What happens when you have a lack of vitamin A?: Understanding the Health Impacts

October 6, 2025 •

4 min read

Globally, vitamin A deficiency is the leading cause of preventable childhood blindness. Understanding what happens when you have a lack of vitamin A is crucial for preventing serious health consequences related to vision, immunity, and overall development.

Quick Summary

This article explores the health impacts of vitamin A deficiency, detailing its effects on vision, the immune system, skin, and growth, as well as its causes, diagnosis, and prevention.

Key Points

Vision impairment: Night blindness is one of the earliest and most common signs of a vitamin A deficiency.
Irreversible blindness: Untreated deficiency can lead to dry eyes (xerophthalmia) and corneal ulcers, potentially causing permanent vision loss.
Compromised immunity: A lack of vitamin A weakens the immune system, increasing susceptibility to infections, especially respiratory and diarrheal illnesses.
Skin problems: Dry, scaly skin and acne are common symptoms resulting from a deficiency.
Stunted growth: In children, insufficient vitamin A can lead to delayed growth and development.
Risk factors: Individuals with fat malabsorption disorders like cystic fibrosis, chronic diarrhea, and liver disease are at increased risk.
Preventable: Prevention is most effectively achieved through a balanced diet rich in both animal and plant-based sources of vitamin A.

The Impact on Vision: From Night Blindness to Blindness

Vitamin A, also known as retinol, is essential for healthy eyesight. It produces the pigments needed for the retina to function properly, especially in low-light conditions. When intake is insufficient, the eyes cannot create these necessary pigments, leading to a cascade of problems that can worsen over time.

Stages of Eye Damage

The ocular manifestations of vitamin A deficiency, collectively known as xerophthalmia, follow a specific progression.

Night Blindness (Nyctalopia): This is often the earliest and most sensitive indicator of a deficiency. Individuals struggle to see in dim light or darkness because their eyes cannot adapt properly. This condition is reversible with prompt treatment.
Conjunctival Xerosis: As the deficiency progresses, the conjunctiva—the thin membrane covering the whites of the eyes—becomes dry and thick. This is due to the loss of mucus-producing goblet cells. Foamy, whitish patches called Bitot's spots may also appear on the conjunctiva.
Corneal Xerosis: The dryness advances to the cornea, the clear outer layer of the eye. The cornea becomes hazy and dull, and if left untreated, can lead to ulceration and irreversible damage.
Keratomalacia: In the most severe cases, the cornea softens and liquefies, leading to significant structural damage and, ultimately, irreversible blindness. Keratomalacia is particularly devastating in children, with a high mortality rate associated with the condition.

Systemic Health Consequences

While visual problems are the most prominent, a lack of vitamin A affects several other critical bodily functions.

Compromised Immune Function

Vitamin A plays a crucial role in maintaining a robust immune system. It helps the body fight off illness and infection by maintaining the integrity of mucosal barriers in the respiratory, urinary, and intestinal tracts. These barriers are the first line of defense against pathogens. A deficiency weakens these defenses, making individuals, especially children, more susceptible to infections like measles, pneumonia, and diarrheal diseases. This increased susceptibility can significantly increase the risk of morbidity and mortality.

Skin and Growth Issues

Vitamin A is essential for the growth and repair of epithelial cells, which line the skin and internal organs. A deficiency can lead to a condition called hyperkeratosis, where the skin becomes dry, scaly, and rough. In children, a lack of this nutrient can also cause stunted growth and delayed development. Fertility can also be negatively impacted, with a deficiency potentially causing challenges in conception.

Causes and Risk Groups

For most people in developed countries, vitamin A deficiency is rare due to widespread food availability and fortified products. However, it remains a major public health concern in many developing regions.

Inadequate Dietary Intake: This is the most direct cause, common in areas where diets are poor and lack vitamin A-rich foods, often relying on staple crops like rice that contain no vitamin A.
Fat Malabsorption: Since vitamin A is fat-soluble, conditions that interfere with the absorption of fats can lead to a deficiency. This includes diseases like celiac disease, cystic fibrosis, chronic diarrhea, and liver disorders.
Vulnerable Populations: Certain groups are particularly at risk, including:
- Infants and young children in developing countries.
- Pregnant and breastfeeding women, who have increased nutritional needs.
- Individuals with severe protein-energy undernutrition.

Diagnosis, Treatment, and Prevention

Diagnosis is typically based on a clinical examination for symptoms like night blindness and xerophthalmia, often confirmed by a blood test to measure serum retinol levels. A therapeutic trial of vitamin A supplements can also be used to confirm the diagnosis.

Treatment

For diagnosed deficiency, treatment involves vitamin A supplementation, usually with high doses administered over several days. While supplementation can reverse night blindness and dry eyes, it cannot restore vision lost due to corneal scarring. Early detection and intervention are therefore critical to prevent permanent damage.

Prevention

The most effective way to prevent deficiency is through a balanced diet rich in vitamin A. Prevention strategies include:

Consuming diverse foods: Include a variety of animal and plant sources in the diet.
Food fortification programs: In high-risk areas, fortifying staple foods with vitamin A is a proven public health strategy.
Supplementation programs: Mass distribution of vitamin A capsules in endemic regions helps reduce child mortality and morbidity.

Comparing Vitamin A Sources

It's important to understand the different forms of vitamin A found in foods.


Feature	Preformed Vitamin A (Retinol)	Provitamin A Carotenoids (e.g., Beta-carotene)
Source	Animal products (liver, eggs, dairy, fish)	Plant-based foods (carrots, sweet potatoes, dark leafy greens, mangoes)
Body Conversion	Readily available and used by the body	Converted into vitamin A by the body, conversion efficiency can vary
Absorption	Generally more efficiently absorbed	Requires cooking or homogenization and dietary fat for optimal absorption
Risk of Toxicity	High doses, especially from supplements, can be toxic	High intake of beta-carotene from food is generally harmless, though it can cause temporary skin discoloration

Conclusion

Ignoring the early signs of vitamin A deficiency can lead to irreversible and devastating health consequences, particularly vision loss. Beyond the eyes, a lack of this essential nutrient severely impairs the immune system and can hinder childhood development. By ensuring a balanced diet rich in both preformed vitamin A and provitamin A carotenoids, individuals can effectively prevent deficiency and maintain their overall health. For populations at higher risk, supplementation and fortification programs are invaluable public health measures. Taking a proactive approach to your nutrition is the best defense against this preventable condition. More detailed information can be found on authoritative sources such as the National Institutes of Health website.

Frequently Asked Questions

Night blindness is often one of the first symptoms of a deficiency and can develop relatively early in its progression.

Yes, if left untreated, the severe eye damage from a prolonged deficiency, such as keratomalacia, can result in irreversible blindness.

Infants, young children, and pregnant or breastfeeding women in developing countries are at the highest risk. Individuals with fat malabsorption disorders are also vulnerable.

A diagnosis typically involves a clinical examination of symptoms, especially eye-related ones, and can be confirmed with a blood test to measure serum retinol levels.

Excellent sources include animal products like liver, eggs, and dairy, as well as plant-based sources rich in beta-carotene like carrots, sweet potatoes, and leafy greens.

Yes, excess preformed vitamin A, usually from supplements, can be toxic and cause serious side effects like headache, blurred vision, and liver damage. High beta-carotene intake is generally harmless.

Vitamin A helps maintain the linings of the respiratory and intestinal tracts and supports immune cell function. A deficiency weakens these defenses, increasing the risk of infection.

Preformed vitamin A (retinol) is found in animal products and is readily used by the body. Provitamin A (carotenoids) is found in plants and is converted into vitamin A by the body.