Are you eating your vegetables? This laser can tell you

11 hrs.

Devin Coldewey

Invasive tests and unreliable recall make getting good information on food intake difficult for nutritionists and healthy eaters alike. A new device may allow doctors to tell how well you've been eating after doing nothing but shining a laser on your skin for 30 seconds.

It's well known among those in the field that what you eat can show externally ? and not just in your waistline?or smeared on your sleeve. As the body metabolizes certain things, like vegetables, some of the byproducts make their way to your skin, your hair, even your eyes. You are what you eat, and apparently you look like it too.

But only in subtle ways: a vegetable-rich diet will produce lots of what are known as skin carotenoids. They accumulate in the skin and can be measured to infer one's eating habits. But no one wants to give skin samples, and doctors would rather not waste time sending them in to the lab. Luckily, a chance meeting between two experts?produced something better.

Susan Mayne, a nutritional epidemiologist at Yale, happened to sit next to a laser physicist from the University of Utah on the way to a conference. By the time their?16-hour flight was over, they were drafting a grant proposal.

Using a technique called resonance Raman spectroscopy, results can be gotten in as little as a minute simply by shining a special blue laser on a person's palm and observing the results. Thirty seconds of laser, 30 seconds of processing on the computer, and your skin carotenoid levels are there for you and your doctor to talk about.

The test is non-invasive, cheap to administer and quick. It's so easy to use that one researcher managed to check the levels of 60 children in one afternoon. It could even be done while they napped.

It's not perfect; no one knows yet just how long it takes for the levels of carotenoids to build up or fade away in the skin, and they're not sure whether it will work on people with different levels of pigmentation in the skin. The technique?is promising and its?creators are already imagining many applications, but it's still in a fairly early phase and would face years of clinical testing before being deployed widely.

More information can be found at this article from Yale's School of Public Health magazine.

Devin Coldewey is a contributing writer for msnbc.com. His personal website is coldewey.cc.

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