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Wearables have mastered tracking how we move, breathe, and sleep with near-clinical accuracy. But they’re still missing one of the most important pieces of the health puzzle: diet. Beyond calorie-tracking apps or invasive lab tests, our nutrition has essentially lived outside of diet Smart watch Ecosystem.
Samsung aims to change that with the new Antioxidant index On new Galaxy Watch 8, classicand Ultra. This feature uses an advanced biosensor to measure carotenoids, natural antioxidants found in fruits and vegetables, directly through the skin (no food diary needed). Samsung believes this new metric can help unlock a deeper understanding of how lifestyle and diet affect overall health, longevity and the aging process.
“If we can get a larger percentage of the population to consume one additional serving of fruits and vegetables per day, we will see a significant reduction in these chronic conditions over time.” says Marcella Radtke, Ph.D., a postdoctoral researcher in epidemiology at Stanford University.
It can also be worn from apple, Fitbit and Ora Competing to be a one-stop health and wellness hub, with features ranging from advanced vitals tracking to AI health coaches, Samsung is taking a different approach. By focusing on nutrition – the one health metric that remains largely unrestricted – and combining it with other indicators such as vascular load and sleep guidance, Samsung’s approach can provide a competitive advantage and deliver a more complete picture of overall wellness.
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Galaxy Watch 8 has a new BioActive sensor that unlocks advanced health metrics like vascular load and antioxidant levels.
Why should you care about antioxidants?
Antioxidants play a crucial role in maintaining the body’s internal balance. According to National Institutes of HealthThese compounds help remove harmful free radicals, unstable oxygen molecules that form naturally but can multiply due to factors such as poor diet, alcohol consumption, smoking, stress, and even environmental pollution. When free radicals accumulate, they cause oxidative stress, a process that destroys cells and can contribute to chronic diseases, including cancer, heart disease, and premature aging.
Ok K says “Antioxidants neutralize[free radicals]before they can cause damage,” says Chun, a professor in the Department of Nutritional Sciences at the University of Connecticut. “By increasing antioxidants in the body, you can fight these diseases, increase longevity as well as quality of life.”
While antioxidants come in many forms, including vitamins C and E, Chun explains that carotenoids—particularly beta-carotene, the compound measured by… Galaxy watch -Among the most reliable indicators of fruit and vegetable intake and the only antioxidants that can currently be measured through the skin. Beta carotenoids are commonly found in colorful fruits, grains, oils, and vegetables such as carrots and leafy greens. According to the National Institutes of Health.
According to Radtke, weight is one of the most commonly used indicators of diet in the clinical setting, but it is not always synonymous with health. Antioxidants can provide a more reliable reflection of nutrition, although measuring them usually requires a blood test—a procedure not often used for preventive purposes and usually requiring an order from a doctor once there’s already something of concern. While antioxidant levels appear more quickly in the blood, Radtke points out that “carotenoids in the skin are closely related to carotenoids in the blood.”
The only non-surgical alternative currently on the market is the vegetable measuring device. Launched in 2018, it is a standalone device that uses a method similar to the Galaxy Watch to detect skin carotenoid concentrations on the tip of a finger. But even this has not seen widespread adoption in clinical settings.
The new Galaxy Watches use different colored LEDs to detect carotenoids (antioxidants in the skin).
How the Galaxy Watch does it
The company first announced the antioxidant index earlier this year alongside Galaxy Watch 8 and Galaxy Watch 8 Classic. While most modern wearables rely on infrared PPG (photoplethysmography) sensors to track heart rate, blood oxygen (SpO₂) and other metrics from the wrist, new watches (including 2024’s Galaxy Watch Ultra) have active biosensors with yellow, blue, violet and infrared LEDs that can reflect antioxidants that build up in the skin. But not just any part of the skin, the sensor only works when it is away from the wrist.
According to Dr. Jinyoung Park, lead engineer on Samsung’s digital health team, the fingertip — especially the thumb — is ideal for measuring carotenoids due to its thicker outer layer and lower melanin overlapping (pigmentation of the lower part of the skin). “By pressing firmly on the sensor with the thumb for 5 seconds, the blood is removed which reduces noise and produces (a) better reading,” says Park.
After those five seconds, the watch analyzes how the skin absorbs and reflects different wavelengths of light to estimate the carotenoid concentration.
The antioxidant indicator on the Galaxy Watch 8 shows a decent level of carotenoids.
Results appear as a score from 0 to 100, ranging from very low to adequate, either on the watch or plotted over time in the Samsung Health app. The score refers to the World Health Organization’s daily recommendation to eat at least 400 grams of fruits and vegetables, and the app also provides general suggestions to help improve the quality of the diet.
Don’t expect to see immediate results from the green juice you had for lunch. “Blood levels change faster, while skin levels respond more gradually and last longer,” Chun says. This means that it may take about a week or more for the antioxidant index to reflect changes in diet or lifestyle. She recommends daily readings to track progress over time, cautioning that visual improvements may lag behind behavioral changes.
However, readings can vary based on several personal factors. Radtke points out that BMI and body composition can affect antioxidant levels, as people with higher BMIs tend to use more antioxidant reserves. “Even if two people eat the same diet, the person with a higher BMI may show lower levels of carotenoids in the skin simply because their body is using more of those antioxidants,” she says.
She adds that skin pigmentation can also affect accuracy, even when using a finger method designed to minimize melanin interference. Together, these variables reinforce that the antioxidant index is best viewed as a baseline indicator, rather than a clinical measure—a point both Samsung and nutrition experts agree on.
Galaxy Watch 8, Galaxy Watch 8 Classic and Galaxy Watch Ultra all have a new BioActive sensor that enables antioxidant tracking.
Samsung’s vision for a comprehensive approach to data collection
Samsung says the antioxidant index data has been validated in internal clinical trials against blood carotenoid levels, but this feature has not been approved by the FDA or is not intended for diagnostic use. Instead, the company positions it as an essential tool; A non-invasive, low-effort way to visualize how lifestyles affect your long-term health.
“There’s a lot of enthusiasm now about nutrition monitoring, and having something like this, it allows consumers to monitor their behavior … and how small changes can impact overall health,” Radtke says.
It’s also worth noting that the feature only measures one aspect of nutrition. Carotenoids are only part of the antioxidant story, and diet is just one piece of overall wellness. However, the fact that a smartwatch can measure this otherwise invisible process indicates how light-based sensors could open up more data tracking in the future.
Samsung says it’s already exploring new applications for its biosensor technology beyond antioxidants that use different light wavelengths to peer beneath the skin’s surface. The company’s long-term goal is to build a more integrated and sustainable view of health, where factors such as stress, sleep, diet and recovery contribute to creating one personalized ecosystem. Future updates could provide nutrition coaching and recipe suggestions tailored to people’s antioxidant trends.