Hot Tea vs. Cold Tea: Does Brewing Temperature Affect Antioxidants?

Research shows hot water extracts more polyphenols, but cold brewing still offers solid benefits.

Reviewed by Dietitian Jane Leverich, M.S., RDN

Key Points

• Tea is the second most consumed beverage in the world, after water.
• The temperature you use to brew your tea may influence its antioxidant content.
• Both hot- and cold-brewed teas contain beneficial compounds, so choose the one you enjoy most.

Tea is the second most consumed beverage in the world, sitting right behind water. People across the globe enjoy its rich flavors, comforting warmth and refreshing chill. Beyond its taste, tea offers a robust profile of health-promoting properties. True teas, or teas made from the leaves of the Camellia sinensis plant like green and black tea, as well as herbal varieties like rooibos, contain polyphenols and flavonoids. These compounds act as antioxidants in your body, helping to support cellular health and reduce oxidative stress.

As you steep your daily cup, you might wonder if the temperature of the water changes the chemical makeup of your drink. Whether you prefer a steaming mug on a crisp morning or a glass filled to the brim with ice on a warm afternoon, the brewing method plays a role in what ends up in your glass. This leads to an important question: Does iced tea or hot tea have more antioxidants?

Antioxidant Content of Cold Brew Tea

“Cold brewing involves steeping tea leaves in room-temperature or cold water for an extended period, typically between eight and 16 hours. This slow extraction process yields a beverage that many find smoother, sweeter and less bitter than its hot counterpart,” explains Jamie Lee McIntyre, M.S., RDN.

When it comes to extracting beneficial compounds found in tea leaves, temperature plays a major role. In fact, research suggests that cold brewing generally extracts fewer beneficial polyphenols than hot water. Without heat acting as a catalyst, the water simply cannot pull as many compounds from the leaves, even with an extended steeping time.

However, the type of tea you use may change the equation. Some research comparing cold- and hot-brewed rooibos tea found that unfermented green rooibos steeped in cold water for eight hours delivered antioxidant capacity and total polyphenol content similar to those of a standard five-minute hot brew. On the other hand, fermented red rooibos steeped in cold water showed slightly lower antioxidant levels than its hot-brewed counterpart. This suggests that while cold water extraction is generally less efficient, certain unoxidized teas can still deliver a highly beneficial antioxidant profile when steeped for longer periods.

Antioxidant Content of Hot Tea

Hot water is the traditional method for brewing tea, and may be more effective than cold-brewing when it comes to extracting antioxidants from tea leaves. The application of heat helps break down the structure of the tea leaves, allowing water to act as a highly effective solvent for the beneficial compounds.

Research suggests that hot brews tend to have a higher antioxidant potential than cold-brewed teas because the higher temperature improves extraction efficiency. Green teas, which do not undergo the oxidation process that black teas do, often display the highest antioxidant capacities when brewed hot.

Some studies have also found that higher brewing temperatures force more polyphenols into the liquid. In fact, research on rooibos tea suggests that brewing with boiling water may yield the highest total phenolic content as well as maximize the release of catechins and other beneficial compounds.

Research indicates that heat is highly effective for extracting antioxidants from tea, and Johannah Katz, M.A.,RDN, agrees: “One study showed that hot-water extraction is significantly more efficient than cold brewing for antioxidant yield. At the same steeping time, teas brewed at higher temperatures (around 90 to 100°C) consistently produced higher concentrations of total polyphenols and flavanols compared with cold-water extraction.”

Which One Has More Antioxidants?

If you are looking strictly at the numbers, hot tea generally contains more antioxidants than cold-brewed iced tea. The heat acts quickly to dissolve and extract beneficial compounds—like flavonoids, catechins and phenolic acids—from the tea leaves. When you steep tea in cold water, you leave some of those compounds behind.

That said, you should not discount cold-brew tea. Because cold brewing requires a much longer steep time, the extended exposure allows the water to gradually extract a substantial amount of polyphenols. If you use unoxidized varieties like green tea or green rooibos, your cold-brewed beverage will still offer an impressive supply of antioxidants. Furthermore, if you drink larger volumes of cold tea—perhaps pouring two glasses on a hot day compared to sipping just one mug of hot tea—your overall intake of antioxidants may balance out.

It is also important to note that the scientific data points to differences in extraction efficiency rather than an absolute lack of benefits. While hot brewing may extract antioxidants more efficiently, cold-brewed tea still contains beneficial compounds that can support your overall health.

Tips to Brew Tea

Next time you make a cup of tea, keep a few simple brewing tips in mind to get the best flavor and the most out of your tea leaves. Here are some expert-backed tips for brewing tea properly:

• Use boiling water for classic hot tea. Bring fresh water to a full boil (212°F) to ensure proper extraction for robust black teas. Steep 1 teaspoon or one tea bag per cup for three to five minutes.
• Brew iced tea hot first. Steep tea in boiling water for three to five minutes before pouring it over cold water and ice. The high initial temperature acts to eliminate potential bacteria found on the leaves.
• Let water cool slightly for green tea. Allow boiling water to stand for about 10 minutes, until it drops to between 165°F and 185°F. Pour this water over the green tea and steep for just one minute to prevent a bitter taste.
• Use gentler heat for white tea. Boiling water easily scorches large, delicate white tea leaves, so use water between 180°F and 190°F instead of boiling water. Steep the leaves for three to four minutes to reach the optimal flavor profile.
• Give oolong tea more time to steep. Use the same 180°F to 190°F water temperature that you use for white tea. However, allow oolong leaves to steep for five to seven minutes to properly extract their compounds.

Our Expert Take

While research suggests that hot water extracts antioxidants more efficiently, the best brewing method is the one that encourages you to drink tea regularly. Both hot- and cold-brewed teas provide valuable hydration and a boost of health-supporting polyphenols, so you do not need to overthink your beverage preparation to reap the benefits. “Both are great, so however someone prefers to get in their flavanols, catechins and antioxidants is the best way,” says Katz. Whether you reach for a steaming mug to start your morning or a chilled glass of cold brew to cool down in the afternoon, you are making a choice that supports your cellular health. Drink the version you enjoy most.