Is grapefruit poisonous? The love-hate relationship between grapefruit and drugs

This is the 3656th article of Da Yi Xiao Hu

Is grapefruit poisonous?

Yes!

Although grapefruit is delicious, it can have toxic side effects on the human body if eaten improperly. Grapefruit is also known as grapefruit. Many people love to eat delicious and juicy grapefruit. Drinking a glass of grapefruit juice every day can keep blood vessels healthy and help people stay away from cardiovascular diseases. This is mainly because grapefruit and other citrus fruits are rich in flavonoids, which are beneficial to cardiovascular health. However, grapefruit cannot be eaten when taking certain medications, otherwise serious adverse consequences will occur. Grapefruit contains chemical ingredients such as naringin, furanocoumarins and flavonoid compounds such as citrus naringenin. These ingredients will inhibit the drug metabolizing enzyme CYP3A4 in the human body, making the ingested drugs stay in the body for a longer time, resulting in an increase in the drug concentration in the blood. The half-life of the above ingredients in grapefruit juice is about 12 hours, that is, after 12 hours, the effect of grapefruit juice on the human body can be reduced to half. After drinking a glass of grapefruit juice, its effect is enough to last for 3 days. We understand that drug overdose can be toxic, but we often overlook the interaction between drugs and food, especially in this grapefruit season. Studies have shown that 1 cup of grapefruit juice + 1 pill is sometimes equivalent to taking 20 pills of the same drug! This is not an exaggeration!

The human body has a very important metabolic enzyme - P450 enzyme, which metabolizes the food and drugs we eat. After decomposition and metabolism, they are converted into non-toxic substances through P450 enzymes and excreted from the body. This enzyme is a large super gene family with many types, including CYP3A4, CYP2C19, CYP2A6, CYP 2B6, CYP 2C8, CYP 2C9, CYP 2D6, etc. In addition to being delicious, grapefruit also contains many active ingredients such as furanocoumarins, naringenin, bergamot, etc., which can inhibit the activity of the metabolic enzyme P450 enzyme CYP3A4 in the body, resulting in the inability to decompose, metabolize, and excrete drugs in time, resulting in the accumulation of drugs in the body instead of metabolism, and the dosage exceeds the toxic amount and causes death.

Studies have shown that most drugs will react with certain components in grapefruit, resulting in an increase in the amount of some drugs entering the blood. When the drug concentration in the blood exceeds the safe range, the side effects and adverse reactions of the drug will also increase the harm to the human body. In 1989, Bailey discovered that grapefruit juice can increase the bioavailability of drugs such as felodipine, which is the "grapefruit juice effect." Currently, a large number of literatures have also reported that grapefruit interacts with drugs that act on multiple systems. In addition to increasing the blood concentration of drugs, studies have shown that grapefruit juice can also cause a decrease in the absorbed dose of some drugs, such as the anti-allergic drug fexofenadine.

What medicines should not be taken with grapefruit?

1. Do not take lipid-lowering drugs with grapefruit

If you eat grapefruit while taking lipid-lowering drugs such as atorvastatin, lovastatin, and simvastatin, the patient's likelihood of experiencing muscle pain and rhabdomyolysis will increase, and in severe cases, acute renal failure may occur.

Clinical observations have found that for patients with hyperlipidemia, taking a tablet of lovastatin with a glass of grapefruit juice is equivalent to the lipid-lowering effect of taking 12 to 15 tablets of lovastatin with a glass of water. As a result, patients may experience muscle pain and even kidney disease.

2. Do not take antihypertensive drugs with grapefruit

Since grapefruit itself has antihypertensive effects, and it can increase the blood concentration of antihypertensive drugs, eating grapefruit or drinking grapefruit juice while taking antihypertensive drugs such as nifedipine, nimodipine, and verapamil is like an overdose of medication, causing a sudden drop in blood pressure, which can cause dizziness, palpitations, and fatigue at the mildest, and may induce angina pectoris, myocardial infarction, or stroke at the worst.

The antihypertensive drugs that have significant interactions with grapefruit juice reported in the literature are mainly dihydropyridine calcium antagonists, such as felodipine and nifedipine. Therefore, not all types of antihypertensive drugs cannot be taken with grapefruit.

3. Do not take sedatives and sleeping pills with grapefruit

Grapefruit will increase the possibility of diazepam (Valium), midazolam and other drugs causing dizziness and drowsiness. High-altitude workers and drivers should be especially careful when taking these drugs.

4. Do not take contraceptive pills with grapefruit

An article circulating on the Internet says: If a woman who takes birth control pills eats 1 to 2 grapefruits after sex, or takes birth control pills with a large glass of grapefruit juice, she may become a mother because grapefruit hinders women's absorption of birth control pills. In fact, this statement is wrong. In fact, the result is just the opposite. Currently, the female oral contraceptives on the market are mainly steroid hormone drugs, and the main ingredients they contain, such as ethinyl estradiol, norethindrone, and desogestrel, are all CYP3A4 substrates. These drugs are all metabolized by the metabolic enzyme CYP3A4. If taken with grapefruit or grapefruit juice, the furanocoumarins in grapefruit will inhibit the production of CYP3A4 in the human body, increase the blood concentration of birth control pills, and enhance the efficacy and toxic side effects.

5. Do not take cardiotoxic drugs with grapefruit

Cardiotoxic drugs, such as the antibiotics erythromycin and moxifloxacin, the gastrointestinal motility drugs cisapride and domperidone, and the antiallergic drug terfenadine, should never be taken with grapefruit, otherwise they may cause symptoms such as dizziness, palpitations, arrhythmias, and even be life-threatening.

6. Do not take immunosuppressants with grapefruit

Grapefruit can increase the blood concentration of immunosuppressants such as cyclosporine and increase liver and kidney toxicity. If such drugs are taken with grapefruit and other fruits for a long time, there is a risk of inducing tumors.

It is worth noting that with the deepening of food processing, many beverages, pastries and other foods also contain grapefruit juice or pulp ingredients. When purchasing, you should also pay attention to the ingredient list to avoid interactions with drugs. If necessary, you should consult a doctor or pharmacist.

References

1. Seden, Dickinson, Khoo, et al. Grapefruit-drug interactions. Drugs. 2010; 70(18): 2373-407.

2.Hanley, Cancalon, Widmer, et al. The Effect of Grapefruit Juice on Drug Disposition. Expert Opin Drug Metab Toxicol. 2011; 7(3): 267-86.

3.Cristóbal-Luna, Álvarez-González, Madrigal-Bujaidar, et al. Grapefruit and Its Biomedical, Antigenotoxic and Chemopreventive Properties. Food Chem Toxicol. 2018; 112: 224-34.

4. Xin Huawen. CYP3A4 and P-glycoprotein and intestinal disposition of drugs. Chinese Journal of Clinical Pharmacology and Therapeutics. 2005; 10: 721-5.

Author: The First Affiliated Hospital of Zhejiang Chinese Medical University

Written by Lv Jiani

Wang Jianping reviewed the policy

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