Vitamin A deficiency is the cause of night blindness. Your eyes rely on a form of vitamin A to build the light-sensitive pigment in the cells responsible for low-light vision. When stores of this vitamin drop too low, those cells can’t regenerate the pigment fast enough, and your ability to see in dim light deteriorates. Night blindness is often the earliest sign that your body isn’t getting or absorbing enough vitamin A.
How Vitamin A Powers Low-Light Vision
The retina at the back of your eye contains two types of light-detecting cells: cones for color and bright-light vision, and rods for seeing in the dark. Rods depend on a pigment called rhodopsin, which is made from a protein (opsin) chemically bonded to a molecule derived from vitamin A called 11-cis retinal.
When even a small amount of light hits rhodopsin, the vitamin A portion changes shape. That shape change triggers the protein to activate a signaling chain inside the rod cell, which ultimately sends an electrical signal to your brain. After firing, the pigment has to be rebuilt with a fresh supply of vitamin A before the rod can respond to light again. If vitamin A is scarce, rhodopsin regeneration slows down. The result is that your rods become sluggish, and dim environments that used to look manageable start to feel impossibly dark.
Who Is Most at Risk
In wealthier countries, vitamin A deficiency is relatively uncommon in the general population. But certain groups face a much higher risk. People with fat malabsorption conditions top the list, because vitamin A is fat-soluble and needs dietary fat to be absorbed properly. Crohn’s disease, celiac disease, cystic fibrosis, chronic liver disease, pancreatic insufficiency, and bile duct blockages can all interfere with absorption. People who have had gastric bypass or other bariatric surgery are also at elevated risk, as are those with alcohol use disorder.
Globally, children between ages 2 and 6 are especially vulnerable, along with pregnant and lactating women. In regions where diets are low in animal products and orange or green vegetables, night blindness can affect entire communities.
What Happens as Deficiency Worsens
Night blindness is the mildest stage of a spectrum of eye problems caused by vitamin A deficiency, collectively called xerophthalmia. The World Health Organization grades this spectrum from mild to severe, and progression can be surprisingly fast in young children if the deficiency isn’t corrected.
After night blindness, the next stage involves dryness of the conjunctiva, the clear membrane covering the white of your eye. The surface loses its normal moisture and begins to look dull and rough. At this point, small foamy, triangular patches may appear on the white of the eye, usually on the side closest to the ear. These are called Bitot’s spots, and they’re a hallmark clinical sign of vitamin A deficiency that an eye doctor can spot during an exam.
If deficiency continues, the cornea itself dries out and can develop ulcers. In the most severe form, called keratomalacia, the cornea essentially melts away through a process of tissue breakdown. This stage is a medical emergency that can result in permanent scarring or total blindness. Prolonged deficiency can also cause structural damage to the retina itself.
Getting Diagnosed
If you’re struggling to see when driving at dusk or walking into a dimly lit room, a blood test measuring serum retinol can confirm whether vitamin A is the issue. In children aged 6 months to 5 years, a level below 0.70 µmol/L is considered deficient. A reading below 1.05 µmol/L in any age group suggests insufficiency, meaning stores are low enough to cause problems even if outright deficiency hasn’t set in yet.
Your doctor may also look for the physical eye signs described above, particularly Bitot’s spots, which can confirm the diagnosis without blood work in resource-limited settings. If you have a known malabsorption condition, your provider may check vitamin A levels as part of routine nutritional monitoring.
How Much Vitamin A You Need
The recommended daily intake varies by age and sex. Adults need 700 to 900 micrograms of retinol activity equivalents (mcg RAE) per day, with men at the higher end. Pregnant women need about 770 mcg RAE, and breastfeeding women need the most at 1,200 to 1,300 mcg RAE, reflecting the vitamin A passed through breast milk.
Children need less: 300 mcg RAE for ages 1 to 3, 400 mcg RAE for ages 4 to 8, and 600 mcg RAE for ages 9 to 13. Infants get adequate amounts through breast milk or formula under normal circumstances.
Best Food Sources of Vitamin A
Vitamin A comes in two forms from food. Preformed vitamin A (retinol) is found in animal products and is ready for your body to use immediately. The richest sources include beef liver, which contains many times the daily requirement in a single serving, along with egg yolks, dairy products, and fatty fish like salmon and mackerel.
The second form, provitamin A carotenoids, comes from colorful plant foods. Your body converts these into active vitamin A, though less efficiently. Sweet potatoes, carrots, spinach, kale, butternut squash, red bell peppers, and cantaloupe are all excellent sources. As a rough guide, the deeper the orange or green color, the more carotenoids the food contains. Cooking these vegetables with a small amount of fat improves absorption significantly, since the carotenoids need fat to cross the intestinal wall.
Recovery and What to Expect
The good news is that night blindness caused by vitamin A deficiency is usually reversible once levels are restored. In mild cases caught early, improvement in night vision can begin within days to weeks of increasing vitamin A intake, whether through diet changes or supplementation. The more advanced stages of xerophthalmia, particularly corneal scarring, may leave permanent damage even after vitamin A levels normalize.
If you have a malabsorption condition, simply eating more vitamin A-rich foods may not be enough. You may need higher-dose supplements or a form that bypasses the usual absorption pathway, depending on the underlying condition. Addressing the root cause of malabsorption, such as managing celiac disease with a gluten-free diet or treating pancreatic insufficiency, is equally important.
Can You Take Too Much?
Preformed vitamin A from supplements and animal foods can accumulate in the liver and become toxic at high doses. Symptoms of excess include nausea, headaches, dizziness, blurred vision, and in chronic cases, liver damage. During pregnancy, excessive vitamin A intake is linked to birth defects, which is why prenatal vitamins use carefully controlled amounts.
Carotenoids from plant foods do not carry the same toxicity risk. Your body regulates how much it converts to active vitamin A, so eating large amounts of carrots or sweet potatoes won’t push you into dangerous territory. The worst that happens is a harmless orange tint to the skin, which fades when you cut back. If you’re considering a vitamin A supplement, especially at doses above the standard daily recommendation, it’s worth checking your serum levels first to avoid overcorrecting.