Over the last few years, grapefruit has been under scrutiny because of possible side effects. If you’re someone who enjoys having a glass of grapefruit juice with your breakfast, these side effects might give you some cause for concern. The good news is that grapefruit is generally safe to consume for most people, but under certain conditions, it can have adverse effects on your body. This list should give you a clear picture of whether you should be worried at all.
Reacts With Other Drugs
Grapefruit has many health benefits which is why nutritionists recommend having it regularly as part of your diet. However, the notoriety of grapefruits is largely to do with how they react with certain medications. Research has shown that a group of compounds known as furanocoumarins found in grapefruit and few other citrus fruits has a unique effect on a specific enzyme called CYP3A4 in your intestines.
This enzyme controls the amount of drug that’s absorbed into your bloodstream. Furanocoumarins stop this enzyme from working, resulting in the absorption of drugs in higher doses than intended causing an overdose.1 Grapefruit is known to affect blood pressure and cholesterol drugs but the list of drugs has increased over time.
The FDA has listed the following categories of drugs that have been known to interact with grapefruit.2
- Statins: This class of drugs is prescribed by doctors to help prevent strokes and heart attacks by lowering cholesterol levels in the body. Specific statins that react with grapefruit include simvastatin3 and atorvastatin4
- Nifedipine: It is used to treat high blood pressure and angina (chest pain) and having it with grapefruit could result in increased absorption.5
- Cyclosporine: This drug is an immunosuppressant and is usually prescribed to patients who have undergone organ transplant. Research has shown that grapefruit juice inhibits the metabolism of cyclosporine for a brief period after having the drug.6
- Buspirone: It is used to treat symptoms of anxiety, such as fear, tension, irritability, and dizziness. Having grapefruit juice considerably increases buspirone concentrations.7
- Amiodarone: This drug is an antiarrhythmic medication used to treat and prevent several of types of irregular heartbeats. Just a single glass of grapefruit juice has been found to increase the concentration of this drug.8
- Fexofenadine: This drug is an antihistamine used in the treatment of allergy symptoms, such as hay fever, nasal congestion, and urticaria. While grapefruit makes other drugs more potent, in the case of fexofenadine, it decreases the absorption making the drug less effective.9
Since grapefruit interferes with the metabolic process of drug absorption, its side effects are usually limited to drugs taken orally. Also, you might not have to give up grapefruit just yet as it does not react with all the drugs in a given category. If you’re taking drugs that fall under any of the above categories, talk to your doctor about alternatives.
May Increase Risk Of Breast Cancer
There is no direct answer to whether grapefruit, in general, can increase or decrease the probability of developing breast cancer. While a 2007 research paper published in the British Journal of Cancer shows that grapefruit increases the chances of breast cancer in postmenopausal women10, there is also evidence that flavonoids found in grapefruit have anticancer properties and are effective at stopping breast cancer cells from growing and spreading.11 12
Could Increase Probability Of Kidney Stones
The debate is still on about whether grapefruit can cause kidney stones or help reduce the risk. Kidney stones are formed when dissolved minerals form crystals along the inner lining of the kidneys. These crystals are usually made up of calcium oxalate but may also contain other compound deposits.
A 6-year study done on men between the age of 40 and 75 years found that having 8 ounces of grapefruit juice every day increased the risk of kidney stones by about 37%.13 However, a short-term study found that having grapefruit juice regularly helped in flushing out citrates, calcium, and magnesium, thus reducing the risk of stone formation.14
Considering both studies, if you have a history of kidney stones or medical conditions which increase the risk of stone formation, it’s best to have grapefruit in moderation and not make it a part of your daily diet. Medical conditions that increase the probability of kidney stones include15:
- Urinary tract infections
- Renal tubular acidosis
- High Blood Pressure
- Inflammatory Bowel Disease (Crohn’s disease/ulcerative colitis)
Might Trigger Citrus Allergy
Grapefruit belongs to the family of citrus fruits which also include limes, lemons, and oranges. If you are allergic to a particular citrus fruit, it’s highly likely that others too can trigger an allergic reaction. In severe cases, an allergic reaction could cause anaphylaxis, a potentially life‑threatening reaction that requires immediate medical attention. Citrus allergy has been reported to orange, mandarin, and grapefruit, but contrary to the name of the allergy, it’s not caused by citric acid.
Citrus allergy is caused by immune responses to lipid transfer proteins known as profilin and pectin.16 Studies have also shown that there is a connection between allergens in food and those in the air. Allergic reactions to profilin are intensified when exposed to airborne allergens like grass pollen.17 So if you have a history of citrus allergy, it’s recommended that you avoid grapefruit along with other fruits from the citrus family.
Safety Tips To Avoid Side Effects Of Grapefruit
- Talk to your doctor about having fresh grapefruit or grapefruit juice when you’re on medication. In case you cannot, check for other juices that you need to avoid.
- Read through your patient information sheet or medication guide to check if there is a mention of grapefruit in the list of foods to avoid when taking prescription drugs.
- If you’re taking non-prescription drugs, read the Drug Facts label to find out if you are required to avoid grapefruit or other fruit juices.
- If you have been asked to avoid grapefruit by your doctor, check the labels on fruit juice bottles and flavored drinks to ensure they don’t contain grapefruit.
Other Fruits That Have Similar Side Effects
Furanocoumarins, the compound in grapefruit that’s responsible for drug reactions, is also present in few other fruits belonging to the citrus family. If you have been asked to avoid grapefruit, it’s best to also avoid seville oranges (used to make orange marmalade), tangelos (a cross between tangerines and grapefruit), limes, and pomelos.18
Grapefruits are a great food to add to your diet. They are rich in vitamin A and C, potassium, and a host of other beneficial compounds like lycopene (antioxidant) and naringin (flavonoid).19 20 As long as you’re careful about not mixing them with certain types of medications, you don’t really have to worry about the side effects.
|↑1||He, Kan, Krishna R. Iyer, Roger N. Hayes, Michael W. Sinz, Thomas F. Woolf, and Paul F. Hollenberg. “Inactivation of cytochrome P450 3A4 by bergamottin, a component of grapefruit juice.” Chemical research in toxicology 11, no. 4 (1998): 252-259.|
|↑2||Grapefruit Juice and Medicine May Not Mix. FDA.|
|↑3||Lilja, Jari J., Kari T. Kivistö, and Pertti J. Neuvonen. “Grapefruit juice—simvastatin interaction: Effect on serum concentrations of simvastatin, simvastatin acid, and HMG‐CoA reductase inhibitors.” Clinical Pharmacology & Therapeutics 64, no. 5 (1998): 477-483.|
|↑4||Ando, Hitoshi, Shuichi Tsuruoka, Hayato Yanagihara, Koh‐ichi Sugimoto, Masaaki Miyata, Yasushi Yamazoe, Toshinari Takamura, Shuichi Kaneko, and Akio Fujimura. “Effects of grapefruit juice on the pharmacokinetics of pitavastatin and atorvastatin.” British journal of clinical pharmacology 60, no. 5 (2005): 494-497.|
|↑5||Mohri, Kiminori, and Yoshihiro Uesawa. “Effects of furanocoumarin derivatives in grapefruit juice on nifedipine pharmacokinetics in rats.” Pharmaceutical research 18, no. 2 (2001): 177-182.|
|↑6||Hollander, Adrianus AMJ, Jeroen Rooij, Eef GWM Lentjes, Francis Arbouw, Joost B. Bree, Rik C. Schoemaker, Leendert A. Es, Fokko J. Woude, and Adam F. Cohen. “The effect of grapefruit juice on cyclosporine and prednisone metabolism in transplant patients.” Clinical Pharmacology & Therapeutics 57, no. 3 (1995): 318-324.|
|↑7||Lilja, Jari J., Kari T. Kivistö, Janne T. Backman, Tommi S. Lamberg, and Pertti J. Neuvonen. “Grapefruit juice substantially increases plasma concentrations of buspirone.” Clinical Pharmacology & Therapeutics 64, no. 6 (1998): 655-660.|
|↑8||Libersa, Christian C., Serge A. Brique, Kokou B. Motte, Jacques F. Caron, Laurence M. Guédon‐moreau, Luc Humbert, A. Vincent, Patrick Devos, and Michel A. Lhermitte. “Dramatic inhibition of amiodarone metabolism induced by grapefruit juice.” British journal of clinical pharmacology 49, no. 4 (2000): 373-378.|
|↑9||Dresser, George K., Richard B. Kim, and David G. Bailey. “Effect of grapefruit juice volume on the reduction of fexofenadine bioavailability: possible role of organic anion transporting polypeptides.” Clinical pharmacology & therapeutics 77, no. 3 (2005): 170-177.|
|↑10||Monroe, K. R., S. P. Murphy, L. N. Kolonel, and M. C. Pike. “Prospective study of grapefruit intake and risk of breast cancer in postmenopausal women: the Multiethnic Cohort Study.” British journal of cancer 97, no. 3 (2007): 440-445.|
|↑11||Harmon, Anne W., and Yashomati M. Patel. “Naringenin inhibits glucose uptake in MCF-7 breast cancer cells: a mechanism for impaired cellular proliferation.” Breast cancer research and treatment 85, no. 2 (2004): 103-110.|
|↑12||So, Felicia V., Najla Guthrie, Ann F. Chambers, Madeleine Moussa, and Kenneth K. Carroll. “Inhibition of human breast cancer cell proliferation and delay of mammary tumorigenesis by flavonoids and citrus juices.” (1996): 167-181.|
|↑13||Curhan, Gary C., Walter C. Willett, Eric B. Rimm, Donna Spiegelman, and Meir J. Stampfer. “Prospective study of beverage use and the risk of kidney stones.” American Journal of Epidemiology 143, no. 3 (1996): 240-247.|
|↑14||Trinchieri, A., R. Lizzano, P. Bernardini, M. Nicola, F. Pozzoni, A-L. Romano, M. P. Serrago, and S. Confalonieri. “Effect of acute load of grapefruit juice on urinary excretion of citrate and urinary risk factors for renal stone formation.” Digestive and Liver Disease 34 (2002): S160-S163.|
|↑15||Medical Conditions. Kidney Stones. The University of Maryland Medical Center.|
|↑16||Citric Acid and Citrus Allergy. The American Academy of Allergy, Asthma & Immunology.|
|↑17||Alvarado, M. I., L. Jimeno, F. De La Torre, P. Boissy, B. Rivas, M. J. Lazaro, and D. Barber. “Profilin as a severe food allergen in allergic patients overexposed to grass pollen.” Allergy 69, no. 12 (2014): 1610-1616.|
|↑18||Boullata, Joseph I. , Armenti, Vincent T. Handbook of Drug-nutrient Interactions. Humana Press. 2004.|
|↑19||Wilson, T., Temple, Norman J. Beverages in Nutrition and Health. Humana Press. 2004.|
|↑20||Grapefruit, raw, pink and red, Florida. National Nutrient Database for Standard Reference. USDA.|