Good news: The salad dressing you may disdain for adding extra calories could actually be what makes the superfoods on your plate, well, super.
A recent study published in the scientific journal Food Nutrition concludes that oil-based dressings or sauces, including mayonnaise-based sauces, can help the body absorb kale’s valuable nutrients.
Kale has a number of beneficial compounds that promote overall well-being, but these nutrients are fat-soluble. That essentially means they break down only in the presence of a fat. In other words, it’s hard for the body to absorb the nutrients in kale unless it is eaten with fat.
Ruojie “Vanessa” Zhang, one of the study authors, explains: "Kale is a nutrient-rich vegetable that contains carotenoids, including lutein, alpha-carotene and beta-carotene, which have beneficial effects on overall health. The problem is our bodies have a hard time absorbing these nutrients because they are fat-soluble rather than water-soluble."
Carotenoids are nutrient-rich pigments that give certain fruits and vegetables their color. They are linked to better vision, a stronger immune system, and a lower risk of conditions such as diabetes, heart disease, and some cancers.
In the study, researchers used a simulated gastrointestinal tract model to mimic human digestion. They tested kale raw, cooked, raw or cooked with dressing or sauce, and cooked in sauce. The results showed that raw kale on its own had very low nutrient absorption, and cooking the kale actually worsened absorption. But once researchers added an oil-based nanoemulsion sauce-a finely mixed oil-based dressing-the model absorbed far more of the carotenoids.
This remained the case whether the kale was raw or cooked, and whether the sauce was added before or after cooking, suggesting flexibility in preparation.
Kale also carries vitamins C and E and other plant compounds that support overall health. But again, they’re largely fat-soluble. So, a modest amount of olive oil vinaigrette, an oil-based sauce, or a mayonnaise-based dressing makes kale’s nutrients more accessible to your body.