Fat-free and low-fat salad dressings may not be as good for you as regular salad. It's not because the dressings are not as healthy as they claim but because they don't unlock the full nutrient potential of salads.
In the case of salad dressings, some fat may be a good thing. Olive oil and canola oil-based dressings may help you get the most of your salad without ruining your diet. The reason for this is that there are many nutrients in salads that are fat soluble nutrients that won't be absorbed by your body if you choose fat-free or low-fat dressings.
The study was led by Mario Ferruzzi, PhD, associate professor of food science at Purdue University. Researchers tested human absorption of carotenoids when using different types of fat-based dressings. The trial included 29 people being fed salad that was topped with either saturated, monounsaturated or polyunsaturated-based dressings and having blood samples taken to measure carotenoid levels. The salad dressings were topped with three, eight or 20 grams of fat from the dressing.
Carotenoids such as lutein, lycopene, beta-carotene and zeaxanthin can help reduce the risk of cardiovascular disease, cancer and macular degeneration. These nutrients dissolve in fat and when humans consume fat-free or low-fat dressings, there will be fewer calories consumed but also less carotenoids that can be absorbed by humans.
Certainly too much fat in dressing is a bad thing and that's why researchers factored in dosage. In the 29 participants, monounsaturated fat-based dressings required the lowest dose of fat, three grams, to have the participants gain the most carotenoid absorption from the salad. Three grams of fat from the monounsaturated fat-based dressing absorbed as much carotenoids as 20 grams of fat.
Both the saturated fat-based, such as butter, and polyunsaturated-based, such as soybean oil, dressings required more fat to get more carotenoids from the salad.
While watching how many calories and how much fat you consume is important in daily diet choices, understanding nutrient absorption is just as important. With just a little bit of fat from using canola oil or olive oil-based dressings you'll be getting even more value from that salad thanks to all the nutrients you'll be absorbing.
The study was published in Molecular Nutrition and Food Research.