Adding fat makes salad healthier, doubles nutrients’ absorption

Olive oil prevents food poisoning as omega-3 fatty acids ‘switch off’ listeria
Adding fat to your salad makes it healthier, new research reveals.

Tucking into a plate of lettuce and cucumber with a drizzle of oil could increase the absorption of eight nutrients that are linked to human health, a study found.

Such nutrients include vitamins A, E and K, which have previously been associated with cancer prevention and improved vision, the research adds.

The most recent study’s findings were published in the American Journal of Clinical Nutrition.

Lead author Professor Wendy White from Iowa State University, United said: “The best way to explain it would be to say that adding twice the amount of salad dressing leads to twice the nutrient absorption.”

Past research reveals adding fat to vegetables in the form of oil, nuts or cheese boosts the absorption of fat-soluble nutrients, such as lycopene, which is found in tomatoes, and beta-carotene, which is abundant in carrots.

Walnuts, olive oil and salmon could prevent potentially life-threatening food poisoning by ‘switching off’ genes for the listeria bacteria, research revealed in May.

Omega-3 fatty acids, found in the aforementioned foods, reduce the bacteria’s ability to cause infection by ‘switching off’ its genes, a study found.

Not killing the bacteria may be beneficial, as they only develop resistance when their growth is threatened, the researchers said.

Study author Professor Birgitte Kallipolitis, from the University of Southern Denmark, said: “It’s interesting that naturally occurring, completely harmless and actually healthy fatty acids can be used to suppress dangerous bacteria such as listeria.

“The long-term perspective is that it may prove possible to develop new treatment methods – not only against listeria, but also against other dangerous bacteria that are currently resistant to antibiotics.”

The researchers analyzed 12 women who each ate five salads with 0, 2, 4, 8 or 32g of soybean oil. This oil is frequently added to salad dressings.

Blood samples were taken to assess the study’s participant’s degree of nutrient absorption.

Only women were included in the trial due to their faster speed of nutrient absorption and metabolism.

Results reveal eating salad with added fat increases the absorption of eight nutrients that are linked to human health.

Such nutrients include vitamins A, E and K, which have previously been associated with cancer prevention and improved vision.

Nutrient absorption increases proportionally to the amount of oil added.

White said: “The best way to explain it would be to say that adding twice the amount of salad dressing leads to twice the nutrient absorption.”

Maximum absorption occurred at 32g, which is the equivalent of around two tablespoons and is the recommended daily intake according to United States (U.S.) dietary guidelines.

Previous research reveals adding fat to vegetables in the form of oil, nuts or cheese boosts the absorption of fat-soluble nutrients, such as lycopene, which is found in tomatoes, and beta-carotene, which is abundant in carrots.