Is it better to get vitamin A from animal or plant foods?

There is no single valid answer for everyone. Animal foods provide retinol, which the body uses directly, while plant foods provide carotenoids that are converted into vitamin A as needed. A combination of both groups, adapted to each person's lifestyle and preferences, is usually the most balanced option. In general, prioritizing intensely colored vegetables is a safe and beneficial strategy for overall health.

Can I have too much vitamin A just by eating a lot of vegetables?

In healthy people, it is very unlikely. Pro-vitamin A carotenoids from vegetables are converted into retinol in a regulated way, so they do not usually cause vitamin A toxicity. Very high and prolonged consumption can lead to carotenodermia (an orange skin tone), but this is not intoxication and reverses when the diet is adjusted.

Is vitamin A deficiency common in developed countries?

Severe clinical deficiency is rare in countries with stable access to fresh food. However, subclinical deficiencies or insufficient intakes can occur in people with very poor vegetable diets, chronic digestive problems, high alcohol consumption, or situations of malnutrition. In these cases, individual assessment by a professional is key.

Should I take vitamin A supplements as a precaution?

In most healthy adults with a varied diet, vitamin A supplementation is not necessary. Since excess retinol can be toxic, supplementation with moderate or high doses should always be indicated on a case-by-case basis, especially during pregnancy, lactation, childhood, or when liver or digestive diseases exist. The priority is usually to optimize nutrition first.

Does vitamin A improve established vision problems?

Vitamin A is essential for maintaining normal vision, particularly for night vision. However, it does not correct refractive errors such as myopia, hyperopia, or astigmatism. Its role is functional and preventive support, not direct treatment of these problems, which still require ophthalmological evaluation.

Vitamin A: What is it for?

💡 Key Takeaways

Vitamin A is one of those micronutrients that rarely comes up in everyday conversation, yet it works silently in almost every key system of the body. When we talk about vitamin A, we're talking about normal vision, immune defense, skin and mucous membrane integrity, growth, cell specialization, and iron metabolism. In other words, functions that determine how you feel today and how your body adapts over time.

This article brings together, in one place, the essential information about vitamin A: what it is, how it works, what health claims are authorized in the European Union, and how you can safely meet your needs through your diet. All of this is presented in clear language, without exaggeration or miracle promises, but with a solid scientific basis and a practical approach.

Table of Contents

What exactly is Vitamin A?

Vitamin A is a fat-soluble vitamin, meaning it dissolves in fat and can be stored in the body, primarily in the liver. The name "vitamin A" encompasses a group of compounds with similar biological activity, acting in processes as diverse as vision, immune response, tissue development, reproduction, and the maintenance of organs such as the heart, lungs, and kidneys.

An important characteristic is that the body cannot produce vitamin A from scratch: we must obtain it through diet, either as retinol (active form) or from carotenoids that the body will convert into vitamin A according to its needs.

Forms of Vitamin A: Retinol and Carotenoids

When we talk about vitamin A, we are actually referring to two broad families of molecules:

Retinoids: include retinol, retinal, and retinoic acid. These are the "active" forms of vitamin A, found primarily in animal-derived foods. The body can use them directly.
Provitamin A carotenoids: these are plant pigments, such as beta-carotene, alpha-carotene, or beta-cryptoxanthin. The body converts them to retinol when needed.

This distinction is not merely theoretical: it influences bioavailability, safety, and how the diet should be structured. Retinoids are very effective, but in excess, they can accumulate. Carotenoids, on the other hand, are better regulated: the body limits how much vitamin A it generates from them.

Dietary Sources of Vitamin A

Animal-derived foods (preformed retinol)

Animal foods provide vitamin A in its direct form, mainly as retinol or retinyl esters. Notable sources include:

Liver (beef, chicken, pork, or fish): by far the most concentrated source.
Egg yolk.
Full-fat dairy such as whole milk, butter, and fatty cheeses.
Cod liver oil and other fish liver oils.

These sources are useful when the diet is varied and they are present in moderate amounts. However, due to their high concentration, excessive consumption of liver or supplements containing retinol can easily approach maximum tolerable levels if there is no professional supervision.

Plant-based foods (provitamin A carotenoids)

Carotenoids that the body can convert into vitamin A are found in brightly colored vegetables: oranges, yellows, reds, and dark greens. Among the most interesting sources are:

Carrot.
Sweet potato.
Pumpkin.
Red and orange peppers.
Spinach, kale, and other dark leafy greens.
Apricots, mango, cantaloupe melon.
Microgreens rich in carotenoids, such as red cabbage, kale, or spinach in their tender form.

These vegetables have a double advantage: they provide provitamin A and also offer fiber, additional antioxidants, and other micronutrients that work synergistically. In practice, a diet based on varied colored plants is one of the safest ways to meet vitamin A needs without overdoing it.

How the Body Absorbs and Uses Vitamin A

As a fat-soluble vitamin, vitamin A is absorbed in the small intestine along with dietary fat. This process requires bile, digestive enzymes, and a healthy intestinal lining. Once absorbed, vitamin A travels through the lymph, reaches the liver, and is stored there as esters.

Factors that promote absorption

Consuming vitamin A sources along with healthy fats (extra virgin olive oil, nuts, seeds, avocado).
Maintaining good intestinal health (avoiding uncontrolled chronic inflammation, taking care of the microbiota).
Ensuring adequate production of bile and digestive enzymes.

Factors that reduce bioavailability

Chronically very low-fat diets.
Malabsorption disorders (untreated celiac disease, active inflammatory bowel disease, intestinal resections).
Chronic and high consumption of alcohol, which alters liver metabolism.
Zinc deficiency, which is involved in retinol transport.

All of this means that it's not just about "how much vitamin A you eat," but also the digestive and nutritional context in which it is found.

Vitamin A and Vision: Official Claim and Physiological Reality

European legislation allows the following health claim for vitamin A: "Vitamin A contributes to the maintenance of normal vision."

In practice, this legal phrase translates into several very specific processes:

Retinal, a derivative of vitamin A, is part of rhodopsin, a light-sensitive pigment in the retina. Without it, rhodopsin does not function correctly.
Vitamin A enables dark adaptation, meaning your eyes can transition from a bright environment to one with low light without vision deteriorating.
It contributes to the maintenance of the ocular surface and the mucous membranes that protect the eye.

When vitamin A intake is insufficient for a prolonged period, one of the first signs can be night blindness (difficulty seeing in low light). In severe and sustained deficiencies, more serious alterations such as xerophthalmia can occur, which can irreversibly compromise vision.

Vitamin A and the Immune System: Barriers and Adaptive Response

Vitamin A also has an authorized claim related to defenses: "Vitamin A contributes to the normal function of the immune system."

Its role goes far beyond a simple, temporary "boost of defenses." It is involved in:

The maintenance of the respiratory, digestive, and genitourinary mucous membranes, which act as the first line of defense against pathogens.
The maturation of T and B lymphocytes, key cells in adaptive immunity.
The modulation of inflammation, helping the immune response to be effective without becoming excessive.

Therefore, a sustained, even moderate, deficiency can be associated with an increased risk of infections, especially in the respiratory tract and digestive system. At the other extreme, very high intakes above recommended levels have not been shown to provide an "extra" boost to immunity; rather, they can approach risk levels if derived from retinol in supplements.

Vitamin A, Skin, and Mucous Membranes: Renewal and Protective Barrier

The third major official claim associated with vitamin A is: "Vitamin A contributes to the maintenance of normal skin and mucous membranes."

This phrase summarizes processes we know well at a biological level:

Epidermal renewal: Vitamin A participates in the rate at which skin cells mature, rise to the surface, and renew.
Skin barrier integrity: Skin with good structure and barrier function provides better protection against external agents, excessive water loss, and daily micro-aggressions.
Mucous membrane health: In the mouth, nose, respiratory tract, and digestive tract, vitamin A helps the epithelium remain intact and functional.

For these same mechanisms, vitamin A derivatives (retinoids) are used in dermatology for various skin conditions. However, these uses are pharmacological and must always be supervised by healthcare professionals.

Growth, Cell Specialization, and Development

European regulations also recognize that vitamin A "has a role in the process of cell specialization" and is "necessary for the normal growth and development of children."

In biological terms, this means that vitamin A is involved in the expression of genes that determine what type of cell an immature cell will become. This "specialization" process is key during embryonic development, childhood, and also in tissue repair in adulthood.

In contexts of severe deficiency, especially in countries with food insecurity, a lack of vitamin A has been associated with a higher risk of complications in childhood and higher rates of morbidity and mortality in the first years of life.

Vitamin A and Iron Metabolism

Another authorized claim states that "Vitamin A contributes to normal iron metabolism."

Iron is essential for forming hemoglobin and transporting oxygen in the blood, but for it to function correctly, it needs to be properly mobilized and utilized. Vitamin A helps in this process:

Facilitates the mobilization of iron stored in the liver.
Helps ensure that iron can be properly utilized in the bone marrow and other tissues.

This explains why, in some cases, vitamin A deficiency can coexist with anemia or worsen its progression, even when iron intake is seemingly adequate.

Recommended Amounts and Safety Limits

Scientific bodies establish reference values to guide the safe intake of vitamin A. In Europe, EFSA has proposed reference intakes for adults of around 600–700 µg of retinol equivalents (RE) per day, slightly higher during pregnancy and lactation, and adjusted values for childhood and adolescence.

Additionally, to avoid toxicity, a tolerable upper intake level (UL) is defined for preformed vitamin A (retinol from animal foods and supplements). For adults, this UL is around 3000 µg RE/day of preformed vitamin A. This is not usually reached through a normal diet, but it is relevant when very retinol-rich foods (especially liver) are combined with concentrated supplements.

Provitamin A carotenoids, on the other hand, do not have an established UL in healthy individuals, as the body regulates their conversion and they are rarely associated with vitamin A toxicity. In very high and prolonged consumption, they can color the skin an orange tone (carotenodermia), a reversible and benign effect.

Vitamin A Deficiency: Causes, Signs, and Consequences

Most common causes

In countries with regular access to fruits, vegetables, and animal-derived foods, severe clinical vitamin A deficiency is rare. However, it can occur in specific situations such as:

Diets very low in colored vegetables and animal foods.
Extremely restrictive or monotonous diets (for example, based on ultra-processed foods poor in micronutrients).
Chronic intestinal absorption disorders.
Liver diseases that alter the storage or release of vitamin A.
Chronic high alcohol consumption.

Signs and symptoms of deficiency

Vitamin A deficiency can progress from mild to severe forms. Among the most described symptoms are:

Night blindness or difficulty seeing in low-light environments.
Dry eyes (xerophthalmia), gritty sensation, photophobia.
Increased susceptibility to infections, especially respiratory and gastrointestinal.
Dry, rough, or scaly skin, sometimes accompanied by hyperkeratosis (thickening).
In severe and prolonged deficiencies, alterations in growth and child survival.

In many cases, the deficiency does not occur in isolation but alongside other deficiencies (iron, zinc, proteins), which amplifies its impact.

Excess and Toxicity: When to Be Careful

Just as insufficient intake is problematic, a sustained excess of preformed vitamin A (retinol) can also cause adverse effects. This is almost always observed in relation to:

High and continuous consumption of liver (several times a week) in combination with other retinol-rich sources.
Use of high-dose supplements without professional supervision, especially when combined with a retinol-rich diet.

Possible manifestations of chronic toxicity

Nausea, digestive discomfort, and loss of appetite.
Headache, irritability, fatigue.
Bone or joint pain.
Liver alterations (increased liver enzymes, liver damage).

In special situations, such as pregnancy, it is especially important to avoid excessive retinol from supplements or large amounts of liver. Therefore, any supplementation with medium or high doses of vitamin A should always be evaluated with a healthcare professional.

How to Integrate Vitamin A into Your Daily Life

The good news is that, for most people, there's no need to do anything "extraordinary" to meet vitamin A needs. The most effective approach is usually to adjust the quality of your diet and the variety of vegetables.

Practical and simple ideas

Include orange or dark green vegetables daily (carrots, pumpkin, spinach, kale, broccoli).
Always accompany them with a source of healthy fat (extra virgin olive oil, nuts, seeds, avocado) to facilitate absorption.
If you consume animal-derived foods, moderately incorporate egg yolk and full-fat dairy, and reserve liver for occasional consumption (for example, once a month or as recommended by your healthcare professional).
Vary your fruits: add mango, cantaloupe melon, or apricots when they are in season.
Experiment with microgreens or tender vegetables, which concentrate carotenoids and other micronutrients in a very practical way.

If you are interested in learning more about how to easily integrate more plant-based micronutrients into your daily life, a general article on what microgreens are and another focused on their nutritional value will be useful. You can link them as related content on your blog to build thematic authority.

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Vitamin A: What is it for?

💡 Key Takeaways

What exactly is Vitamin A?

Forms of Vitamin A: Retinol and Carotenoids