The Pharmacist’s Prohibition

In a consultation, a sixty-five-year-old patient once confided that she had been drinking a large glass of fresh grapefruit juice every morning for years, convinced it was excellent for her health. What she didn’t know was that she was also taking a statin for cholesterol. Her doctor had never made the connection between her unexplained muscle pain and this simple morning glass of juice.

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Bioactive molecules

Grapefruit is a textbook case in pharmacology. Naringin and furanocoumarins inhibit cytochrome P450 3A4, the liver enzyme that metabolizes over 85 medications¹. Naringoside is a powerful liver protector and natural lipid-lowering agent². Grapefruit is an excellent health fruit ONLY if you are not taking any medications metabolized by CYP3A4 (statins, immunosuppressants, antiarrhythmics)³. It is the only juice in this book that requires prior medical advice⁴.

Grapefruit is a textbook case in naturopathy and pharmacology. Let’s start with the elephant in the room : drug interactions. Naringin and furanocoumarins from grapefruit inhibit cytochrome P450 3A4, a liver enzyme that metabolizes over fifty common medications. When this enzyme is blocked, the medication accumulates in the blood at dangerous concentrations. Statins (cholesterol), calcium channel blockers (blood pressure), certain immunosuppressants, certain antihistamines, and many other medications are affected.

Grapefruit contains naringin, a flavonoid responsible for its bitterness, which is metabolized into naringenin, a potent inhibitor of cytochrome P450 3A4. Fuhr (‘Drug Interactions with Grapefruit Juice,’ Drug Safety 18, no. 4 (1998) : 251-272) documents grapefruit drug interactions with statins, immunosuppressants, and antihypertensives. Grapefruit is rich in vitamin C (38 mg/100g) and limonoids, triterpenes with antiproliferative properties.

Grapefruit stimulates hepatic lipid metabolism via naringin. Beware of drug interactions : it inhibits liver cytochrome P450 3A4, altering the metabolism of many medications.

Grapefruit stimulates hepatic lipid metabolism via naringin. Beware of drug interactions : it inhibits cytochrome P450 3A4, altering the metabolism of many medications. If you take medications, ask your pharmacist’s advice.

Key micronutrients table

Cold press preparation

Ingredients:

• 3 to 4 fresh garlic cloves
• 1 peeled lemon
• 1 large piece of ginger (5 cm)
• 1 teaspoon of organic honey

WARNING : grapefruit interacts with many medications via cytochrome P450. If you take any treatment, consult your doctor or pharmacist BEFORE drinking this juice.

My personal thoughts

Grapefruit is the only juice in this book that requires a serious warning. The furanocumarin (bergamottin) it contains inhibits cytochrome P450 3A4 in the liver, the enzyme that metabolizes over 85 medications. Result : the medication is no longer broken down and its concentration in the blood spikes. This is dangerous with statins (cholesterol), immunosuppressants (cyclosporine), certain antihypertensives, benzodiazepines, and anticoagulants. If you take any treatment, ask your doctor or pharmacist before drinking grapefruit juice. That said, for those taking no medications, it’s an extraordinary juice : vitamin C, lycopene, anti-inflammatory naringin.

My recommended cold press

For this recipe, I use the Hurom H330P. Cold pressing preserves all the enzymes, vitamins, and phytonutrients that the heat from a centrifuge would destroy.

Promo code : FRANCOIS10 for -10% off everything at Hurom.

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Related articles

• Immunity and inflammation
• Vitamin C and immunity

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• Questionnaire : Vitality
• Questionnaire : Vitamin C deficiency

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• All my health questionnaires
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• My Living Juices ebook