Salads are becoming increasingly popular choices as healthy meals, but Purdue University research shows that diners should choose dressings carefully to get the most out of their vegetables.
Common salad vegetables are chock full of compounds called carotenoids — lutein, lycopene, beta-carotene and zeaxanthin — which are associated with reduced risk of several chronic and degenerative diseases such as cancer, cardiovascular disease, and macular degeneration. But the body absorbs these carotenoids only when paired with fats, so choosing the right type and amount of dressing is important for getting the most nutritional value from a salad.
Mario Ferruzzi, a professor of food science, and Wayne Campbell, a professor of nutrition science, conducted a human trial that showed monounsaturated fat-rich dressings, such as those based in canola and olive oils, required the least amount of fat to get the most carotenoid absorption. Saturated fat dressings, such as those based in butter, and polyunsaturated fat dressings, such as those based in soybean oils, required higher amounts of fat to get the same benefit.
"Overall, pairing with fat matters," Ferruzzi said. "If you have a salad with a fat-free dressing, there is a reduction in calories, but you lose some of the benefits of the vegetables."