The patient assumed that there was a relation between his symptoms and his tea consumption, and stopped drinking Earl Grey after 5 months, reverting to pure black tea again. Within 1 week, his symptoms had completely disappeared. Symptoms also remained absent if he completely withdrew from tea, which he did in the nature of experiment, for about a week. He found that his symptoms did not recur as long as he consumed no more than 1 L of Earl Grey daily.

and the conclusion:

Tea is regarded a delicious, aromatic stimulant worldwide. However, even tea may lead to health problems if flavoured and consumed in extraordinarily high quantities. Bergamot essence in Earl Grey tea, when consumed in excess, may induce muscle cramps, fasciculations, paraesthesias and blurred vision.