Simvastatin and grapefruit: Are they compatible?

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You recently tried to answer a question about grapefruit and simvastatin, but in my opinion you evaded the question. The questioner asked whether half a grapefruit each morning can cause a problem, but you only offered the same old response about a glass of grapefruit juice being potentially harmful. The manufacturers of simvastatin feel obliged to warn against this. Please address yourself to the question: can half a grapefruit each morning cause problems for someone who is taking simvastatin?

To answer this question properly, I bought a medium-sized (300g) grapefruit. I squeezed all the juice out of half of it, producing 70ml of juice. The original research into grapefruit juice and simvastatin looked at the effect of 200ml of grapefruit juice. The juice from half a grapefruit is about one-third of this amount. Even this amount will cause some people problems. The effect of each dose of grapefruit juice lasts for several days, so if you have half a grapefruit every morning the effect accumulates. My advice is to stick to oranges and orange juice if you are taking statins.

Please send your questions and suggestions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182 or email to health@independent.co.uk. Dr Kavalier regrets that he is unable to respond personally to questions.