Tea & Caffeine

We are very lucky that we are asked a great number of specific questions in our teahouses. One of the most common topics is caffeine.

This blog will look to answer these questions and a few more. Firstly, all true teas (teas made from the Camellia Sinensis plant) contain caffeine. Caffeine is a naturally occurring stimulant that is soluble in water and extracted when brewed. Teas in general have around a third of the caffeine of a similar serving of coffee, although as we will see there are many factors which effect this. Simply put, it is not possible to generalise about caffeine levels in tea. However, there are some factors which allow an informed decision to be made. The best explanations I could find were in an article by tea expert Nigel Melican and in Jane Pettigrew's book 'The New Tea Companion' which you can buy online or at Comins tea houses.  Before getting into the details it useful to understand that caffeine is a methylxanthine, a compound that is used by plants and humans as a pesticide.

This natural insect repellent is produced by the plant to discourage the nibbling of new buds or the damaging of shoots. This helps explain why many of the various factors explored below effect the level of caffeine in your tea.  So lets get into the detail :

Factor 1 THE PLANT :

a. The Variety : The two varieties of Camellia Sinensis (the tea plant) are 'Assamica' and 'Sinensis' meaning 'from Assam' and 'from China' respectively. The Chinese 'Sinensis' has smaller leaves of 5-12cm with bushes growing up to 1m high while the Assam 'Assamica' has larger leaves of up to 20cm with trees growing up to 20 metres.   In general Sinensis plants are lower in caffeine than Assamica ones. So African teas that are mainly Assamica variety are higher in caffeine than Chinese ones. 

Camellia Sinensis bush : Source plantsrescue.com

b. The varietal : Taking this to a smaller scale we can look at the different varietals (or bush varieties) of the tea plant. This also includes the different cultivated variations (cultivars) which have been developed by farmers over time. There are variations in caffeine levels between all these, caused by the plant evolving over time to best suit its environment. This change can also be controlled by the farmer, by his or her propagation of plants and the choosing a certain plant because of a desirable characteristic (increased resistance to insects for example).

c. The Altitude : Another controlling factor is the altitude at which the plant grows. The higher the growing environment the lower the caffeine level, presumably due to the reduced numbers of insects. This variation in insect numbers may also be why growing season is also a factor. The faster growing seasons of spring and summer produce greater levels of caffeine. Fewer insects are present in colder times.

Tea Fields : Taiwan : Source Comins

d. How the plant is grown : The final element concerned with the plant itself is how it is grown in the first place. If it is from clonal vegative propagation (a cutting fixed to root stock) rather than planted as a seedling, caffeine levels can be 100% higher. A real life comparison is between new planting in Africa and old seedling planting in Asia. Eg older leaf, China type seedling bushes, under fertilised in the autumn season = low caffeine levels of 1-1.5%.  This is compared to well fertilised, fast growing young tips African in  clonal plants which yield caffeine levels of 5-6% source Nigel Melican

Factor 2 HUMAN IMPACT :-