Vitamin A is not just the "eye vitamin". The fat-soluble vitamin is necessary for normal vision, immune defence, skin and mucous membranes, iron metabolism and cell specialisation.
For most people, food is the very basis, but a well-thought-out supplement may be relevant when the diet provides little vitamin A, the conversion from beta-carotene is limited, or the absorption of fat is reduced.
The crucial thing is to know the form and the total dose. Retinol works predictably, but can be stored in the body. Beta-carotene must first be converted and regulated differently. Thus, "vitamin A" on two different labels is not necessarily the same.
In short
- Vitamin A contributes to normal vision, immune system, skin, mucous membranes, iron metabolism and cell specialisation.
- NNR 2023 recommends 700 µg RE daily for adult women and 800 µg RE for adult men.
- EFSA has set an upper tolerable level of 3,000 µg RE per day for ready-made vitamin A from all sources in adults.
- The upper limit is a safety level - not a recommended daily dose.
- A moderate supplement that fills the gap between diet and need usually makes more sense than a high dose.
- Pregnant women, people using retinoid drugs and people with liver disease should clarify retinol supplements with their healthcare professional.
- Smokers and former heavy smokers should avoid beta-carotene supplements. The warning does not apply to beta-carotene from ordinary food.
What is vitamin A?
Vitamin A is a collective term for several closely related substances.
Ready-made vitamin A exists as retinol and retinyl esters, including retinyl palmitate and retinyl acetate. These forms can be used directly by the body.
Provitamin A carotenoids are mainly found in plants. Beta-carotene is the most important of these and must be converted to retinol before the body can use it as vitamin A.
Retinol can further be converted into:
- Retinal, which is part of the vision cycle.
- Retinoic acid, which affects gene expression, cell maturation and cell specialization.
This explains why vitamin A has functions in such diverse tissues as the retina, skin, mucous membranes and the immune system.
Retinol or beta-carotene - what's the difference?
Retinol and retinyl esters
- Provides a direct and relatively predictable source of vitamin A.
- Found naturally in liver, eggs, dairy products and some fish products.
- Can be stored in the liver.
- Therefore, attention is required with long-term use of high doses.
- May be relevant when the conversion from carotenoids is insufficient.
Beta-carotene
- Found in, among other things, carrot, sweet potato, kale, spinach and red pepper.
- Must be converted to active vitamin A.
- The transformation is partially regulated according to the body's needs.
- Absorption and transformation varies between people.
- Absorption is affected by fat in the meal, the food's structure, preparation and individual differences.
- High-dose supplements should not be used by smokers.
EFSA concludes that beta-carotene from ordinary food is not associated with known harmful effects. At the same time, EFSA recommends that supplementary beta-carotene be limited to amounts that are necessary to cover the vitamin A requirement. EFSA: Vitamin A and beta-carotene
What do RE, RAE and IU mean?
Vitamin A can be stated as:
- µg RE – micrograms of retinol equivalents.
- µg RAE – micrograms of retinol activity equivalents.
- IU or IE – international units.
The safest thing is to compare products using the declared amount in µg RE or µg RAE and at the same time check the vitamin form.
For retinol corresponds to:
- 1 µg of retinol approximately 3.33 IU.
- 300 µg of retinol approximately 1,000 IU.
- 1,500 µg retinol approximately 5,000 IU.
- 3,000 µg retinol approximately 10,000 IU.
Other conversion factors apply to retinyl acetate, retinyl palmitate and beta-carotene. Therefore, one should not convert the IU without knowing which form the product contains.
Documented features and benefits
Normal vision and dark adaptation
Retinal is part of rhodopsin, the light-sensitive pigment in the rod cells of the retina. These cells are particularly important in low light.
Inadequate vitamin A can therefore first manifest as poorer dark adaptation or night blindness. Vitamin A helps to maintain normal vision.
However, an extra high intake does not necessarily provide better vision when the need is already met.
Immune defense and mucous membranes
Skin and mucous membranes form an important physical boundary between the body and the environment.
Vitamin A contributes to:
- The normal function of the immune system.
- Maintenance of normal mucous membranes.
- Maintenance of normal skin.
In the case of a real deficiency, correction may be important for normal immune function. It does not mean that high doses prevent or treat infections in otherwise well-nourished people.
Skin and normal cell differentiation
Retinoic acid affects how cells mature and specialize. This gives vitamin A a central role in normal epithelial tissue, including in the skin and mucous membranes.
However, oral vitamin A supplementation is not the same as:
- Prescription retinoid drugs.
- Retinol used in skin care.
- Medical treatment of acne or other skin diseases.
Effect, dose and risk cannot be transferred directly between these product types.
Normal iron metabolism
Vitamin A contributes to normal iron metabolism.
Iron status is simultaneously affected by many other conditions. Vitamin A should therefore not be used as a substitute for examination or treatment of iron deficiency and anaemia.
Growth, reproduction and development
Vitamin A is necessary for normal reproduction, growth and development.
During pregnancy, both insufficient and very high intakes are harmful. The aim is therefore sufficient vitamin A – not to eliminate the vitamin and also not to use a high dose.
A pregnancy-adapted product with a controlled dose is a better starting point than a random high-dose product.
Who can benefit from considering a grant?
A vitamin A supplement may be particularly relevant for:
- People who eat little eggs, dairy products, fish and other sources of ready-made vitamin A, while the intake of colorful vegetables is low.
- People with very one-sided or restrictive diets.
- People after bariatric surgery.
- People with conditions that reduce the absorption of fat.
- People with certain diseases of the intestine, pancreas, liver or bile ducts.
- People with documented vitamin A deficiency.
- Vegans with a low intake of carotenoid-rich vegetables or reduced conversion of beta-carotene.
- People who over time consume very low-fat diets.
Severe vitamin A deficiency is unusual in Norway. Globally, the deficiency is nevertheless an important cause of visual impairment and weakened resistance to infections. WHO: Vitamin A deficiency
Possible signs of deficiency
- Poorer dark adaptation.
- Night blindness.
- Dry eyes.
- Pronounced dryness of the skin and mucous membranes.
- Frequent infections.
- Slow recovery.
- In children: affected growth and development.
These symptoms are non-specific and can have many other causes. They are not in themselves a basis for self-diagnosis or the use of high doses.
Can vitamin A deficiency be measured with a blood test?
Serum retinol can be used as part of a medical assessment, but the result has limitations.
The liver stores vitamin A and helps to keep the concentration in the blood relatively stable. Serum retinol may therefore be normal even if stores start to run low.
The result is also affected by:
- Inflammation and infection.
- Liver function.
- Protein status.
- Production of retinol-binding protein.
- Zinc status.
Diet, risk factors, symptoms and laboratory tests should therefore be assessed together.
Correct dosage – a practical model
NNR 2023 states the following recommended intake for adults:
- Women: 700 µg RE daily.
- Men: 800 µg RE daily.
EFSA's recent European reference values are close to these levels, with 650 µg RE for women and 750 µg RE for men. The difference is due to different assessment frameworks and does not mean that one of the values is a treatment dose. Norwegian Directorate of Health: NNR 2023
Step 1: Calculate what you're already getting
Look at vitamin A from:
- Normal diet.
- Multivitamins.
- Cod liver oil and fish liver oil.
- Meal replacements.
- Protein and nutritional shakes.
- Fortified foods.
- Separate eye, skin or immune products.
Liver and liver paste can contain significant amounts of ready-made vitamin A. A separate supplement must be considered on top of this intake.
Step 2: Choose a dose that fills the gap
For an adult who needs a supplement, a product around the reference intake or lower will often make more sense than a high dose.
A dose of approximately 300–800 µg RE can fill a moderate gap between diet and need.
This is not a universal prescription. In the event of a documented deficiency or reduced fat intake, healthcare personnel may recommend a different dose and follow-up.
Step 3: Take vitamin A with food
Vitamin A and carotenoids are fat soluble. The product should therefore be taken with a meal that contains some fat, for example:
- Eggs.
- Fish.
- Avocado.
- Olive oil.
- Nuts or seeds.
- Dairy products.
This is usually more important than finding a complicated time for dosing.
Step 4: Do not use the upper limit as a target
EFSA has set 3,000 µg RE daily as the upper tolerable level for preformed vitamin A in adults.
The limit applies to the total intake from:
- Food.
- Liver and offal.
- Fortified products.
- Multivitamins.
- Separate food supplements.
3,000 µg RE is equivalent to approximately 10,000 IU retinol. This is a safety limit for long-term intake - not a recommended daily dose. Children have lower age limits. EFSA 2024
Step 5: Reassess the need
A grant should have a defined reason. The need should be reassessed if the following changes:
- Diet.
- Health and digestion.
- Pregnancy.
- Medicinal use.
- Other dietary supplements.
- Use of cod liver oil, fish oil or meal replacements.
When should you be extra careful?
Pregnancy and desire for pregnancy
Vitamin A is necessary during pregnancy, but long-term high intake of ready-made vitamin A can harm fetal development.
Pregnant women should:
- Avoid accidental high-dose products with retinol.
- Do not combine several vitamin A-containing products without calculating the total.
- Check the form and dose of the prenatal product.
- Take into account the intake of liver and liver products.
- Ask for professional advice when using separate retinol supplements.
EFSA's upper level of 3,000 µg RE also includes pregnant women, but this is still a safety limit – not a desired pregnancy dose.
Retinoid drugs
Isotretinoin, acitretin and other retinoid drugs are related to vitamin A.
Vitamin A supplements should not be combined with such drugs without the express approval of the attending physician.
Liver problems and high alcohol intake
The liver stores and metabolizes vitamin A.
People with liver disease or long-term high alcohol intake should clarify the use of ready-made vitamin A with healthcare professionals.
Smoking and beta-carotene
Large long-term studies found an increased risk of lung cancer in heavy smokers who received high doses of beta-carotene.
EFSA therefore recommends that smokers avoid beta-carotene supplements. This does not apply to beta-carotene from vegetables and fruit.
Signs of excessive intake
Prolonged excess of ready-made vitamin A can lead to, among other things:
- Headache.
- Nausea.
- Dry or irritated skin.
- Hair loss.
- Visual disturbances.
- Musculoskeletal disorders.
- Liver influence.
Acute poisoning usually requires significantly higher doses than a normal daily dose, but misuse of concentrated products can be serious. Contact the Poisons Information Center or a doctor in the event of a possible overdose.
How to read the label
- Find the amount of vitamin A per recommended daily dose - not just per capsule.
- Look for µg RE or µg RAE rather than comparing IU alone.
- Find the vitamin form: retinol, retinyl palmitate, retinyl acetate, beta-carotene or a combination.
- Add up vitamin A from all supplements.
- Check whether the product is intended for adults, pregnant women or children.
- Never share an adult high-dose product with children.
- Follow the product's recommended daily dose.
Relevant products at Uno Vita
Product selection, formulation and stock status are subject to change. Always check the appropriate label before use.
- Natural Daily Multi is a vegan multivitamin stated with 100 percent of the reference intake for essential vitamins per capsule. It can be a practical alternative when the goal is broad and moderate basic support.
- Life Extension One-Per-Day Multivitamin combines vitamin A with other micronutrients in one daily tablet. Vitamin A from other products must still be taken into account.
- Two-Per-Day Multivitamin states 1,500 µg RE vitamin A from retinyl acetate and beta-carotene per full daily dose. This is above the Norwegian reference intake and requires extra control of diet and other products.
- Paleo Wild Salmon Roe provides a smaller amount of vitamin A, stated at 30 µg per daily dose, together with marine nutrients. The product is not intended to correct vitamin A deficiency.
What does recent media coverage say?
Media articles often present vitamin A either as a beauty and immune vitamin or as something to be primarily feared.
A more useful conclusion can be found in a more recent, benefit-oriented review: Vitamin A has real functions for vision, the immune system, skin, mucous membranes and reproduction. Subsidies may be relevant in the case of low intake or poor uptake. At the same time, a fat-soluble vitamin must be dosed more consciously than many water-soluble vitamins.
Can I take vitamin A every day?
Yes, an appropriate daily dose can be used when it meets a real need. What is important is the total amount of ready-made vitamin A from food and all products over time.
Is 10,000 IU of vitamin A safe?
10,000 IU retinol corresponds to approximately 3,000 µg RE, which is the EFSA's upper tolerable level for adults. It is not a normal recommended daily dose and should not be used as a standard measure.
Which is better – retinol or beta-carotene?
Retinol is more direct and predictable. Beta-carotene must be converted, and the conversion varies. The choice depends, among other things, on diet, smoking, pregnancy, digestion and the purpose of the supplement.
Can vitamin A help the skin?
Vitamin A contributes to maintaining normal skin and to normal cell specialization. A supplement does not necessarily treat a skin disease, and more vitamin A does not automatically improve skin.
Can vitamin A help night vision?
In the case of vitamin A deficiency, correction can improve poor dark adaptation. In people with sufficient vitamin A status, it has not been documented that extra vitamin A gives better than normal night vision.
Should vegans take vitamin A?
Many vegans get beta-carotene from vegetables. Low vegetable intake, reduced fat absorption or less efficient conversion can still make a supplement relevant. The product must be vegan and the dose controlled.
Can vitamin A be taken together with vitamins D and K?
Yes, these vitamins often occur in the same product. All are fat soluble, so the total dose of each vitamin must be controlled.
How quickly does vitamin A work?
It depends on the starting point. In the event of a deficiency, biological markers and symptoms can change over time. A person who already has enough will not necessarily notice any effect.
Can a blood test show vitamin A deficiency?
Serum retinol can contribute to the investigation, but the test does not always detect a marginal deficiency. The result must be interpreted together with diet, symptoms, inflammation and liver function.
Conclusion
Vitamin A is a necessary nutrient with well-documented functions for vision, immune defense, skin, mucous membranes, iron metabolism and cell specialisation.
Supplements can be a valuable tool when the diet or intake does not cover the need. The best strategy is still precision:
- Choose the right shape.
- Fill a real dietary gap.
- Take the product with food.
- Count the total dose.
- Avoid unnecessary overlap between products.
For most adults, a moderate dose around or below the reference intake is a more natural starting point than 3,000 µg RE. The upper limit is a safety net – not a target.
This is how vitamin A can be used as it should be used: targeted, knowledge-based and without exaggerated promises or unnecessary fear.
Disclaimer
The article is general information and does not replace individual medical assessment. Dietary supplements should not replace a varied diet. Pregnant women, breastfeeding women, children, people with liver disease, people using retinoid drugs and people with suspected deficiency should consult a qualified healthcare professional. The recommended daily dose of the product must not be exceeded.
