If you want to get the biggest nutritional bang from your salad greens, be sure your dressing is made with a monounsaturated fat such as olive oil or canola oil. A new study from Purdue University found that salad dressings made with monounsaturated fat – canola oil was the one used in the study – enhanced absorption of the health-promoting carotenoids in salad vegetables. What’s more, the monounsaturated-based dressing resulted in the same amount of carotenoid absorption whether it contained three grams of fat or 20 grams.
Researchers at Purdue fed 29 study volunteers salads topped with saturated, monounsaturated and polyunsaturated dressings and then ran blood tests to see how well their subjects absorbed carotenoids including lutein, lycopene, beta-carotene and zeaxanthin.
The investigators found that polyunsaturated or saturated fat-based dressings also boost carotenoid absorption, but amounts were dose-dependent. That is, to absorb more nutrients you have to use more dressing. If you use a fat-free dressing, you cut calories but also lose out on carotenoids.