Contrary to popular belief, green tea caffeine content can be higher than black tea. It really depends on the kind of green tea you are drinking.

Oxidation doesn't increase caffeine content. In fact, some studies have found that the longer tea oxidises, the lower the caffeine content.

Colour is a poor guide to the amount of caffeine tea contains. The finest Japanese green tea - Gyokuro - contains more caffeine than the black Lapsang Souchong.

So what influences green tea caffeine content?

Plant Variety

Camellia sinensis has two sub varieties: the Chinese sinensis and the Indian Assamica.

The Chinese green tea is a slow growing shrub that produces small, narrow leaves. Usually cultivated from seeds, it has less caffeine, ranging from 1% to 3% in dry weight.

The Indian black tea is a quick growing tree that yields large, broad leaves. Usually cultivated using the vegetable propagation method, it contains more caffeine, ranging from 3% to 5% in dry weight.

It is the plant variety, not oxidation, that causes black tea to have roughly the twice the caffeine as green tea.

But not all parts of the tea plant have the same amount of caffeine.

Leaf Style

Many high grade green teas are made from the bud and its adjacent two leaves. These tender shoots are the sweetest, tastiest and healthiest.

They are the richest in catechins, which contains all the antioxidants, and the sweet and fresh tasting theanine, which calms and soothes the mind. Unfortunately, they also contain the most caffeine.

The younger the leaf, the more caffeine it contains. According to Upton Tea, the bud and first leaf contain 5% caffeine in dry weight, the second leaf 3.5%, the upper stem 2.5% and lower stem 1.4%.

It is no coincidence that the finest green tea from China (Longjing or Dragon Well) and Japan (Gyokuro) have one of the highest caffeine content.

Teabags have less green tea caffeine content, and a poorer favor to match.

Black tea is made from larger, more mature leaves. This means that a high grade loose-leaf green can have as much caffeine as black tea, sometimes even more.

Growing and Making Conditions

Now we are in the realm of uncertainty.

The local growing conditions can influence the green tea caffeine content. An often quoted example is the Japanese Gyokuro, which is shaded away from sun to preserve its theanine and caffeine content.

Other less obvious contributing factors are soil, climate and when the tea is harvested. Processing method, such as withering and oxidation also play a part. The longer the leaves are left to wither, the higher the caffeine. But the longer they are left to oxidise, the lower the caffeine.

Now you see why depending on who you ask, green tea caffeine content can vary from 8 to 75 milligrams a cup?

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Julian Tai writes regularly for, an info-site dedicated to providing unbiased and accurate information to the art and science of tea drinking.

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