Vitamin A is a fat-soluble vitamin that plays a vital role in many aspects of your health. It is involved in maintaining your vision, immune system, skin, and organ function, as well as supporting your growth and development. Vitamin A can be obtained from both animal and plant sources, but you need to consume it in the right amounts to avoid deficiency or toxicity. In this article, we will explore the health benefits of vitamin A, the sources and recommended intake of this vitamin, and the potential risks of getting too much or too little of it.
What are the health benefits of vitamin A?
Vitamin A has many functions in your body, and it can provide various health benefits, such as:
- Protecting your eyesight. Vitamin A helps your eyes convert light into signals that are sent to your brain, allowing you to see in dim or dark conditions. Vitamin A also helps your eyes produce moisture and protects them from infections and inflammation. Vitamin A deficiency can cause night blindness, dry eyes, and increased risk of eye diseases, such as cataracts and age-related macular degeneration12.
- Boosting your immune system. Vitamin A helps your body fight off infections and diseases by supporting the production and function of white blood cells, which are the main components of your immune system. Vitamin A also helps maintain the integrity of the mucous membranes that line your respiratory, digestive, and urinary tracts, which act as barriers against pathogens and toxins. Vitamin A deficiency can impair your immune system and make you more susceptible to infections, such as measles, pneumonia, and diarrhea13.
- Keeping your skin healthy. Vitamin A helps your skin grow and repair itself by promoting the production of collagen, a protein that gives your skin its structure and elasticity. Vitamin A also helps your skin heal from wounds and injuries and protects it from sun damage and aging. Vitamin A deficiency can cause dry, rough, and scaly skin, as well as increased risk of skin infections and conditions, such as acne, eczema, and psoriasis14.
- Supporting your growth and development. Vitamin A is essential for the normal development of your bones, teeth, and organs, especially during pregnancy and childhood. Vitamin A also helps regulate your genes and hormones, which are involved in various biological processes, such as reproduction, metabolism, and growth. Vitamin A deficiency can cause growth retardation, birth defects, and increased risk of mortality in infants and children13.
What are the sources and recommended intake of vitamin A?
Vitamin A can be found in two different forms: preformed vitamin A and provitamin A. Preformed vitamin A, also known as retinol, is the active form of vitamin A that your body can use directly. It is found in animal products, such as meat, poultry, fish, eggs, and dairy. Provitamin A, also known as carotenoids, is the inactive form of vitamin A that your body needs to convert into the active form. It is found in plant products, such as fruits, vegetables, and fortified foods. The most common carotenoid is beta-carotene, which gives plants their orange and red colors13.
The recommended intake of vitamin A varies depending on your age, sex, and life stage. The Dietary Reference Intakes (DRIs) for vitamin A are expressed in micrograms (mcg) of retinol activity equivalents (RAE), which account for the different bioavailability and potency of the two forms of vitamin A. The DRIs for vitamin A are as follows3:
- Infants 0–6 months: 400 mcg RAE
- Infants 7–12 months: 500 mcg RAE
- Children 1–3 years: 300 mcg RAE
- Children 4–8 years: 400 mcg RAE
- Children 9–13 years: 600 mcg RAE
- Males 14 years and older: 900 mcg RAE
- Females 14 years and older: 700 mcg RAE
- Pregnant females 18 years and younger: 750 mcg RAE
- Pregnant females 19 years and older: 770 mcg RAE
- Lactating females 18 years and younger: 1,200 mcg RAE
- Lactating females 19 years and older: 1,300 mcg RAE
Some examples of foods that are rich in vitamin A are3:
- Liver (beef, pork, chicken, turkey, fish): 3 ounces provide 149%–631% of the DRI for adults.
- Sweet potato (cooked): 1/2 cup provides 184% of the DRI for adults.
- Carrot (raw): 1 medium provides 44% of the DRI for adults.
- Spinach (cooked): 1/2 cup provides 49% of the DRI for adults.
- Kale (cooked): 1/2 cup provides 47% of the DRI for adults.
- Pumpkin (cooked): 1/2 cup provides 38% of the DRI for adults.
- Cantaloupe: 1/4 medium provides 30% of the DRI for adults
- Mango: 1/2 cup provides 15% of the DRI for adults
- Milk (fortified): 1 cup provides 10%–29% of the DRI for adults.
- Cheese (cheddar): 1 ounce provides 10% of the DRI for adults.
- Egg: 1 large provides 8% of the DRI for adults
What are the potential risks of vitamin A deficiency or toxicity?
Vitamin A deficiency and toxicity are both rare in developed countries, but they can have profound consequences for your health. Vitamin A deficiency is more common in developing countries, where people have limited access to foods that contain vitamin A or have conditions that impair their absorption or utilization of vitamin A, such as infections, malabsorption, or liver disease. Vitamin A toxicity is more likely to occur from taking high doses of vitamin A supplements, rather than from eating foods that contain vitamin A13.
Some of the signs and symptoms of vitamin A deficiency are13:
- Night blindness
- Dry eyes
- Bitot’s spots (white patches on the conjunctiva of the eye)
- Xerophthalmia (severe dryness and damage of the cornea and conjunctiva of the eye)
- Keratomalacia (softening and ulceration of the cornea of the eye)
- Increased susceptibility to infections, especially respiratory and gastrointestinal infections
- Impaired growth and development
- Anemia
- Poor wound healing
- Dry, rough, and scaly skin
- Hair loss
- Acne
- Fertility problems
- Birth defects
Some of the signs and symptoms of vitamin A toxicity are13:
- Nausea
- Vomiting
- Headache
- Dizziness
- Blurred vision
- Fatigue
- Irritability
- Loss of appetite
- Weight loss
- Dry, itchy, and peeling skin
- Hair loss
- Cracked lips.
- Enlarged liver and spleen.
- Bone and joint pain
- Increased intracranial pressure.
- Birth defects
- Liver damage
- Coma
- Death
The tolerable upper intake level (UL) for vitamin A is the maximum amount of vitamin A that you can consume daily without adverse effects. The UL for vitamin A is as follows3:
- Infants 0–12 months: 600 mcg RAE
- Children 1–3 years: 600 mcg RAE
- Children 4–8 years: 900 mcg RAE
- Children 9–13 years: 1,700 mcg RAE
- Adolescents 14–18 years: 2,800 mcg RAE
- Adults 19 years and older: 3,000 mcg RAE
Conclusion
Vitamin A is a fat-soluble vitamin that has many health benefits, such as protecting your eyesight, boosting your immune system, keeping your skin healthy, and supporting your growth and development. Vitamin A can be obtained from both animal and plant sources, but you need to consume it in the right amounts to avoid deficiency or toxicity. The recommended intake of vitamin A varies depending on your age, sex, and life stage, and the upper limit of vitamin A is the maximum amount that you can consume safely. Vitamin A deficiency and toxicity are both rare in developed countries, but they can have profound consequences for your health. Therefore, it is important to eat a balanced and varied diet that provides adequate amounts of vitamin A and consult your doctor before taking any vitamin A supplements.
Sources:
6 Health Benefits of Vitamin A, Backed by Science (healthline.com)
Vitamin A: What It Is and How Much You Need (clevelandclinic.org)
