Does black tea have the highest level of caffeine? If so, why


It's said that tea, in general, has lower levels of caffeine than coffee, and that black tea has more caffeine than green tea (which has more caffeine than white tea).

This suggests that the higher degree of fermentation of the tea, the higher the caffeine level. Is that correct? Does fermentation concentrate caffeine?

How is it that these teas, all coming from the same plant, have different levels of caffeine?

Best Answer

Rate Tea tells us this is a myth:

Many tea companies, and even some reputable entities such as the U.S. Department of Agriculture, have made misleading generalizations about the caffeine content of broad classes of tea. It is a widespread myth that black tea contains more caffeine than green tea, and another myth that white tea contains the least caffeine of all teas.

They indicate that brewing method is the main determiner of caffeine levels in the brewed tea.

The source article goes on to cite various credible scientific sources, which raise the credibility of this assertion. Unfortunately, most of their links have gone bad, which makes it harder to check the background science.

This caffeine level table from Mayo Clinic does indicate slightly different levels, but that is likely to be a result of different brewing details across tea types rather than fundamental to the tea plant itself.