The Era of Healthy Aging ① Measuring and Managing Antioxidant Levels With Professor Hyojee Joung of Seoul National University
Aging is not fixed — it can speed up or slow down depending on diet and lifestyle. That’s why healthy aging has become a growing focus in recent years.
Antioxidants play a key role in this process, helping neutralize free radicals and protect the body from oxidative stress. The Galaxy Watch8 series debuts Antioxidant Index — the first smartwatch feature to measure the body’s antioxidant status and support more effective health monitoring.
Samsung Newsroom spoke with Hyojee Joung — President of the Korean Nutrition Society and professor at Seoul National University (SNU), who participated in developing and validating the new feature — about this breakthrough and the importance of antioxidant care.
Free radicals are natural byproducts of energy production in the body, but unhealthy habits can cause them to build up. “Tobacco use, alcohol consumption, poor diet, UV exposure and stress drive overproduction — triggering oxidative stress and accelerating aging,” said Joung.
Persistent exhaustion may signal excess free radicals in the body. “They can weaken immunity, cause fatigue and speed up visible signs of aging such as wrinkles or pigmentation,” Joung explained. “As oxidative stress accumulates, the risk of chronic diseases such as type 2 diabetes and certain cancers increases — making antioxidant management essential.
“Antioxidant capacity isn’t a matter of youth or fitness — it requires consistent care throughout life,” Joung emphasized, noting that daily fruit and vegetable intake is the easiest and most effective place to start.
Fruits and vegetables are rich in antioxidants such as carotenoids and vitamins C and E. Because the body’s natural production of antioxidant enzymes declines with age, sufficient dietary antioxidant intake provides the foundation for sustainable health.
However, for most people, it’s not easy to objectively assess whether their everyday diet is truly balanced. The Galaxy Watch8 series’ Antioxidant Index was developed to address this challenge
For anyone wondering how healthy their diet is, Samsung Health now offers a quick answer. Using rear sensors, the Galaxy Watch8 series measures an Antioxidant Index — based on carotenoid levels in the skin — to assess fruit and vegetable intake within seconds.
“Carotenoids are the red, yellow and green pigments in fruits and vegetables,” said Joung. “Because the human body cannot produce them, carotenoid levels reflect dietary intake.”
The Galaxy Watch8 series uses a reflection spectroscopy sensor. When light of a specific wavelength shines on the skin, carotenoids absorb some and reflect the rest. By analyzing the reflected light, the device estimates carotenoid levels.
Previously, measuring antioxidant levels required blood samples and complex laboratory procedures. Now, users can simply place a thumb on the back sensor for five seconds to see instant results. Based on the World Health Organization’s (WHO) daily recommendation of 400 grams of fruits and vegetables, results appear as.
Joung explained that although Antioxidant Index does not represent the body’s full antioxidant capacity, it serves as a practical and meaningful indicator of daily antioxidant status by reflecting carotenoid intake from fruits and vegetables — major sources that help strengthen the body’s antioxidant system.
The Galaxy Watch8 series is the first smartwatch to measure antioxidant levels — a breakthrough built on years of research. Samsung began collaborating with Joung and her team in 2018 to explore how this capability could be applied to wearables.
A dietary intervention study conducted by the Graduate School of Public Health at SNU confirmed that skin carotenoid levels reliably indicate fruit and vegetable intake. “Over six weeks, we provided meals with varying carotenoid content to 80 participants and observed their skin carotenoid levels increased within one to two weeks,” Joung said.
When users measure their Antioxidant Index, the Samsung Health app provides feedback such as “Have one more tomato today” or “Try 50 grams of pumpkin.” These recommendations are based on proposals from Joung’s team. “It’s important to give dietary guidance in language users can easily understand,” she explained. “We created the foundational data that trained an algorithm to adapt suggestions to individual preferences.”
The research team plans to keep refining the feature to deliver more accurate insights and support more effective antioxidant management.
