Grapefruit: Grapefruit Nutrition, Benefits and Medication

Grapefruit is a large, tart citrus fruit that is low in calories and high in vitamin C, and it is also the fruit behind a well-known FDA medicine warning. In USDA data, half a medium grapefruit (128 grams) has about 41 calories and 49% of the Daily Value for vitamin C. The FDA has required some prescription and over-the-counter medicines to carry warnings against drinking grapefruit juice or eating grapefruit. This guide covers grapefruit nutrition, the difference between pink and white grapefruit, what studies actually show about grapefruit benefits, and what grapefruit and medication warnings mean for you.

Peptide Labs does not sell grapefruit or grapefruit products. This article is general nutrition information, not medical advice. If you take any medicine, ask your pharmacist or prescriber before changing how much grapefruit or grapefruit juice you have.

Grapefruit nutrition (USDA)

These values come from the USDA FoodData Central SR Legacy entry Grapefruit, raw, pink and red and white, all areas (FDC 173033). Percent Daily Values use the FDA Daily Values.

Grapefruit is also mostly water: USDA lists about 91 grams of water per 100 grams of fruit. A cup of sections gives 88% of the vitamin C Daily Value for 74 calories, which is why grapefruit appears on most lists of vitamin C foods, including our vitamin C food guide.

Pink, red and white grapefruit

The color of the flesh changes the nutrient profile in one clear way: carotenoids. USDA tested pink and red grapefruit separately from white grapefruit, and the gap is large for lycopene and vitamin A.

Lycopene is the red pigment widely known from tomatoes; our lycopene guide covers what research on it does and does not show. Beta-carotene is a provitamin A carotenoid, explained in our beta-carotene article. Vitamin C is similar in both colors, so pick by taste: white grapefruit is often described as more tart, pink and red as slightly sweeter.

Grapefruit benefits: what the research shows

Most real grapefruit benefits come from its nutrients. The NIH Office of Dietary Supplements notes that vitamin C is needed to make collagen and certain neurotransmitters, plays a role in immune function and improves absorption of nonheme iron from plant foods, and it names citrus fruits as major sources of vitamin C in the American diet. For more on the vitamin itself, see our vitamin C supplement guide.

Grapefruit also has a long reputation as a weight-loss food, from the “grapefruit diet” onward. The trials are small and the results are mixed:

• 2006, Journal of Medicinal Food. A 12-week randomized trial in 91 adults with obesity compared fresh grapefruit, grapefruit juice and grapefruit capsules before meals with placebo. The fresh grapefruit group lost modestly more weight than the placebo group. It was a single, small study.
• 2011, Nutrition and Metabolism. A 12-week trial in 85 adults with obesity, after a calorie-restriction phase, compared grapefruit, grapefruit juice and water before meals, matched for calories. Weight fell in all three groups, but the differences between groups were not statistically significant. HDL cholesterol rose more in the two grapefruit groups than in the water group.
• 2017, Critical Reviews in Food Science and Nutrition. A systematic review and meta-analysis pooled three randomized trials with 250 overweight or obese participants. It found no significant difference in body weight between grapefruit and control groups, and a small decrease in systolic blood pressure. The authors said the few trials and short durations limit any conclusions.

Taken together, grapefruit is a filling, low-calorie fruit, but there is no good evidence that it has a special fat-loss effect. The 2011 trial is a useful reminder: water before meals did about as well as grapefruit when calories were matched. If you are comparing fruits by sugar, our low-sugar fruits guide includes grapefruit.

Grapefruit and medication: the FDA warning

The FDA explains that grapefruit and grapefruit juice can change how some medicines work. For most of the affected drugs, grapefruit blocks an enzyme in the small intestine called CYP3A4, so more of the drug enters the blood and stays in the body longer. Too much drug can mean more side effects; with certain statins, the FDA says this can raise the risk of liver and muscle damage that can lead to kidney failure. For a few drugs, such as the antihistamine fexofenadine, grapefruit has the opposite effect: it affects drug transporters, so less drug is absorbed and it may not work as well.

The FDA gives these examples of drug types that grapefruit juice can interact with:

• Some statin drugs for cholesterol, such as simvastatin and atorvastatin.
• Some blood pressure drugs, such as nifedipine.
• Some organ-transplant rejection drugs, such as cyclosporine.
• Some anti-anxiety drugs, such as buspirone.
• Some corticosteroids used for Crohn’s disease or ulcerative colitis, such as budesonide.
• Some heart-rhythm drugs, such as amiodarone.
• Some antihistamines, such as fexofenadine.

Grapefruit juice does not affect every drug in those groups, and the FDA says the severity depends on the person, the drug and how much grapefruit juice is involved. The amount of CYP3A4 in the gut varies between people, so two people on the same drug can react differently. The FDA advises asking your doctor or pharmacist, reading the Medication Guide or patient information that comes with a prescription, and checking the Drug Facts label on over-the-counter medicines. It also suggests checking juice blends and juice-flavored drinks for grapefruit juice.

The same FDA page names Seville oranges, pomelos and tangelos as fruits that might have the same effect, and says not to eat them if your medicine interacts with grapefruit juice. Clementines and tangerines are not on that list; our clementine guide covers what that means. If you use CBD, our CBD drug interactions guide explains a separate set of interaction questions. Do not stop or change a prescribed medicine on your own; ask your pharmacist first.

Grapefruit juice vs whole grapefruit

Grapefruit juice keeps the vitamin C but loses nearly all the fiber, and a cup carries more sugar and calories than a cup of sections. For drug interactions, the FDA warning covers both the juice and the fruit. Our high-fiber foods guide explains why whole fruit usually beats juice for fiber.

How to choose and eat grapefruit

• Choosing. Look for fruit that feels heavy for its size, with smooth, firm skin.
• Eating. Halve it across the middle and loosen the segments with a serrated or grapefruit knife, or peel it and remove the membranes for salads.
• Storing. Whole grapefruit keeps for several days at room temperature and longer in the refrigerator; cut fruit should be covered and chilled.
• Allergy. Citrus is not one of the nine major food allergens under US law, but citrus allergies exist. If you react to citrus, talk with an allergist.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Clementine: Clementine Nutrition and Clementine vs Tangerine, Pomelo: Pomelo Fruit Nutrition, Pomelo vs Grapefruit and Safety, Foods High in Vitamin C: USDA List of Fruits and Vegetables, Ugli Fruit: What Is Ugli Fruit and How to Eat the Jamaican Tangelo.