Grapefruit: Nutrients, What Research Shows and Safety

Grapefruit is the fruit of Citrus x paradisi, a citrus tree in the rue family (Rutaceae). The juicy sections inside the peel are eaten, or squeezed for juice. People eat it mainly for its vitamin C and its fresh, tart taste. This page keeps the whole fruit apart from supplements and from hype, and it gives the medicine warning first because that is the best-documented thing about grapefruit.

Read this first

• Medicines: the US FDA says grapefruit juice can change how much of some medicines enters the blood, including some statins, some blood pressure medicines, some transplant medicines and some heart-rhythm medicines. It does not affect every medicine in those groups. Ask a pharmacist before eating it if you take any regular medicine. [2]
• Allergy: citrus allergy exists and can be linked to pollen allergy. For trouble breathing or swelling of the face or throat, call 911. [10]
• Kidneys and potassium: people with kidney problems, or who take an ACE inhibitor, an ARB or a potassium-sparing diuretic, are told to watch potassium-rich foods, and citrus is on that list. [11]
• Evidence in one line: vitamin C from foods like this prevents scurvy; claims for weight loss, cancer prevention or "detox" are weak or based only on observation studies.

What is in it (USDA values)

Per USDA FoodData Central item 173033 (raw grapefruit, pink, red and white, all areas). [1] The USDA portion used here is 1 cup of sections with juice, 230 g. Half a medium grapefruit (128 g) gives a little over half of these amounts.

% Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage. [1]

USDA also measured carotenoids (plant pigments) in this item: beta-carotene 552 µg and lycopene 1,135 µg per 100 g. [1] We did not find, in the sources we read, a trial showing that these amounts in grapefruit change health outcomes in people. Other plant compounds in grapefruit were not covered by a source we read, so we do not describe them.

What research says

Observation studies compare what people report eating with what happens to them later. They cannot show that the fruit caused the difference.

Eaten as food vs taken as a supplement or extract. The weight and blood-pressure trials above tested grapefruit products, which can mean juice, fresh fruit or capsules, so a result may not apply to the plain fruit. [5] We did not find a source we read that tested grapefruit seed or peel extracts, so we make no claim about them. The cancer and kidney-stone studies are about eating citrus or drinking juice.

How much is a normal serving

• The USDA household portions in the FoodData Central entry are 1 cup of sections with juice (230 g) or half of a medium grapefruit (128 g). [1] This is information, not a prescription.
• The NHS says 80 g of fresh, canned or frozen fruit counts as one portion of 5 A Day, and that juice and smoothies together count as at most one portion a day (150 ml). [12]
• Vitamin C can fall with cooking, long storage and light, according to MedlinePlus. [4] We did not find a source we read that compares fresh and canned grapefruit.

Safety, allergy and medicines

• Medicine interactions: the FDA says grapefruit juice blocks an enzyme in the gut (CYP3A4) that breaks down many medicines, so more of the medicine can reach the blood and side effects can increase. [2]
• Examples the FDA names: the statins simvastatin and atorvastatin, nifedipine for blood pressure, cyclosporine for transplants, buspirone for anxiety, budesonide for bowel disease and amiodarone for heart rhythm. [2]
• The opposite effect: for the antihistamine fexofenadine, grapefruit juice can mean less medicine in the blood. [2]
• Other fruit: Seville oranges, pomelos and tangelos might act like grapefruit juice. [2] The FDA gives no safe amount or timing, and says the effect depends on the person, the drug and the amount. [2]
• Statins: the NHS tells people taking simvastatin to avoid grapefruit juice. [3]
• Mental-health medicines: a 2024 review says the gut-enzyme effect explains most reported grapefruit-psychotropic interactions, but not all, and that more real-world study is needed. [9]
• Allergy: a study of people with pollen allergy found 39% were sensitised to citrus fruits, and linked this to cross-reactivity with some pollens and fruits such as apple. [10]
• Potassium: MedlinePlus lists citrus among potassium-rich foods and says ACE inhibitors, ARBs and potassium-sparing diuretics can raise blood potassium; people with kidney problems are told to limit potassium-rich foods. [11] A cup of sections has 7% of the Daily Value. [1]
• Kidney stones: results are mixed (see the table). People who have had stones should ask a clinician. [8]
• Skin: a 2025 review found moderate evidence that high intake of furocoumarins (compounds that react with sunlight) from foods may raise melanoma risk, but it could not say how much. It did not say how much grapefruit contributes, and the EPIC study found only a small link with citrus. [7][14]
• Sugar and teeth: grapefruit juice has less fiber than the fruit; see fruit juice vs whole fruit. The NHS says juice is best with meals because of the sugars. [12]
• Pregnancy: Proper evidence not found in the sources we read.

Choosing, storing and food safety

• Wash fruit under running water before cutting; the FDA says not to use soap or produce wash. [13]
• The FDA advises scrubbing firm produce, such as melons and cucumbers, with a clean produce brush; we did not find grapefruit-specific advice in the page we read. [13]
• Keep cut fruit refrigerated at 40°F (4°C) or below. [13]

Related pages

• Citrus fruits
• Foods and medicine interactions: vitamin K, grapefruit and others
• Grapefruit and medicine interactions
• Fruit juice vs whole fruit
• Kidney disease, potassium and oxalates in foods
• Observational vs trial evidence in nutrition