A Galaxy Watch8 can take about five seconds to produce a nutrition-related score: place your thumb on the sensor on the back of the watch, and Samsung Health reports an Antioxidant Index. But it does not scan meals, count nutrients or diagnose deficiencies. It measures a narrower signal—carotenoids in the skin—and turns that into a wellness prompt, not a nutritionist in your wrist.
What Samsung’s Antioxidant Index does
Samsung introduced Antioxidant Index with the Galaxy Watch8 series and One UI 8 Watch. The feature uses the watch’s BioActive Sensor to measure skin carotenoid levels. Carotenoids are pigments and antioxidant compounds found in many fruits and vegetables; Samsung presents the reading as an indicator that may reflect diet and lifestyle. Samsung announced the feature in June 2025, then described the sensor technology in more detail in August 2025.
In Samsung’s description, the sensor uses multi-wavelength absorption spectroscopy. In practical terms, it shines different wavelengths of light into the skin and reads the resulting optical signal. Samsung says the thumb scan takes about five seconds. The watch is measuring a carotenoid-related signal in the skin—not the contents of your lunch, your blood carotene level or your total antioxidant status. Samsung’s sensor explainer describes the measurement and its intended interpretation.
How to take a reading
- Open the relevant Antioxidant Index feature in Samsung Health on a compatible watch.
- Place your thumb against the sensor on the back of the watch, as Samsung demonstrates.
- Keep your thumb still and in contact with the sensor while the scan runs, for about five seconds.
- Review the result as a broad wellness signal, not a diagnosis or a prescription.
Samsung’s public materials confirm the thumb-on-sensor scan, but do not establish a single current menu path for every device and software version. Check the Samsung Health interface on your watch rather than relying on a navigation path that may differ by region or update.
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What the score can—and cannot—tell you
Samsung describes a score from 0 to 100 with three broad categories; its U.S. product page shows an example score of 92 labeled “Adequate.” The public material cited here does not provide a complete authoritative table of score thresholds, so a particular number should not be translated into a more specific claim than the app itself makes. Samsung’s Galaxy Watch8 product page describes the feature and displays the example.
A reading may be useful as a nudge to pay attention to habits over time. It cannot tell you which food to eat, how much of a nutrient you need, or whether you have a deficiency. Samsung notes that factors beyond diet—including ultraviolet exposure, alcohol and stress—may affect the result. A low or changing score therefore does not establish why the result changed.
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- It measures: an optical signal associated with carotenoids in the skin.
- It displays: Samsung’s Antioxidant Index score and category.
- It does not directly measure: calories, protein, fiber, sodium, blood vitamin levels, blood carotene or the nutrients in a particular meal.
- It does not diagnose: a vitamin deficiency, illness or the cause of a dietary problem.
Think of it as one dashboard indicator, not a full inspection of diet quality. A favorable carotenoid-related score cannot establish that a diet is balanced or adequate in other nutrients.
Antioxidant Index, Food Tracker and AGEs Index are different tools
Samsung groups several health features in its Galaxy Watch ecosystem, but they answer different questions. Antioxidant Index is an optical reading; Food Tracker relies on what the user logs; AGEs Index is a separate metabolic-health indicator. They are not interchangeable ways to measure a meal.
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- YOUR RUN, YOUR COACH: Step up your running routine with a Running Coach³ that analyzes your performance and gives you real-time feedback. Training for an event? Try specific programs built for 5Ks, marathons and more.
- NEW DESIGN. LIGHTWEIGHT FEEL: Maximize your days with a minimalist design. The sleek, thinner-than-ever silhouette makes Galaxy Watch8 look as good as it functions. With a snug fit and sporty style, it gives you readings without getting in your way.
- A PERSONAL ASSISTANT, RIGHT ON YOUR WRIST: Your Watch just became your personal assistant.⁴ Stay one step ahead of your day with a watch that helps you navigate your tasks and to-do lists.
| Feature | Input | What it provides | Useful for |
|---|---|---|---|
| Antioxidant Index | Thumb placed on the watch’s rear sensor | A skin-carotenoid-related score | A broad wellness prompt related to diet and lifestyle |
| Food Tracker | User-entered meals and calorie information | A log of the entries you record | Building awareness of meals and reported intake |
| AGEs Index | A separate watch-based measurement | An index Samsung presents across four levels | Additional lifestyle and metabolic-health context—not a diagnosis |
Samsung describes Food Tracker as a way to log meal and calorie information, while the Antioxidant Index uses the sensor. Logging can offer more detail about what you ate, but it depends on accurate, complete entries. Samsung describes AGEs Index as associated with metabolic health; it should not be treated as a direct measure of sugar consumption or a diagnosis. Samsung’s product page outlines these features.
Which Galaxy Watch supports Antioxidant Index?
The clearest confirmed retail association is the Galaxy Watch8 series. Samsung introduced the feature alongside One UI 8 Watch, and its current U.S. Galaxy Watch8 product page lists Antioxidant Index. Check the product and support information for your country, exact watch model, phone operating system and Samsung Health version before buying or troubleshooting; availability and compatibility can vary.
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Samsung’s June 2025 beta announcement said that a limited beta in the United States and South Korea was open to users with Galaxy Watch5 or later, Android 10 or newer and Samsung Health 6.30.2 or later. Those were beta eligibility conditions, not confirmation that every listed watch has permanent retail access. Do not assume support for Watch5, Watch6, Watch7, Galaxy Watch Ultra or another model based on that beta alone. Samsung’s announcement details the beta and the Galaxy Watch8 launch.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Should you buy a Galaxy Watch for nutrition tracking?
It may suit you if
- You already use Samsung Health and want another simple wellness signal alongside activity, sleep and other health features.
- A quick, visible prompt might help you pay more attention to fruit and vegetable intake.
- You are interested in the broader Galaxy Watch8 health feature set, not a standalone nutrition test.
It is a poor fit if
- You expect automatic meal recognition, calorie counting or a complete nutrient breakdown.
- You want a test for vitamin or mineral deficiencies, or a personalized meal plan.
- You need nutrition guidance for a medical condition, allergies, an eating disorder or a prescribed diet.
Samsung markets the feature as part of its health and healthy-aging tools, but the score alone is not evidence that a person will avoid disease or live longer. If you have a suspected deficiency or need nutrition advice for a health condition, discuss it with a qualified clinician or registered dietitian rather than trying to interpret a wearable score.
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What to do if a scan does not work
Samsung’s cited public materials explain how to take the reading but do not establish every failure cause or a universal troubleshooting sequence. As general, non-device-specific steps, make sure the sensor and skin are clean and dry, seat the watch securely, keep your thumb still against the sensor for the full scan, then retry. If the feature remains unavailable, check current Samsung support information for your model, region and software. Do not treat an implausible result—or a failed scan—as evidence of a health problem.
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