If you take calcium channel blockers to treat high blood pressure, consult your doctor or pharmacist before consuming any grapefruit. Grapefruit can elevate the levels of calcium channel blocker medication in your bloodstream, which can lead to dangerous side effects. Grapefruit also reacts adversely with some other medications used to treat heart-related conditions.
Calcium Channel Blockers
Doctors may prescribe a calcium channel blocker to treat hypertension -- high blood pressure. Calcium channel blockers block calcium from getting into your blood vessels and heart. The blocking of calcium from your heart and blood vessels works to reduce your blood pressure. Calcium channel blockers known to react adversely with grapefruit include felodipine and nifedipine. The reason for the adverse reaction is that grapefruit stops your body's CYP34A enzyme from metabolizing the medication. This means that more medication gets into your bloodstream, increasing the likelihood and severity of side effects.
Blood Pressure, Cholesterol and Statins
High blood pressure can cause high cholesterol. This is because high blood pressure can stretch or tear your arteries. Your body will typically heal itself and repair the damage, but scar tissue will form. The problem with this is that unhealthy low-density lipoprotein cholesterol, as well as triglycerides, another type of harmful lipid, can get caught in your scar tissue, causing blockages in your arteries. The buildup of cholesterol and fat in your arteries can further elevate high blood pressure. A doctor may prescribe statins to lower low-density lipoprotein -- LDL or "bad" cholesterol. If you take statins, you should not include grapefruit in your diet.
Blood Pressure and Grapefruit Benefits
Shela Gorinstein, a researcher from the Hebrew University of Jeruselem, conducted a study that pointed to benefits for cholesterol and blood pressure from eating grapefruit. The study, published in the "Journal of Agriculture and Food Chemistry" in 2006, tested the effects of white and red grapefruit consumption on 57 men and women with high blood pressure. Participants who ate grapefruit realized benefits to their triglyceride and blood pressure levels. Red grapefruit proved especially effective. So, eating grapefruit could benefit your heart health but only if you do not take calcium channel blockers or statins.
Other Drug Interactions
Grapefruit can cause serious side effects when mixed with many other medications.You should not combine grapefruit with birth control pills, for instance, because the fruit can elevate the estrogen levels in a woman's blood to a dangerous extreme, possibly leading to gangrene, heart attack or stroke. Grapefruit also becomes dangerous if consumed with certain antidepressants, anti-anxiety medications and other psychiatric drugs. Immunosuppresants, prescribed to prevent organ transplant rejection, react adversely with grapefruit. The list of drugs that react poorly with grapefruit is long -- and may grow -- so do not take grapefruit with any medication without consulting a trusted health-care professional.
References
- The Harvard Medical School Family Health Guide: Grapefruit and Medication: A Cautionary Note; Feb. 2006
- MayoClinic.com: Calcium Channel Blockers; Dec 16 2010
- "The New York Times"; Experts Reveal the Secret Powers of Grapefruit Juice; Nicholas Bakalar; March 21 2006
- American Heart Association: About High Blood Pressure
- "The Evening Standard"; Have a Heart, Have a Red Grapefruit; Mark Prigg; Feb. 9 2006
- ACS Publications: Journal of Agriculture and Food Chemistry: Red Grapefruit Positively Influences Serum Triglyceride Level in Patients Suffering from Coronary Atherosclerosis: Studies in Vitro and in Human; Shela Gorinstein et al; Feb 3 2006
