Lung cancer risk was most elevated in men who reported concurrently low intake of both carotenes. This group might be comparable to the men in the ATBC trial, who are taking beta-carotene supplements while consuming relatively low levels of vegetables and fruits rich in other carotenoids and phytochemicals. However, these are tiny numbers, and while provocative, these results are far from conclusive. Men concurrently in the lowest tertile of intake of both vegetable groups had 2.5 times the lung cancer risk of men in the highest tertile of both. We and other researchers are also examining individual carotenoid levels in blood samples that have been collected from cohorts and stored.
Preliminary analyses suggest they are.
In conclusion, a wealth of observational epidemiology shows a consistent protective effect of carotenoids, vegetables, and fruits. Blood beta-carotene levels are very reliable biomarkers of whatever is protective in these foods. Because of the ATBC trial, beta-carotene can no longer be considered the simple explanation of the extensive observational epidemiology. We need to be careful. I wanted to clarify a point.