Carotenoids

Beta carotene increases the number of infection-fighting cells, natural killer cells, and helper T-cells, as well as being a powerful antioxidant that mops up excess free radicals that accelerate aging. Together with vitamins C and E, it reduces the risk of cardiovascular disease by interfering with how the fats and cholesterol in the bloodstream oxidize to form arterial plaques. Studies have shown that beta carotene can lower the risk of cardiovascular disease, especially strokes and heart attacks. Beta carotene also protects against cancer by stimulating the immune cells called macrophages to produce tumour necrosis factor, which kills cancer cells. It has also been shown that beta carotene supplements can increase the production of T-cell lymphocytes and natural killer cells and can enhance the ability of the natural killer cells to attack cancer cells.

The body converts beta carotene to vitamin A, which has anticancer properties and immune-boosting functions. But too much vitamin A can be toxic to the body, so it's better to get extra beta carotene from foods and let the body naturally regulate how much of this precursor is converted to the immune-fighting vitamin A. It's highly unlikely that a person could take in enough beta carotene to produce a toxic amount of vitamin A, because when the body has enough vitamin A, it stops making it.

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