Natural Health Products
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Vitamin A
General Information
Vitamin A is a fat-soluble vitamin and can be stored in the liver and fat tissues for long periods of time. It is available in two different forms: retinoids and carotenoids. Retinoids, one of the most usable forms of vitamin A, come from animal sources such as eggs, dairy products, liver, and meat. Carotenoids are made into retinol once inside the body; they are found in certain plants such as dark or yellow vegetables, squash, spinach, broccoli, and carrots.
Common Name(s)
Scientific Name(s)
How is this product usually used?
Vitamin A is taken by mouth. It is available in different forms, including tablets, chewable tablets or gummies, capsules, powders, strips, drops, and liquids. Retinoids can also be applied topicallytopicallyto be applied on the skin to the skin in the form of creams for the treatment of acne.
Vitamin A dosage is written in micrograms (µg) or milligrams (mg) of retinol activity equivalents (RAE). Table 1 lists the usual dose and the recommended dietary allowance for vitamin A for different age groups. People with vitamin A deficiency might need doses at or above the RDA.
Table 1. Usual daily dose and RDA for vitamin A for different age groups
|
Age groups |
Vitamin A (µg RAE/day) |
||
|
RDA |
Usual daily dose |
||
|
Infants |
0–6 months |
400 |
30–600 |
|
7–12 months |
500 |
30–600 |
|
|
Children |
1–3 years |
300 |
30–600 |
|
4–8 years |
400 |
30–900 |
|
|
Adolescent males |
9–13 years |
600 |
30–1700 |
|
14-18 years |
900 |
65–2800 |
|
|
Adult males |
≥19 years |
900 |
65–3000 |
|
Adolescent females |
9–13 years |
600 |
30–1700 |
|
14–18 years |
700 |
65–2800 |
|
|
Adult females |
≥19 years |
700 |
65–3000 |
|
Pregnancy |
14–18 years |
750 |
65–3000 |
|
19–50 years |
770 |
65–3000 |
|
|
Breast-feeding |
14–18 years |
1200 |
65–3000 |
|
19–50 years |
1300 |
65–3000 |
|
Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.
What is this product used for?
Vitamin A is important to help maintain overall good health. It helps to maintain healthy eyesight, skin membrane, and immune function. Vitamin A can help develop and maintain night vision, bones, and teeth. At doses at or above the RDA, it is also used to treat vitamin A deficiency, which is a condition that can cause night blindness or slow growth rate in children.
Vitamin A supplementation is highly effective in the treatment and prevention of vitamin A deficiency. It is well studied for the treatment of acne, acute promyelocytic leukemia (a type of cancer of blood and bone marrow), anemia, dry eyes, age-related macular degeneration and sunburn. It may also be used as a supportive agent for the treatment of malaria and measles.
There is not enough evidence to recommend its use in other conditions such as preventing certain types of cancer or improving immune function.
Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.
What else should I be aware of?
Vitamin A is safe for most people when taken in recommended amounts. Large amounts of vitamin A can cause headaches, blurred vision, dizziness, loss of appetite, nausea, vomiting, bone pain, benign yellow-orange skin, and hair loss. If large amounts are taken for a long time, you may experience dry, scaly, and peeling skin, tiredness, irritability, psychiatric changes, depression, vomiting, fever, and coma or even death.
High doses of vitamin A can also harm the liver. People who drink alcohol on a regular basis or have liver diseases or are take medications that can affect the liver should consult a health care professional before taking a vitamin A supplement.
People who smoke are at an increased risk of lung cancer if taking vitamin A (specifically beta-carotene). Consult a health care professional if you are currently smoking or recently quit smoking before taking vitamin A supplement.
Avoid taking vitamin A if you have:
- poor fat absorption
- an intestinal infection
- liver disease
Vitamin A is safe to use if you are pregnant or breast-feeding, provided that you do not take more than the recommended amount. High intake of retinol during pregnancy can cause birth defects.
Vitamin A can interact with certain medications, including selected antibiotics (e.g., tetracyclines), some acne products, bile acid sequestrants, blood-pressure-lowering medications, and agents that increase the risk of bleeding (e.g., warfarin). Speak to a pharmacist if you are concerned about this.
Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.
Source(s)
- Skokovic-Sunjic D. Vitamins and the role of the pharmacy technician. Pharmacy Practice: Tech Talk CE May/June 2004. www.pharmacygateway.ca/tech_ce/pdfs/TT_CEMayEng.pdf
- Vitamins and the role of the pharmacy technician. http://ods.od.nih.gov/factsheets/vitamina.asp, accessed 4 July 2012.
- Repchinsky C. Compendium of pharmaceuticals and specialties. Ottawa, ON: Canadian Pharmacists Association, 2008.
- Health Canada. Licensed Natural Health Products database. Vitamin A. http://webprod.hc-sc.gc.ca/nhpid-bdipsn/monoReq.do?id=178&lang=eng accessed 03 July 2014.
- Vitamin A (monograph). Natural Medicines Comprehensive Database (subscription required) www.naturalmedicines.com. Accessed 4 July 2012.
- Vitamin A (monograph). Natural Standard Database (subscription required) www.naturalstandard.com . Accessed 03 July 2014.
- Vitamin A. National Institutes of Health – Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/VitaminA-QuickFacts/. Accessed 03 July 2014
- Vitamin A (monograph). Lexicomp (subscription required) www.lexi.com. Accessed 03 July 2014
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