Caffeine, a natural stimulant found in various plants, is one of the central components of both tea and coffee. However, despite their similarities, the experience and effects of consuming these beverages can vary significantly. This piece aims to debunk common myths about caffeine in tea, providing a comprehensive understanding of its presence, variations, and impact on the body.
Photo: Boseong, South Korea. Katrina Wild.
A Bit About the History
Photo: Coffeehouse in Palestine, c. 1900. B. L. Singley.
The use of caffeine-rich plants has a rich history across various cultures. According to a Chinese legend, Emperor Shennong discovered tea around 2737 BCE when tea leaves fell into boiling water, producing a fragrant and restorative drink. Possibly originating from Ethiopia, the earliest credible evidence of coffee consumption dates back to the mid-15th century in Sufi monasteries in Yemen. Coffee then spread from Mocha (Red Sea port in Yemen) to Egypt, North Africa, and by the 16th century, to the Middle East, Persia, Turkey, and eventually Europe. Kola nuts have ancient origins in West Africa, where they are chewed to restore vitality and ease hunger pangs. The Mayans used cocoa beans as early as 600 BCE, consuming chocolate in a drink called xocolatl, believed to fight fatigue due to its theobromine and caffeine content. This beverage became popular in Europe after being introduced by the Spaniards, who also brought the cacao tree to the West Indies and the Philippines. Yerba mate has been drunk in South America for centuries and it was originally consumed by the Guaraní people, who live in what today is Paraguay, north of Argentina, south of Brazil and parts of Uruguay and Bolivia. It was consumed first chewing the green leaves of Ilex paraguariensis and then they would use the mate gourd and a small straw made out of cane. Additionally, Native Americans used the leaves and stems of the yaupon holly to brew a caffeinated infusion called asi or "black drink," with evidence of its use dating back to Late Archaic times.
The scientific discovery of caffeine dates back to 1819 when German chemist Friedlieb Ferdinand Runge first isolated relatively pure caffeine, which he called "Kaffebase" (coffee base), at the behest of Johann Wolfgang von Goethe. In 1821, French chemists Pierre Jean Robiquet and the team of Pierre-Joseph Pelletier and Joseph Bienaimé Caventou also independently isolated caffeine. Robiquet's work led to the first use of the term "caféine" in print. In 1827, a chemist named Oudry isolated a compound from tea he called "théine," but by 1838, it was proven by Mulder and Carl Jobst to be identical to caffeine. This unified understanding led to the universal term "caffeine" for the stimulant found in both coffee and tea.
The Chemistry of Caffeine in Tea
Caffeine is one of several methylxanthines found in tea, alongside theobromine and theophylline, all belonging to the alkaloid family. This specific methylxanthine, known chemically as 1,3,7-trimethylxanthine, is naturally present in at least 63 types of plants, including coffee, tea, and cacao. Caffeine interacts with our body's chemistry by mimicking adenosine, a compound that binds to adenosine receptors and slows down nerve cell activity, making us feel drowsy. When caffeine binds to these receptors, it accelerates nerve cell activity instead. Additionally, caffeine increases dopamine levels, enhancing feelings of happiness and pleasure. Individual tolerance to caffeine varies, but generally, it is recommended not to consume more than 300 mg of caffeine per day, which is approximately equivalent to 2-3 cups of coffee or 4-10 cups of tea, depending on the type. In tea, caffeine contributes to its stimulating effects and distinct bitterness, while also serving as a natural defense mechanism for the tea plant against insects and pests. On average, methylxanthines constitute 2% to 5% of the dry weight of fresh tea leaves. However, numerous factors influence the actual caffeine levels in a brewed cup, making precise measurement challenging outside a laboratory setting. For a deeper exploration of the chemical composition of tea, you can read our previous blog post HERE.
Photo: Nagasaki Ikedoki Tea, Marjolein Raijmakers. Here we can observe how after a few hours above a tea light, the leaves get covered with tiny white crystals - caffeine! Which can serve as a visual representation why the roasted teas like houjicha are known for less caffeine content as the high temperature roasting literally makes the caffeine "exit" the leaves.
Factors Influencing Caffeine Levels in Tea
1. Harvest Time: The timing of the harvest impacts caffeine levels. Spring-harvested teas, particularly tea buds, often have higher caffeine compared to those harvested later in the year. Mature leaves generally contain less caffeine.
2. Growing Practices: Shade-grown teas, such as gyokuro and matcha, have higher caffeine levels due to increased stress responses in the plant.
3. Brewing Techniques: Water temperature, steeping time, and the amount of tea used significantly affect caffeine levels. Hotter water and longer steeping times extract more caffeine, while cold brewing reduces caffeine extraction, favoring the release of sweeter compounds over bitter ones.
4. Processing Methods: The way tea is processed affects caffeine release. Teas processed by cutting, crushing, or tearing (e.g., CTC black teas) release more caffeine more quickly into the brew compared to whole leaf teas.
Photo: Slices of Blue Sky
5. Plucking Standards: The choice of leaf plucked affects caffeine content. Tea buds contain more caffeine than older leaves. The caffeine content decreases as one moves down from the budset to the lower leaves. The presence of "down" (fine hairs on the tea bud) in spring teas may also contribute to higher caffeine levels, although this is less scientifically documented.
6. Leaf Age: Younger leaves and buds have higher caffeine levels than older leaves. For instance, the fourth leaf on a branch may have 30% less caffeine than the budset.
7. Plant Growth Cycle: The caffeine content can vary depending on the plant's growth cycle and the specific time of harvest. After pruning or damage, the plant may produce new growth with higher caffeine content.
Considering these factors, it is clear that making definitive statements about the caffeine content of a brewed cup of a tea type is challenging. Understanding the source of the tea and the brewing technique is essential for a more accurate estimation.
Myths About Caffeine in Tea
Myth 1: "Green Tea Has Less Caffeine Than Black Tea"
Feels a bit contradictory, right? And yet, you might see online a lot of statements like this for one reason or another, and it is not neccessarily true that green tea contains less caffeine than black tea. Once again, factors such as the specific tea variety, growing conditions, harvest time and picking standard, as well as brewing methods play a more significant role. Some green teas, like matcha, typically contain the most caffeine since the whole leaf is consumed rather than just the infusion.
Photo: Kyoto Obubu Tea Farms, Wazuka, Japan. Katrina Wild. Tencha being ground into matcha with a hand mill.
Myth 2: "You Can Decaffeinate Tea by Steeping It for 30 Seconds"
Another odd yet popular myth suggests that briefly steeping tea and discarding the initial infusion removes most of the caffeine. In reality, caffeine extraction is gradual, and a significant amount remains in subsequent infusions. Additionally, this method removes many of the beneficial antioxidants and other compounds alongside some caffeine. So do not throw out the first infusion in this way, unless you are brewing certain tea gong fu style and wish to rinse the leaves.
Myth 3: "White Tea Is Caffeine-Free"
All teas from the Camellia sinensis plant contain caffeine, including white tea. While some white tea generally can have lower caffeine levels compared to other teas, it is not caffeine-free. Variations within white teas can also lead to differences in caffeine content. For instance, tea buds such as Silver Needle can be quite high in caffeine while more mature leaf material in white teas such as Shou Mei (Longevous Eyebrow; 壽眉; mostly large leaves) tends to have less caffeine
Myth 4: "Higher Oxidation Increases Caffeine Levels"
The process of oxidation, which differentiates black tea from green and white teas, does not directly increase caffeine content. Instead, the perceived higher caffeine in black tea results from typical brewing practices—using hotter water and longer steeping times. You might have also heard that the least processed teas have more caffeine.
Comparing Caffeine in Tea and Coffee
While dry tea leaves contain more caffeine by weight than coffee beans, a brewed cup of tea typically has less caffeine than a cup of coffee. This difference arises because tea is usually brewed with fewer leaves (about 2 grams per 180 ml of water) compared to coffee beans (about 10 grams per 180 ml of water). On average, a cup of tea contains 12-50 mg of caffeine (except for matcha with around 70-120 mg), whereas a cup of coffee contains 85-100 mg. Additionally, tea contains small amounts of theobromine and slightly higher levels of theophylline compared to coffee. Tea tends to provide a more sustained release of caffeine compared to coffee. This is partly due to the presence of L-Theanine, an amino acid found in tea that enhances mental focus, cognitive performance, and mood while providing a calming effect. The interaction between caffeine and L-Theanine results in a balanced energy boost with relaxing health benefits. In contrast, the caffeine in coffee is absorbed more quickly, often leading to a more immediate but short-lived energy spike with potential jittery effect. For those seeking caffeine-free options, herbal teas, or tisanes, such as chamomile, rooibos, and peppermint, are made from botanicals other than Camellia sinensis and naturally contain no caffeine. Albeit, there are some exceptions such as yerba mate, guarana, guayusa, etc.
Comments