary systems.
Strengthening the immune system — Vitamin A contributes to the development and function of various immune cells, including lymphocytes and phagocytes. It maintains the integrity of mucous membranes, which serve as the first line of defense against pathogens, and modulates antibody production.

👉 End result: Vitamin A ensures optimal functioning of key body systems, leading to better health, a stronger immune system, and improved vision.

What are the proven benefits of Vitamin A intake?

✅ Improves vision, especially in low light — Necessary for the synthesis of rhodopsin, which aids in the eye's adaptation to darkness and prevents night blindness.
✅ Strengthens the immune system — Supports the production and function of white blood cells that fight infections and maintains the integrity of barrier tissues.
✅ Maintains skin and mucous membrane health — Regulates cell growth and differentiation, which is key to maintaining healthy skin, hair, and mucous membranes of the respiratory, digestive, and genitourinary systems.
✅ Antioxidant protection (especially beta-carotene) — Provitamin A carotenoids act as antioxidants, protecting cells from free radical damage, which may reduce the risk of chronic diseases.

How to take Vitamin A for best results?

Dosage: The recommended daily intake for adults is around 700 mcg RAE (retinol activity equivalents) for women and 900 mcg RAE for men. For supplementation, doses between 1500-3000 mcg RAE are often recommended, but it's important not to exceed the upper tolerable limits (usually 3000 mcg RAE per day from supplements) due to the risk of toxicity.

When to take: Since Vitamin A is fat-soluble, it is best absorbed when taken with food containing fat. It can be taken at any time of day – morning, noon, or evening – as long as it is combined with fats.

Practical tip: Always combine Vitamin A intake (especially in supplement form) with a small amount of healthy fat, such as avocado, nuts, or olive oil, for maximum absorption.

Should you take Vitamin A?

✅ Yes, if:

You have deficiency symptoms like night blindness, dry skin, or frequent infections, as Vitamin A is key for these functions.
Your diet is low in orange and green fruits and vegetables, as well as animal products like liver, which can lead to insufficient intake.
You are an athlete or an active person exposed to increased oxidative stress, as the antioxidant properties of provitamin A can aid recovery.

❌ No, if:

You are already taking high doses of other supplements containing Vitamin A to avoid accumulation and potential toxicity.
You regularly consume large amounts of animal liver or other Vitamin A-rich foods, which may provide sufficient amounts.
You are pregnant or planning pregnancy and have not consulted a doctor, as excessive doses of Vitamin A can be teratogenic.

Who is Vitamin A NOT suitable for?

Pregnant women in excessive doses: High doses of Vitamin A (over 3000 mcg RAE per day from supplements) can be teratogenic and cause birth defects.
People with liver diseases: The liver metabolizes Vitamin A, and excessive intake can worsen the condition in cases of existing liver damage.
People consuming large amounts of liver: Liver is extremely rich in Vitamin A, so additional intake can easily lead to toxicity.
Smokers (when taking beta-carotene): Some studies suggest an increased risk of lung cancer in smokers taking high doses of beta-carotene.

Who is Vitamin A most suitable for?

🏋️‍♂️ Strength athletes — Supports tissue recovery after intense workouts and maintains immune function, which can be compromised by stress.
🏃 Endurance athletes — Enhances antioxidant defense against free radicals generated during prolonged exertion and supports vision in various conditions.
🧍‍♂️ Active people — Strengthens overall health, supports immunity against seasonal illnesses, and ensures healthy skin, especially when exposed to external factors.
🌿 Vegans and vegetarians — Since preformed Vitamin A is mainly found in animal products, they may need additional intake of provitamin A (beta-carotene) or supplements to obtain adequate levels.

What combines well with Vitamin A for maximum effect?

Vitamin D — These two fat-soluble vitamins often work synergistically, with Vitamin A potentially modulating the effects of Vitamin D and vice versa, maintaining balance in calcium metabolism and immune function.
Zinc — Zinc is necessary for transporting Vitamin A from the liver and for converting retinol to retinal, making it important for its full absorption and function.
Vitamin E — As a fat-soluble antioxidant, Vitamin E helps protect Vitamin A from oxidation in the body, especially when stored in fatty tissues.

Pros and Cons of Vitamin A

✅ Pros

Key for healthy vision, especially in low light.
Significantly boosts the immune system and resistance to infections.
Maintains skin and mucous membrane health and integrity.
Important for reproductive health and proper fetal development.

❌ Cons

It is fat-soluble and can accumulate in the body, leading to toxicity with excessive intake.
High doses during pregnancy can cause birth defects.
Beta-carotene intake in smokers may increase the risk of lung cancer.

What to compare Vitamin A with?

Understand how Vitamin A differs from other supplements:

Vitamin C — Vitamin A is fat-soluble and key for vision and immunity, while Vitamin C is water-soluble, a powerful antioxidant, and essential for collagen synthesis.
Beta-carotene — Beta-carotene is a provitamin A that the body converts into Vitamin A; it is safer to take in high doses as the body regulates conversion, whereas direct Vitamin A can be toxic.
Omega-3 fatty acids — Vitamin A supports vision and immunity, while Omega-3s are important for brain function, heart health, and reducing inflammation; both are fat-soluble and often work synergistically.