Antioxidants at a glance
- Definition: Antioxidants are compounds that neutralise free radicals, helping to protect our cells.
- Counterpart: Free radicals form constantly in the body – totally normal, but stressful for cells in large amounts.
- Where to find them: Antioxidants are found mainly in fruit, vegetables and plant compounds – think vitamin C, vitamin E and polyphenols.
- Tea connection: Green tea is one of the richest sources of polyphenols, thanks to its catechins.
- Context: A real, noticeable benefit, not a miracle cure – antioxidants are just one part of a much bigger system in your body.
Description
To understand antioxidants, it helps to look at their counterpart first: free radicals. These are small, unstable molecules missing an electron. They're formed constantly in the body – for example whenever we turn food into energy. A few extra ones sneak in from outside, too, through sun exposure, stress or cigarette smoke. Free radicals try to "borrow" that missing electron from other molecules, which can trigger a chain reaction that puts a strain on cells over time.
This is where antioxidants step in: they give up one of their own electrons and stop the reaction in its tracks, without turning into a new free radical themselves. Think of it as a balance – free radicals on one side, antioxidants neutralising them on the other. As long as both sides stay roughly even, that's completely normal for the body. But if there are significantly more free radicals than antioxidants able to keep up over a longer period, that's what experts call oxidative stress. Luckily, your body has its own defence system for this – and you can support it with the right diet.
Antioxidants aren't actually a single substance, by the way – they're more of an umbrella term for anything that can do this job: vitamins like C and E, trace elements like zinc and selenium, and above all polyphenols – plant compounds that give fruit, vegetables and green tea their colour and character. In green tea, these polyphenols are called catechins, with EGCG as their best-known member.
Historical background
Antioxidants were, for a long time, mostly a topic for chemists: used to stop fats from turning rancid or metal from rusting. It wasn't until the mid-20th century that they came into focus for human health, too. In 1956, aging researcher Denham Harman proposed that free radicals could be one of the causes behind the aging process – an idea that made quite a splash.
The 1990s and 2000s brought a full-blown antioxidant craze: superfoods, supplements and cosmetics everywhere started advertising a high so-called ORAC value – a lab measurement meant to show how many free radicals a substance can neutralise. Since then, research has become a lot more cautious: free radicals aren't inherently the enemy, and a high ORAC value doesn't actually tell you much about how well a food performs inside your body (more on that below, in the fun facts).
Tea has been part of this story for a long time, too, long before anyone used the word "polyphenol": across East Asia, green tea has been linked to vitality and wellbeing for centuries.
Fun facts
- Free radicals aren't the villains they're made out to be: your body actually puts them to good use, for example to fight off pathogens. Things only get tricky when there are too many at once.
- The ORAC value was quietly shelved: ORAC stands for "Oxygen Radical Absorbance Capacity" and was once the go-to measure for antioxidant power. In 2012, the USDA (the US Department of Agriculture) pulled its own ORAC database offline – because the value was too often misused as a marketing claim without saying anything about its effect inside the body.
- Green tea is a polyphenol powerhouse: roughly 20 to 30 percent of its dry weight is made up of polyphenols – considerably more than in fully oxidized black tea, since catechins break down partly during oxidation and fermentation.
- Matcha packs even more of it in: because the leaves are shaded before harvest, the plant produces more of these protective compounds – which is why matcha has a reputation among green tea fans for being especially rich in catechins.
