By: Carlos Alaniz, CSUN Dietetic Intern Cohort 2021-2023
The fourth-most often cultivated citrus species in the world is grapefruit; with oranges, tangerines, and lemons being the first three in that order.1 The grapefruit, which is a cross between a sweet orange and a pomelo, is remarkable for the variety of nutrients it has to offer.2 Although grapefruits have therapeutic benefits due to their high nutritional content, they also contain certain components that may interact negatively with medications.
Grapefruits’ Health Benefits & Forms
The citrus fruit is desirable due to its high nutritional content.3 Grapefruits are high in vitamin C, dietary fiber, and minerals.2 Not only are they rich in vitamins and minerals, but also contains a great number of bioactive phytochemicals, including flavonoids, carotenoids, coumarins, and organic acids, making the fruit notable for its anti-oxidative, anti-inflammatory, and neuroprotective properties.2
Grapefruits are an excellent food source. A single serving of this fruit contains 100% of the Recommended Daily Allowance of vitamin C!4 Due to the grapefruit’s capacity to offer nutritional advantages, the fruit is processed into a variety of dietary supplements. The grapefruit’s pectin, fruit juice, and oils—all rich in vitamins and bioactive compounds—are used to produce grapefruit supplements. Grapefruit and its seeds can be freeze dried and processed into a powder to create supplements in the forms of capsules or tablets. Fruit extracts in liquid form are another popular and useful choice.
The Interaction Between Grapefruit and Drugs
Grapefruit’s bioactive phytochemicals have been demonstrated to have a variety of health-promoting qualities like anti-inflammation and anti-oxidation, but certain components have also been linked to negative side effects when combined with other drugs.2 Furanocoumarins and flavanones are the main active components in grapefruit that are responsible for medication interactions. When an interaction between grapefruit and medication occurs, it is due to furanocoumarins and flavonoids inhibiting the enzyme cytochrome P450, an enzyme responsible for the metabolism of drugs in the liver.4 When this happens, the metabolism is slowed down therefore increasing the action of drugs.
A dosage of about 200 to 250 mL of whole grapefruit or grapefruit juice is enough to produce a significant pharmacokinetic interaction.5 Because there are so many drugs that interact with the fruit, it is recommended to avoid consuming grapefruit when taking medication. If you happen to forget and consume grapefruit, wait at least 2 to 3 hours before taking your medications to avoid interactions.6 One of the most well-known drug-nutrient interactions is the one between grapefruit and antilipidemic medications such as statins, a type of medication that lowers cholesterol. For instance, if taking the medication Atorvastatin, it is important to restrict grapefruit juice for at least 2 hours before taking this medication.7 When an interaction occurs between Atorvastatin and grapefruit juice, research has shown an increase of liver and muscle damage due to the increased concentration of the drug in the blood.7 The following are other types of drugs that have been found to interact with grapefruit 8:
- Nifedipine, a drug used to treat high blood pressure.
- Buspirone, an anti-anxiety drug.
- Budesonide, corticosteroids that are used to treat Crohn’s disease or ulcerative colitis.
- Amiodarone, a drug used to treat abnormal heart rhythms.
- Fexofenadine, an antihistamine drug used to alleviate allergy symptoms
It is important to note that the extent of a reaction between grapefruit and a drug is dependent upon the amount of fruit consumed, time between drinking or eating the fruit and consumption of the medication, as well as the anthropometric characteristics of an individual.7
Considerations
Taking into account the nutrient-drug interactions associated with grapefruit consumption, it is worth considering whether the fruit’s juice should be on the menu in nursing homes and acute care facilities, where many patients are prescribed multiple medications. Grapefruit juice is a popular drink of choice in nursing homes. Due to this, eliminating this drink from menu selections may help avoid potential nutrient drug interactions that can cause harm.6 Providing juice only when a resident is cleared to consume it is another way to avoid intoxication from medications.6 If you know older adults or other individuals that take multiple medications, you might want to inform them of the grapefruit interaction.
Taking Precaution
Although many medications have an interaction with grapefruit, some may not cause an effect. If you are taking medications, how would you know if you must take certain precautions? Usually, medications that have an interaction with grapefruit have a label contraindicating consumption of the fruit. Below is the label typically used on medication:
If you have any questions or concerns regarding the consumption of grapefruit or grapefruit supplements, consult a Registered Dietitian Nutritionist for further information. If you have specific questions regarding the interaction between grapefruit and a certain medication, contact your primary care physician.
Contact the CSUN Marilyn Magaram Center at magaram.center@csun.edu or call (818) 677-3102 for any questions regarding how you can meet with a Registered Dietitian Nutritionist.
References
- Citrus | FAO | Food and Agriculture Organization of the United Nations. www.fao.org. https://www.fao.org/markets-and-trade/commodities/citrus/en/
- Hung W-L, Suh JH, Wang Y. Chemistry and health effects of furanocoumarins in grapefruit. Journal of Food and Drug Analysis. 2017;25(1):71-83. doi:10.1016/j.jfda.2016.11.008
- Sharma R, Dubey A, Awasthi O, Kaur C. Growth, yield, fruit quality and leaf nutrient status of grapefruit ( Citrus paradisi Macf.): Variation from rootstocks. Scientia Horticulturae. 2016;210:41-48. doi:10.1016/j.scienta.2016.07.013
- National Institutes of Health. Grapefruit. National Library of Medicine. 2021 https://medlineplus.gov/druginfo/natural/946.html
- Bailey DG, Dresser G, Arnold JMO. Grapefruit–medication interactions: Forbidden fruit or avoidable consequences? Canadian Medical Association Journal. 2013;185(4):309-316. doi:10.1503/cmaj.120951
- McCabe, B. J., Frankel, E. H.,Wolfe, J. J. Handbook of Food-Drug Interactions. CRC Press. 2005
- Chen M, Zhou S- yi, Fabriaga E, Zhang P- hong, Zhou Q. Food-drug interactions precipitated by fruit juices other than grapefruit juice: An update review. Journal of Food and Drug Analysis. 2018;26(2). doi:10.1016/j.jfda.2018.01.009
- FDA. Grapefruit Juice and Some Drugs Don’t Mix. U.S. Food and Drug Administration. Published 2019. https://www.fda.gov/consumers/consumer-updates/grapefruit-juice-and-some-drugs-dont-mix