Vitamin A (retinol) - Restorative Medicine

Background

Vitamin A is a fat-soluble vitamin that comes from two sources: preformed retinoids and provitamin carotenoids. Retinoids, such as retinal and retinoic acid, are found in animal sources such as liver, kidney, eggs, and dairy products. Carotenoids, such as beta-carotene (which has the highest vitamin A activity), are found in plants such as dark or yellow vegetables and carrots.
Natural retinoids are present in all living organisms, either as preformed vitamin A or as carotenoids, and are required for biological processes such as vision and cellular growth. A major biologic function of vitamin A (as the metabolite retinal) is in the visual cycle. Research also suggests that vitamin A may reduce death from measles, prevent some types of cancer, aid in growth and development, and improve immune function.
Recommended dietary allowance (RDA) levels for vitamin A oral intake have been established by the U.S. Institute for Medicine of the National Academy of Sciences to prevent deficiencies in vitamin A. At recommended doses, vitamin A is considered nontoxic. Excess dosing may lead to short or long-term toxicity.
Vitamin A deficiency is rare in developed nations but remains a concern in developing countries, particularly in areas where poor nutrition is common. Prolonged deficiency can lead to xerophthalmia (dry eye) and ultimately to night blindness or total blindness, as well as to skin disorders, infections (such as measles), diarrhea, and lung disorders.

Scientific Evidence

Uses	Grade*
Acne Retinoids that are applied to the skin are considered among the best treatments for acne. Tretinoin (all-trans retinoic acid) and other forms of vitamin A, retinoids, and oral prescription medications, such as isotretinoin (Accutane^®), are available for treatment. Isotretinoin may cause severe side effects, such as burning, erythema, and pruritus, and should be used only for severe resistant acne. Adapalene (Differin^®) is also effective and reported to have fewer side effects. Another retinoid, tazarotene (Tazorac^®), has been shown to be superior to either tretinoin or adapalene. In general, retinoid use (including tretinoin) must be avoided in women that are pregnant, plan to become pregnant, or have a chance of being pregnant, due to a risk of severe birth defects. These medications should be prescribed by a qualified licensed healthcare professional. Multiple retinoid use should be avoided, due to a risk of increased toxicity.	A
Acute promyelocytic leukemia (cancer of blood and bone marrow, treatment) The prescription drug all-trans retinoic acid (ATRA, Vesanoid^®) is a form of vitamin A that is a recognized treatment for acute promyelocytic leukemia that improves survival in this disease. Treatment should be under strict medical supervision. Other vitamin A forms should not be used at the same time with ATRA, due to a risk of increased toxicity.	A
Anemia (decrease in red blood cells) Vitamin A deficiency has been shown to impair iron use, as well as impair red blood cell formation, and increase the risk of infection. Vitamin A supplementation has been shown to raise hemoglobin levels and serum iron concentrations, particularly in children and pregnant women. It has also been shown to enhance the efficacy of iron supplementation in patients with vitamin A deficiency and iron deficiency anemia.	A
Dry eyes (xerophthalmia) Prolonged vitamin A deficiency can lead to xerophthalmia (dry eye). It is widely seen in rural, underdeveloped areas, such as India and Southeast Asia. Oral vitamin A is the treatment of choice for xerophthalmia caused by prolonged vitamin A deficiency, and it should be given immediately once the disorder is established. Bitot's spot, or the buildup of keratin debris in the conjunctiva, is a sign of xerophthalmia and may also be treated with vitamin A supplementation.	A
Eye disorders (retinitis pigmentosa) Retinitis pigmentosa is a genetic disorder that affects night vision. Early symptoms include night blindness and loss of vision over time. Based on recent findings, vitamin A in the palmitate form has been recommended in patients with retinitis pigmentosa.	A
Malaria (supportive agent) Limited research suggests that vitamin A may reduce fever, morbidity, and parasite blood levels in patients with malaria (Plasmodium falciparum infection). However, there is a lack of evidence suggesting that vitamin A is equal to or superior to well-established drug therapies used for the prevention or treatment of malaria. Patients with malaria or those who are living or traveling in diseased areas should speak with a physician about appropriate measures.	A
Measles (supportive agent) Vitamin A should be given to children diagnosed with measles in areas where vitamin A deficiency may be present. Measles is a viral disease that can lead to diarrhea, pneumonia (lung infection), and encephalitis (inflammation of the brain). In children with measles, vitamin A has been shown to be beneficial by decreasing the length and impact of the disease. Side effects such as diarrhea, pneumonia, and death have been reduced with the use of vitamin A. Management of measles should be under strict medical supervision.	A
Mortality reduction (childhood; all-cause) Vitamin A is needed for healthy growth and development, and recommended dietary allowances (RDAs) should be assured, particularly in children. Major causes of vitamin A deficiency in children are maternal vitamin A deficiency (thus low levels of vitamin A in breast milk), inadequate vitamin A intake upon weaning, and prevalent illness. Experts have maintained that in developing countries, diet alone is insufficient to maintain adequate vitamin A levels in children. Vitamin A is associated with a reduced risk of mortality (death) in children.	A
Skin damage caused by the sun Some studies suggest that topical tretinoin (all-trans retinoic acid, the acid form of vitamin A) may improve sun damaged skin. Common adverse effects are skin pain and redness.	A
Vitamin A deficiency Vitamin A deficiency is generally rare in industrialized nations. In developing countries, diet alone may be insufficient to maintain adequate vitamin A levels, especially in children. Vitamin A supplementation can help prevent or treat vitamin A deficiency.	A
Healing after photorefractive keratectomy (adjunct therapy) Photorefractive keratectomy is a type of laser eye surgery used to correct nearsightedness. High-dose vitamin A use in addition to vitamin E has been suggested to help improve eye healing after surgery and to improve visual acuity, although additional evidence is necessary before a definitive conclusion can be reached.	B
HIV support The role of vitamin A in the prevention, transmission, or treatment of HIV is controversial and not well established. A clear conclusion cannot be formed based on the available scientific research.	B
Oral leukoplakia (white patches or plaque in the mouth) Vitamin A may improve clinical resolution of oral leukoplakia (white patches or plaque in the mouth), although relapse is common. Further research is required.	B
Age-related macular degeneration Although this has not been well studied in humans, the use of vitamin A and carotenoids may be useful in the prevention of age-related macular degeneration. Further research is required.	C
Asthma Vitamin A intake is inversely associated with asthma risk and severity. A clear conclusion cannot be formed based on the available scientific research.	C
Breast feeding (nipple pain) Vitamin A and D ointment may be useful for sore and cracked nipples that occur during breastfeeding. However, available studies have not shown vitamin A or any other topical therapy to relieve the pain of breastfeeding.	C
Bronchiolitis (inflammation of the bronchioles) Vitamin A is thought to be important in immune function. A clear conclusion cannot be formed on the effects of vitamin A on bronchiolitis (inflammation of the bronchioles) based on the available scientific research.	C
Bronchopulmonary dysplasia in premature infants (chronic lung condition) Research results are lacking as to whether vitamin A is beneficial for bronchopulmonary dysplasia in premature infants. Further research is needed.	C
Cancer (general) Research has shown mixed results for cancer risk reduction with vitamin A use, and some studies suggest an increased risk of cancer with vitamin A supplementation. According to a review of epidemiological studies, beta-carotene may be most beneficial in prevention of renal cancer, while vitamin A appears to be harmful in heavy smokers at risk for lung cancer. Further research is needed to clarify risk status in various populations.	C
Cataract Antioxidants have been suggested in delaying cataract progression. However, research suggests that beta-carotene lacks the ability to reduce risk. Further trials are required to form conclusions.	C
Cervical cancer Human research suggests that vitamin A may have protective effects in cervical cancer. Compared to low intakes and low serum levels, high intake and high serum levels were associated with a decreased risk of cervical cancer. Further, high quality research is needed.	C
Chemotherapy adverse effects The effect of vitamin A supplementation on chemotherapy-related side effects, including nausea, vomiting, diarrhea, or mouth sores, is unclear. Also, it is unclear if vitamin A interacts with chemotherapy agents. Further research is needed.	C
Colorectal cancer Alpha-carotene and vitamin A may protect against recurrence of colorectal cancer in nonsmokers and nondrinkers. Further research is needed before a conclusion can be drawn.	C
Cystic fibrosis In people with cystic fibrosis, intake and absorption of fat-soluble antioxidants such as carotenoids are reportably lower. However, high-quality human research is lacking, and further research is needed in this field.	C
Liver cancer Some forms of vitamin A may be beneficial in liver cancer prevention. Acyclic retinoid is a synthetic retinoid that has been shown to inhibit cell growth in liver cancer cells. Further research is needed.	C
Liver disease There is insufficient evidence on the use of antioxidant supplements (including vitamin A) in patients with liver disease. More research is needed in this area.	C
Lung cancer Vitamin A has been studied as a possible treatment for lung cancer, without evidence of benefits. The available evidence suggests that high-dose vitamin A and beta-carotene may actually increase the risk of adverse effects, especially among alcohol users and smokers.	C
Miscarriage (prevention) Poor nutrition is associated with an increased risk of miscarriage. However, excess intake of vitamin A has been reported to increase the risks of some birth defects. Vitamin A supplementation above the recommended daily amount is not advised in pregnancy.	C
Mortality reduction Adequate vitamin A (either through diet or supplementation) appears to have a major role in the prevention of morbidity and mortality. Further research is needed.	C
Mortality reduction (maternal; supplementation after childbirth) Maternal supplementation of vitamin A shortly after childbirth provides limited number of benefits to maternal health status. A clear conclusion is lacking based on the available scientific research.	C
Mortality reduction (maternal; supplementation during pregnancy) Vitamin A supplementation during pregnancy and lactation does not appear to reduce infant morbidity and mortality; however, it does appear to reduce maternal morbidity. A clear conclusion cannot be formed based on the available scientific research.	C
Mouth sores (oral lichen planus) Early research suggests a positive effect of retinoid treatment for oral lichen planus; however, more research is required to form conclusions.	C
Nutrition supplementation In developing countries, and in diets of developed countries where limited amounts of vitamin A are consumed, vitamin A intake is of concern. Upon analysis of small fish consumed in developing countries, high levels of vitamin A, iron, and zinc were collected, suggesting an alternative source to increase micronutrient intake. In young children under the age of two, fortified milk and cereals increased levels of vitamin A, and according to some research, micronutrient powders decreased iron deficiency and anemia. Further research is required to make conclusions of vitamin A intake in these populations.	C
Ovarian cancer Research of vitamin A intake suggests a lack of relationship between self-recalled antioxidant consumption from foods and ovarian cancer risk; however, adolescent intake appeared to reduce risk by 46%. Further research is needed to make conclusions based on these findings.	C
Parasite infection (Ascaris reinfection) After deworming, children supplemented with vitamin A may be less prone to the Ascaris parasite reinfection. These benefits may be less in children with stunted growth. More research is needed in this area.	C
Prostate cancer prevention It is unclear whether dietary vitamin A affects prostate cancer risk. Interventional studies are lacking. More research is needed in this area.	C
Psoriasis The use of vitamin A in psoriasis treatment has been reviewed and discussed. Research has shown that treatment with vitamin A reduces psoriasis symptoms.	C
Radiation therapy side effects In some research, vitamin A supplementation appeared to reduce symptoms of chronic radiation proctopathy (damage from pelvic radiation); however, significance was lacking. Further research is needed to form conclusions.	C
Rosacea Isotretinoin is a well-known treatment for rosacea; however, high quality studies and optimal dosages are lacking. Future research is needed.	C
Skin cancer It is unclear if vitamin A or beta-carotene, taken by mouth or used on the skin with sunscreen, is beneficial in the prevention or treatment of skin cancers or wrinkles.	C
Throat cancer (esophageal) Higher intakes of beta-carotene and vitamin A were associated with reduced risk of esophageal adenocarcinoma. There is insufficient evidence to form a clear conclusion at this time.	C
Tuberculosis (bacterial lung infection) There is insufficient evidence to assess the use of vitamin A for tuberculosis. Further research is needed before a conclusion can be drawn	C
Viral infection (Norovirus (NoV) infection) Vitamin A supplementation has been suggested to help prevent NoV infection in children and to reduce the symptoms associated with NoV infections. More research is needed in this area.	C
Weight loss Daily vitamin A with calcium has been suggested for weight loss. In one study, an average loss of two pounds was reported after two years of supplementation in young women. More research is needed in this area.	C
Wound healing In preliminary research, vitamin A (retinol palmitate) significantly reduced rectal symptoms of radiation proctopathy (damage from pelvic radiation), perhaps because of wound-healing effects. Further research is needed to confirm these results.	C
Arthritis The available evidence lacks support for the treatment of any form of arthritis with vitamin A (or combination products containing vitamin A). Further research is needed to confirm these results.	D
Breast cancer Research has suggested that beta-carotene in combination with other antioxidants may reduce mortality in individuals with breast cancer, but the effects of beta-carotene alone are lacking. A reduction in breast cancer risk was reported with high vitamin A or retinol intake; however, significant concerns still exist. Additional research is needed before a conclusion may be made.	D
Childhood growth promotion Vitamin A is necessary for healthy growth and development, and recommended dietary amounts should be assured, particularly in children. Overall, the available evidence has shown a lack of any significant changes in growth in children with respect to height and weight due to vitamin A.	D
HIV (mother-to-child transmission) Overall evidence lacks the support of vitamin A use in HIV-infected pregnant women to reduce mother-to-child transmission of HIV.	D
Infant mortality (maternal supplementation after childbirth) Overall, studies suggest a lack of effect of vitamin A supplementation shortly after childbirth on infant mortality.	D
Infant mortality (maternal supplementation during pregnancy) Overall, studies suggest a lack of effect of prenatal vitamin A supplementation on perinatal or neonatal infant mortality.	D
Infant mortality (neonatal or childhood supplementation) There is a lack of effect of vitamin A on mortality as reported in some research; however, in developing countries, vitamin A supplementation appeared to be helpful in reducing mortality up to six months of age. Further research is needed in this area.	D
Inflammatory bowel disease Some research has shown that isotretinoin lacks a significant effect on the incidence of inflammatory bowel disease (IBD), Crohn's disease (CD), or ulcerative colitis (UC). Additional high quality research is needed before a conclusion may be made.	D
Respiratory tract infections There is insufficient evidence to support the use of vitamin A for the reduction of pneumonia or mortality in children without measles. More research is needed in this area.	D
Cancer (gastrointestinal; prevention) Evidence suggests that vitamin A fails to reduce the rates of gastric cancer or precancerous gastric lesions and also links vitamin A supplementation with increased mortality.	F

*Key to grades:

A: Strong scientific evidence for this use;

B: Good scientific evidence for this use;

C: Unclear scientific evidence for this use;

D: Fair scientific evidence against this use (it may not work);

F: Strong scientific evidence against this use (it likely does not work).

Tradition

Aging, AIDS (adjunct), allergic rhinitis, autism, burns, chemical sensitivities (pollutant protection), chronic diseases (prevention), conjunctivitis, deafness, deficiency (protein), diabetes, diarrhea, dysentery (shigellosis), dysmenorrhea, eczema, epilepsy, fibrocystic breast disease, gastric ulcers, glaucoma, hay fever, headache (persistent), heart disease, herpes (cold sores), hyperthyroidism (increased thyroid function), immune enhancement, increasing sperm count, infections (general, nose), kidney stones, lichen planus pigmentosus, menorrhagia (heavy menstruation), metabolic disorders (Hurler syndrome), mouth cancer, neurodegenerative diseases, pancreatic cancer, pancreatitis, periodontal disease, pityriasis rubra pilaris (skin disorder), premenstrual syndrome (PMS), respiratory disorders, sebaceous cysts, sinus infections, sinusitis, skin disorders (Darier's disease, ichthyosis), sleep (regulation), smell disorders, stroke, sunburn, tinnitus, tumors (neoplasms), ulcers (stress ulcers in severely ill hospitalized patients), urinary tract infection, vaginal atrophy, vaginal infections, vascular diseases (prevention), vision enhancement (nearsightedness, blurred vision), warts.

Dosing

Adults (18 years and older)

Vitamin A is found in dairy products, fish, and darkly colored fruits and vegetables. Five servings of fruits and vegetables daily supplies 5-6 milligrams of provitamin A carotenoids, which provides about 50-65% of the adult recommended dietary allowance (RDA) for vitamin A.
Vitamin A is included in most multivitamins, and the U.S. recommended dietary allowance (RDA) for adults is as follows: 900 micrograms daily (3,000 IU) for men and 700 micrograms daily (2,300 IU) for women; for pregnant women 19 years old and older, 770 micrograms daily (2,600 IU); and for lactating women 19 years old and older, 1,300 micrograms daily (4,300 IU).
For vitamin A deficiency, unrelated to xerophthalmia (dry eye), vitamin A has been given at a daily dose of 100,000 IU by mouth or intramuscularly for three days, followed by 50,000 IU daily for two weeks. After two weeks, daily doses of 10,000-20,000 IU have been given for two months. In mothers six weeks after childbirth, either 400,000 IU of vitamin A (in two doses separated by 24 hours) or 200,000 IU as one dose (plus placebo 24 hours later) has been taken.
For community based intervention, a single dose of 200,000 IU has been given by mouth as monthly doses for six months, four months, or one month.
For acne, isotretinoin was given by mouth daily as 0.5-0.7 milligrams per kilogram (normal and intermittent dose) or 0.25-0.4 milligrams per kilogram daily (low-dose) for one out of every four weeks. Vitamin A and retinoids are available as gels, creams, and liquids and are typically applied to the skin once daily but can be used every other day if poorly tolerated. Tretinoin 0.025% and adapalene 0.1% have been applied to the skin once to twice daily for up to 16 weeks.
For acute promyelocytic leukemia (treatment), all-trans retinoic acid (Vesanoid^® (tretinoin)) has been administered as follows: 45 milligrams per square meter of body surface area daily by mouth, as two evenly divided doses until complete remission; therapy should be discontinued 30 days after the achievement of complete remission or after 90 days of treatment, whichever occurs first. In addition, 25-45 milligrams per square meter daily or 30-40 milligrams of all trans-retinoic acid (ATRA) has been taken daily for two to three years.
For arthritis, 0.5 milligrams per kilogram of etretinate (vitamin A form) was taken daily for four weeks then reduced to 0.25 milligrams per kilogram daily if there was a lack of improvement or if side effects were observed. Vitamin A was also given as 50,000 IU daily for three weeks; however, further research concluded that there was a lack of convincing evidence that vitamin A is effective for treating any type of arthritis.
For breast cancer, 1,000-6,000 milligrams of retinol and 3,000 IU-10,000 IU of vitamin A has been taken daily.
For cancer of the stomach and intestine, 5,000 IU and 50,000 IU have been administered in weekly doses; however, research suggests that these doses of vitamin A may have been associated with an increased risk of mortality.
For cancer (general), 20-50 milligrams of beta-carotene was given by mouth daily or every other day for 5-12 years.
For cancer-related side effects, weekly injections of 100,000 IU of vitamin A have been used.
For cervical cancer, vitamin A supplementation (dosing information was lacking) was taken for 1-3 years.
For colorectal cancer, 25,000 IU of vitamin A in combination with 30 milligrams of beta-carotene has been taken once daily for up to seven years with a lack of effect.
For HIV support, a large dose of vitamin A (400,000 IU in adults and 50,000 IU in infants) was given to women and infants shortly after birth for two years. In other research, high doses (180 milligrams daily or 600,000 IU) of beta-carotene were given for one month. Lower doses of vitamin A (10,000 IU daily) have also been given to adults in areas of high prevalence of vitamin A. Additionally, 200,000-300,000 IU have been given for 4-8 weeks, but reported a lack of benefit on CD4 counts and viral load.
For infant mortality (given to the mother during pregnancy), pregnant women with HIV received iron and folate, either alone or combined with vitamin A (three milligrams of retinol equivalents) daily by mouth from 18-28 weeks of gestation. In other research, pregnant women took 7,000 micrograms of retinol equivalents of vitamin A (as four milligrams of all-trans beta-carotene retinyl palmitate) or 42 milligrams of beta-carotene once weekly by mouth during pregnancy; moreover, vitamin A (5,000 IU-23,300 IU) has been taken with our without 30 milligrams of beta-carotene during pregnancy. Also during 12-24 weeks of gestation, vitamin A (5,000 IU or 10,000 IU) was taken by mouth daily. Doses of 200,000 IU weekly and 200,000 IU at the time of delivery have also been used.
For infant mortality (given to mother shortly after childbirth), vitamin A (≤200,000 IU or >200,000 IU) has been given as a single dose or as multiple doses to mothers within six weeks of delivery. Doses consisting of 200,000-400,000 IU of vitamin A or 7.8 milligrams of beta-carotene, alone or in combination with another supplement, have also been taken daily by mouth.
For inflammation of the oral mucosa (oral lichen planus), 0.1% tretinoin or 0.05-0.18% isotretinoin two to three times daily for 8-16 weeks, 0.05% retinoic acid four times daily for four weeks, and 0.1% vitamin A twice daily for up to seven days have been applied to the mouth.
For liver disease, daily amounts of 5,000 IU of vitamin A have been taken for six months or 10,000 IU for four months.
For lung cancer, 20-50 milligrams of beta-carotene was taken by mouth daily or every other day for 5-12 years.
For treating lung cancer, 0.5-1 milligram per kilogram of 13-cis-retinoic acid has been given daily for 11 weeks to one year; for the prevention of primary lung cancer, 25,000 IU retinyl palmitate daily in combination with 30 milligrams of beta-carotene or 22.5 milligrams of zinc daily for 13 months to 5.5 years has been used; and for the prevention of secondary lung cancer, 150,000-300,000 IU retinyl palmitate daily or 10-30 milligrams of isotretinoin every other day for one to two years has been used. Additionally, all-trans retinoic acid (ATRA) 20 milligrams per square meter of body surface area has been used injected daily in combination with cisplatin and paclitaxel.
For mortality reduction, 1,333-200,000 IU of vitamin A trials has been taken daily or every other day for 28 days to nine years, with a lack of effect on all-cause mortality.
For mortality reduction (for the mother shortly after childbirth), vitamin A has been taken during pregnancy at doses ranging from 5,000-10,000 IU daily, about 200,000 IU weekly, and 200,000 IU at the time of delivery.
For oral leukoplakia, vitamin A (as retinyl acetate) was given by mouth at doses of 300,000 IU weekly for 12 months, 200,000 IU of vitamin A (form unclear) weekly (0.14 milligrams per kilogram of body weight) daily for six months, or 13-cis-retinoic acid 1-2 milligrams per kilogram of body weight daily for three months. In addition, 0.05-0.18% isotretinoin gel three times daily for four months, 0.05% tretinoin gel four times daily for a mean follow-up of 23 months, or 20 milligrams of acitretin daily have been applied to the mouth.
For psoriasis, one milligram per kilogram of retinoids was taken daily (frequency information lacking). Additionally, 10-75 milligrams of acitretin was taken by mouth daily either alone or in combination with psorlen plus ultraviolet A/B (PUVA/PUVB) light, and one milligram per kilogram or 75 milligrams of etretinate was taken by mouth daily for six weeks to 12 months.
For radiation therapy side effects, 10,000 IU retinol palmitate was taken daily for 90 days.
For retinitis pigmentosa (vision disorder), the National Eye Institute (NEI) recommends that patients with typical forms of retinitis pigmentosa receive 15,000 IU of vitamin A palmitate daily under medical supervision.
For skin cancer, 100,000 IU of vitamin A was taken daily by mouth for 18 months; however, there was an overall lack of benefit with vitamin A therapy.
For skin damage caused by the sun, 0.02% or higher doses of tretinoin have been applied to sun-damaged skin once daily for a treatment duration of 4-11 months; other retinoids, tazarotene 0.01-0.1% and isotretinoin 0.1%, were also applied to the skin once daily.
For tuberculosis, 5,000-200,000 IU has been taken three times before starting tuberculosis therapy with one study having a treatment duration of six months.

Children (under 18 years old)

Recommended dietary allowances (RDAs) have been established by the U.S. Institute of Medicine of the National Academy of Sciences. The recommendations are as follows: for children 1-3 years old, 300 micrograms (1,000 IU) daily; for children 4-8 years old, 400 micrograms (1,300 IU) daily; and for children 9-13 years old, 600 micrograms (2,000 IU) daily. For pregnant women 14-18 years old, 750 micrograms (2,500 IU) daily is recommended. For lactating women 14-18 years old, 1,200 micrograms (4,000 IU) daily is recommended.
The World Health Organization (WHO) has established dosage guidelines for children 6-11 months old to receive 100,000 IU of vitamin A. This increases to 200,000 IU every six months from 12 to 59 months of age.
For acute promyelocytic leukemia, 25-45 milligrams of all-trans retinoic acid (ATRA) has been taken daily until complete remission or for up to two years in combination with cancer therapy.
For anemia, 3,000 micrograms of vitamin A has been taken by mouth daily for two months.
For bronchopulmonary dysplasia in premature infants, 2,000 IU has been taken every other day or 4,000 IU has been taken three times weekly by mouth.
For childhood growth promotion, 60 milligrams of vitamin A has been taken in one to six doses separated by 4-6 months, for 12-104 weeks. Other studies administered 2,500 micrograms of vitamin A weekly for one year or as a single large dose of 60,000 micrograms.
For cystic fibrosis, the 2002 cystic fibrosis guidelines recommend vitamin A supplements for all children with cystic fibrosis and pancreatic insufficiency, specifically 3,000 micrograms of retinol activity equivalents (RAEs) daily for children over the age of eight years.
For infant mortality, the following has been taken: three milligrams by mouth daily from 18 to 28 weeks' gestation; 7,000 micrograms by mouth once weekly during gestation; 5,000-10,000 IU daily by mouth from 12-24 weeks' gestation; 200,000 IU weekly, or 200,000 IU at time of delivery; and 200,000-400,000 IU daily by mouth shortly after childbirth. A dose of 2,000 IU has been injected into the muscle of infants every two days for 28 days. Also injected into the muscle, 4,000 IU every two days or 3,750 IU every two days for 16 days has been used. Doses between 1,500 IU and 5,000 IU, by mouth or injected into the muscle of the infant, have been used every other day or three times weekly. Doses from 8,333 IU weekly to 200,000 IU every six months by mouth have been used. In neonates, 5,000 IU per kilogram of vitamin A has been used daily for four weeks or 25,000-50,000 IU of vitamin A (cumulative dose). Within 24-72 hours of delivery, 25,000-400,000 IU of vitamin A divided in one to two oral doses has been taken. Intramuscular injections of vitamin A were given as follows: 2,000 IU every two days for 28 days (14 injections in total), 4,000 IU every two days (duration unclear), 5,000-10,000 IU vitamin A three days weekly, 15,000 IU vitamin A weekly for four weeks, or 3,750 IU every two days for 16 days (eight injections in total). Injections of 1,500-4,000 IU vitamin A every other day or three times weekly for up to four weeks and a lipid emulsion containing 80,000 retinol equivalents per liter of retinyl palmitate for 16 hours plus 1,300-3,300 IU per kilogram of vitamin A daily for two weeks have also been used.
For malaria, children aged 6-60 months were given one capsule (or half a capsule if younger than 12 months) of 200,000 IU of vitamin A (in 200 microliters of peanut oil with 10 micrograms of vitamin E as a preservative) every three months for 13 months.
For measles, the World Health Organization (WHO) recommends 200,000 IU daily by mouth for two days for children with measles who live in areas of vitamin A deficiency. For infants with measles, the WHO recommends 100,000 IU daily by mouth for two days.
For childhood mortality, doses from 8,333 IU weekly to 200,000 IU every six months by mouth have been used. Doses from 10,000 IU weekly for 40 weeks to 206,000 IU once every four months, for up to six doses, have been used.
For HIV, a large dose of vitamin A (400,000 IU in adults and 50,000 IU in infants) has been given to women and infants shortly after childbirth for two years.
For neuroblastoma (cancer of nerve tissue), 22.5-200 milligrams daily of 13-cis-retinoic acid has been taken daily for up to four years alone or with chemotherapy.
For respiratory tract infections, oral doses of vitamin A were as follows: 25,000 IU for a total of three doses, 10,000 IU weekly for a total of 40 doses, 200,000 IU (half dose for infants less than 12 months old) for a total of 2-3 doses at 4-6-month intervals, 206,000 IU (half dose for infants less than 12 months old) for a total of six doses over two years, 200,000 IU (half dose for infants less than 12 months old) for a total of six doses over 23 months, 200,000 IU (half dose for infants less than 12 months old) for a total of three doses over 12 months, 2,500 micrograms weekly for 52 weeks.
For tuberculosis, 5,000 IU or 200,000 IU of vitamin A, alone or in combination with zinc, was taken up to twice daily and 5,000 IU or 8,000 IU of vitamin A as part of a multi-supplement regimen was taken daily, weekly, or as a single dose for 2-24 months.
For xerophthalmia (dry eye), the World Health Organization (WHO) recommends 200,000 IU daily by mouth immediately on diagnosis, 200,000 IU on the following day, and then 200,000 IU prior to discharge, or if clinical deterioration occurs, or 2-4 weeks later. Infants under 12 months of age and very small and very-low-weight children should be given half the dosage.

References

Armstrong AW, Cheeney S, Wu J, et al. Harnessing the power of crowds: crowdsourcing as a novel research method for evaluation of acne treatments. Am J Clin.Dermatol. 12-1-2012;13(6):405-416. View Abstract
Bjelakovic G, Nikolova D, Gluud LL, et al. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane.Database.Syst.Rev. 2012;3:CD007176. View Abstract
Bremner JD, Shearer KD, and McCaffery PJ. Retinoic acid and affective disorders: the evidence for an association. J Clin.Psychiatry 2012;73(1):37-50. View Abstract
Cortes-Jofre M, Rueda JR, Corsini-Munoz G, et al. Drugs for preventing lung cancer in healthy people. Cochrane.Database.Syst.Rev. 2012;10:CD002141. View Abstract
Etminan M, Bird ST, Delaney JA, et al. Isotretinoin and risk for inflammatory bowel disease: a nested case-control study and meta-analysis of published and unpublished data. JAMA Dermatol. 2013;149(2):216-220. View Abstract
Gamble R, Dunn J, Dawson A, et al. Topical antimicrobial treatment of acne vulgaris: an evidence-based review. Am J Clin.Dermatol. 6-1-2012;13(3):141-152. View Abstract
Girard AW, Self JL, McAuliffe C, et al. The effects of household food production strategies on the health and nutrition outcomes of women and young children: a systematic review. Paediatr.Perinat.Epidemiol 2012;26 Suppl 1:205-222. View Abstract
Hanson B, MacDonald R, and Shaukat A. Endoscopic and medical therapy for chronic radiation proctopathy: a systematic review. Dis.Colon Rectum 2012;55(10):1081-1095. View Abstract
Masetti R, Biagi C, Zama D, et al. Retinoids in pediatric onco-hematology: the model of acute promyelocytic leukemia and neuroblastoma. Adv.Ther. 2012;29(9):747-762. View Abstract
Masset E, Haddad L, Cornelius A, et al. Effectiveness of agricultural interventions that aim to improve nutritional status of children: systematic review. BMJ 2012;344:d8222. View Abstract
Thorne-Lyman AL and Fawzi WW. Vitamin A and carotenoids during pregnancy and maternal, neonatal and infant health outcomes: a systematic review and meta-analysis. Paediatr.Perinat.Epidemiol 2012;26 Suppl 1:36-54. View Abstract
Wallace A, Ryman T, Mihigo R, et al. Strengthening evidence-based planning of integrated health service delivery through local measures of health intervention delivery times. J Infect.Dis. 2012;205 Suppl 1:S40-S48. View Abstract
Wallace AS, Ryman TK, and Dietz V. Experiences integrating delivery of maternal and child health services with childhood immunization programs: systematic review update. J Infect.Dis. 2012;205 Suppl 1:S6-19. View Abstract
Zeichner JA. Optimizing topical combination therapy for the treatment of acne vulgaris. J Drugs Dermatol. 2012;11(3):313-317. View Abstract
Zhang X, Dai B, Zhang B, et al. Vitamin A and risk of cervical cancer: a meta-analysis. Gynecol.Oncol. 2012;124(2):366-373. View Abstract