supplements are of little or no value in preventing
cardiovascular disease and the major cancers occur- ring in well-nourished populations, and may actually
increase, rather than reduce, lung cancer incidence
in smokers. As a consequence of these findings, some of the ongoing trials of beta-carotene and disease prevention have been terminated or have dropped
beta-carotene from their interventions. Researchers
should now seek explanations for the apparently discordant findings of observational studies vs. inter- vention trials. The most pressing research issues
include studies of interactions of carotenoids with
themselves and with other phytochemicals and mechanistic studies of the actions of beta-carotene
in lung carcinogenesis and cardiovascular disease. Paradoxically, the finding that lung carcinogenesis and cardiovascular disease can be enhanced by sup- plemental beta-carotene may ultimately lead to a
clearer understanding of the role of diet in the
etiology and prevention of these diseases. The con- clusion that major public health benefits could be achieved by increasing consumption of carotenoidrich fruits and vegetables still appears to stand; however, the pharmacological use of supplemental beta-carotene for the prevention of cardiovascular disease and lung cancer, particularly in smokers, can
no longer be recommended.-Mayne, S. T. Beta- carotene, carotenoids, and disease prevention in
humans.