Vitamin Spotlight: Vitamin A - Pathway Genomics
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Vitamin Spotlight: Vitamin A

There are a number of vitamins and minerals that are essential for your body to stay healthy. One of them is vitamin A. Here, we’re looking at the essentials of this vitamin, including its benefits and purpose.

What is Vitamin A?

In scientific terms, vitamin A refers to a family of fat-soluble retinoids, including retinyl esters, retinol and retinal. In simpler terms, this vitamin is a powerful antioxidant that is important to your body.

There are two basic forms of vitamin A—retinoids and carotenoids. Each plays different roles and are found in different food groups. We’ve mentioned the family of retinoids already, but the family of carotenoids includes beta-carotene (the most important of carotenoids), alpha-carotene and beta-cryptoxanthin. There are more than 500 carotenoids that have been identified, but fewer than 10% can be converted into vitamin A. Lycopene, lutein and zeaxanthin are three such carotenoids that can’t be converted into vitamin A.

Both forms of this vitamin have to metabolize intracellularly to the active forms of vitamin A (retinal and retinoic acid) in order to support the vitamin’s biological functions. The different forms of this vitamin are solubilized into micelles in your intestinal lumen where duodenal mucosal cells absorb them. Here, both forms of vitamin A are converted to retinol. Once in this form, the retinol is oxidized first to retinal and next to retinoic acid. Most of the vitamin A in your body stores in your liver as retinyl esters.

What Does Vitamin A Do for the Body?

Vitamin A is important for a number of reasons. As it’s an antioxidant, it fights free radical damage, thereby helping to reduce inflammation. Both carotenoids and retinoids play a key role in helping with:

  • Healthy vision. Vitamin A plays a key role in helping to prevent night blindness, dry eyes, cataracts and macular degeneration. It helps your eyes to adjust to light changes and maintain optimal moisture levels.
  • A strong immune system. Vitamin A increases your body’s lymphocytic responses against antigens that cause diseases, thereby boosting the body’s immunity against infections. It also helps mucous membranes stay moist to boost immunity and enhances white blood cell activity.
  • Cell and bone tissue growth. Similar to calcium or vitamin D, vitamin A helps you maintain strong bones and teeth by assisting in forming dentin, which is a hard layer that sits below the surface of your teeth. Vitamin A also assists with muscle growth in adolescents and children and helps replace worn-out tissues with new ones.
  • Healthy skin. Vitamin A is also known as a beauty treatment by helping reduce acne and eliminate wrinkles. By cutting down the production of excess sebum and reinforcing the skin’s protective tissues, it can reduce acne, age spots and fine lines.

Along with getting vitamin A in foods, some people take topical retinoids to treat acne or combat wrinkles. Oral vitamin A is occasionally used to treat measles and dry eyes among people who are deficient in the vitamin. While the results thus far are inconclusive, some doctors have started studying vitamin A as a treatment for leukemia, cataracts and HIV.

What Foods Contain Vitamin A?

Vitamin A in the form of retinoids is found naturally in animal products, including liver, oily fish, eggs, milk, cheese and butter. Vegetarians and vegans can have a hard time getting vitamin A in the form of retinoids, so they may need to increase their intake of carotenoids or take a retinol supplement. Carotenoids are found in vegetables and fruits, including kale, carrots, sweet potato, collards and spinach.

What are the Side Effects of Vitamin A Deficiency?

Vitamin A deficiencies are problematic among young children and pregnant women in low-income countries, alcoholics, the chronically ill and the elderly. Among children, a lack of vitamin A can cause visual impairments or even blindness, as well as increased risk of measles and pneumonia.

Another common side effect of vitamin A deficiency is night blindness, which can become permanent if the deficiency isn’t addressed. Other signs of a deficiency include scaly skin, brittle nails and a low immunity. It’s not uncommon for people low on vitamin A to also experience low iron levels, which can result in anemia.

How Can I Tell if I’m Deficient in Vitamin A?

If you’re experiencing any of the side effects mentioned above, you may have a vitamin A deficiency. Even if you’re eating a healthy diet, you may still not be getting enough vitamin A. Some groups of people have a genetic mutation that negatively impacts their ability to convert carotenoids into vitamin A, which could result in a deficiency. Even if you’re eating enough vitamin A-rich vegetables, you may still be deficient.

Can You Get Too Much Vitamin A?

If you eat a healthy diet and aren’t deficient in vitamin A, be wary of taking supplements. Getting too much vitamin A can cause negative side effects. As vitamin A is stored in the liver, excessive amounts of the vitamin can cause hypervitaminosis, which is a toxic condition of abnormally high storage levels of vitamins. Side effects of this include nausea, dizziness, joint and bone pain, headaches and liver damage.

While everyone’s dietary needs are different, the general recommended dietary allowance for vitamin A among adults is 900 mcg/day (or 3,000 IU/day). Concerned you may not be getting enough vitamin A? Consider taking a DNA test, such as Pathway Fit, which looks at which vitamins you may need to optimize. With the guidance of your physician, you can determine an effective diet for you.