Vitamin A

Vitamin A (retinol) is not one molecule but a family of fat-soluble compounds. The NIH (the US National Institutes of Health) calls this group retinoids, mainly retinol and retinyl esters. Your body needs them for vision, immune function, cell communication, growth and reproduction.

Retinol and its esters (preformed vitamin A) come from animal foods such as liver, fish, eggs and dairy. Plants supply provitamin A carotenoids, mainly beta-carotene, which the gut converts into vitamin A.

Here is the part most people do not know: plant sources pay out at a poor and uneven rate. The US counts 12 mcg (micrograms) of beta-carotene from food as 1 mcg RAE, the unit used for vitamin A. And 1 mcg of retinol counts as 1 mcg.

A review of human studies reports ratios from 3.8 to 1 up to 28 to 1 by weight, and common gene variants cut conversion further. So the vitamin A you get from a carrot depends on the carrot, how it is cooked and what you eat it with. It also depends on you.

Vitamin A is a nutrient with two problems. Where food is scarce, deficiency is one of the top causes of preventable blindness in children. In 2013, an estimated 29% of children aged 6 months to 5 years in 138 low- and middle-income countries were deficient.

In rich countries, frank deficiency is rare, and the risk runs the other way. Preformed vitamin A from liver and supplements can pass the upper limit (the most you should take in a day). In pregnancy, too much can cause birth defects. One 3-ounce serving of pan-fried beef liver holds 6,582 mcg RAE, more than twice the adult upper limit of 3,000 mcg.

Health benefits of vitamin A

• ★★★Fewer deaths in young childrenVitamin A supplements cut deaths from any cause by 12% in children aged 6 months to 5 years (19 trials). Vomiting in the first 48 hours was more common.
• ★★★Higher lung cancer risk in smokersIn 3 trials of supplements in smokers and asbestos workers (beta-carotene with or without retinyl palmitate), lung cancer risk was 1.10 times higher. One trial of beta-carotene plus retinol (vitamin A) found a 28% higher risk.
• ★★★No lower risk of maternal deathIn a review of 19 trials in pregnancy (over 310,000 women), vitamin A supplements alone did not change maternal deaths (four trials) or preterm birth. It did lower night blindness and anemia in mothers.
• ★★A nutrient mix slowed late macular degenerationIn people with this eye disease, multivitamins cut the odds of reaching the late stage to 0.72 times. The mix held vitamins C and E, beta-carotene and zinc, so vitamin A cannot be credited alone.
• ★★Beta-carotene pills raised death risk slightlyIn 26 trials at low risk of bias, beta-carotene raised the risk of death to 1.05 times. Vitamin A gave 1.07 times (12 trials), which could be chance, though higher vitamin A doses were linked to more deaths.

Foods high in vitamin A

Food has two kinds of vitamin A. Preformed vitamin A is highest in liver, fish, eggs and dairy products, according to the NIH. Provitamin A comes from leafy greens, orange and yellow vegetables, tomato products and fruit.

In the US and other high-income countries, about 65% to 80% of the vitamin A people eat is preformed. In low-income countries, provitamin A is the main form. Fortified foods such as milk and some cereals add more.

Our USDA ranking is plant-heavy and has no organ meats. Per serving, sweet potatoes lead with 1,188 mcg RAE in one medium potato (151 g). That is 132% of the 900 mcg Daily Value, the FDA’s daily target for food labels. Carrots follow with 509 mcg in one medium carrot (61 g), then cantaloupe at 270 mcg per cup.

The ranking shows the rest, from bell peppers to eggs. Per 100 g the order changes: carrots hold 835 mcg and sweet potatoes 787 mcg. Spinach (469 mcg), parsley (421 mcg) and dill (386 mcg) come next.

The NIH table adds what our ranking lacks. Pan-fried beef liver has 6,582 mcg RAE in 3 ounces (731% of the Daily Value).

A whole baked sweet potato has 1,403 mcg, frozen boiled spinach 573 mcg per ½ cup and raw carrots 459 mcg per ½ cup. Pickled herring has 219 mcg in 3 ounces and a hard-boiled egg 75 mcg. Skim milk with added vitamin A and D has 149 mcg per cup.

Cooking can raise the amount of beta-carotene the body can use, the NIH says. In one trial, a salad with fat-free dressing gave almost no carotenoid absorption, while full-fat dressing gave the most. In another, breaking up the cell walls of spinach raised beta-carotene absorption.

A review of food science explains that light, heat and acids turn the natural trans form of carotenoids into cis forms. The main cause of loss in processing and storage is oxidation (reaction with oxygen), which depends on oxygen, light and storage conditions.

How vitamin A works

Most of this section comes from reviews, physiology studies and animal work, not from trials of vitamin A in people. Four ideas cover it.

Vitamin A is part of the light-sensing pigment of the eye, and its active form, retinoic acid, switches genes on and off. The liver stores it and releases it as needed, and the body makes it from plant pigments at a poor and uneven rate. Then comes what has been seen in people.

It is part of the light-sensing pigment of the eye

Vitamin A is an essential part of rhodopsin, the light-sensitive protein in the retina that responds to light entering the eye. It also supports the normal specialization and function of the membranes that cover the eye and the cornea, according to the NIH.

Historians trace the chemistry to George Wald and colleagues. From the 1930s, they showed that light splits rhodopsin into retinal, the aldehyde form of vitamin A, and a protein called opsin.

When vitamin A runs low, rhodopsin falls. The first sign is night blindness, the inability to see in low light. If the shortage continues, the cornea is affected (xerophthalmia, a drying of the eye), and this can end in permanent blindness.

Its active form switches genes on and off

Cells turn retinol into retinal and then into retinoic acid, the two main active forms in the body, according to the NIH. Retinoic acid works as a signal. A review of its biology explains that it binds retinoic acid receptors in the cell nucleus. These receptors sit on response elements near target genes and regulate their activity.

This is how vitamin A guides cells as they specialize, which is the subject of one of the EU claims. It is also how embryos form organs and limbs. Too much retinoic acid disturbs that development. That is why high intakes of preformed vitamin A in early pregnancy are teratogenic (cause birth defects), according to EFSA.

A second review describes experiments in mice and rats. In them, retinoic acid helps T cells, a part of the immune system, specialize and move into tissues. Its author notes that data from human studies are still needed.

The liver stores it and releases it as needed

After a meal, liver cells take up dietary vitamin A. More than 80% of the vitamin A in the liver is stored in hepatic stellate cells, according to a review of its absorption and storage. The NIH adds that most of the body’s vitamin A is stored in the liver as retinyl esters. A carrier protein, RBP4, is needed to mobilize the stored vitamin A.

Because the liver acts as a buffer, blood retinol does not fall until liver stores are almost used up. Infections lower it too, the NIH says. So a blood test can miss low stores, and it can read low during an infection when stores are fine.

The NIH says a blood level of 20 mcg/dL (0.70 µmol/L) or less often reflects moderate deficiency. A level of 10 mcg/dL (0.35 µmol/L) or less often reflects severe deficiency. Both units describe how much is in your blood.

It is made from plant pigments at a poor, uneven rate

The gut enzyme BCMO1 converts provitamin A carotenoids such as beta-carotene into vitamin A. The NIH says the body may absorb 75% to 100% of retinol but, in most cases, only 10% to 30% of beta-carotene from foods. That is why units differ by source.

In the US, 1 mcg RAE equals 1 mcg of retinol or 2 mcg of beta-carotene from supplements. It also equals 12 mcg of beta-carotene from food, or 24 mcg of alpha-carotene or beta-cryptoxanthin. EFSA still counts 6 mcg of beta-carotene (and 12 mcg of other provitamin A carotenoids) as 1 mcg retinol equivalent. That is why EU and US numbers are not the same size.

Human trials found ratios that vary with the food, the dose, the method and the person, as the chart shows.

A review of the human evidence puts absorption of beta-carotene from plants at 5% to 65%. It puts the ratios at 3.8 to 1 up to 28 to 1. They depend on the food matrix (the food’s structure), the processing and the fat and fiber in the diet, the review says. The person’s own status and genes matter too.

What has been seen in people

The human findings match the mechanisms best where vitamin A is short. In deficient populations, supplements restored stores and cut night blindness (0.32 times the risk in children, 0.79 in pregnant women). They also lowered child deaths by 12%.

Where status is already adequate, extra vitamin A showed no clear benefit. Large doses of beta-carotene, with or without retinyl palmitate, harmed smokers. The gene and immune findings above come from lab and animal work, and the human trials do not test them directly. All the trials are among the study cards above.

How much vitamin A do you need?

Adult men need 900 mcg RAE of vitamin A a day and adult women 700 mcg RAE. These are the US recommended dietary allowances (RDAs), amounts that cover nearly all healthy people. EFSA’s population reference intakes in the EU are 750 mcg RE for men and 650 mcg RE for women.

RAE (retinol activity equivalents) account for how well each form turns into vitamin A. RE (retinol equivalents) is the older EU unit with a different beta-carotene factor, so the two are not the same size. On older labels, 1 IU of retinol equals 0.3 mcg RAE. So the 900 mcg RAE allowance is 3,000 IU of retinol, or 18,000 IU of beta-carotene from food, according to the NIH.

Needs rise in pregnancy and breastfeeding. The US allowance is 770 mcg RAE a day in pregnancy at ages 19 to 50 (750 mcg at ages 14 to 18). When breastfeeding it is 1,300 mcg RAE (1,200 mcg at ages 14 to 18).

EFSA sets 700 mcg RE in pregnancy. That covers about 51 mcg RE a day more for the growing baby in the second half of pregnancy. EFSA sets 1,300 mcg RE when breastfeeding, to replace the retinol lost in milk.

For older adults, the US allowance stays at 900 mcg RAE for men and 700 mcg RAE for women from age 51. Children need 300 mcg RAE at ages 1 to 3, 400 mcg at ages 4 to 8 and 600 mcg at ages 9 to 13.

The NIH notes that people with cystic fibrosis get lifelong vitamin A as part of standard care. They take 750 to 3,000 mcg RAE a day, depending on age. EFSA advises smokers to avoid beta-carotene supplements.

According to the NIH, average US intakes from foods and drinks in 2017 to 2018 were 682 mcg RAE for men. Women got 616 mcg. In 2003 to 2006 survey data, fewer than 1% of Americans had a blood retinol below 20 mcg/dL, so frank deficiency is uncommon there.

Vitamin A deficiency: signs and who is at risk

The first sign is night blindness, trouble seeing in low light. Later the cornea is affected (xerophthalmia), and left untreated it can cause permanent blindness. The NIH calls vitamin A deficiency one of the top causes of preventable blindness in children.

Chronic deficiency also makes infections, especially measles and diarrhea, more severe and more deadly. It is linked to abnormal lung development, anemia and death. Bitot’s spots, another eye sign, fell by about half with supplements in the Cochrane review of children (0.42 times the risk).

Deficiency is common where diets lack both animal foods and orange or green plant foods. An analysis of surveys looked at children aged 6 months to 5 years in 138 low- and middle-income countries. In 2013, 29% were deficient (blood retinol below 0.70 µmol/L).

Rates were highest in sub-Saharan Africa (48%) and south Asia (44%). Deficiency was linked to 94,500 deaths from diarrhea and 11,200 from measles that year.

In richer countries, premature infants are most at risk, according to the NIH, because they have low liver stores at birth. So are people who absorb fat poorly. Up to 90% of people with cystic fibrosis have pancreatic insufficiency (the pancreas makes too few digestive enzymes). About one quarter of children with Crohn’s disease and ulcerative colitis are deficient, and so are some people with newly diagnosed celiac disease.

Testing is harder than it sounds. Doctors usually measure blood retinol, but it does not fall until liver stores are nearly gone. A low reading can also come from infection or inflammation, because the carrier protein drops during inflammation. Liver stores give the best answer, but researchers can only estimate them indirectly, with isotope or dose-response tests.

Forms of vitamin A: absorption and effects

Supplements and fortified foods use different forms of vitamin A. Stand-alone pills and multivitamins often contain retinyl acetate, retinyl palmitate, beta-carotene or a combination, according to the NIH. Amounts vary widely: 3,000 mcg RAE is common in a stand-alone pill, and multivitamins often have 750 to 1,050 mcg RAE.

The upper limit covers only the retinol part. So if a label says 3,000 mcg RAE and 60% of it is beta-carotene, only the other 40% (1,200 mcg RAE) counts toward it.

The honest bottom line: the best comparisons measure vitamin A stores or blood markers, not health outcomes, and most are small. Preformed vitamin A and beta-carotene both raised vitamin A status in the trials we found, with beta-carotene needing a larger dose.

Beta-carotene pills carried a specific risk for smokers in the ATBC and CARET trials. EFSA found no indication that beta-carotene from the background diet is linked to harm.

We found no human trial that compared retinyl acetate with retinyl palmitate, and none that compared natural with synthetic vitamin A. In the benefits section, DEVTA used retinyl acetate in oil and CARET used retinyl palmitate with beta-carotene. ATBC and AREDS used beta-carotene, and Berson used vitamin A of unstated form.

Form	Activity or conversion	What studies show	Source
Retinol and retinyl esters (acetate, palmitate)	1 mcg retinol = 1 mcg RAE	The NIH puts absorption of retinyl esters from supplements at 70% to 90% and of retinol from food at up to 75% to 100%. In Bangladeshi men, retinyl palmitate raised vitamin A stores by 0.065 mmol, about the same as synthetic beta-carotene (0.062 mmol). Weekly preformed vitamin A cut night blindness in pregnant women in Nepal more than beta-carotene did. EFSA’s upper level covers retinol, retinyl acetate and retinyl palmitate. We found no human trial comparing acetate with palmitate.	1, 2, 3, 4
Water-miscible, emulsified or solid retinol	Not stated	In a review of 259 case reports, these forms caused chronic toxicity at doses about 10 times lower than oil-based forms (0.2 mg versus 2 mg of retinol per kg of body weight a day). The authors recommend careful consideration before using them in supplements and fortification. Case reports, not a trial.	12
Beta-carotene supplements	US: 2 mcg = 1 mcg RAE. EU: 6 mcg = 1 mcg RE	The NIH puts absorption from supplements at 8.7% to 65%. In Bangladeshi men the ratio was about 6 to 1. In Nepal weekly beta-carotene cut pregnancy deaths by 49%, against 40% for vitamin A. ATBC and CARET found more lung cancer in smokers. EFSA set no upper level and advises smokers to avoid beta-carotene supplements. Long-term excess can turn the skin yellow-orange, which is harmless and reversible, according to the NIH.	1, 2, 3, 5, 14, 15, 4
Beta-carotene in food	US: 12 mcg = 1 mcg RAE. EU: 6 mcg = 1 mcg RE	Trials found about 10 to 26 mcg of beta-carotene per 1 mcg of retinol, depending on the food: orange maize 10.4, orange fruit 12, sweet potato 13, carrots 14.8, spinach 20.9 and leafy greens with carrots 26. Fat in the meal and breaking up the leaf raised carotenoid absorption. A review gives 3.8 to 1 up to 28 to 1.	3, 6, 8, 9, 10, 11, 17
Other provitamin A carotenoids (alpha-carotene, beta-cryptoxanthin)	US: 24 mcg = 1 mcg RAE. EU: 12 mcg = 1 mcg RE	These factors come from the NIH and EFSA. We found no trial that tested these carotenoids as separate supplements.	1, 2
Biofortified orange crops	Orange maize: 10.4 mcg beta-carotene equivalents = 1 mcg retinol	Orange maize raised vitamin A stores about as much as a daily vitamin A supplement in Zambian children. Orange-fleshed sweet potato improved a vitamin A status test in South African schoolchildren.	6, 7
Multivitamins and fortified foods	Mixed forms: read the label	The NIH says multivitamins often have 750 to 1,050 mcg RAE. A Cochrane review found staple foods fortified with vitamin A alone left blood retinol little changed (very low certainty), while vitamin A with other nutrients probably lowered subclinical deficiency.	1, 16

Here are the head-to-head and form-specific studies, strongest evidence first, 9 in all.

Is vitamin A safe? Supplements, dose and interactions

Carotenoids from plant foods do not cause vitamin A toxicity, but preformed vitamin A from liver and supplements can. For preformed vitamin A, the US tolerable upper intake level (UL) is 3,000 mcg a day for adults, including during pregnancy and breastfeeding. The UL is the highest daily intake unlikely to cause harm.

It is 2,800 mcg at ages 14 to 18 and 1,700 mcg at ages 9 to 13. It is 900 mcg at ages 4 to 8 and 600 mcg at ages 1 to 3. It applies to animal foods and to supplements whose vitamin A comes from retinol or its esters, not to beta-carotene.

For beta-carotene the US panel set no UL, but it advises against supplements for the general population except as a source of vitamin A.

EFSA’s 2024 opinion keeps a UL of 3,000 mcg RE for adults, including women who may become pregnant, and for pregnant, breastfeeding and postmenopausal women. For children, it is 600 mcg for infants 4 to 11 months and 800 mcg at ages 1 to 3. It rises to 1,100 mcg at 4 to 6 and 1,500 mcg at 7 to 10. It is 2,000 mcg at 11 to 14 and 2,600 mcg at 15 to 17.

EFSA’s limit counts all sources, including fortified foods, and covers retinol, retinyl acetate and retinyl palmitate. It was set on birth defects, which EFSA says are irreversible and occur at relatively low intakes.

• Too much. One or a few very high doses can cause severe headache, blurred vision, nausea, dizziness, aching muscles and poor coordination. Such doses are typically more than 100 times the allowance. In severe cases they can cause coma and death. Regular high doses can cause dry skin, painful muscles and joints, fatigue, depression and abnormal liver tests, according to the NIH. Water-miscible and solid forms were far more toxic than oil-based ones in case reports. In young children, a high dose caused more vomiting in the first 48 hours (1.97 times the risk).
• Pregnancy and liver. Intakes of preformed vitamin A above the UL can cause birth defects of the eye, skull, lungs and heart, according to the NIH. In one cohort, the rate of certain defects was 4.8 times higher at more than 10,000 IU a day of supplemental vitamin A. EFSA advises women who are pregnant or planning to be not to eat liver products. It says the UL is unlikely to be exceeded if liver and offal are eaten once a month or less. A 3-ounce serving of pan-fried beef liver has 6,582 mcg RAE, more than twice the adult UL. Check prenatal vitamin labels for the retinol share.
• Bones. Two large cohorts linked high retinol intake or high blood retinol to more hip fractures. EFSA reviewed the evidence in 2024. It concluded that cause cannot be established at intakes below the UL. It also found that the evidence does not support harm to bone at 3,000 mcg RE a day or less.
• Smokers and beta-carotene. High-dose beta-carotene raised lung cancer and deaths in smokers and asbestos-exposed workers in ATBC and CARET. Lung cancer was also higher with beta-carotene in AREDS2, mostly in former smokers. EFSA says smokers should avoid beta-carotene supplements. It found no indication that beta-carotene from the background diet is linked to harm.
• Drug interactions. Orlistat, a weight-loss drug, can lower absorption of vitamin A and beta-carotene, and its makers advise a multivitamin with vitamin A. Prescription retinoids such as acitretin and bexarotene can raise the risk of vitamin A toxicity when combined with vitamin A supplements. Some retinoid medicines, such as isotretinoin and etretinate, can cause birth defects, according to the NIH.
• Who should ask a doctor. Ask if you are or might be pregnant, or are breastfeeding. Experts advise these women not to take more than 3,000 mcg RAE (10,000 IU) of vitamin A a day as supplements. Also ask if you take retinoid medicines or orlistat, or if you smoke or used to smoke and are considering beta-carotene. People with macular degeneration should ask about their vitamin A intake and the AREDS formulas. People with cystic fibrosis or fat malabsorption often need vitamin A, and the amount belongs under medical care.

How to get more vitamin A

• Best foods. In our ranking, one medium sweet potato gives 1,188 mcg RAE and one medium carrot 509 mcg. For preformed vitamin A, the NIH lists a hard-boiled egg at 75 mcg. A cup of milk with added vitamin A and D has 149 mcg, and three ounces of pickled herring 219 mcg.
• Eat orange foods with some fat. A salad with full-fat dressing gave the most carotenoid absorption in one trial. The NIH says cooking can raise how much beta-carotene the body can use.
• Keep liver occasional. Three ounces of beef liver hold 6,582 mcg RAE. EFSA says the UL is unlikely to be passed if liver is eaten once a month or less, and advises against it in pregnancy.

History of vitamin A

People described the symptoms long before they knew the cause. Night blindness was recognized by the ancient Egyptians and Greeks, and many authorities from Galen onward advised liver as a cure.

In 1816, the physiologist François Magendie fed dogs a poor diet and saw corneal ulcers and high mortality. It was much like what happened to poorly fed, abandoned infants in Paris. In the 1880s, Nicolai Lunin showed that milk held an unknown substance that animals needed.

In 1913, two American teams reached the same conclusion. They were Elmer McCollum and Marguerite Davis at Wisconsin, and Thomas Osborne and Lafayette Mendel at Yale. Butter and egg yolk helped rats grow and survive better than lard and olive oil. The growth factor became known as “fat-soluble A” in 1918 and as “vitamin A” in 1920.

During World War I, Bloch ran a controlled diet trial among malnourished Danish children. Bloch concluded that whole milk, butter and cod-liver oil contain a fat-soluble substance that protects against xerophthalmia.

Chemistry followed. Paul Karrer described the structure of vitamin A in 1932, and Harry Holmes and Ruth Corbet isolated and crystallized it in 1937. Methods to make it in the lab came in 1946 and 1947. From the 1930s, George Wald and colleagues worked out how vitamin A powers vision.

Large trials in the 1980s and 1990s reported marked drops in child deaths from vitamin A supplements. Later, larger trials found smaller or no effects. The pooled result in the latest Cochrane review is a 12% reduction in deaths from any cause.

Frequently asked questions about vitamin A

Is beta-carotene the same as vitamin A?

No. Beta-carotene is a plant pigment that the body converts into vitamin A in the intestine, according to the NIH. It counts toward vitamin A at an exchange rate. In the US, 12 mcg of beta-carotene from food equals 1 mcg RAE, and so do 2 mcg from supplements. Preformed vitamin A (retinol) comes from animal foods and supplements. The difference matters for safety. Beta-carotene is not known to cause birth defects, and its usual long-term effect is harmless yellow-orange skin. But high-dose beta-carotene pills raised lung cancer in smokers in ATBC and CARET.

Are vitamin A and retinol the same?

Not quite. Retinol is the main preformed form of vitamin A. Vitamin A is the group name for fat-soluble retinoids, mainly retinol and retinyl esters. Labels give vitamin A in mcg RAE so forms can be compared (1 mcg retinol equals 1 mcg RAE). Prescription retinoids such as isotretinoin, acitretin and bexarotene are drugs related to vitamin A, not supplements. The NIH says they can raise toxicity risk when combined with vitamin A supplements.

Can you get too much vitamin A from carrots?

Not toxic vitamin A. The NIH says the most common effect of long-term excess beta-carotene is carotenodermia, a harmless yellow-orange skin color that fades when intake stops. Beta-carotene is not known to cause birth defects or reproductive toxicity. Toxicity comes from preformed vitamin A in liver and supplements. The exception to watch is large beta-carotene supplements in smokers.

Is vitamin A safe in pregnancy?

At recommended amounts, yes. Needs rise slightly, to 770 mcg RAE a day in the US at ages 19 to 50, or 700 mcg RE in the EU. Preformed vitamin A above the 3,000 mcg upper limit can cause birth defects. In one cohort, the rate of certain defects was 4.8 times higher above 10,000 IU a day of supplemental vitamin A. The excess was mostly before the seventh week. EFSA advises women who are pregnant or planning to be not to eat liver products. Check prenatal vitamin labels for the retinol share and ask a midwife or doctor.

Which foods are highest in vitamin A?

In our USDA ranking per serving, sweet potatoes lead with 1,188 mcg RAE in one medium potato. Carrots (509 mcg), cantaloupe (270 mcg per cup), bell peppers (187 mcg) and garden cress (173 mcg) follow. Per 100 g, carrots (835 mcg) and sweet potatoes (787 mcg) lead. Liver is higher than all of them but is not in our ranking. The NIH lists 6,582 mcg RAE in 3 ounces of pan-fried beef liver.

Does cooking destroy vitamin A?

Cooking can raise how much beta-carotene you absorb. The NIH says cooking and heat treatment can increase the bioavailability of beta-carotene (how much your body can absorb and use). In one trial, breaking up the cell walls of spinach raised beta-carotene absorption from 5.1% to 9.5% relative to a supplement. A review of food science says the main cause of loss in processing and storage is oxidation, helped by oxygen, light and long storage. We found no loss figure for retinol in cooking.

Does vitamin A help acne?

Vitamin A from food or ordinary supplements has not been shown to treat acne. Prescription retinoids are the acne treatments. A Cochrane review of 31 trials in 3,836 people found low-quality evidence on them. Against oral antibiotics plus skin treatments, oral isotretinoin may slightly improve doctor-rated severity (1.15 times) but caused more minor side effects (1.67 times). The NIH says retinoid medicines can cause birth defects. The only trial of oral vitamin A for acne we found, from 1978, reported blood levels of zinc and retinol-binding protein, not skin results.

Does vitamin A improve eyesight?

Only if you are short of it. Vitamin A is part of rhodopsin, and night blindness is the first sign of deficiency. In the Cochrane review of children, supplements cut night blindness (0.32 times the risk), mostly in places where deficiency is common. The EU authorizes the claim that vitamin A contributes to the maintenance of normal vision. In the studies on this page, we found no trial showing that extra vitamin A improves sight in people who already have enough. The macular degeneration trials used a mix of nutrients.