The Danger of Grapefruit and what is a natural food?

In the past I have been a member of the American Association for Clinical Chemistry but have let my membership lapse. However, they keep sending me interesting items over the internet including a presentation on drug interactions caused by activity modifications of P450 cytochrome enzymes. These enzymes function to help remove chemicals that could be harmful to the body by oxidizing them. We have a number of these enzymes with somewhat different specificities and considerable genetic variation. Certain compounds can increase or decrease the activity of these enzymes and cause problems in drug therapy. The dose of a drug is selected based on the “normal” levels of activity of the P450 enzymes. If the activity of these enzymes are altered, then there could be more of less of the drug available resulting toxicity due to high levels or under treatment due to low levels.

This phenomenon is one of the reasons that doctors continually as you what drugs you are taking. It turns out that there are flavonoids in grapefruit juice that can down regulate the cytochrome P450 3A4 causing certain drug concentrations to be elevated to the point of toxicity. Lipitor is one such drug.

Today at breakfast a friend said that his doctor told him that since he took Lipitor before going to bed that the effect of drinking grapefruit juice in the morning would not be problematic as the Lipitor levels would be low at that time anyway. This suggestion sound reasonable but one should check with one’s physician before following this advice. I don’t like the stuff anyway so avoiding it is fine with me. However, other “natural foods” also have compounds that can affect this system so one should be careful. From the genetic point of view, there is very little even in a natural foods store that is natural. Growers have engineered most foods we eat through selection over the centuries so that our foodstuffs are some distance from their “natural” origins.

http://www.holistic-online.com/Herbal-Med/_Herbs/grapefruit-interactions-what-is-present-in-grapefruit.htm

http://gcrc.med.unc.edu/investigators/diet/diet_cyp450.html