Interesting story about tea recently:
A 44-year-old man presented in May, 2001, with muscle cramps. He had recently switched to drinking Earl Grey tea in preference to his regular black tea.I should add he was drinking four litres (a gallon, say) a day.
One week after the change, he noticed repeated muscle cramps for some seconds in his right foot. The longer he drank Earl Grey tea, the more intense the muscle cramps became. After 3 weeks, they also occurred in the left foot...
Earl Grey tea is composed of black tea and the essence of bergamot oil, an extract from the rind of bergamot orange (Citrus aurantium ssp bergamia), which has a pleasant, refreshing scent.
(You can skip this paragraph, if you wish) The adverse effects of bergamot oil in this patient are explained by the effect of bergapten as a largely selective axolemmal potassium channel blocker, reducing potassium permeability at the nodes of Ranvier in a time-dependent manner. This may lead to hyperexcitability of the axonal membrane and phasic alterations of potassium currents, causing fasciculations and muscle cramps.
In other words, it disrupts the way chemicals flow through the membrane of the nerve fibres, causing the neurons that connect to the muscles to malfunction.
But it plays into my constant refrain: too much of anything is bad for you.
Food-wise, at least.