Have you had your daily serving of vegetables? This seemingly simple question is in fact very difficult to answer, for children and adults alike. Luckily, a new handheld laser scanner devised by researchers at Yale University and the University of Utah promises to put a swift end to veggie dodging, while also helping scientists to measure exactly how our diet affects our health.

Normally scientists would look for traces of telltale substances in the body, that would indicate how much of a given type of food has been consumed. Current methods require taking blood or urine samples or performing serum and skin biopsies, so establishing what a patient has recently been munching on may be time consuming, expensive and unpleasant. The new method, on the other hand, gets the measuring done in 30 seconds (another 30 seconds are needed for the attached laptop to return the measurement results). Most importantly, however, it’s completely non-invasive, which is extremely important if you’re dealing with kids.

The device is made up of a flexible fiber optic probe attached to a central unit linked to a laptop. The probe essentially bounces blue laser light off the skin of the palm, and uses a long-known technique called resonance Raman spectroscopy (RRS) to measure the levels of skin carotenoids - high carotenoid levels are responsible for that slight yellowish skin discoloration that can be observed in people with high-vegetable diets.

RSS provides information about the vibrations of molecules whose electrons have been exposed to laser light. The frequency of the laser light is adjusted so as to make sure that only the vibrations of carotenoid molecules are picked up and measured. The measurement results were shown to be closely correlated with the results obtained via traditional methods.

The latest working prototype of the device uses a solid-state laser and is portable enough to be used in field tests with children, but other improvements still need to be made.

Further research is necessary in order to make readings obtained with the RRS method more valuable to scientists, and there are several important goals on the agenda. The researchers want to measure the half-life of carotenoids in the skin, to be able to say how long of an intake period is being reflected by the measurement results. Another thing they want to look into is how to account for differences between the tested individuals (such as how other skin components influence the readings). Also, it is not yet clear how well the device can spot changes in carotenoid levels following shifts in fruit and veg intake.

Susan T. Mayne, the head of Yale’s Chronic Disease Epidemiology division, says that next in line are “so-called metabolic studies, where they carefully control the dietary intake of carotenoids and track people over time to see how their skin responds, how quickly it responds, how much it changes and whether everybody changes similarly.” Hopefully these efforts will soon result in new, effective tools to aid in the fight against diet-related obesity and other ailments in children.