Carotenoids, or carotenes are substances that are produced by plants; they are vitamin A precursors (ie can be converted to vitamin A). Research appearing in the Journal of Nutrition (February 2008, Volume 138, Pages 344-350) shows that they may protect from heart disease. The study  looked at the dietary intakes of 559 men (average age 72) and over the course of 15 years, 197 died form cardiovascular disease. High intake of alpha-carotene was associated with a 19% reduction of death from cardiovascular disease and high intake of beta-carotene was associated with a reduction of 20%.