Preliminary research by Mark Farnham from the U.S. Department of Agriculture, Agricultural Research Service (USDA ARS) and Dean Kopsell from the University of Tennessee confirmed that broccoli heads contain abundant levels of lutein, an antioxidant commonly thought to provide nutritional support to eyes and skin.
Other carotenoids like beta-carotene, violaxanthin, neoxanthin, and antheraxanthin were also found in broccoli heads, but lutein was clearly the most significant, accounting for about half of all carotenoids measured, report the researchers in the journal HortScience.
The lutein levels are dictated by plant’s genetics, they report, noting that environment in which the vegetables were grown had little effect on carotenoid production.
“To our knowledge, this study is the first to present a detailed examination of carotenoids in field-grown broccoli and the relative importance of genotype in influencing levels of specific carotenoid compounds,” they report.
Being in its early stages, it is not known if such broccoli could lead to lutein-enriched extracts, or an alternative source of lutein. Currently, most natural lutein on the market is derived from marigolds, like Kemin’s FloraGlo and Cognis’ XanGold.
The study found that lutein was the most abundant carotenoid in broccoli heads, and was found to be present up to a level of 139.6 micrograms per gram of dry mass, according to data in HortScience.
“Results indicated that most carotenoids measured were positively and significantly correlated with one another, indicating that higher levels of one carotenoid were typically associated with higher levels of others,” wrote Farnham and Kopsell.
“This study emphasizes the relative importance of lutein in broccoli heads and the key role that genotype plays with this compound, ultimately indicating that breeding cultivars with increased levels of this particular carotenoid may be feasible,” they added.
A significant body of research supports the beneficial effects of broccoli and its extracts. The majority of the science has looked at the vegetable’s anti-cancer benefits, linked to the high levels of the active plant chemicals glucosinolates. These are metabolised by the body into isothiocyanates, which are known to be powerful anti-carcinogens. The main isothiocyanate from broccoli is sulphoraphane.
Volume 44, Pages 1248-1253
“Importance of Genotype on Carotenoid and Chlorophyll Levels in Broccoli Heads”
Authors: M.W. Farnham, D.A. Kopsell