A new study from Purdue University showed that olive oil might be the best choice of salad dressing when it comes to absorbing nutrients from the vegetables. It appears that monounsaturated fats provide the most efficient absorption of carotenoids, pigments with antioxidant activity present in vegetables and fruit.
Previous research has showed that carotenoids, such as beta-carotene were more bioavailable, in other words were more easily absorbed by the body when fat was present in the salad. Carotenoids are pigments that are responsible for the bright colors of fruit and vegetables and are associated with a variety of health benefits such as protection from cancer and heart disease and promotion of eye health.
For this study published in the journal Molecular Nutrition & Food Research, researchers gave 29 participants salad with either a saturated fat dressing, a monounsaturated fat dressing or a polyunsaturated fat dressing. Each salad was served with 3 grams, 8 grams or 20 grams of fat from dressing. The participants had their blood tested for absorption of fat-soluble carotenoids, compounds such as lutein, lycopene, beta-carotene and zeaxanthin.
While all fats promoted absorption of the carotenoids, the salad dressing that contained the monounsaturated fat (the main type of fatty acids in olive oil) promoted the equivalent carotenoid absorption at 3 grams of fat as it did 20 grams. In other words it required the least amount of fat to get the most carotenoid absorption, while saturated fat and polyunsaturated fat dressings required higher amounts of fat to get the same benefit. This makes monounsaturated fat such as olive oil, a great choice for those watching their fat or calorie intake.
It is important to note that the researchers used canola oil as their source of monounsaturated fat dressing. However, olive oil actually contains more monounsatured fat than canola oil, in fact olive oil has the highest amount of monounsaturated fat among commonly used cooking oils, but it is also a source of beneficial antioxidants as well, providing a double benefit.