Grapefruit
Citrus × paradisi
Fruits. Modern nutrition.
Also called Toronja, Pink grapefruit, Ruby red grapefruit
Pinyin: Pú Tao Yòu
Spanish: Toronja (pomelo)
Clashes with many medicinesGrapefruit is a large sour-sweet citrus fruit, eaten fresh or as juice, and best known for its strong interactions with many medicines.
Did you know? Grapefruit probably arose as a natural cross between a sweet orange and a pomelo, and it was first described in the Caribbean in the 1700s.
What it may help, and how strong the proof is
- Weight. A small 12-week trial found that people who ate half a grapefruit before meals lost a little weight. Eating less may explain much of the effect.Early proof
- Colds, flu & immunity. Grapefruit is a good source of vitamin C. Food amounts have not been tested for colds.Traditional proof
Parts of the body
Traditional use
Grapefruit has little traditional medicine use. It is mostly a modern breakfast fruit grown in Florida, Texas and the Caribbean.
How it is classified
- Herbal actions
- Nutritive, Antioxidant. Energy: neutral.
How people take it
Eaten fresh or as juice. The weight trial used half a fruit before meals. People on medicines should check with a doctor or pharmacist before eating grapefruit or drinking its juice.
Food and juice.
Where to get it
Grown in Florida, Texas, California, Arizona, South Africa, Israel and the Caribbean. Sold fresh (white, pink and red), as juice, and as seed-extract supplements. Key nutrients: vitamin C, potassium and flavonoids such as naringin.
Be careful
Grapefruit slows down CYP3A4, a liver and gut enzyme (a protein that breaks down many drugs), so drug levels can rise too high. The effect can last a day or more after one glass. Grapefruit seed extract is not a safe swap, because it can contain synthetic preservatives.
Avoid if: statin medicines; calcium channel blockers; transplant anti-rejection drugs.
Mixing with other things
- Don't mixStatins (Lipitor, Zocor, Crestor)
Can raise simvastatin and lovastatin levels to unsafe levels, raising the risk of muscle damage. Atorvastatin levels can also rise.
- Don't mixBlood pressure medicine (lisinopril, amlodipine, losartan)
Can raise levels of felodipine and some other calcium channel blockers, which can drop blood pressure too far.
- Don't mixImmune-suppressing medicine (transplant drugs, some arthritis drugs)
Can raise cyclosporine and tacrolimus levels, which can harm the kidneys. Avoid it unless a transplant team says it is safe.
- Don't mixSleep or anxiety medicine (Ambien, Xanax, Ativan)
Can raise levels of midazolam and triazolam, which can cause deep sleepiness and slowed breathing.
- Use caution
Grapefruit raises lovastatin levels, and this compound is the same molecule. Avoid large amounts.
- Use cautionAlcohol (beer, wine, spirits)
Alcohol adds to the drowsiness.
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The honest take
Grapefruit is a healthy fruit, but it is one of the best-known food and drug clashes. The weight-loss claims come from small, short trials, and the effect is modest. Grapefruit seed extract and detox claims are not supported.