How many servings of vegetables did you have this week? It’s hard to recall what we eat, making nutrition research difficult. Instead of asking, some researchers look for biomarkers in the body that give information about how much of a certain type of food a person has eaten. Measuring biomarkers often requires blood, urine or even skin samples, and can be costly or painful. But Yale School of Public Health scientists are testing a new technology that measures a biomarker by simply bouncing blue laser light off the skin. It is painless and fast and gives results in about a minute. Susan T. Mayne, head of the division of Chronic Disease Epidemiology, and her longtime collaborator, Brenda Cartmel, a research scientist in the same division, have worked with a group of physicists at the University of Utah to create and test two prototype devices that measure skin carotenoids, which are biomarkers for fruit and vegetable intake that are usually measured in the blood.