How does beta-carotene work?

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Preformed vitamin A is found only in foods from animal sources, such as liver and eggs, and is added to all processed milk. Plant food sources do not contain preformed vitamin A, but some do contain provitamin A carotenoid, which can be converted to retinol in your body. Carotenoids are the yellow-red pigments that give carrots, butternut squash, and cantaloupe their vibrant, deep orange color.

There are over 600 different carotenoids, but only 3 -- beta-carotene (β-carotene), beta-cryptoxanthin (β-cryptoxanthin), and alpha-carotene (α-carotene) -- can be converted to vitamin A. These three provide approximately 25 to 35 percent of the dietary vitamin A consumed by adults in the United States, with the majority of it coming from beta-carotene. Other nutritionally significant carotenoids, including lycopene, lutein, and zeaxanthin, may function as antioxidants or provide health benefits, but cannot be converted to vitamin A.

Beta-carotene also acts as an antioxidant in your body. Just as their names implies, antioxidants counteract oxidation, a harmful chemical reaction that takes place in your cells.
 
Picture of milk & carrots
Deborah Beauvais
Nutrition & Dietetics
Beta-carotene is one of approximately 50 carotenoids of the known 600, which are called "provitamin A" compounds because the body can convert them into retinol, an active form of vitamin A.

As a result, foods that contain beta-carotene can help prevent vitamin A deficiency. In addition to alpha-carotene and beta-cryptoxanthin, beta-carotene is among the most commonly consumed provitamin A carotenoids in the North American diet.

Antioxidant & Immune-Enhancing Activity
In recent years, carotenoids including beta-carotene have received a tremendous amount of attention as potential anti-cancer and anti-aging compounds. Beta-carotene is a powerful antioxidant, protecting the cells of the body from damage caused by free radicals. It is also one of the carotenoids believed to enhance the function of the immune system.

Promoting Proper Cell Communication
In addition to their antioxidant and immune-enhancing activity, carotenoids including beta-carotene have shown the ability to stimulate cell to cell communication. Researchers now believe that poor communication between cells may be one of the causes of the overgrowth of cells, a condition which eventually leads to cancer. By promoting proper communication between cells, carotenoids may play a role in cancer prevention.

Supporting Reproductive Health
It is also believed that beta-carotene may participate in female reproduction. Although its exact function in female reproduction has not yet been identified, it is known that the corpus luteum has the highest concentration of beta-carotene of any organ in the body, suggesting that this nutrient plays an important role in reproductive processes.
Beta-carotene is a precursor to vitamin A, meaning your body uses this carotenoid to make vitamin A in your body. Vitamin A promotes clear skin as well as healthy eyes, bones and reproduction. Beta-carotene is available in pill, capsule and liquid forms. It is important to treat beta-carotene supplements as you would any medication and take them only as prescribed by your doctor.