Eating a little “good fat” along with your vegetables appears to help your body absorb their protective phytochemicals, like lycopene from tomatoes and lutein from dark-green vegetables. A recent study conducted by scientists at Ohio State University in Columbus measured how well phytochemicals were absorbed after people ate a lettuce, carrot, and spinach salad with or without 2 1/2 tablespoons of avocado. The avocado-eating group absorbed 8.3 times more alpha-carotene and 13.6 times more beta-carotene (both of which help protect against cancer and heart disease), and 4.3 times more lutein (which helps with eye health) than those who did not eat avocados.
Another study found similar results when they tested absorption of several key carotenoids (alpha-carotene, beta-carotene, and lycopene) in 7 adults after eating salads with fat free dressing or dressing containing 6 or 28 grams of canola oil. The amount of carotenoids in the plasma increased with the reduced fat dressing (from the fat free dressing) and increased even more after the higher canola oil salad dressing. Canola oil is composed of mainly monounsaturated fat (like avocados), 8 grams per tablespoon, with about a third polyunsaturated fat, 4 grams per tablespoon, some of which are plant omega-3s.
[Am J Clin Nutr August 2004 Vol. 80 No. 2, 396-403 Brown M.J., et al.,
"Carotenoid bioavailablility is higher from salads with full-fat than with
fat-reduced salad dressings as measured with electrochemical detection."]