The late Tony Benn was renowned for his love of tea. Apparently he once spent a train journey calculating just how much he had drunk over his life; the Labour politician discovered he had drunk enough to float the QE2 .

Imbibing from huge mugs, Benn claimed he was drinking one pint of tea every hour.

His tea habit reportedly landed him in hospital some 20 years or so ago, with a suggestion that a polyneuritis (inflammation involving a number of nerves) diagnosed at the time may have been induced by his prodigious intake.

I’m fond of more than a drop myself – not the thick sugary brew of the building site but rather a well-diluted cup of Earl Grey, lightly milked.

But even this refined variety, replete with a hint of bergamot, has been linked to side effects. Writing in The Lancet , an Austrian doctor described the case of a 44-year-old man who suffered muscle cramps.



Four litres a day

He had been drinking four litres of black tea every day over the past 25 years. However, one week after changing to Earl Grey, he noticed repeated muscle cramps in his right foot.

After five weeks the cramps had spread to his left foot, both hands and his left calf. The patient also developed pins and needles in all four limbs and occasionally he noticed involuntary movements in the muscles of his thumb and calf.

All tests were normal, leaving the doctor stumped. Convinced that it was the change of tea, the patient decided to stop drinking Earl Grey and reverted to pure black tea again. One week later, his symptoms had completely disappeared.

The culprit, it later emerged, was the bergamot oil which contains the psoralen derivative bergapten.

The adverse effects of bergamot oil in this patient are explained by the action of bergapten as a potassium channel blocker within muscle cells.

By interrupting the normal flow of potassium, the cells become hyper-

excitable, leading to the visible movements and cramps within the muscles.

Drinking the equivalent of at least 16 cups of tea a day, the Austrian man had been overdosing on essence of bergamot.

Earl Grey and bergamot were in the news again last week. This time it was for a health benefit, albeit one rather overhyped in reports in the Daily Mail and Daily Telegraph .

Headlines proclaiming “A cup of Earl Grey as good as statins at fighting heart disease” were guilty of overstating the science behind the report.

Statins are powerful cholesterol- lowering drugs so, clearly, had the headlines been true, it would have been a breakthrough of some magnitude.



Rats with high cholesterol

The research involved an extract called HGMF, taken from the bergamot fruit. Rats with high cholesterol levels were fed a high-cholesterol diet for three weeks and given either the bergamot extract (HMGF) or the drug simvastatin.

The Italian researchers found that HMGF had cholesterol-lowering effects similar to that of simvastatin. But only 48 rats were tested. And while laboratory animals are frequently used in early stage research, rats are not humans.

So it is not possible to say that HMGF would work the same way in humans.

Furthermore, this study tested a pure extract rather than tea containing the extract, the effects of which may be different.

So reportage suggesting Earl Grey was “as good as” statins at lowering cholesterol is simply untrue.

It could have provoked some readers, already at high risk of having a heart attack or stroke, to abandon their drugs and replace them with Earl Grey – even though neither this nor any other kind of tea was mentioned in the original scientific paper.

Hopefully, no harm was done and (ahem) it was all a storm in a tea cup. And don’t give up on your favourite cuppa.

As another even more famous British politician, William Gladstone, said of tea: “If you are depressed, it will cheer you; if you are excited, it will calm you.”



mhouston@irishtimes.com

muirishouston.com