Dieters who fret about adding dressing to their salad can feel less guilty, a new small study of 12 women suggests.
The findings show that added fat from soybean oil promotes absorption of seven different micronutrients in salad vegetables.
“For most people, the oil is going to benefit nutrient absorption…”
Those nutrients include four carotenoids—alpha and beta carotene, lutein, and lycopene—two forms of vitamin E and vitamin K. The oil also promotes the absorption of vitamin A, which forms in the intestine from the alpha and beta carotene.
The study builds on previous research that focused on alpha and beta carotene and lycopene.
Better absorption of the nutrients promotes a range of health benefits, including cancer prevention and eyesight preservation, says Wendy White, an associate professor of food science and human nutrition at Iowa State University.
Further, the amount of oil added to the vegetables has a proportional relationship with the amount of nutrient absorption. That is, more oil means more absorption.
“The best way to explain it would be to say that adding twice the amount of salad dressing leads to twice the nutrient absorption,” White says.
But don’t go drenching your greens in dressing, White cautions. The US dietary recommendation is for about two tablespoons of oil per day.
The study included 12 college-age women who ate salads with various levels of soybean oil, a common ingredient in commercial salad dressings. Researchers then tested the participants’ blood to measure the absorption of nutrients. Women were chosen for the trial because of differences in the speed with which men and women metabolize the nutrients in question.
The results showed maximal nutrient absorption occurred at around 32 grams of oil, which was the highest amount studied, or a little more than two tablespoons, but there was some variability.
“For most people, the oil is going to benefit nutrient absorption,” White says. “The average trend, which was statistically significant, was for increased absorption.”
The researchers published their work in the American Journal of Clinical Nutrition.
Unilever, a global food company, funded the work but had no input in the publication of the study.
Source: Iowa State University