Caffeine In Teas-What's The Deal?

Caffeine is a stimulant that occurs naturally in the leaves, seeds, and fruits of over 60 plants. These plants include coffee beans, tea leaves, cocoa beans, and kola nuts. When a caffeinated drink is consumed, it is absorbed quickly in the stomach and small intestine and then circulated through the bloodstream to the brain (which affects the central nervous system). Once in the brain, it attaches to receptors and blocks adenosine from performing its function of making us feel sleepy. As a result, we feel more alert, awake, more focused and this may increase our heart rate and blood pressure. It is also a diuretic, which means it can cause you to urinate more frequently. The effects of caffeine can be felt as soon as 15 minutes after ingestion and can last for several hours. In moderate amounts, caffeine is generally safe for most people. However, consuming large amounts of caffeine can lead to side effects such as headaches, insomnia, anxiety, and irritability. 

 How Much Caffeine Is In Tea? The amount of caffeine in tea depends on several factors. The type of tea plant used, how long the leaves are brewed, and whether or not the leaves are fully oxidized. For example, Camellia sinensis var. Sinensis (Chinese/Japanese teas) generally contain more caffeine than Camellia sinensis var. assamica (Indian/Nepalese teas). Black teas usually contain more caffeine than oolong, green, or white teas because they are fully oxidized, while green and white teas contain less caffeine because they are only partially oxidized. Brewing time also affects the amount of caffeine in tea; longer brewing times result in higher concentrations of caffeine. Finally, weight (or quantity) plays a role in determining caffeine content; more leaves equal more caffeine. Matcha is considered a green tea yet has higher caffeine than black tea because it is a powdered leaf. In general, most teas contain between 14-60 mg of caffeine per 8 oz cup. This is about half the amount of caffeine found in a similarly sized cup of coffee, which typically contains around 95-200 mg of caffeine.

 So how much caffeine is in your favorite teas? Here's a breakdown of the average content of some common types of tea: Black Tea: 40-60 milligrams Oolong Tea: 30-50 milligrams Green Tea: 25-35 milligrams White Tea: 15-20 milligrams Herbal Tea: 0 milligrams* *Note that some herbal "teas" may contain small amounts of caffeinated herbs such as guarana or yerba mate. However, most herbal "teas" on the market are entirely caffeine-free.

 How Much is Too Much? For most healthy adults, 400 milligrams of caffeine per day is perfectly safe. That's roughly equivalent to four cups of black tea or five cups of green tea. However, pregnant women and people with heart conditions should limit their intake to 200 milligrams per day- that's two cups (16 oz) of black tea or two and a half cups of green tea. As always, though, it's best to check with your doctor before consuming any caffeinated beverage if you're pregnant or breastfeeding. Caffeine affects kids differently than adults because their bodies are still developing, and they weigh less. As a result, even small amounts of caffeine can have big effects on kids' behavior and sleep patterns. It's important to limit kids' intake of caffeinated beverages to no more than 100 mg per day - that's about one cup (8 ounces) of coffee or two cups (16 ounces) of black tea or just give them herbal teas. Green tea has less caffeine than black tea so it's generally considered safe for kids to consume in larger quantities - up to 3 cups (24 ounces) per day should be fine for most children above 12.

 Now that you know a little bit more about the caffeine content of tea, the next time you sit down with a cup, you can do so with even greater enjoyment. And who knows? Maybe you'll even impress your friends with your newfound knowledge! Cheers!