GoKawiilSamsung says it validated its sensor against Raman spectroscopy, a lab technique used to measure skin carotenoids, and compared readings with blood tests, food logs and clinical data from several hundred participants. Separately, a 2023 randomized controlled trial involving Samsung researchers also found a strong correlation between reflection spectroscopy and Raman spectroscopy when measuring skin carotenoids.
But there's a big caveat. Samsung has not published a simple consumer-facing accuracy percentage or margin of error for the Galaxy Watch 8 feature, and it says Antioxidant Index isn't intended to diagnose or treat medical conditions. Think of the score as another health trend to monitor, rather than a blood test wrapped up in a little computer on your wrist.
The number can be stubborn, according to Engadget's Galaxy Watch 8 review. After Amy Skorheim deliberately changed her diet for a day, her score dropped by two points. On subsequent days, her readings ranged from 56 to 60.
Samsung's current US comparison chart doesn't list Antioxidant Index for the Galaxy Watch 7. It does list the feature for the Galaxy Watch 8, Watch 8 Classic and Galaxy Watch Ultra (along with the newer Watch 9 and Ultra2), but Samsung hasn't specified why the Watch 7 misses out. The company says it usually takes two to three weeks for carotenoids from food to build up in the skin to detectable levels.