What Is Vitamin A and What Does It Do?

While vision support is a well-known vitamin A function, this fat-soluble nutrient is also vital for immune balance, skin maintenance, and supporting the integrity of the body’s protective tissues.

Discover the impressive health benefits of consuming vitamin A-rich foods and learn how to maintain optimal levels through natural sources.

What is vitamin A? 

Vitamin A is an essential fat-soluble nutrient that supports vision, immune cell activity, and the maintenance of epithelial tissues throughout the body. 

It also plays a critical role in cellular function and cell renewal, helping maintain the overall functional and structural integrity of various tissues, such as the skin, eyes, respiratory tract, and gut lining. 

Because vitamin A is fat-soluble, it can readily pass through cell membranes, directly influencing cellular functions, including cell growth and regeneration, which is critical for maintaining the stability of various tissues. 

Its fat-soluble nature also allows the body to store vitamin A in the liver and release it gradually as needed. 

Vitamin A exists in two primary dietary forms: 

• Preformed vitamin A (retinol) 
• Beta-carotene

Preformed vitamin A is found in animal foods and is already in the active form the body uses. Because retinol requires minimal conversion, it’s considered an efficient and readily available source of vitamin A.

Beta-carotene, found in colorful vegetables, is classified as a provitamin A carotenoid. This means that it must be converted into retinol before the body can use it. 

The efficiency of this conversion varies significantly among individuals and may depend on factors such as digestion, genetics, thyroid function, and the presence of dietary fat. 

While foods containing beta-carotene can contribute to the body’s vitamin A status, it’s generally a less efficient source than the retinol found in animal foods. 

Watch the video below to learn more about vitamin A sources and signs of deficiency. 

Top vitamin A functions

Vitamin A influences several key physiological processes that help maintain the body’s epithelial tissues and immune system integrity. 

These roles include vision support, tissue renewal, and protecting the surfaces of organs that depend on continuous cellular turnover.

Here are four top functions of vitamin A.

1. Supports healthy vision

Vitamin A is essential for producing rhodopsin, the visual pigment that enables the eyes to see in low light conditions, as well as supporting the stability of the corneal surface and the tear film. 

When vitamin A levels are low, these surface tissues are affected, which may contribute to dry eyes and impaired vision in dim light.

Vitamin A also supports the overall function of retinal tissues, which are central to many aspects of long-term eye health. Insufficient intake over time has been associated with an increased risk of vision concerns, including age-related macular degeneration.

A study published in the UGC CARE Journal notes that retinol and retinyl esters play an important role in maintaining the health of retinal tissues.

The author states, “Vitamin A is known for its antioxidant and anti-inflammatory properties, which

helps counteract the oxidative stress and inflammation in the retina.”

2. Maintains immune balance

Vitamin A helps regulate immune cell communication, particularly in barrier tissues that interact with the external environment, such as the intestinal lining and mucus membranes of the respiratory tract. 

Its active form, retinoic acid, plays a central role in T-cell activity, guiding how these cells recognize exposures, coordinate other immune cells, and maintain balanced immune responses.

Research published in Frontiers in Nutrition highlights how vitamin A metabolites shape T-cell signaling and support coordinated immune regulation, underscoring their importance in maintaining immune balance throughout the body.

3. Promotes skin health

Vitamin A plays a central role in epithelial tissue differentiation, the process by which surface cells develop, mature, and renew themselves. In the skin, this process supports optimal cell turnover and helps maintain a stable, resilient surface. 

Adequate vitamin A availability also supports the organization and integrity of the epidermis, helping the skin function as a protective barrier against environmental exposures. 

Evidence published in Nutrients notes that adequate consumption of vitamin A is vital for the maintenance of healthy skin.

4. Supports nervous system function

The central nervous system controls movement, sensation, mood regulation, and the body’s response to stress. 

Vitamin A supports this system by helping nerve cells develop properly, maintain their structure, and communicate efficiently through retinoic-acid-dependent signaling.

“Vitamin A has potent neuroprotective properties and is essential for the proper function of the nervous system,” explains Dr. Berg. “A healthy nervous system can better cope with stress, as it helps regulate the physical responses to stressors.”

Signs of vitamin A deficiency 

While vitamin A deficiency occurs most often in developing countries, it can affect anyone with low intake or poor absorption.

Prolonged lack of adequate vitamin A intake can cause deficiency symptoms in tissues that require a constant supply, such as the skin, eyes, and immune system.

Common signs of vitamin A deficiency include:

• Dry skin
• Poor night vision
• Dry eyes
• Increased susceptibility to infections
• Rough or bumpy skin (phrynoderma)

Research published in Nutrition Reviews reported that vitamin A deficiency interfered with the normal development and renewal of surface tissues, including those of the eyes, skin, and respiratory tract. 

These tissues rely heavily on vitamin A, which helps explain why deficiency signs commonly appear in these areas.

Best food sources of vitamin A

Vitamin A is derived from retinol in animal foods and beta-carotene in colorful plant foods, and each form affects vitamin A levels differently due to variations in absorption and conversion.

Foods high in retinol

Animal foods supply retinol, the active form of vitamin A that the body can utilize immediately without requiring complex conversion, making retinol-rich foods highly bioavailable.

Some of the best food sources of retinol include:

• Liver and organ meats
• Egg yolks
• Grass-fed butter 
• Full-fat dairy
• Fish and seafood

Like other fat-soluble vitamins, pairing vitamin A-rich foods with healthy fats can support better absorption.

Processed foods often lack vitamin A, highlighting the importance of a diet rich in minimally processed whole-food sources to maintain adequate intake.

Foods high in beta-carotene

Many plants contain beta-carotene, a group of protective pigments that the human body can partially convert into vitamin A. 

Some of the best dietary sources of carotenoids include:

• Dark green leafy vegetables, including spinach and kale
• Orange and yellow vegetables, such as bell peppers and squash 
• Cruciferous vegetables, including broccoli, bok choy, and Brussels sprouts
• Herbs such as parsley and cilantro

However, the conversion rate of carotenoids into active vitamin A is limited and varies widely among individuals, making animal sources of preformed vitamin A a more reliable way to meet the body’s nutritional needs.

FAQ

Sources

1. https://www.researchgate.net/publication/373335526_Role_of_Vitamin-_A_in_the_Prevention_of_Age_Related_Macular_Degeneration_AMD_A_Comprehensive_Review
2. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.914457/full
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC9324272/
4. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1753-4887.1994.tb01386.x