Beta-carotene is one of a group of red, orange, and yellow pigments called carotenoids, which can be found in fruits, vegetables, and whole grains. There is also a synthetic version, which is made from acetylene gas, but this should be avoided at all costs as it is "incomplete" and does not perform as well as natural beta-carotene -- and it may actually be harmful. The most concentrated sources of beta-carotene are yellow, orange, and green leafy fruits and vegetables, such as carrots, lettuce, cantaloupe, spinach, and tomatoes.

Carotenoids are phytonutrients that protect plants from damage caused by UV radiation and other environmental factors. In humans, they have been shown to inhibit the proliferation of various types of cancer cells such as those affecting the lungs, stomach, cervix, breast, bladder, and mouth. They also have been proven to protect against atherosclerosis, cataracts, macular degeneration, and other major degenerative disorders. The key carotenoids are: beta-carotene, alpha carotene, lycopene, and zeaxanthin.

Probably the best known of the carotenoids, beta-carotene is converted by the body into vitamin A as needed to strengthen the immune system and promote healthy cell growth. In addition, beta-carotene is a potent antioxidant, offering particular benefits to the immune system and the lungs. (Note: In nature, beta-carotene always comes as part of a carotenoid complex, not in isolation. There are more than 400 carotenoids in a single carrot, for example.) Also, it is important to understand that beta-carotene is not the most important of the carotenoids. It's just the only one that has a recommended daily requirement.

Once again, the FDA and the USDA are several decades behind the times. For example, recent studies have shown that alpha carotene is one of the most powerful carotenoids and greatly inhibits growth of various types of cancers. It works by allowing normal cells to send growth-regulating signals to premalignant cells.

The bottom line is this: while beta-carotene is an important ingredient that is essential to your health, you don’t want to supplement with synthetic beta-carotene. For the best results, you want to supplement with natural beta-carotene that is part of a full carotenoid complex containing multiple antioxidants.