Vitamin A is an important nutrient for skin, vision, immunity, growth, and reproduction. It is an essential part of the diet and is an important part of many integrative medicine treatment plans. However, vitamin A carries with it the risk of toxicity. Therefore, it is important to understand safe dose ranges. Vitamin A is often supplied as provitamin A (or beta carotene), which is a safer form of the supplement that doesn’t carry risk of toxicity.
Conditions That May Be Improved By Vitamin A Supplementation
- Vitamin A deficiency
- Certain cancers
- Cataracts
- Measles
- Night blindness
- Eye diseases
- Viral illness/immunizations
- Skin conditions
- Wound healing
- Anemia
- Infertility
- Acne
Vitamin A Intake Guidelines
Vitamin A is essential for normal growth and development in children and for maintaining good health through adulthood. The recommended daily allowance (RDA) is the minimum amount needed for good health. The tolerable upper limit (UL) is the maximum safe intake for long term consumption.
Measurements of vitamin A are mcg of retinol activity equivalents (RAE). This allows for simplified calculation of total active vitamin A by combining both preformed vitamin A (retinol) and provitamin A (carotenoids). Vitamin A may also be measured in International Units (IU). 1 IU of vitamin A = 0.3 mcg.
When considering if the minimum vitamin A intake is reached, both vitamin A and provitamin A are counted (RDA).
When considering the maximum tolerable intake of vitamin A, provitamin A (beta-carotene) is not included in the calculation because it isn’t toxic. Only preformed vitamin A has an upper limit.
Amounts higher than the UL are often prescribed for various conditions for limited periods of time. Dosages higher than the UL should always be monitored by a health professional.
Vitamin A Intake Guidelines |
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| Age Range | Recommended Daily Allowance
(Retinol + Carotenoids) |
Tolerable Upper Limits (Retinol Only) |
| Birth – 6 months | 400 mcg | 600 mcg |
| Infants 7- 12 months | 500 mcg | 600 mcg |
| Children 1- 3 years | 300 mcg | 600 mcg |
| Children 4- 8 years | 400 mcg | 900 mcg |
| Children 9- 13 years | 600 mcg | 1700 mcg |
| Teen Boys 14- 18 years | 900 mcg | 2800 mcg |
| Teen Girls 14- 18 years | 700 mcg | 2800 mcg |
| Adult Men 19+ | 900 mcg | 3000 mcg |
| Adult Women 19+ | 700 mcg | 3000 mcg |
| Pregnant Teens | 750 mcg | 2800 mcg |
| Pregnant Women | 770 mcg | 3000 mcg |
| Breastfeeding Teens | 1200 mcg | 2800 mcg |
| Breastfeeding Women | 1300 mcg | 3000 mcg |
Table adapted from Vitamin A – Health Professional Fact Sheet
Zinc & Vitamin A Deficiency Link
Zinc is required for the storage and handling of vitamin A in the body. If zinc is deficient, vitamin A deficiency symptoms may occur. Zinc supplementation may be required alongside vitamin A supplementation to address a deficiency.
Short Term Dosing For Children
When prescribing vitamin A to children and infants over 6 months of age, I will often have them take 1500 mcg daily for up to two weeks. These courses of vitamin A treatment are usually part of a larger immune support plan for viral illness or vaccinations.
For treating skin conditions in children, I expect that vitamin A may have to be supplemented for a month or more. In these cases, I aim for doses closer to the RDA and often include zinc.
Alternatively, a single mega dose of 30,000 mcg can be prescribed alongside the MMR vaccine. This is routinely done in countries where vitamin A deficiency is common. Two consecutive mega doses of 30,000- 60,000 mcg can also be used at the beginning of serious viral infections like Covid-19, measles, and ebola. Consult a doctor before adding vitamin A to any health routine.
Read more about vitamin A megadoses: Vitamin A Megadose For Viral Infections – Dr. Green Mom
Long Term Vitamin A Supplementation For Children
A well rounded multivitamin formulated for children will usually have satisfactory amounts of vitamin A alongside provitamin A. If a child has a condition that may lead to vitamin A deficiency, such as poorly managed inflammatory bowel disease or celiac disease, then daily, weekly or monthly vitamin A may be recommended.
Megadoses for Adults
Vitamin A megadoses for adults have been used for the treatment of acne. Doses of 100,000-150,000 mcg of vitamin A were used for up to 12 weeks.
Megadoses of 60,000 mcg of vitamin A have also been used for serious viral conditions including Covid-19, measles, and ebola.
To read more about vitamin A mega doses, see Vitamin A Megadose For Viral Infections – Dr. Green Mom
Long Term Vitamin A Supplementation For Adults
As with children, a well-formulated adult (or prenatal) multivitamin will generally contain good levels of vitamin A alongside provitamin A. Adults on a vegan diet who have a genetic polymorphism that impairs the conversion of provitamin A to vitamin A may need to take preformed vitamin A as a supplement.
Vitamin A Toxicity Symptoms
Vitamin A is a fat soluble vitamin that is stored in the liver. Over time vitamin A can build up and cause toxicity symptoms. After stopping vitamin A supplementation, it takes a long time for the body to get rid of excess vitamin A. In extreme cases, vitamin A toxicity may cause liver damage that is not always reversible.
In adults, taking large amounts of vitamin A over a long period can cause side effects like fatigue, irritability, mental problems, dizziness, dry skin, gastrointestinal symptoms, sweating, fever, and more.
In children, taking too much vitamin A can cause dry or peeling skin, increased risk of infection, headache, sleepiness, irritability, gastrointestinal symptoms, impaired vision, and more.
Beta carotene (provitamin A) can cause temporary yellowing of the skin if taken in extreme amounts. However, this isn’t harmful and reverses itself in time.
Vitamin A Contraindications
Excess vitamin A can cause birth defects. It should be used with extreme caution in pregnancy. Vitamin A should also be avoided by people with substance use disorder, kidney disease, liver disease, and by people who smoke.
Summary
Vitamin A is an important micronutrient for good health at all stages of the lifespan. Supplementation may be required to correct deficiencies or to address certain conditions. When supplementing with vitamin A, it’s important to keep in mind safe doses because toxicity is possible. Provitamin A is a safer option for long term supplementation. Zinc supplementation may be required alongside vitamin A when correcting a vitamin A deficiency.
References:
Vitamin A – Health Professional Fact Sheet
Vitamin A Deficiency – Nutritional Disorders – Merck Manuals Professional Edition
Christian, P., & West, K. P., Jr (1998). Interactions between zinc and vitamin A: an update. The American journal of clinical nutrition, 68(2 Suppl), 435S–441S.
Bollag, W., & Ott, F. (1999). Successful treatment of chronic hand eczema with oral 9-cis-retinoic acid. Dermatology (Basel, Switzerland), 199(4), 308–312.
Tang G. (2010). Bioconversion of dietary provitamin A carotenoids to vitamin A in humans. The American journal of clinical nutrition, 91(5), 1468S–1473S.
Marjorie J Haskell, The challenge to reach nutritional adequacy for vitamin A: β-carotene bioavailability and conversion—evidence in humans, The American Journal of Clinical Nutrition, Volume 96, Issue 5, November 2012, Pages 1193S–1203S,
dela Seña, C., Riedl, K. M., Narayanasamy, S., Curley, R. W., Jr, Schwartz, S. J., & Harrison, E. H. (2014). The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase. The Journal of biological chemistry, 289(19), 13661–13666.
https://lpi.oregonstate.edu/mic/vitamins/vitamin-A
Vitamin A: Health Benefits, Side Effects, Uses, Dose & Precautions
Al Nasser Y, Jamal Z, Albugeaey M. Carotenemia. [Updated 2022 Jan 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
