Vitamin A Deficiency: Night Blindness, Dry Eyes, and At-Risk Groups

Short answer: Vitamin A is a fat-soluble nutrient that your body cannot make on its own, so it must come from food or supplements. Deficiency is uncommon in the United States but can cause night blindness, dry eyes, and impaired immune function, particularly in people with certain medical conditions or dietary restrictions.

What Vitamin A Does in the Body

According to the NIH Office of Dietary Supplements (ODS), vitamin A supports several important physiological processes:

• Vision: Vitamin A is an essential component of rhodopsin, the light-sensitive protein in the retina that allows the eyes to adjust to low-light conditions. It also helps maintain the conjunctival membranes and cornea. The evidence that vitamin A is necessary for normal vision is rated strong by the NIH ODS.
• Immune function: Vitamin A supports normal immune cell activity, and evidence for its role in immune function, cell growth, differentiation, reproduction, and organ development is also rated strong.
• Cell signaling: Vitamin A is involved in cellular communication, influencing how cells respond to signals that regulate growth and development.

Signs of Vitamin A Deficiency

Early deficiency often shows up in the eyes. Night blindness, meaning difficulty seeing in dim light or after moving from a bright environment to a dark one, is one of the earliest recognizable symptoms. This happens because without adequate vitamin A, the body cannot produce enough rhodopsin to support low-light vision.

As deficiency progresses, the conjunctiva and cornea can dry out, a condition called xerophthalmia. In severe cases, the cornea can become ulcerated, which may lead to permanent vision loss. Dry, rough skin and increased susceptibility to infections are also associated with inadequate vitamin A status.

In high-income countries like the United States, severe deficiency is uncommon because most people consume enough vitamin A through a varied diet. However, certain groups are at greater risk.

Who Is at Higher Risk

The NIH ODS identifies several populations that may not get enough vitamin A:

• Premature infants: Preterm infants have lower liver stores of vitamin A at birth and may have difficulty absorbing adequate amounts from formula or breast milk.
• Infants and young children in low-income countries: Vitamin A deficiency remains a leading cause of preventable blindness in children globally. The NIH ODS notes that vitamin A supplementation reduces measles mortality in vitamin A deficient children in low-income settings, though this evidence is rated limited and does not apply broadly to well-nourished populations.
• People with fat malabsorption conditions: Because vitamin A is fat-soluble, conditions such as celiac disease, Crohn's disease, and cystic fibrosis can significantly reduce absorption.
• People with chronic liver disease: The liver is the primary storage site for vitamin A, so liver disease can impair both storage and conversion of the nutrient.
• People with very limited diets: Those who avoid animal products and do not eat enough provitamin A carotenoid-rich fruits and vegetables may have lower intake over time.

How Much Vitamin A Do Adults Need

The NIH ODS expresses vitamin A requirements in micrograms of retinol activity equivalents (mcg RAE), a unit that accounts for the different potencies of preformed vitamin A and provitamin A carotenoids such as beta-carotene.

The Recommended Dietary Allowance (RDA) for adults, as established in the Dietary Reference Intakes published by the National Academies, is 900 mcg RAE per day for men and 700 mcg RAE per day for women. When the source is preformed vitamin A (retinol), 900 mcg RAE is equivalent to approximately 3,000 IU.

The Tolerable Upper Intake Level (UL) for adults aged 19 and older is 3,000 mcg of preformed vitamin A per day, which is approximately 10,000 IU. This upper limit applies to retinol and retinyl esters from both food and supplements combined. Importantly, no upper limit has been set for provitamin A carotenoids such as beta-carotene, because the body regulates how much it converts from plant sources.

Safety and Toxicity

Preformed vitamin A can accumulate in the liver and become toxic when intake consistently exceeds the UL. Symptoms of toxicity, called hypervitaminosis A, can include nausea, dizziness, headaches, and in severe cases, liver damage.

People who are pregnant or may become pregnant should be particularly cautious. The NIH ODS advises that pregnant and lactating individuals should not take high-dose vitamin A supplements exceeding 3,000 mcg per day, as excess preformed vitamin A is associated with birth defects.

For most people eating a varied diet in the United States, vitamin A from food alone is unlikely to reach harmful levels. Concerns about toxicity are primarily relevant to high-dose supplementation.

Drug Interactions to Know

Vitamin A can interact with certain medications. Always talk to a doctor or pharmacist before combining vitamin A supplements with any prescription or over-the-counter drug. Key interactions identified by the NIH ODS include:

• Orlistat (Alli, Xenical): This weight-loss medication can reduce absorption of vitamin A and other fat-soluble vitamins. Manufacturers recommend taking a multivitamin containing vitamin A and beta-carotene when using orlistat.
• Synthetic retinoids such as acitretin (Soriatane) and bexarotene (Targretin): These medications can increase the risk of hypervitaminosis A when combined with vitamin A supplements.
• Retinoid-based therapies such as isotretinoin and etretinate: When combined with excess preformed vitamin A, these medications can contribute to teratogenic effects and birth defects.

A Note on Supplements and Cancer Risk

Some people wonder whether vitamin A or beta-carotene supplements might reduce cancer risk. The NIH ODS rates the evidence for this as insufficient. More importantly, the evidence that high-dose beta-carotene supplements increase lung cancer risk in people who smoke or who were exposed to asbestos is rated strong. People in these groups should avoid high-dose beta-carotene supplements.

When to Talk to a Doctor

If you are experiencing symptoms such as difficulty seeing at night, persistent dry eyes, or frequent infections, speak with a clinician before starting any supplement. A blood test can help determine whether your vitamin A status is actually low.

Supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA. Consult a clinician or pharmacist for personal dosing guidance, especially if you have a medical condition, take prescription medications, or are pregnant or planning to become pregnant.

Sources: NIH Office of Dietary Supplements Vitamin A fact sheets (health professional and consumer versions); National Academies Dietary Reference Intakes for Vitamin A, Vitamin K, and other nutrients (2001).