Adding eggs to a salad with a variety of raw vegetables is an effective method to improve the absorption of carotenoids, which are fat-soluble nutrients that help reduce inflammation, a research has found.

"Eating a salad with a variety of colourful vegetables provides several unique types of carotenoids, including beta-carotene, lutein, zeaxanthin and lycopene," said Wayne Campbell, professor of nutrition science at Purdue University in the US.

"The lipid contained in whole eggs enhances the absorption of all these carotenoids," Campbell said.

Most people do not eat enough vegetables in their diets, and at the same time, people are consuming salad dressings that have less fat or are fat-free," said Jung Eun Kim, postdoctoral researcher in Purdue University.

"Our research findings support that people obtained more of the health-promoting carotenoids from raw vegetables when cooked whole eggs were also consumed," Kim said.

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, Kim said.

In the study, 16 participants consumed a raw mixed-vegetable salad with no eggs, a salad with one and a half eggs, and a salad with three eggs at different times.

All salads were served with three grams of canola oil.

The second salad had 75 grams of scrambled whole eggs and the third 150 grams of scrambled whole eggs.

The absorption of carotenoids was 3.8-fold higher when the salad included three eggs compared to no eggs.

The study used scrambled eggs to make sure the participants consumed both the yolk and egg whites.

This research was published online in the American Journal of Clinical Nutrition.