What Happens if Vitamin A is Low? Unpacking the Consequences

October 31, 2025 •

4 min read

According to the World Health Organization (WHO), vitamin A deficiency is the leading preventable cause of childhood blindness globally. This startling fact highlights the critical importance of this nutrient and raises the question: what happens if vitamin A is low? The consequences extend far beyond just vision, impacting immunity, skin health, and more.

Quick Summary

A deficiency in vitamin A can trigger serious health problems, including night blindness, xerophthalmia leading to permanent blindness, weakened immunity, and dry, inflamed skin. Untreated deficiency also compromises reproductive health and stunts growth in children.

Key Points

Vision Loss: A key consequence of low vitamin A is night blindness, which can progress to irreversible blindness if left untreated.
Weakened Immune System: Deficiency severely compromises immune function, leading to increased susceptibility to infections, especially in children.
Skin Problems: Low vitamin A levels can cause dry, scaly skin and a condition called follicular hyperkeratosis, where hair follicles become clogged.
Reproductive Issues: Infertility and a higher risk of miscarriage can result from a vitamin A deficiency.
Causes of Deficiency: Inadequate dietary intake is the main cause, but malabsorption disorders (like cystic fibrosis) and chronic liver disease can also lead to low vitamin A.
Prevention and Treatment: The best prevention is a balanced diet rich in vitamin A, while severe deficiencies are treated with supplementation under a doctor's supervision.

The Crucial Role of Vitamin A

Vitamin A is a fat-soluble vitamin essential for numerous bodily functions, playing a vital role in vision, immune function, cell differentiation, and maintaining the integrity of epithelial tissues. It is found in two primary forms: preformed vitamin A (retinol), sourced from animal products, and provitamin A carotenoids, found in plants, which the body converts into retinol. When dietary intake or absorption is inadequate, the body's reserves, primarily stored in the liver, become depleted, leading to a cascade of health issues.

The Impact on Vision: From Night Blindness to Blindness

One of the most well-known consequences of low vitamin A is its devastating effect on vision.

Night Blindness

Night blindness, or nyctalopia, is one of the first and most common signs of a vitamin A deficiency. The vitamin is a key component of rhodopsin, a light-sensitive pigment in the retina's rod cells that enables sight in low-light conditions. A shortage of vitamin A impairs rhodopsin production, making it difficult to see in dim lighting.

The Progression to Xerophthalmia

As the deficiency worsens, it can lead to xerophthalmia, a serious dry eye condition that can cause permanent vision damage. The stages of xerophthalmia, as defined by the WHO, include:

Conjunctival xerosis: Dryness and thickening of the conjunctiva, the clear membrane covering the white of the eye.
Bitot's spots: The appearance of foamy, triangular patches on the conjunctiva, caused by a buildup of keratin.
Corneal xerosis: The cornea becomes dry and hazy.
Keratomalacia: A severe stage where the cornea softens, ulcerates, and can lead to irreversible blindness.

Skin and Immune System Compromise

Vitamin A is vital for the health of both the skin and the immune system, and a deficiency can cause significant issues in these areas.

Weakened Immunity

A lack of vitamin A can be considered a nutritional immunodeficiency disorder. It impairs the body's ability to fight off infections by compromising the production and activity of T- and B-cells. This leaves the individual, especially children, more susceptible to severe infections like measles, pneumonia, and diarrhea, which can increase mortality risk. Vitamin A also helps maintain the integrity of mucosal surfaces in the respiratory, urinary, and gastrointestinal tracts, which act as a barrier against pathogens.

Skin Problems

Vitamin A is crucial for the creation and repair of skin cells. A shortage can lead to several skin conditions:

Dry, rough, and scaly skin: A common symptom, as vitamin A promotes healthy skin cell turnover and function.
Follicular hyperkeratosis (Phrynoderma): This condition causes small, hardened bumps on the skin, particularly on the shoulders, buttocks, elbows, and knees, due to clogged hair follicles.
Poor wound healing: Vitamin A promotes collagen production, and a deficiency can slow the healing of wounds.

Beyond the Obvious: Other Health Risks

Reproductive Issues: Vitamin A is necessary for reproduction in both men and women. Deficiency can lead to infertility, and in pregnant women, it increases the risk of maternal mortality, miscarriage, and birth defects.
Delayed Growth: In children, inadequate vitamin A intake can cause stunted or delayed growth and development.
Poor Bone Health: Vitamin A plays a role in bone cell formation and mineralization. Both insufficient and excessive amounts can compromise bone strength.

What Causes Vitamin A Deficiency?

While most common in developing countries due to poor diet, deficiency can also occur due to other factors.

Malnutrition: Insufficient intake of vitamin A-rich foods is the most frequent cause worldwide.
Malabsorption Disorders: Conditions that affect the absorption of fat-soluble vitamins can lead to a deficiency. This includes celiac disease, cystic fibrosis, chronic diarrhea, and chronic liver disease.
Alcohol Use Disorder: Excessive alcohol consumption can interfere with vitamin A absorption and metabolism.
Increased Requirements: Pregnant and lactating women, as well as rapidly growing children, have higher vitamin A needs.

How to Address Low Vitamin A Levels

For mild cases, increasing dietary intake of vitamin A is often sufficient. In more severe deficiencies, supplementation is necessary and should be administered under medical supervision.

Diagnosis: A doctor may diagnose a deficiency based on clinical symptoms and a blood test measuring serum retinol levels.
Dietary Sources: Incorporate a variety of foods rich in preformed vitamin A and provitamin A carotenoids into your diet.
Supplementation: High-dose vitamin A supplements are used to treat acute deficiency, though infants and pregnant women require carefully managed dosages.

A Comparison of Vitamin A Sources


Feature	Animal Sources (Preformed Vitamin A)	Plant Sources (Provitamin A Carotenoids)
Examples	Beef liver, oily fish (salmon), eggs, dairy products	Orange/yellow vegetables (carrots, sweet potatoes), dark leafy greens (spinach, kale), yellow fruits (mango, cantaloupe)
Absorption	Generally absorbed more efficiently (80-90%).	Variable absorption (40-60%) depending on the food matrix.
Potency	Retinol is the active form and requires no conversion by the body.	Requires conversion by the body, which can be less efficient than direct retinol absorption.
Toxicity Risk	High doses can be toxic due to accumulation in the liver.	High intake does not cause toxicity, though it can cause a harmless yellow-orange skin discoloration.

Conclusion

Understanding what happens if vitamin A is low reveals the essential nature of this nutrient for overall health. The consequences range from serious eye conditions like night blindness and potential blindness to a compromised immune system, poor skin health, and reproductive issues. By ensuring adequate dietary intake from a balanced mix of animal and plant-based foods, and considering supplementation under medical guidance when necessary, these preventable health problems can be effectively avoided. This is particularly crucial for vulnerable populations to protect against morbidity and mortality associated with severe deficiency.

Frequently Asked Questions

The earliest and most common symptom of a vitamin A deficiency is night blindness (nyctalopia), which makes it difficult to see in dim light.

Yes, if left untreated, a severe vitamin A deficiency can lead to xerophthalmia, a dry eye condition that can cause corneal ulcers and ultimately result in permanent blindness.

Yes, low vitamin A compromises the immune system by impairing the function of immune cells. This increases the risk of severe infections like measles and respiratory illnesses, especially in young children.

A deficiency can cause dry, scaly skin and follicular hyperkeratosis, a condition with small, hard bumps on the skin due to blocked hair follicles.

Good sources of vitamin A include animal products like beef liver, oily fish, eggs, and dairy, as well as plant-based foods like sweet potatoes, carrots, spinach, and other leafy greens.

Globally, infants, young children, pregnant women, and lactating women in developing countries are most at risk due to poor dietary intake. In developed nations, those with malabsorption disorders or liver disease are also vulnerable.

Treatment involves vitamin A supplementation, with dosage depending on the patient's age and severity of deficiency. For less severe cases, increasing intake of vitamin A-rich foods is recommended.

Yes, a zinc deficiency can impair the body's ability to transport vitamin A from the liver to other tissues. Therefore, proper vitamin A supplementation may require concomitant zinc supplementation.