Dietary assessments today often rely on food diaries and self-reporting, which are prone to inaccuracies, or invasive blood tests that are costly and time-consuming. Detecting nutrient deficiencies, age-related changes, and overall health markers early remains a major challenge in preventing chronic diseases such as obesity and diabetes. Now, a light-based device can noninvasively and accurately measure these critical health indicators through the skin.

Scientists at Texas A&M AgriLife Research (College Station, TX, USA) have developed a handheld, keychain-sized light-based sensor that uses Raman spectroscopy to analyze skin composition. The device scans biochemical patterns in the skin and translates them into data on diet, age, sex, and nutrient levels. By focusing on biomolecules like collagen and lipids, the system captures clear signatures linked to dietary patterns and metabolic changes.

To test the device, researchers fed live animal models six common diets, including vegan, ketogenic, and Mediterranean, then scanned their skin for chemical signatures. The results, published in Analytical Chemistry, showed the tool could distinguish diet types with nearly 90% accuracy. Beyond diet, the scans revealed markers of biological age and identified folate deficiencies, providing a window into metabolic health.

The findings suggest that portable, noninvasive sensors could transform personalized nutrition and health monitoring. Detecting nutrient imbalances such as folate deficiency, which is linked to birth defects and poor metabolic outcomes, could allow for earlier interventions. As chronic diseases rise, such technologies may support proactive public health strategies and improve individualized dietary recommendations.

Going forward, researchers envision the device being miniaturized into wearables capable of continuous monitoring. Future versions could provide users with real-time data on nutrient status, diet response, and metabolic health, bringing personalized nutrition into daily life. The team aims to expand testing and explore applications beyond nutrition, advancing its role as a broad health-monitoring tool.

“Right now, dietary assessments mostly rely on self-reporting, which is often inaccurate,” said Dmitry Kurouski, Ph.D. But with this technology the size of a keychain, we can look directly at how diet changes the body and learn what is and isn’t working at the individual level.”

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