Beta-carotene and cancer:
Beta-carotene in foods vs. supplements and cancer risk: Cancer risk is lower in those who consume beta-carotene containing foods but not beta-carotene supplements according to the National Research Council, Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. (6)
High blood concentrations of beta-carotene and other carotenoids, plant pigments found in carrots, sweet potatoes, spinach, kale, collard greens, papaya, bell peppers, tomatoes, have been linked to a lower risk of cancer, especially lung, mouth, throat, and cervical cancers.
A blood beta-carotene concentration less than 0.28 micromol/L has been linked with a higher risk of several cancers, while a concentration of more than 0.28 to 0.37 micromol/L have been associated with a reduced risk of several cancers in prospective blood concentration studies. However, three other large randomized studies reported no cancer benefit from beta-carotene supplements given at 20, 30, or 50 mg/d for 4 to 12 years.
