Sir, - As a medical student in his final year, your correspondent Mr Kirwan (November 1st) surely appreciates the rigorous demands of evidence-based medicine. Yet he cites an Irish Medical Times editorial rather than a bona-fide medical article as the basis of his assertion that Hypericum perforatum (St John's Wort) inhibits the enzyme monamine oxidase (MAO) thereby raising adrenaline and noradrenaline levels to the point that someone taking St John's Wort may be at risk from eating a cheese sandwich or drinking a glass of red wine.
Published research - e.g. Bladt and Wagner, 1994: "Inhibition of MAO by Fractions and Constituents of Hypericum Extract", J. Ger. Physch. Nerolol.7 (suppl 1:S 57.9) - clearly makes the point that the clinically proven anti-depressive effect of Hypericum extract cannot be explained in terms of MAO inhibition.
Hypericum perforatum has been in use as an effective herbal medicine for at least 1,000 years. Its safety in therapeutic doses was recently borne out by the finding that, in 15 clinical trials involving over 1,000 patients suffering from depressive illness, those taking a placebo recorded a higher percentage of side-effects than those taking Hypericum (Bloomfield, H. Hypericum and Depression, Prelude 1996). - Yours, etc.,
Michael McIntyre, Chairman, European Herbal Practitioners' Association, Nether Westcote, Kingham, Oxfordshire, England.