Fresh-squeezed grapefruit juice is a nutritious and relatively low-calorie beverage that promotes health in most people. However, if you have a kidney disease or take prescription medications, you should be cautious with grapefruit juice and probably avoid it in favor of other beverages. Grapefruit juice interacts with some medications in ways that can trigger kidney damage. Consult your doctor about foods and beverages that may interact with your medications.
About 20 percent of Americans drink grapefruit juice on a regular basis, especially during breakfast. Grapefruit juice is an excellent source of citric acid, vitamin C and dietary fiber, as well as a good source of potassium and other trace minerals. It’s significantly lower in sugar than most other fresh juices such as orange and grape juice. In addition to nutrients, grapefruit also contains a variety of compounds that directly or indirectly affect how medications are absorbed and metabolized in your body.
Grapefruit and Medications
The main compounds in grapefruit juice that affect medications are called furanocoumarins, although some flavonoids such as naringin also interact with drug metabolism. Furanocoumarins block some enzymes in your small intestine, which causes destruction of some pharmaceuticals and prevents their absorption. They also block enzymes needed to fully metabolize certain pharmaceuticals so that they can be removed from your body, which increases the risk of toxic side effects in the kidneys and liver. Your kidneys and liver are most susceptible to damage because they are responsible for filtering metabolites, or end-products of metabolism, out of your blood. If the end-products of drug metabolism are not fully broken down, they get stuck in the filtering organs and cause damage and dysfunction. Many medications are affected by furanocoumarins in grapefruit juice, but the ones most likely to cause serious complications include cholesterol-reducing statin drugs, beta-blockers for hypertension, psychiatric drugs for depression, erectile dysfunction drugs and some antihistamines and immune system suppressants.
Potassium and Kidney Damage
Potassium is an essential mineral that acts as an electrolyte in your body, which means it conducts electricity when it is dissolved in water. Electrolytes are important for nerve communication and the movement and distribution of fluids in your body. However, a buildup of too much potassium is dangerous for your heart and other muscles. Your kidneys are responsible for regulating potassium levels, so if you currently have kidney disease, watch your dietary consumption of potassium. Grapefruit juice is relatively high in potassium, containing about 400 milligrams per cup, so people with chronic kidney failure are usually told by their doctors to avoid it and other high-potassium or high-sodium juices and foods.
Potential Kidney Benefits
Grapefruit juice may help dissolve and prevent the recurrence of certain types of kidney stones made of calcium oxalate. It may also help to reduce blood cholesterol levels, repair damaged tissue, reduce the effects of free radicals, stimulated the production of liver enzymes and boost immunity, which could all be beneficial for kidney health in different ways. The main issues are whether serious kidney damage already exists or if grapefruit juice is being consumed with certain medications.
- Contemporary Nutrition: Functional Approach; Gordon M. Wardlaw et al.
- Encyclopedia of Human Nutrition; Benjamin Caballero et al.
- The Nutribase Complete Book of Food Counts; Art Ulene
- Natural Standard Herb & Supplement Reference: Evidence-based Clinical Reviews; Catherine E. Ulbricht and Ethan M. Basch
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.