There is a way you can get an even bigger nutritional boost from a salad — just add an egg to it. Carotenoids are the compounds in plant foods that help reduce inflammation and oxidative stress in the body. Eggs help the body absorb these antioxidants.

Eggs, a nutrient-rich food containing essential amino acids, unsaturated fatty acids and B vitamins, may be used to increase the nutritive value of vegetables, which are under-consumed by the majority of people living in the United States.

What makes eggs so special? It’s the yolk, or more specifically, the fat in the yolk. Carotenoids are fat-soluble compounds so they are better absorbed into the blood stream when eaten with a source of fat.

Purdue University researchers gave study participants different versions of the same raw, mixed-vegetable salad. One salad contained no egg, one was topped with 1½ scrambled eggs, and one with three scrambled eggs. Otherwise, the salads were the same.

After testing the men’s blood, the team found found that people who ate salads containing three eggs absorbed almost four times more carotenoids than who ate the salad with no egg. Two eggs, said the researchers, should be enough to have a significant effect on absorption.

“…[P]eople obtained more of the health-promoting carotenoids from raw vegetables when cooked whole eggs were also consumed,” Jung Eun Kim, a researcher in Purdue's Department of Nutrition Science, said in a statement. “Eggs, a nutrient-rich food containing essential amino acids, unsaturated fatty acids and B vitamins, may be used to increase the nutritive value of vegetables, which are under-consumed by the majority of people living in the United States.”

The fats used in salad dressings also improve carotenoid absorption, but with salad dressing it’s too easy to consume too many calories. Most dressings contain between 140 and 160 calories in a serving (two tablespoons). A large egg contains that many calories, offers six grams of protein and many other beneficial nutrients.

Carotenoids are fat-soluble compounds so they are better absorbed into the blood stream when eaten with a source of fat.

“People are at a greater risk of putting too many calories on a salad because they don’t always know proper portion sizes for salad dressings, but you do know the portion size of an egg,” added Wayne Campbell, professor of nutrition science at Purdue.

The study is published in the American Journal of Clinical Nutrition.