This is Why Grapefruit Juice Can Harm You

Grapefruit juice is delicious and healthy. But it can affect one of your body’s enzymes – with pretty bad consequences.

Grapefruit, pomelo and pomelos are healthy and provide a lot of vitamin C. But if you take certain medications, you have to be extremely careful with such citrus fruits, explains Robert Hermann, specialist in clinical pharmacology.

Among other things, remedies for headaches, hay fever or allergies are affected. Grapefruits can significantly increase the drug’s active ingredient. The reason: the body’s own enzyme CYP3A4, which is mainly found in the liver and in the intestinal wall and is responsible for breaking down many drugs, is inhibited. It normally breaks down the active ingredients in medicines there.

Possible consequence: overdose

Of 100 percent of the active ingredients, often only 20-30 percent arrive. Such drugs have poor bioavailability. This degradation is taken into account when dosing medication. However, if this enzyme is inhibited by grapefruit juice, for example , larger amounts of the drug enter the body. The bioavailability is then up to five times higher.

The result: an overdose. With certain diseases and with certain medications, this can be life-threatening. Just one glass of grapefruit juice is enough to inhibit the enzyme for about three days.