How grapefruit affects blood pressure, increases or decreases it, what is the relationship?

Medicines interact not only with each other. One of the food products that gives potentially dangerous combinations with a large amount of drugs is grapefruit and its juice. This property of grapefruit should not be underestimated, since in some cases reactions can develop even fatal! Knowing how and with what medications grapefruit interacts is critically important for pharmacists and pharmacists.

Principle of interaction

Grapefruit juice is a powerful inhibitor of one of the most important enzymes of the cytochrome P450 system - CYP3A4, which is involved in the life cycle of up to 60% of drugs [1]. The furanocoumarins contained in grapefruit and, to a lesser extent, flavonoids (naringin, bergamottin and others) are responsible for this. Other citrus fruits have the same property: pomelo, bitter varieties of oranges, lime - that is, those that are related to grapefruit and also contain furanocoumarins [2].

Sweet oranges, tangerines, and lemon do not have this effect. The inactivating effect of grapefruit is on CYP3A4, which operates in the intestine. However, consuming grapefruit or its juice in large quantities can lead to a decrease in the concentration of CYP3A4 in the liver. Furanocoumarins in grapefruit juice block the enzyme irreversibly, so intestinal cells need time to reproduce it. After a glass of grapefruit juice or one fruit eaten, it takes 72 hours for the enzyme activity to return to its original level. Within 24 hours, CYP3A4 enzyme activity is restored by 50%. Therefore, an interval of even a few hours between taking the medicine and grapefruit juice will not make sense.

The effects of grapefruit juice on CYP3A4 have been well studied. In addition to CYP3A4, grapefruit can suppress CYP1A2. This explains the increased effect of caffeine. There is evidence of its effect on isoenzymes of the cytochrome system.

Weaken and enhances the effect

Grapefruit can affect drug metabolism in two ways:

1. If a drug is metabolized by an enzyme to inactive compounds (this is most drugs), then taking it together with grapefruit will help increase the concentration of the active substance in the blood. Consequently, this will lead to the appearance or intensification of its side effects and even toxic effects on the body - severe adverse drug reactions (ADRs). For example, grapefruit juice can increase the concentration of simvastatin by 9 times! And this is fraught with an increase in such common serious side effects of statins as myopathies, which can manifest from mild myalgia to fatal rhabdomyolysis, in which muscle tissue is destroyed with the development of acute renal failure [3]. Let us recall that with the usual regimen of taking statins, fatal rhabdomyolysis accounts for 1.5 deaths per 10 million medical prescriptions.
2. If a drug is converted to an active metabolite by CYP3A4 cytochromes, inhibition of the enzyme will reduce the effectiveness of the drug. Examples include combining grapefruit juice with clopidogrel and losartan. Simultaneous use with cyclophosphamide will lead to the same result.
3. Additional mechanisms of action of grapefruit juice are associated with the effect on the work of transporter proteins: it reduces the activity of P-glycoprotein (P-gp) and organic anion transport polypeptides (OATP-A, OATP-B), while increasing the activity of OATP-C. All these transporter proteins prevent the entry and promote the removal of xenobiotics and drugs from the blood. These additional mechanisms can be combined with each other and with effects on CYP3A4 and ultimately produce different effects: the bioavailability of the drug increases or decreases.

One additional mechanism is associated with the loss of effectiveness of the antiallergic fexofenadine when taken with grapefruit juice, although it is not a substrate for the CYP3A4 enzyme. If the pharmacokinetics of a drug is only with additional mechanisms of action of grapefruit, then a break of 4 hours between taking the fruit and the drug will be enough to ensure that the interaction does not occur.

High risk of interaction

More than 85 drugs in combination with grapefruit can cause serious adverse reactions. And 43 drugs can potentially lead to fatal consequences [4]. Moreover, whether grapefruit juice will affect the pharmacokinetics of a drug depends not on the group affiliation, but on whether the drug is a substrate for the CYP3A4 enzyme or transporter proteins. Grapefruit juice only affects oral forms of medications that are absorbed in the small intestine.

Clinically significant combinations with a high and very high risk of interaction with grapefruit juice occur in:

Statins : lovastatin, atorvastatin, simvastatin up to fatal rhabdomyolysis. At the same time, grapefruit juice has no effect on pravastatin, rosuvastatin, fluvastatin .

Antineoplastic drugs such as crizotinib, dasatinib, erlotinib, everolimus, lapatinib, nilotinib, pazopanib, sunitinib, vandetanib, venurafenib - myelotoxicity (damage to bone marrow cells involved in hematopoiesis) and increases the risk of life-threatening disorders of the blood. Together with everolimus there is a risk of myelotoxicity, with erlotinib - myelotoxicity and nephrotoxicity.

In combination with

Erythromycin - “pirouette”, increased nausea, vomiting, diarrhea;

Amiodarone - prolongation of the QT interval, ventricular arrhythmias, including pirouette type;

Apixaban - gastrointestinal bleeding;

Ergotamine - gangrene, stroke;

Ticagrelor - gastrointestinal, renal bleeding;

Verapamil - marked decrease in blood pressure, atrioventricular block;

Dextromethorphan - hallucinations, drowsiness;

Domperidone - “pirouette”;

Cyclosporine, tacrolimus - nephrotoxicity, acute renal dysfunction;

Clopidogrel - loss of effectiveness.

Composition and beneficial properties

This cultivation is the result of a selective cross between orange and pomelo. The fruit is rich in vitamins, minerals and essential oils. Naringin, contained in the partitions of the fruit, imparts a specific bitterness.

Benefits include:

• improving the functioning of the digestive system;
• reduce blood cholesterol levels;
• Has a positive effect on depressive disorders and nervous exhaustion.

People just need to inhale the aromas of citrus fruits to improve their emotional state. To bring your nervous system back to normal, you can add fruit oil to your bath, and anxiety is often the cause of high blood pressure. Grapefruit helps achieve weight loss results, which is also a common trigger for high blood pressure. This product lowers blood sugar and is often recommended for diabetics.

Chemical composition

100 g of product contains 35 kcal. It has a positive effect on the digestive and vascular systems due to its high content of glycosides.

This consists of:

• beta-carotene;
• vitamins A, B, C, E, PP;
• minerals including iron, magnesium, potassium, phosphorus;
• essential oils;
• peptides.

The content of natural sugars and vitamin C in grapefruit is higher than in oranges. At the same time, the preservation time of the beneficial properties of the fruit is much longer.

Grapefruit and medications: an unpleasant surprise

Juices, especially freshly squeezed ones, have always been considered extremely healthy. Lots of vitamins, microelements - and everything is natural without any “chemicals”! But any plant, even grown in environmentally friendly conditions, is still a biochemical laboratory of nature, which is capable of presenting surprises.

Everyone knows that medications can interact with other foods they consume. But most often scientists are interested in the problem of compatibility of drugs and alcohol.

So, once a group of pharmaceutical scientists from the University of Western Ontario studied the question of how compatible blood pressure medications (calcium channel blockers) and alcohol are. To prevent psychological factors from influencing the results of the experiment, they decided to mask the taste of alcohol with white grapefruit juice. And unexpectedly it turned out that pure juice caused much more side effects and signs of overdose than alcohol.

What's so "bad" about grapefruit?

There's nothing wrong with it. Almost all substances that can affect the use of medications have a positive effect on the body, but together with medications they can play a cruel joke. Among these substances:

1. Furanocoumarins.
   They block the work of one of the most important enzymes, thanks to which a large number of drugs are metabolized. As a result, more medications enter the bloodstream than they should, and they have a toxic effect on the body. It takes 72 hours after eating grapefruit for this enzyme to function properly again.
2. Flavonoids.
   They also block a number of enzymes that are responsible for processing drugs in different organs. Metabolism of drugs slows down. As a result, an increased concentration of drugs accumulates in the body.
3. There is still an unknown component that blocks the so-called P-glycoprotein, which is responsible for “cleansing” cells of unnecessary foreign substances: for example, it “throws” excess drugs out of the cell. If P-glycoprotein does not work well, then high concentrations of drugs accumulate in the cell, which can become toxic.

How much grapefruit is enough?

Surprisingly, not so much. If you take freshly squeezed juice, then to change the functioning of enzymes and disrupt the metabolism of drugs, it is enough to drink a little more than a glass.

It should be noted that the indicated dose is calculated approximately, because there are many additional factors on which the effect of the juice depends. Age, heredity, and also whether the person took some food with the juice or drank it on an empty stomach are important.

The type of medication also plays a big role. If, when treating with a specific drug, the exact dose is very important and deviation from it may negatively affect the patient’s condition, then grapefruit may cause more undesirable reactions.

What medications is grapefruit juice incompatible with?

Currently, 85 drugs are known. Among them:

• tranquilizers benzodiazepines (Phenazepam, Diazepam, etc.);
• antiepileptic drugs (Carbamazepine, Lamotrigine);
• statins - drugs that lower cholesterol (Lipitor, Mevacor, Zocor);
• antiarrhythmic (Cordarone);
• antimigraine (Ergotamine);
• drugs for erectile dysfunction (Viagra, Cialis);
• paracetamol;
• antiallergic (Fexofenidine);
• Omeprazole

and others.

Should I give up grapefruit?

There are undoubted grapefruit lovers for whom giving up their favorite fruit would be, although possible, very sad. Fortunately, pharmacologists believe that such sacrifices are not necessary. You should only eat these fruits or drink juice 4 hours before taking medications.

It is possible that grapefruit juice will not have such an adverse effect on you at all, but it is nevertheless best to be aware of this possibility.

Some fruits contain the same substances as grapefruits, but in lower concentrations. Among them are apples, oranges, pomelo. Therefore, pharmacologists warn that it is better not to take medications with juices at all.

Natalia Stilson

Photo thinkstockphotos.com

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The effect of grapefruit on blood pressure

The positive effect of fruits on the body is due to the presence of a large number of useful substances. In this case, the fetus increases or decreases pressure, it depends on many circumstances. In traditional medicine recipes, this product is traditionally used as an ingredient that can be used to lower blood pressure. The ability of the drug to have a positive effect on the walls of blood vessels and reduce cholesterol levels can improve the well-being of a patient with hypotension.

Thanks to the special properties of grapefruit, the use of this product helps prevent heart pathologies and prevents the development of atherosclerosis. The ability to strengthen the body's defenses has a positive effect on the well-being of people who have problems with blood pressure.

How does grapefruit affect blood pressure?

The hypotensive effect of grapefruit is realized by:

• reducing excess body weight (obese people have a high risk of developing hypertension);
• normalization of the blood lipid spectrum (atherosclerotic plaques are one of the factors of arterial hypertension);
• prevention of cardiovascular pathology.

The therapeutic effects of individual components of grapefruit juice are presented in the table.

Grapefruit juice has diuretic properties (removes excess fluid from the body), and therefore reduces blood pressure.

Use for high blood pressure

To combat and prevent hypertension, it is recommended to consume 1 grapefruit per day. A positive effect on the problem of arterial hypertension provides a decrease in cholesterol and glucose levels.

The high content of vitamin C helps to resist stress and fight nervous disorders, which are often precipitating factors of the disease.

The drug contains a large number of antioxidants that improve metabolic processes and strengthen blood vessel cells. This complex effect of the fruit on the body strengthens it and lowers blood pressure.

For the best blood pressure lowering effect, use red grapefruit varieties. People with hypertension require constant monitoring of blood pressure. If the result is positive and the pressure has stabilized and there are no sharp jumps in values, you can consult with your doctor on how to adjust your medication intake and reduce their dosage.

People with hypertension can consume not only the fruit, but also its juice to normalize blood pressure. The daily norm is 200 ml, which should be divided into several servings. For better taste, it is recommended to add a little honey to the juice.

Harm from grapefruit

Nutritionists do not recommend eating fruit for certain categories of patients:

• with ulcers in the gastrointestinal tract, both acute and chronic;
• inflammatory processes in the kidneys, including pyelonephritis;
• increased blood pressure;
• allergic reactions to components of citrus crops;
• liver diseases - hepatitis, etc.

Grapefruit juice lovers need special caution. Active ingredients can cause irritation on the oral mucosa and negatively affect the condition of tooth enamel, causing partial destruction.

Use with low blood pressure

Many patients with low blood pressure try to avoid consuming this product, thereby depriving themselves of a valuable source of vitamins and minerals. Eating fruits indirectly affects blood pressure, that is, the product does not directly affect the indicators.

With low blood pressure, thanks to the beneficial properties of the fruit, it can strengthen the immune system to dissolve cholesterol platelets and strengthen blood vessels. Grapefruit can and should be used, but it pays to maintain reasonable standards.

Tablet compatibility

The inclusion of grapefruit in the menu should take into account its compatibility with several medications. Most often, these restrictions apply to drugs used in the treatment of heart and kidney disease. Grapefruit can enhance the work of such drugs, so there is a risk of overdose. Therefore, consuming grapefruit and taking medications should be separated over time.

When using oral contraceptives, it is worth knowing that fruit leads to a decrease in the active ingredients of active drugs. At the same time, frequent use of grapefruit in large quantities promotes the growth of estrogens, which are burdened with hormonal background disorder.

Is it possible to eat fruit if you have hypertension?

Grapefruit affects blood pressure through the main risk factors, which is characterized by a complex and safe effect on pathology. Therefore, citrus fruits are actively prescribed in the diet of hypertensive patients.

However, the active components of the fruit are not enough to treat the disease. The drug is not used for hypertensive crises or complicated types of hypertension. The effectiveness of grapefruit is based on a combination with traditional pharmacological methods of blood pressure correction.

If objective symptoms appear (pain in the back of the head, dizziness, rapid heartbeat), it is necessary to consult a doctor and prescribe drug therapy.

Reception features

It is necessary to use grapefruit for blood pressure after consulting a specialist to exclude contraindications and compatibility with concomitant therapy.

Rules for safe and effective consumption of fruit:

1. For the purpose of treating or preventing cardiovascular diseases, it is recommended to consume 1 fruit daily.
2. You can replace the fruit with 1 glass of freshly squeezed juice with pulp (“fresh”). To reduce bitterness, it is recommended to add 1 tablespoon of honey.
3. Patients with sensitive tooth enamel need to drink juice through a straw.
4. The fruit is consumed after meals, since the extractive substances of the fruit cause irritation of the mucous membrane.
5. Patients with reduced secretory function (hypoacid gastritis) are recommended to drink juice on an empty stomach.
6. Grapefruit should be prescribed with caution to pregnant women, nursing mothers and children due to the risk of allergic reactions. Start with small portions of the fruit (1 slice), gradually increasing the dose.
7. If signs of hypersensitivity appear, you should stop taking the fruit.

The combination of grapefruit, medications and herbal medicines that lower blood pressure enhances the effectiveness of therapy.