Writing in this month's issue of the Journal of Nutritional Biochemistry, UCLA scientists note that avocados are the richest source of lutein among commonly eaten fruits. This carotenoid acts as an antioxidant and has been linked to a reduced risk of prostate cancer in previous studies.
In a new study, they looked at the inhibition of human prostate cancer cell growth when exposed to an extract of whole avocado fruit versus treatment with pure lutein.
Dr David Heber, director of the UCLA center for human nutrition, and colleagues showed that when avocado extract was added to two lines of prostate cancer cells, cell growth was inhibited by up to 60 percent, whereas purified lutein alone was ineffective.
"What's really exciting about this study is that the results indicate that the carotenoids, vitamins, and diverse compounds in avocados might have additive or synergistic effects against prostate cancer compared with pure lutein alone," said Heber.
"Our results suggest that further studies should be done to investigate the effects of the naturally occurring combinations of thousands of different bioactive substances (phytonutrients) found in avocados and other plant foods."
Lutein is normally associated with green vegetables such as parsley, celery and spinach, but was recently discovered in the avocado fruit and research suggests that avocados are the highest fruit source of lutein among the 20 most frequently consumed fruits.
In addition to prostate cancer, lutein is also thought to protect against eye disease such as cataracts and macular degeneration, the leading cause of blindness in the elderly.
The researchers used California avocados for their research, which are said by the vegetable's marketing website to contain more fiber, thiamin, riboflavin, niacin and folate ounce for ounce than any other commonly eaten fruit.