When the doctor prescribes a medicine, he usually informs about the timing of the takings, whether it should be administered with meals or on an empty stomach … but he rarely refers to foods with which it can or cannot be combined. And it is that, as explained by María del Carmen Lozano Estevan, member of Food and Nutrition of the Official College of Pharmacists of Madrid (COFM) and head of Pharmacy studies at the Alfonso X el Sabio University, in Madrid, “ food and drugs are destined to undergo interactions ”. This mutual relationship can occur in two directions: that the drugs modify the normal absorption of nutrients or that the foods alter the effectiveness of the drugs.
In the first case, as the expert points out, the prescribed treatment can even cause a deficiency of vitamins or minerals. This occurs, for example, with isoniazid – a drug normally indicated to treat tuberculosis – which, in prolonged use, lowers vitamin B6 levels.
In the second case, it is food that affects the effectiveness of therapeutic substances. “The effect may be greater, less, or appear later than expected,” says Lozano Estevan. A good example is the mixture of drugs, such as benzodiazepines and statins – for example, diazepam – with grapefruit, a citrus fruit that reduces the liver’s ability to eliminate the medicine, and consequently increases its action or toxicity. Other drugs that interact with the aforementioned fruit are antihypertensives, calcium channel blockers, antihistamines and immunosuppressants. Sometimes, according to the COFM’s Food and Nutrition Board, “the pharmacological response and the nutritional value of the food may be affected at the same time, as occurs, for example, with the joint intake of tetracyclines –a group of antibiotics– and dairy products”. In this case, the absorption of both calcium and the drug will be less than expected.
And what drinks pair best with medicines?
The expert assures that, although there are no general guidelines and each case must be assessed, “as a general rule, the joint taking of drugs with milk, tea, coffee and fiber and mineral supplements should be avoided.” For example, acidic fluids break down antibiotics before they reach the stomach. Although not all interactions are negative : “iron absorption is increased by the presence of foods rich in vitamin C,” says Lozano Estevan.
At the right time
We must not only look at what the drugs are taken with, but when they are ingested. ” When administering a drug orally, it is important to know whether it should be done with meals (at the beginning, during or at the end) or on an empty stomach (an hour before ingestion or two after), ” says Lozano Estevan. And it is that, often, mixing the medicines with the meals can diminish the therapeutic action; while on other occasions, ingesting them on an empty stomach can injure the stomach or lessen the effect, as Lozano Estevan recalls. When in doubt, always pay attention to the information in the advertisements and consult with the pharmacist.
By Marta Riesgo
