Vitamin A
In children aged 6 months to 5 years, mostly in Asia and Africa, vitamin A lowered deaths by 12%. In adults, beta-carotene did not prevent cancer or heart disease. In smokers it raised lung cancer, by 18% in ATBC and 28% in CARET. In a pregnancy cohort, birth defects rose above 10,000 IU a day of supplemental vitamin A.
Add to Bio HackChecked 2026-11-09
- Status
- Dietary supplement in the US.
- Also called
- retinol, retinyl palmitate, retinyl acetate, preformed vitamin A, beta-carotene, β-carotene, provitamin A, carotenoids
- Taken for
- vision, eye health, macular degeneration, immunity, skin, acne, cancer prevention, heart health, antioxidant, pregnancy
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help1
Reported risks5
- ModerateShown to raise lung cancer 16% to 28% with beta-carotene in smokers and asbestos-exposed workers.How often is not known
- ModerateShown to raise death from any cause 8% to 17% with beta-carotene in smokers and asbestos-exposed workers. Deaths did not differ in mostly nonsmoking physicians.How often is not known
- ModerateShown to raise eye pain, dryness and burning with topical vitamin A on or near the eye, mostly at prescription strength. Serious events did not differ.How often is not known
- LimitedLinked to about 4.8 times more of certain birth defects in babies of women taking over 10,000 IU of preformed vitamin A a day, mostly before week 7.How often is not known
- LimitedLinked to about 48% more hip fractures in postmenopausal women with the highest vitamin A intake, mainly from retinol. Beta-carotene showed no clear link.How often is not known
What people take it for, and what was found
Shown to help1
Child deaths and illness
Shown to lower child deaths about 12% in children aged 6 months to 5 years, mostly in Asia and Africa.
The numbers and sources
- Effect
- Across 19 trials, death from any cause was 12% lower with vitamin A than with control (RR 0.88, 95% CI 0.83 to 0.93). Deaths from diarrhea were also 12% lower (RR 0.88, 95% CI 0.79 to 0.98). Deaths from measles did not significantly differ (RR 0.88, 95% CI 0.69 to 1.11) [1].
- Population
- 47 trials with about 1,223,856 children aged 6 months to 5 years in 19 countries, mostly in Asia and Africa. 19 trials with 1,202,382 children reported mortality [1].
- Sources
- [1]
- Caveats
- The authors rated the mortality evidence high certainty. Children in hospital or with disease were left out. Most trials ran about a year [1].
Mixed results1
Age-related macular degeneration
Limited evidence: an antioxidant and zinc mix lowered the odds of advanced macular degeneration in older adults, and dropping beta-carotene from it did not change progression.
The numbers and sources
- Effect
- Over 6.3 years, antioxidants (vitamin C, vitamin E and 15 mg beta-carotene) plus zinc lowered the odds of advanced macular degeneration (OR 0.72, 99% CI 0.52 to 0.98). Antioxidants without zinc did not significantly differ (OR 0.80, 99% CI 0.59 to 1.09) [6]. In AREDS2, dropping beta-carotene from the formula did not change progression [7].
- Population
- 3,640 people aged 55 to 80 with macular changes [6]; 4,203 people aged 50 to 85 at risk of advanced macular degeneration [7].
- Sources
- [6], [7]
- Caveats
- Beta-carotene was tested only as part of a combination. Both trials were run by the US National Eye Institute [6][7].
Not shown to help3
Pregnancy outcomes
Not shown to lower maternal or newborn death or preterm birth in pregnant women. Night blindness and anemia in mothers were lower.
The numbers and sources
- Effect
- Vitamin A alone did not change maternal death (RR 0.88, 95% CI 0.65 to 1.20), perinatal death (RR 1.01, 95% CI 0.95 to 1.07) or preterm birth (RR 0.98, 95% CI 0.94 to 1.01). Maternal night blindness (RR 0.79, 95% CI 0.64 to 0.98) and maternal anemia (RR 0.64, 95% CI 0.43 to 0.94) were lower [2].
- Population
- 19 trials with over 310,000 women, mostly in Nepal, Ghana and Bangladesh [2].
- Sources
- [2]
- Caveats
- Baseline vitamin A status differed between populations. The reduction in maternal infection (RR 0.45, 95% CI 0.20 to 0.99) came from low quality evidence [2].
Cancer prevention
Not shown to lower cancer rates or cancer deaths with beta-carotene in adults. Pooled trials found more bladder cancer.
The numbers and sources
- Effect
- Across 6 trials, beta-carotene did not change cancer incidence (RR 1.08, 95% CI 0.99 to 1.18) or cancer death (RR 1.00, 95% CI 0.87 to 1.15) [3]. Over 12 years, cancer occurred in 1,273 physicians on beta-carotene and 1,293 on placebo (RR 0.98, 95% CI 0.91 to 1.06) [4].
- Population
- 40,544 participants in 6 trials [3]; 22,071 US male physicians aged 40 to 84 [4].
- Sources
- [3], [4]
- Caveats
- In the pooled trials, bladder cancer was higher on beta-carotene (RR 1.52, 95% CI 1.03 to 2.24) [3]. Lung cancer in smokers is under Risks.
Heart disease
Not shown to lower heart attack, stroke or cardiovascular death with beta-carotene in male physicians. One trial in smokers found 26% more cardiovascular deaths, not significant.
The numbers and sources
- Effect
- Over 12 years, heart attack (468 against 489), stroke (367 against 382) and cardiovascular death (338 against 313) did not significantly differ between beta-carotene and placebo [4]. In CARET, cardiovascular death was 26% higher on beta-carotene with retinyl palmitate (RR 1.26, 95% CI 0.99 to 1.61) [5].
- Population
- 22,071 US male physicians [4]; 18,314 smokers, former smokers and asbestos-exposed workers [5].
- Sources
- [4], [5]
- Caveats
- The CARET interval crosses 1. CARET combined beta-carotene with retinol, so the two cannot be separated [5].
Doses studied
ATBC used 20 mg of beta-carotene a day [8]. CARET used 30 mg of beta-carotene with 25,000 IU of retinol as retinyl palmitate a day [5]. The Physicians' Health Study used 50 mg of beta-carotene every other day [4], and AREDS 15 mg a day in a combination [6]. EFSA sets a tolerable upper intake level of 3,000 µg retinol equivalents a day (10,000 IU) of preformed vitamin A for adults, including during pregnancy and lactation. It applies to retinol and retinyl esters. EFSA found no adequate data to set one for beta-carotene, and advises smokers against food supplements containing it [9].
Risks
Reported risks5
Lung cancer in smokers
Shown to raise lung cancer 16% to 28% with beta-carotene in smokers and asbestos-exposed workers.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- In ATBC, lung cancer was 18% higher on beta-carotene (95% CI 3% to 36%) [8]. In CARET, it was 28% higher (RR 1.28, 95% CI 1.04 to 1.57), and death from lung cancer 46% higher (RR 1.46, 95% CI 1.07 to 2.00) [5]. Across 8 trials, beta-carotene raised lung cancer (RR 1.16, 95% CI 1.06 to 1.26), and more so in smokers and asbestos workers (RR 1.21, 95% CI 1.08 to 1.35) [10]. In AREDS2, 23 people on beta-carotene and 11 without it developed lung cancer, mostly former smokers [7].
- Population
- 29,133 Finnish male smokers aged 50 to 69, 5 to 8 years [8]; 18,314 smokers, former smokers and asbestos-exposed workers, mean 4 years [5]; 167,141 participants in 8 trials [10]; 4,203 AREDS2 participants [7].
- Sources
- [5], [7], [8], [10]
- Caveats
- CARET was stopped 21 months early [5]. The meta-analysis found no dose relationship [10]. The AREDS2 finding was a nominal P of .04 [7].
Death from any cause in smokers
Shown to raise death from any cause 8% to 17% with beta-carotene in smokers and asbestos-exposed workers. Deaths did not differ in mostly nonsmoking physicians.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- In ATBC, total mortality was 8% higher on beta-carotene (95% CI 1% to 16%), mainly from lung cancer and ischemic heart disease [8]. In CARET, death from any cause was 17% higher (RR 1.17, 95% CI 1.03 to 1.33) [5].
- Population
- 29,133 male smokers [8]; 18,314 smokers, former smokers and asbestos-exposed workers [5].
- Sources
- [5], [8]
- Caveats
- In healthy male physicians, few of them current smokers, deaths did not differ (979 against 968) [4].
Birth defects
Linked to about 4.8 times more of certain birth defects in babies of women taking over 10,000 IU of preformed vitamin A a day, mostly before week 7.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Defects of cranial neural crest origin were 4.8 times as common in babies of women taking more than 10,000 IU of preformed vitamin A a day from supplements as in those taking 5,000 IU or less (95% CI 2.2 to 10.5). The authors found a threshold near 10,000 IU a day and estimate 1 affected infant in 57 at that intake. The excess was concentrated in intake before week 7 [11].
- Population
- 22,748 pregnant women in the US, 339 babies with birth defects [11].
- Sources
- [11]
- Caveats
- One observational cohort with diet recalled by interview. EFSA chose birth defects as the effect on which it bases the upper limit for preformed vitamin A [9][11].
Hip fracture
Linked to about 48% more hip fractures in postmenopausal women with the highest vitamin A intake, mainly from retinol. Beta-carotene showed no clear link.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Women in the highest fifth of total vitamin A intake, 3,000 µg retinol equivalents a day or more, had more hip fractures than those in the lowest fifth, under 1,250 µg (RR 1.48, 95% CI 1.05 to 2.07). The excess came mainly from retinol (RR 1.89, 95% CI 1.33 to 2.68, 2,000 µg or more against under 500 µg). Beta-carotene intake did not significantly change risk (RR 1.22, 95% CI 0.90 to 1.66) [12].
- Population
- 72,337 postmenopausal US nurses aged 34 to 77, followed 18 years, 603 hip fractures [12].
- Sources
- [12]
- Caveats
- One observational cohort. It measured intake from food and supplements, not a randomized dose.
Eye irritation from topical vitamin A on or near the eye
Shown to raise eye pain, dryness and burning with topical vitamin A on or near the eye, mostly at prescription strength. Serious events did not differ.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Against controls, topical vitamin A products applied to the eye surface or the skin around the eye raised the odds of eye pain (OR 6.37), dryness (OR 2.69), burning (OR 2.44) and any harm (OR 1.71). Serious adverse events did not significantly differ (OR 1.21). Prescription-strength products showed higher odds of harm, and nonprescription products were not significantly linked to more harm [13].
- Population
- 89 randomized and nonrandomized studies with 10,794 participants, 55 of them pooled [13].
- Sources
- [13]
- Caveats
- The authors rated the certainty very low to low. This covers products applied to the eye surface or the skin around it, not vitamin A taken by mouth [13].
Claims tested and not found
- That beta-carotene prevents cancer. Pooled trials found no change in cancer incidence or cancer death [3], and in smokers lung cancer rose [5][8].
- That beta-carotene protects the heart. Heart attack, stroke and cardiovascular death did not differ from placebo over 12 years [4].
- That vitamin A in pregnancy lowers maternal or infant death. Pooled trials found no change in maternal or perinatal mortality [2].
Sources
- Imdad A, Mayo-Wilson E, Haykal MR, et al. Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age. Cochrane Database of Systematic Reviews. 2022. https://doi.org/10.1002/14651858.CD008524.pub4
- McCauley ME, van den Broek N, Dou L, et al. Vitamin A supplementation during pregnancy for maternal and newborn outcomes. Cochrane Database of Systematic Reviews. 2015. https://doi.org/10.1002/14651858.CD008666.pub3
- Jeon YJ, Myung SK, Lee EH, et al. Effects of Beta-Carotene Supplements on Cancer Prevention: Meta-Analysis of Randomized Controlled Trials. Nutrition and Cancer. 2011. https://doi.org/10.1080/01635581.2011.607541
- Hennekens CH, Buring JE, Manson JE, et al. Lack of Effect of Long-Term Supplementation with Beta Carotene on the Incidence of Malignant Neoplasms and Cardiovascular Disease. New England Journal of Medicine. 1996. https://doi.org/10.1056/NEJM199605023341801
- Omenn GS, Goodman GE, Thornquist MD, et al. Effects of a Combination of Beta Carotene and Vitamin A on Lung Cancer and Cardiovascular Disease. New England Journal of Medicine. 1996. https://doi.org/10.1056/NEJM199605023341802
- Age-Related Eye Disease Study Research Group. A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss. Archives of Ophthalmology. 2001. https://doi.org/10.1001/archopht.119.10.1417
- Age-Related Eye Disease Study 2 Research Group. Lutein + Zeaxanthin and Omega-3 Fatty Acids for Age-Related Macular Degeneration. JAMA. 2013. https://doi.org/10.1001/jama.2013.4997
- Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. The Effect of Vitamin E and Beta Carotene on the Incidence of Lung Cancer and Other Cancers in Male Smokers. New England Journal of Medicine. 1994. https://doi.org/10.1056/NEJM199404143301501
- European Food Safety Authority. Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Version 11. 2025. https://www.efsa.europa.eu/sites/default/files/assets/UL_Summary_tables.pdf
- Kordiak J, Bielec F, Jabłoński S, et al. Role of Beta-Carotene in Lung Cancer Primary Chemoprevention: A Systematic Review with Meta-Analysis and Meta-Regression. Nutrients. 2022. https://doi.org/10.3390/nu14071361
- Rothman KJ, Moore LL, Singer MR, et al. Teratogenicity of High Vitamin A Intake. New England Journal of Medicine. 1995. https://doi.org/10.1056/NEJM199511233332101
- Feskanich D, Singh V, Willett WC, et al. Vitamin A Intake and Hip Fractures Among Postmenopausal Women. JAMA. 2002. https://doi.org/10.1001/jama.287.1.47
- Abbott KS, Kruoch Z, Pucker A, et al. Potential Harms of Ocular and Periorbital Topical Vitamin A Application: A Systematic Review and Meta-Analysis. Investigative Ophthalmology & Visual Science. 2026. https://doi.org/10.1167/iovs.67.11.11