What is vitamin A?

Vitamin A is a group of fat-soluble retinoids including retinol, retinal, and retinyl esters. It is involved in immune function, vision, reproduction, and cellular communication. Vitamin A also supports cell growth and differentiation and has a critical role in the normal function and maintenance of the heart, lungs, kidneys, and other organs.

There are 2 forms of vitamin A available in food: preformed vitamin A and provitamin A carotenoids. Preformed vitamin A is found in foods from animal sources. The most important provitamin A carotenoid is beta-carotene. Both forms of vitamin A are metabolized in the body into the active forms of vitamin A. Most of the body’s vitamin A is stored in the liver.1

How much do I need?

Health Canada recommends 900 mcg/day of vitamin A for males age 19 years and over.

Health Canada recommends 700 mcg/day of vitamin A for females age 19 years and over.2

How does vitamin A affect my health?

People who eat a lot of food containing beta-carotene may have a lower risk of some types of cancer, such as lung or prostate cancer. Studies to date have not shown that vitamin A or beta-carotene supplements help prevent cancer or lower the chances of dying from these diseases.4

What are food sources of vitamin A?

  • leafy green vegetables – Swiss chard, kale, spinach, lettuce, bok choy
  • orange and yellow vegetables – carrots, squash, sweet potato, bell peppers
  • broccoli
  • tomato products
  • fruits – cantaloupe, mango
  • some vegetable oils
  • fortified non-dairy beverages – soy, almond, coconut, oat

Non-Vegan

  • liver
  • fish oils
  • milk
  • eggs1,3

Do I need a vitamin A supplement?

Since vitamin A is found in many commonly consumed foods, vitamin A deficiency is rare in North America. However, certain groups of people are more likely than others of having trouble getting enough vitamin A. This includes premature infants and people with cystic fibrosis.

Similar to many micronutrients, consuming too much can be harmful. Health Canada recommends adults 19 years and older stay below 3000 mcg/day of vitamin A to prevent adverse effects.3

Can vitamin A be harmful?

Yes, high intakes of certain forms of vitamin A can be harmful. Too much preformed vitamin A (usually from supplements and some medication) can cause dizziness, nausea, headaches, coma and even death. High intake of preformed vitamin A in pregnant women can cause birth defects in babies. Consuming high amounts of beta-carotene or other forms of provitamin A can turn the skin yellow-orange, but this condition is harmless.4

References

  1. National Institutes of Health – Office of Dietary Supplements. (2020, February 14). Vitamin A. Retrieved from https://ods-od-nih-gov.subzero.lib.uoguelph.ca/factsheets/VitaminA-HealthProfessional/
  2. Health Canada. (2010, November 19). Dietary Reference Intakes. Retrieved from https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-vitamins-dietary-reference-intakes-tables-2005.html
  3. Dietitians of Canada. (2016, September 26). Food Sources of Vitamin A. Retrieved from https://www-pennutrition-com.subzero.lib.uoguelph.ca/viewhandout.aspx?Portal=UbY=&id=JMbtWAQ=&PreviewHandout=bA==
  4. National Institutes of Health – Office of Dietary Supplements. (2020, February 14). Vitamin A Fact Sheet for Consumers. Retrieved from https://ods-od-nih-gov.subzero.lib.uoguelph.ca/factsheets/VitaminA-Consumer

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