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What are the signs of vitamin A (RAE) deficiency?

Vitamin A deficiency damages the cornea and can end in permanent blindness, and it is one of the leading preventable causes of childhood blindness.

Who is most likely to run low

Up to 90 per cent of people with cystic fibrosis cannot absorb fat properly, which puts them at risk of vitamin A deficiency.

What this means for you

Vitamin A deficiency is one of the leading preventable causes of blindness in children worldwide, and it is also rare in countries with a varied food supply. Both halves of that sentence matter.

The first sign is usually difficulty seeing in dim light. If it progresses, the surface of the eye dries out and the cornea is damaged, and at that stage the blindness is permanent.

Established. Where children are short of vitamin A, supplements cut new cases of night blindness by about two thirds. That comes from a Cochrane review pooling trials in 22,972 children aged six months to five years, and the certainty behind the eye outcomes is moderate.

There is an earlier sign that a doctor can see before anything hurts. Bitot's spots are foamy grey patches on the white of the eye, and in the same review supplements more than halved the number of new ones, across trials covering over a million children. Both of those numbers belong to children who were already short of vitamin A. In a child who gets enough, a supplement has nothing to correct.

Pregnancy is the other place where night vision is the early clue. Where deficiency is common, vitamin A given during pregnancy lowered the risk of a mother losing her night vision by about a fifth. Two trials carried that result, and the same review found no effect on whether mothers or babies survived. It is a narrow finding, and not a reason to start a supplement on your own.

Not for everyone. Up to 90 per cent of people with cystic fibrosis have pancreatic insufficiency, which makes absorbing fat, and therefore vitamin A, harder. The same logic applies after some bowel surgery and in long-standing liver disease.

If you eat dairy, eggs, liver occasionally, or orange and dark green vegetables, this page is background reading rather than a warning. Beta-carotene from plants converts to vitamin A as the body needs it, which is why carrots and sweet potato do the job without any risk of overshooting.

Where it is worth a second thought is fat absorption. Vitamin A needs fat to be absorbed, so conditions that interfere with that are the realistic route to deficiency in a well-fed country.

The test that is supposed to answer this

If you are worried enough to ask a doctor, the thing that usually gets measured is retinol in your blood. It is worth knowing how well that works before you lean on the answer.

Myth. A blood test does not tell you whether you are short of vitamin A. A 2025 Cochrane review checked serum retinol against retinol isotope dilution, the closest thing to a reference method, in 23 studies. At the usual cutoff it picked up 10 per cent of the people who were genuinely deficient, and the range around that runs from 2 to 38 per cent. Checked against vitamin A measured in the liver it found 53 per cent. It does the opposite job better, staying negative in 92 per cent of people who have enough. The certainty behind those figures is rated very low, which is its own warning. Anyone telling you that an analysis shows vitamin A deficiency, or rules it out, is leaning on a test that misses about nine cases in ten.

So a normal result does not mean you are covered. The two methods that do work, isotope dilution and a sample of liver, are a research technique and an operation. That is the honest state of it, and it is why doctors go by the eyes and the diet in front of them rather than by a number.

How common this is, and where

Unsettled. How many children this affects is a modelled figure rather than a counted one. Pooling 116 surveys from 40 countries and projecting out to 165, about 14.7 per cent of children and adolescents in low and middle income countries were deficient in 2019, and 19.5 per cent of those under five. Another quarter sat in the marginal band below that. The spread is the part worth keeping. In the least developed regions it reached 29.7 per cent, against 5.2 per cent in the better-off middle ones. Modelling countries that never ran a survey is guesswork with arithmetic on top, so hold the shape and let go of the decimal places.

The scale of this is easy to underestimate from a wealthy country. A Cochrane review of 19 trials in more than 1.2 million children aged six months to five years found vitamin A supplements cut deaths from any cause by 12 per cent. That is the strongest evidence on this whole site for a supplement saving lives, and it applies where deficiency is common rather than where it is not. Even there it has a cost worth naming: a large dose roughly doubled the chance of vomiting in the two days afterwards.

Enough, for the record, means 900 micrograms RAE a day for a man and 700 for a woman, and an ordinary mixed diet passes that without anyone counting.

The line above about vegetables not overshooting has a measurement under it. Seven adults took 20 mg of beta-carotene and then 40. The beta-carotene in their blood doubled. The retinol their bodies made from it rose by 36 per cent. The conversion slows as the dose climbs, which is why a plate of carrots cannot push you into excess the way a capsule of the preformed kind can. Seven people is a small study, and what it shows is a direction rather than a rate.

Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.

Where to get it from food

All vitamin A (RAE) sources ranked →

A symptom list is not a diagnosis. Every sign on this page has other causes that are more common than a nutrient deficiency, and the way to know is a blood test rather than a checklist.

Full guide: Vitamin A: the supplement that increased cancer in a randomised trial

Source. Xerophthalmia also affects the cornea and can eventually lead to permanent blindness; vitamin A deficiency is one of the top causes of preventable blindness in children — NIH Office of Dietary Supplements, Vitamin A - Health Professional Fact Sheet, checked 2026-09-16. Evidence level E.

Source. Up to 90% of people with cystic fibrosis have pancreatic insufficiency, which increases their risk of vitamin A deficiency due to difficulty absorbing fat — NIH Office of Dietary Supplements, Vitamin A - Health Professional Fact Sheet, checked 2026-09-16. Evidence level E.