CAN A GRAPEFRUIT KILL ME?

World of Knowledge (Australia) - - Human Body -

In Aus­tralia, thou­sands of medicines are li­censed for use: around half of us are now reg­u­larly swal­low­ing pre­scrip­tion drugs. To treat some­thing as mun­dane as a com­mon cold, you can now get hold of half a dozen drugs over the counter that can be ad­min­is­tered at home. The prob­lem: it doesn’t mat­ter how harm­less an ac­tive in­gre­di­ent is – when it in­ter­acts with an­other sub­stance, a chem­i­cal re­ac­tion takes place. And the ef­fects of this in­ter­ac­tion can be se­ri­ous: drugs change their com­po­si­tion, can­cel each other out, have the op­po­site of their de­sired ef­fect or even in­crease in strength so much that they be­come poi­sonous. It’s a risky Rus­sian roulette that doc­tors have been warning about for years – par­tic­u­larly in the case of self-pre­scribed treat­ments. What they fail to men­tion so of­ten is that drugs don’t just re­act with other medicines – but with any­thing that has a chem­i­cal ef­fect on the body. And that in­cludes food.

A typ­i­cal day at a GP’S surgery shows the ex­tent to which doc­tors are ig­nor­ing this risk. As a rule, pre­scrib­ing physi­cians won’t usu­ally ask about a pa­tient’s eat­ing habits even though the in­flu­ence of foods on the me­tab­o­lism – the body’s own chem­istry set – is in­dis­putable. It’s a sim­i­lar sit­u­a­tion with stan­dard­ised pa­tient forms. These will nor­mally only ask about pre­vi­ous ill­nesses, med­i­ca­tions or preg­nancy. But what about food? No chance – even though doc­tors know that some­thing as ubiq­ui­tous as fruit can quickly be­come danger­ous. For ex­am­ple, fu­ra­nocoumarin, found in citrus fruits like grapefruit, has a sig­nif­i­cant ef­fect on the break­down of medicines in the hu­man body. This can quickly turn a harm­less dose into a deadly one. This drug in­ter­ac­tion has claimed lives: in the 1990s a 29-year-old Amer­i­can died af­ter tak­ing hayfever med­i­ca­tion while also drink­ing a few glasses of grapefruit juice a week. The amount of the drug in his blood in­creased 30-fold, caus­ing cir­cu­la­tory col­lapse.

Beer, salami or ma­ture cheese can be sim­i­larly danger­ous. As these foods age, they build up large amounts of the sub­stance tyra­mine, which can raise blood pres­sure. If you are also tak­ing mon­amine ox­i­dase in­hibitors for anx­i­ety or de­pres­sion, the break­down of tyra­mine will be af­fected. The con­se­quences: headaches and dan­ger­ously high blood pres­sure. An­other ex­am­ple af­fects the

2.3 mil­lion Aus­tralians with asthma. That’s be­cause some asthma drugs con­tain theo­phylline. If that comes into con­tact with black pep­per, the medicine re­acts with piper­ine – a nat­u­rally oc­cur­ring com­pound in pep­per – and the level of theo­phylline in the blood in­creases. Pos­si­ble symp­toms in­clude heart­burn, anx­i­ety and an ir­reg­u­lar heart­beat.

“Ad­verse re­ac­tions to medicines are im­pli­cated in up to 6.5% of hospi­tal ad­mis­sions.” DR MARTIN DUERDEN, BANGOR UNI­VER­SITY

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