Grapefruit vs orange: the difference that matters is in the juice and your pills

The difference between these two fruits that matters most shows up next to a pill. A meta-analysis of 51 studies, mostly small open-label crossover trials that rarely measured clinical outcomes, found grapefruit juice cut blood levels of the blood pressure drugs aliskiren and celiprolol by about 80 to 90 percent. The same review found that orange and apple juice had comparable effects on certain medications, so switching to orange juice is no automatic way out. A separate review of 73 studies found orange juice significantly reduced how much of the antifungal itraconazole the body absorbs, with no size given in the abstract and the overall evidence rated low. On the plate, the orange carries more vitamin C and fiber. USDA samples put raw navel oranges at 59 mg vitamin C and 2.0 g fiber per 3.5 oz (100 g), against 38 mg and 0.65 g for raw grapefruit, from only 4 grapefruit samples of unstated variety. Every health and drug finding on this page was measured in juice, so it says nothing either way about the whole fruit next to a medicine. We found no trial comparing whole grapefruit with whole orange on any health outcome.

How much is actually in it

• Raw navel oranges averaged 59 mg vitamin C and 2.0 g fiber per 3.5 oz (100 g) in USDA samples, against 38 mg and 0.65 g for raw grapefruit. — USDA Foundation Foods, grapefruit raw 4 samples, navel oranges raw 8 samples (n = 4 + 8) Evidence E source
  Vitamin C 59.1 mg (51.8-65.6) vs 38.0 mg (32.5-43.6); fiber 2.0 g (1.9-2.1) vs 0.65 g (0.45-1.11); potassium 166 vs 156 mg
• The UK table gives raw grapefruit flesh 34 calories, 6.9 g sugars and 35 mg vitamin C per 3.5 oz (100 g), and orange flesh 36 calories, 8.2 g sugars and 52 mg vitamin C. — UK composition table, flesh only Evidence E source
  Grapefruit 34 calories, sugars 6.9 g, vit C 35 mg, fiber 0.9 g vs orange 36 calories, 8.2 g, 52 mg, 1.2 g

What a real portion looks like

• In US survey portions, half a grapefruit and one whole orange both count as 154 g, while a whole grapefruit is 308 g. — US household measures, FNDDS Evidence E source
  Grapefruit half 154 g, whole 308 g; orange 1 fruit 154 g

What your body absorbs

• A review of 73 studies on oral antifungals found orange juice significantly reduced how much itraconazole the body absorbs. — 73 studies from 68 reports on 14 oral antifungal drugs (n = 73 studies) Evidence A source
  Itraconazole bioavailability reduced with orange juice; acidic cola increased it
• A meta-analysis of vitamin D fortified foods, including 5 trials using orange juice, found fortified vehicles raised blood vitamin D by about 9 to 35 nmol/L. — 49 papers of RCTs on vitamin D fortified food vehicles, orange juice n = 5 (n = 49 papers) Evidence A source
  25(OH)D WMD about 9-35 nmol/L across vehicles; plant 15.2 vs animal 15.9 nmol/L

What cooking and storage change

• By the USDA retention table, cooked citrus fruit keeps 95% of vitamin C and 70% of folate. — USDA R6 group Fruits and Fruit Juices, code 270 Evidence E source
  Vitamin C 95%, folate 70%, potassium 100%

What it does to your health

• A meta-analysis of 10 randomized trials found orange juice lowered LDL cholesterol by 9.1 mg/dl and fasting glucose by 2.9 mg/dl against control. — 10 RCTs of orange juice consumption (n = 10 trials) Evidence A source
  LDL-C -9.14 mg/dl (-15.79 to -2.49); glucose -2.92 mg/dl (-5.33 to -0.53); TC -9.84 mg/dl; CRP -0.47 mg/l

Safety, limits and interactions

• A case report describes a 40-year-old man with no known past medical history whose blood potassium reached 9.4 mmol/L after weeks of drinking large amounts of reconstituted dried orange juice powder. — one 40-year-old man with no known past medical history (n = 1) Evidence D source
  Serum potassium 9.4 mmol/L, ICU admission, resolved after stopping the drink

What people believe that the data does not support

• The EU rejected a claim that grapefruit flavonoids support microbial balance in body organs and tissues. — EU Register on nutrition and health claims, snapshot 2026-09-21 Evidence E source
  Status Non-authorized
• The EU rejected claims that orange helps blood circulation in small vessels and eases heavy legs. — EU Register on nutrition and health claims, snapshot 2026-09-21 Evidence E source
  Status Non-authorized

Who this works differently for

• A meta-analysis of 51 studies found grapefruit juice cut blood levels of the blood pressure drugs aliskiren and celiprolol by about 80 to 90%, and orange and apple juice had comparable effects on some drugs. — 51 studies, mostly open-label crossover pharmacokinetic trials in humans (n = 51 studies) Evidence A source
  Aliskiren and celiprolol AUC and Cmax down about 80-90% with grapefruit juice; calcium channel blocker exposure changed variably

The bottom line

The UK table agrees on the vitamin C gap: 35 mg per 3.5 oz (100 g) of grapefruit flesh against 52 mg for orange, with 34 and 36 calories and 6.9 and 8.2 g of sugars. In US survey portions, half a grapefruit and one whole orange both weigh 5.4 oz (154 g), and a whole grapefruit is 308 g, though real fruit size varies. Cooking barely matters here. By the USDA retention table, a 1975 group factor for cooked citrus, the fruit keeps 95 percent of its vitamin C and 70 percent of its folate. Orange juice has the only health trials. A meta-analysis of 10 randomized trials found it lowered LDL cholesterol by 9.1 mg/dl (95% CI 2.5 to 15.8) and fasting glucose by 2.9 mg/dl (95% CI 0.5 to 5.3) against control. That was juice, with no grapefruit arm and no whole fruit. Orange juice is also one of the foods used to carry added vitamin D. Across 49 papers of trials, 5 of them with fortified orange juice, fortified foods raised blood vitamin D by about 9 to 35 nmol/L, and the abstract does not separate the figure for juice. That effect belongs to the fortified product. The EU refused to authorize a claim that grapefruit flavonoids support microbial balance in body tissues, and claims that orange helps circulation in small vessels or eases heavy legs. A refusal means the evidence did not meet the bar when it was assessed. Who should be careful. If you take aliskiren, celiprolol, a calcium channel blocker, itraconazole or any other regular medicine, ask the person prescribing it whether grapefruit or orange, as juice or as fruit, is a problem for you. The review describes grapefruit juice as blocking an enzyme (CYP3A4) and transporters that many drugs pass through, and it found orange juice can matter too. This page covers only the few drugs those reviews named, not every medicine that may be affected. One case report describes a 40-year-old man with no known past illness whose blood potassium reached 9.4 mmol/L after weeks of drinking large volumes of reconstituted dried orange juice powder. That is a single case of extreme intake, and it says nothing about eating oranges.

Sources

1. gfor-r2-01 · composition data
   Grapefruit, raw: Vitamin C, total ascorbic acid 38.0 MG, range 32.5-43.6, samples 4; Fiber, total dietary 0.6525 G, range 0.45-1.11, samples 4; Potassium, K 155.9 MG · Oranges, raw, navels: Vitamin C, total ascorbic acid 59.1 MG, range 51.8-65.6, samples 8; Fiber, total dietary 2.0 G, range 1.9-2.1, samples 4; Potassium, K 166.0 MG
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
2. gfor-r2-02 · composition data
   14-384 Grapefruit, flesh only, raw: Energy (kcal) 34.077, Total sugars (g) 6.94, Vitamin C (mg) 35, AOAC fibre (g) 0.9 · 14-327 Oranges, flesh only: Energy (kcal) 36, Total sugars (g) 8.2, Vitamin C (mg) 52, AOAC fibre (g) 1.2
   CoFID 2021, Public Health England / OGL v3.0, codes 14-384 and 14-327 · checked 2026-10-02
3. gfor-r2-03 · dataset
   FNDDS 61101010 Grapefruit, raw (fdc 2709165): 1 fruit 308 g, 1 half 154 g, 1 cup 180 g · FNDDS 61119010 Orange, raw (fdc 2709171): 1 fruit 154 g, 1 cup 180 g
   USDA FNDDS 2021-2023, food codes 61101010 and 61119010 · checked 2026-10-02
4. gfor-r2-06 · meta-analysis
   The review included 73 studies from 68 reports. ... Acidic beverages such as Coca Cola substantially enhanced the absorption of itraconazole, ketoconazole, and posaconazole, whereas orange juice significantly reduced itraconazole bioavailability.
   Clin Pharmacokinet, 2025 · checked 2026-10-02
5. gfor-r2-08 · meta-analysis of RCTs
   The searches identified 49 papers which described suitable RCTs using vitamin D-fortified bread/savoury biscuits (n = 5), orange juice (n = 5), UV-mushrooms (n = 8), cheese (n = 3), yogurt (n = 5), fluid milk (n = 13), powdered milk (n = 5), eggs (n = 2), edible oils (n = 4), or breakfast cereal (n = 1). ... Random-effects meta-analyses of each food vehicle individually indicated weighted mean differences (WMD) in 25(OH)D in the range ∼9-35 nmol/L (3-15 RCT arms, depending on vehicle), and all statistically significant (P < 0.01-0.0001), with the exception of UV-mushrooms (P = 0.06).
   J Steroid Biochem Mol Biol, 2024 · checked 2026-10-02
6. gfor-r2-04 · dataset
   USDA-RETN-R6:270 FRUITS,CITRUS,CKD: vitamin_c_mg 95%, folate_total_ug 70%, thiamin_mg 95%, potassium_mg 100%
   USDA Table of Nutrient Retention Factors, Release 6 (2007) · checked 2026-10-02
7. gfor-r2-07 · meta-analysis of RCTs
   Ten randomized controlled trials were included in the final analysis. Pooled results demonstrated a significant effect of orange juice on glucose (WMD: -2.92 mg/dl, 95% CI: -5.327, -0.530, p = 0.017), insulin (WMD: -1.229 μU/ml, 95% CI: -2.083, -0.374, p = 0.005), HOMA-IR (WMD: -0.464, 95% CI: -0.747, -0.181, p = 0.001), total cholesterol (WMD: -9.84 mg/dl, 95% CI: -15.43, -4.24, p = 0.001), LDL-C (WMD: -9.14 mg/dl, 95% CI: -15.79, -2.49, p = 0.007), and CRP (WMD: -0.467 mg/l, 95% CI: -0.815, -0.120, p = 0.008) compared to control group.
   Crit Rev Food Sci Nutr, 2022 · checked 2026-10-02
8. gfor-r2-09 · case report
   We report a case of a 40-year-old man with no known past medical history who presented with progressive neuromuscular symptoms, palpitations, and syncope and was found to have life-threatening hyperkalemia with serum potassium levels rising to 9.4 mmol/L and characteristic electrocardiographic changes, including peaked T waves and QRS widening. ... Further history revealed excessive daily consumption of large volumes of a dried orange juice powder reconstituted as a beverage over several weeks.
   Cureus, 2026 · checked 2026-10-02
9. gfor-r2-10 · regulatory register
   POL-HC-6938 Citrus paradise (Common Name : Grapefruit) Flavonoids contained within the Grapefruit contribute to the microbial balance in the body organs and tissues Non-authorised
   EU Register on nutrition and health claims, claim POL-HC-6938, snapshot 2026-09-21 · checked 2026-10-02
10. gfor-r2-11 · regulatory register
    POL-HC-6941 Citrus sinensis - common name : Orange Traditionally used for the good circulation of blood in microvessels / "Traditionally used to decrease the sensations of heavy leggs" / "Used for the good circulation of blood in microvessels" / "Helps to decrease the sensations of heavy leggs" Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6941, snapshot 2026-09-21 · checked 2026-10-02
11. gfor-r2-05 · meta-analysis
    Fifty-one studies were included. Most of them were open-label crossover trials. Grapefruit juice (GFJ), an inhibitor of organic-anion-transporting polypeptide (OATP) transporters and cytochrome P450 (CYP) 3A4, significantly decreased the AUC and Cmax of aliskiren and celiprolol by approximately 80-90 %. Conversely, the AUC and Cmax of calcium channel blockers decreased with variable degrees when co-administered with GFJ. Apple and orange juices have comparable effects on certain medications.
    Complement Ther Med, 2025 · checked 2026-10-02