- Whereas beta-carotene has received more attention than other carotenoids, early research documenting the effects of high beta-carotene diets overlooked the fact that these diets were also high in other carotenoids (J Am Coll Nutr 1995;14:419-27).
- High doses of beta-carotene alone may reduce blood levels of other carotenoids (Am J Clin Nutr 2000; 71:950-5).
- All carotenoids have antioxidant activity, but some are deposited preferentially into specific body tissues, as in the affinity of lutein for the retina (Ann NY Acad Sci 1998;854:443-7; Int J Vitam Nutr Res 1998;68:349-53).
- Synthetic beta-carotene has failed to benefit health in several human clinical trials (Drug Saf 1999;21:253-66), whereas natural beta-carotene was studied in two trials with positive results (J Am Coll Nutr 1995;14:536 [abstr #48]; Ann Allergy Asthma Immunol 1999;82:549-53).
- Provitamin A carotenoids such as alpha- and beta-carotene represent excellent sources of vitamin A with no danger of vitamin A toxicity (Arch Biochem Biophys 2004;430:77-88).
- Lycopene, one of the most abundant carotenoids in the body, has been associated in human studies with optimum immune function (Proc Nutr Soc 1998;57:3A) and prostate health (Nutr Cancer 1999;33:159-64; Cancer Epidemiol Biomarkers Prev 2001;10:861-8).
- The xanthophylls, lutein and zeaxanthin, may play a special role in the health of the eyes; studies have found that their long-term intake appeared to support the health of the macula and the ocular lens (Optometry 2004;75:216-30; Nutrition 2003;19:21-4).
- Alpha-carotene and cryptoxanthin appear to confer preferential protection to lung tissue (J Natl Cancer Inst 1996;88:612-5; Cancer Epidemiol Biomarkers Prev 2001; 10:767-73).
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