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.
My take? I'm not a big fan of salad dressing. Most of the time I use a small amount of olive oil (a monounsaturated fat) on my salads. If you check out some of the recipes for salad dressing on my website, you’ll see that I don’t recommend using much. This study shows that even with a little bit of the healthiest type of fat you get a bigger nutritional pay-off from your salad than you would if you used much more polyunsaturated or saturated fat. Olive oil has the highest percentage of heart-healthy monounsaturated fat of any edible oil, and quality olive oil also contains abundant antioxidants, substances that have been shown to provide cardiovascular and anti-cancer benefits. And, of course, quality olive oil tastes wonderful.