Tea and Caffeine
This is the caffeine molecule C8H10N4O2
There is so much misinformation swirling around about tea and caffeine we are going to de-bunk the most common caffeine and tea myths.
Myth #1: Green Tea has Less Caffeine than Black Tea
Truth: Not necessarily and hard to say. Firstly, it is important to emphasize that caffeine content in tea is not determined by its category of tea (such as white, green, yellow, oolong, black, or pu’er).
Remember when we talked about categories of tea and said the main factor that distinguishes each type is its level of oxidation? Quick recap: tea makers manipulate heat and moisture to control the oxidation levels of each finished tea leaf when crafting and processing tea.
Oxidation and Caffeine Have No Relationship
What determines the caffeine content in any particular tea leaf has more to do with growing variables that are determined before any processing begins.
The main variables that affect the caffeine content in any tea leaf are: when the leaf was picked (earlier or later in the picking season), the growing conditions, and the cultivar and varietal of the plant.
Generally speaking, the earlier in the season the leaf is picked, the higher its caffeine content. So a tea leaf picked earlier in the season that is processed into a black tea would most likely have a higher caffeine content than a tea leaf picked later in the season that is processed into a green tea.
By the same token, black and green tea processed from leaves picked the same day from the same plants will basically have the same caffeine levels.
When the leaf was picked is not the only determinant of the caffeine level of any finished tea. As I mentioned, growing conditions affect the caffeine content of a tea leaf. For instance, the use of nitrogen fertilizers on the tea plant, which is common in Japan, increases caffeine content in the tea leaf.
Remember when we discussed how all tea is from the same plant family camellia sinensis? Well there are two main varietals: camellia sinensis sinensis (the majority of Chinese teas) and camellia sinensis assamica (pu’er teas in China and many Indian black teas). Teas grown of the assamica varietal tend to have higher caffeine content than their sinensis counterparts.
How Brewing Tea Affects the Amount of Caffeine You Drink
So when the leaf was picked, its growing conditions, and the cultivar and varietal of the plant are key contributing factors in determining how much caffeine is in each tea leaf. How much caffeine you actually drink, however, is also affected by how you brew your tea.
How you brew the tea does affect the amount of caffeine released into the brew. Caffeine is water soluble, so when the water temperature used is lowered, less caffeine will be released. Also, the longer you steep your tea the more caffeine will be released into your brew.
White teas like White Peony White Tea have a relatively higher caffeine content because the young buds and leaves are picked early in the spring harvest season. Brewing them according to our suggested brewing guidelines, however, with a lower water temperature, will release less caffeine than a tea you might brew with boiling water.
If you want to read more detailed information about the different factors that affect caffeine content in tea leaves, please read this well researched post from Cha Dao.
Myth #2: Caffeine in Coffee is Stronger than Tea
I’m sure you have noticed how differently caffeine affects your body after drinking tea vs. after drinking coffee.
After drinking coffee, the caffeine effect is often like a surge of energy with a roller coaster like drop off. With tea, however, the sensation is a bit different and more gentle. I often describe the caffeine effect from drinking tea as fade in and fade out of extra alertness.
Why is there a difference?
The Magic Ingredient: L-theanine.
Caffeine is caffeine (C8H10N4O2) no matter where it comes from, some other languages have other words for the caffeine in tea calling it “theanine” but it is still the same substance: caffeine (C8H10N4O2).
The reason caffeine feels so different from tea drinking is its effects are moderated by L-theanine.
In tea, there are two principle psychoactive elements: caffeine and L-theanine.
What is L-theanine and how does it work?
L-theanine is a water soluble amino acid. According to NYU Medical Center, L-theanine is found principally in tea and in mushrooms.
The calming effects of L-theanine counteract the stimulating effects of caffeine and the combination of the two leads to the “fade in, fade out” sensation of heightened alertness I described, as found in this medical study:
L-theanine appears to antagonize the stimulatory effects of caffeine by decreasing serotonin levels that have been artificially elevated by caffeine.
Other studies (all linked to below), have shown that L-theanine promotes alpha waves in the brain which are associated with greater relaxation. Additionally, L- theanine has been studied for its potential ability to reduce stress, improve cognition, and boost mood and cognitive performance in cooperation with caffeine.
Caffeine in a Cup of Coffee vs. a Cup of Tea
I know what you’re thinking right now… ok so just tell me which one has more caffeine? A cup of coffee or a cup of tea?
As discussed above, there are many factors that contribute to caffeine content in any particular tea leaf such as: when the leaf was picked, its growing conditions, and the cultivar and varietal of the plant. This means the caffeine content will vary in each cup of tea you drink.
Similarly, within the world of coffee, the level of caffeine in any particular coffee bean also varies widely based on the type of bean and its growing conditions.
Combined with differences in how you brew your tea or coffee and how that affects the caffeine released into the brew, it is hard to make any definitive statements of comparison.
According to the Mayo Clinic, here are some general rules of thumb when comparing the caffeine content in a cup of coffee vs. a cup of tea:
8 oz. cup of tea: 14-61 mg of caffeine
8 oz. cup of coffee: 95-200 mg of caffeine
The important thing to remember is the main difference in the way caffeine affects your body and mind in coffee and in tea is your friend L-theanine, which is only present in tea.
Links to studies mentioned:
http://www.ncbi.nlm.nih.gov/pubmed/21303262
http://www.ncbi.nlm.nih.gov/pubmed/18006208