Clementine and orange: the vitamin C gap between them, and what it does

By meta-analysis of 15 randomized and controlled trials in 1381 females aged 15 to 74 and children, adding ascorbate-rich fruit to meals raised serum ferritin by 9.39 ug/L in 7 trials of 762 people and hemoglobin by 1.34 g/L in 12 trials of 1141, both at moderate certainty. Iron absorption measured directly moved by 3.36 percent and did not reach significance, on three studies rated low certainty. Those trials tested ascorbate-rich fruit as a class and not citrus in particular, and how much vitamin C went into each meal is not recoverable from what the review reports, so neither the fruit nor the dose behind that result is pinned down. The two fruits are not interchangeable in that job. Raw clementine holds 26.7 mg of vitamin C per 3.5 oz (100 g) against 56.2 mg in a raw orange in the USDA survey dataset. By the same dataset one 85 g clementine carries 22.7 mg and one 154 g orange carries 86.5 mg, so it takes close to four clementines to match one orange. Both fruits get a single representative figure there, with no range attached. Clementine appears in neither the UK CoFID dataset nor the USDA sampled-lot dataset, so nobody has measured how much one clementine differs from the next.

How much is actually in it

• Per 100 g raw, a clementine holds 26.7 mg of vitamin C against 56.2 mg in an orange, about half as much, by the USDA FNDDS survey food dataset. — USDA survey food composition dataset, raw clementine and raw orange Evidence E source
  Clementine 26.7 mg per 3.5 oz (100 g) versus orange 56.2 mg per 3.5 oz (100 g) of vitamin C
• Across 8 sampled lots of raw navel oranges vitamin C ranged from 51.8 to 65.6 mg per 3.5 oz (100 g), a spread of 23 percent, while not-from-concentrate orange juice ranged from 24.8 to 38.6 mg, a spread of 45 percent. — USDA Foundation Foods sampled lots of raw navel oranges and of orange juice (n = 8 lots per item) Evidence E source
  Oranges mean 59.1 mg per 3.5 oz (100 g) (range 51.8 to 65.6, spread 23 percent), juice not from concentrate mean 30.54 mg (range 24.8 to 38.6, spread 45 percent), juice from concentrate mean 26.89 mg (range 15.9 to 38.4, spread 84 percent)
• The UK CoFID dataset gives 52 mg of vitamin C per 3.5 oz (100 g) for orange flesh against 56.2 mg in the USDA survey dataset, and holds no entry for clementine at all. — UK national food composition dataset, oranges flesh only, code 14-327 Evidence E source
  52 mg per 3.5 oz (100 g) vitamin C, 122 mg potassium, 8.2 g total sugars, 87.0 g water

What a real portion looks like

• One clementine weighs 3 oz (85 g) and carries about 22.7 mg of vitamin C, while one orange weighs 5.4 oz (154 g) and carries about 86.5 mg, so it takes close to four clementines to match one orange. — USDA survey portion sizes for raw clementine and raw orange Evidence E source
  Clementine 1 fruit 85 g with 22.7 mg vitamin C, orange 1 fruit 154 g with 86.5 mg, 1 cup of orange 180 g with 101.2 mg

What your body absorbs

• By meta-analysis of 15 RCTs in 1381 females and children, eating ascorbate-rich fruit with meals raised serum ferritin by 9.39 ug/L and hemoglobin by 1.34 g/L over the trial periods, with no measurable change in iron absorption itself. — females aged 15 to 74 years and children, 15 randomized and controlled clinical trials pooled (n = 1381) Evidence A source
  Serum ferritin MD +9.39 ug/L (P < 0.001, moderate certainty), hemoglobin MD +1.34 g/L (P = 0.01), iron absorption MD +3.36 percent (P = 0.07, low certainty)

What cooking and storage change

• By the USDA retention table for fruits and fruit juices cooked as citrus, 95 percent of vitamin C survives and 70 percent of folate survives, and no retention factor exists for clementine separately. — USDA food group Fruits and Fruit Juices, cooking method FRUITS,CITRUS,CKD Evidence E source
  Vitamin C retention 95 percent (5 percent loss), folate retention 70 percent (30 percent loss), minerals 100 percent

What it does to your health

• By meta-analysis of 3 RCTs in 252 overweight and obese adults, Moro orange juice extract reduced body weight by 4.6 lb (2.08 kg) versus placebo. — overweight and obese adults, 3 randomized controlled trials pooled (n = 252) Evidence A source
  Body weight MD -4.6 lb (95% CI -7.7 to -1.5; metric: -2.08 kg, -3.50 to -0.67), fat mass MD -3.4 lb (95% CI -6.4 to -0.33; metric: -1.53 kg, -2.92 to -0.15)

Safety, limits and interactions

• By meta-analysis of 51 pharmacokinetic studies, orange juice changes the bioavailability of some antihypertensive drugs to a degree comparable with apple juice, while grapefruit juice cut aliskiren and celiprolol exposure by roughly 80 to 90 percent. — human pharmacokinetic studies of fruit juice taken with antihypertensive drugs, mostly open-label crossover trials (n = 51 studies) Evidence A source
  Grapefruit juice reduced AUC and Cmax of aliskiren and celiprolol by about 80 to 90 percent, orange juice comparable on certain medications
• By the NIH Office of Dietary Supplements, the tolerable upper intake level for vitamin C is 400 to 2,000 mg a day depending on age, and excess intake mainly causes diarrhea, nausea and abdominal cramps. — general population by age group, agency fact sheet for health professionals Evidence E source
  Upper intake level 400 to 2,000 mg per day by age

What people believe that the data does not support

• The EU Register lists the orange (Citrus sinensis) claim about blood circulation in microvessels and heavy legs as non-authorized. — EU health claim assessment, claim POL-HC-6941 Evidence E source
  Status non-authorized, so the wording may not be used on a label in the EU
• The EU Register lists the claim that cryptoxanthin from orange juice strengthens the immune system as non-authorized, and across orange, citrus and hesperidin the register holds zero authorized claims against 21 rejected ones. — EU health claim assessment, claim POL-HC-7000, register snapshot of 2330 claims Evidence E source
  Authorized claims for orange 0 of 3, citrus 0 of 14, hesperidin 0 of 4

Who this works differently for

• By the NIH Office of Dietary Supplements, high vitamin C intake can raise urinary oxalate and uric acid excretion and may contribute to kidney stones, chiefly in people with renal disorders. — people with renal disorders and pre-existing hyperoxaluria, agency fact sheet for health professionals Evidence E source
  Higher urinary oxalate and uric acid excretion, direction of risk upward in renal disorders
• Observational data link vitamin C deficiency in high-income countries to identifiable vulnerable groups, with 147 pooled patients showing on average 2.29 affected organ systems each. — 147 patients with clinically or biochemically confirmed scurvy in high-income countries, 25 studies published 2012 to 2025 (n = 147) Evidence C source
  Pooled mean 2.29 affected organ systems per patient (95% CI 1.62 to 2.96), musculoskeletal involvement OR 1.82 (95% CI 0.98 to 3.38), neurological OR 0.42 (95% CI 0.28 to 0.62)

The bottom line

Orange juice is not neutral around medication. By meta-analysis of 51 human pharmacokinetic studies, mostly small open-label crossovers, grapefruit juice cut the AUC and Cmax of aliskiren and celiprolol by roughly 80 to 90 percent. Apple and orange juice had comparable effects on certain medications, which is as specific as that review gets about orange. Most of the included studies did not measure blood pressure itself, so how much any of this changes a treatment is unsettled. If you take a drug for blood pressure, what you swallow it with is a question for the person who prescribed it. The NIH Office of Dietary Supplements puts the tolerable upper intake level for vitamin C at 400 to 2,000 mg a day depending on age, with diarrhea, nausea and abdominal cramps as the usual result of going past it. The same agency warns that high intakes can raise urinary oxalate and uric acid excretion and may contribute to kidney stones, chiefly in people who already have a renal disorder. It also says that trials from 30 mg to 10 g a day have come out contradictory. Two things sold as citrus benefits are not supported. The EU register lists the orange claim about blood circulation in microvessels and heavy legs as non-authorized. It lists the claim that cryptoxanthin from orange juice strengthens the immune system as non-authorized as well. Across orange, citrus and hesperidin the register holds zero authorized claims against 21 rejected ones. The weight loss figure you may have read belongs to a Moro orange juice extract rather than to fruit. Three randomized trials in 252 overweight and obese adults pooled to 4.6 lb (2.08 kg) of body weight lost, with a confidence interval of 7.7 to 1.5 lb (3.50 to 0.67 kg), and the authors of that meta-analysis say the optimal dose and duration are not established. Juice trades away consistency. Across 8 sampled lots, raw navel oranges ranged from 51.8 to 65.6 mg of vitamin C per 3.5 oz (100 g), a spread of 23 percent. Juice from concentrate ranged from 15.9 to 38.4 mg, a spread of 84 percent. Cooking costs less than people expect. The USDA retention factor for cooked citrus leaves 95 percent of the vitamin C and 70 percent of the folate, and that factor is set for the whole fruit group rather than for one fruit, on a table dated 1975. Deficiency has not disappeared from rich countries either. A synthesis of 25 observational studies and case series, 147 patients in all, found a pooled mean of 2.29 affected organ systems per patient. Those cases clustered in children with neurodevelopmental disorders, restrictive eating and medically complex conditions.

Sources

1. clemor-daily-r2-09 · food composition dataset
   Clementine, raw: Vitamin C, total ascorbic acid 26.7 MG per 100 g [fdc_id 2709164] ... Orange, raw: Vitamin C, total ascorbic acid 56.2 MG per 100 g [fdc_id 2709171]
   USDA FoodData Central, FNDDS survey foods, release 2024-10-31 · checked 2026-09-25
2. clemor-daily-r2-10 · food composition dataset
   Oranges, raw, navels: Vitamin C, total ascor 59.1 MG, range 51.8-65.6 (median 58.0), 8 samples, spread 23% ... Orange juice, no pulp, not fortified, not from concentrate: Vitamin C, total ascor 30.54 MG, range 24.8-38.6 (median 28.95), 8 samples, spread 45% ... Orange juice, no pulp, not fortified, from concentrate: Vitamin C, total ascor 26.89 MG, range 15.9-38.4 (median 24.35), 8 samples, spread 84%
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-25
3. clemor-daily-r2-11 · food composition dataset
   Oranges, flesh only, CoFID code 14-327: Vitamin C (mg) 52, Potassium (mg) 122, Total sugars (g) 8.2, Water (g) 87.0, Folate (ug) 33
   CoFID 2021, Public Health England · checked 2026-09-25
4. clemor-daily-r2-12 · food portion dataset
   Clementine, raw, FNDDS code 61100600: 1 fruit 85 g with 22.7 MG vitamin C, 1 cup 200 g with 53.4 MG ... Orange, raw, FNDDS code 61119010: 1 fruit 154 g with 86.5 MG vitamin C, 1 cup 180 g with 101.2 MG
   USDA FoodData Central, FNDDS survey foods, release 2024-10-31 · checked 2026-09-25
5. clemor-daily-r2-02 · systematic review and meta-analysis of interventions
   Including ascorbate-rich fruits in meals had a positive impact on serum ferritin [7 trials, n = 762; mean difference (MD) = 9.39 μg/L; P < 0.001; moderate certainty], hemoglobin (12 trials, n = 1141; MD = 1.34 g/L; P = 0.01; moderate certainty), serum transferrin receptor (6 studies; MD = -0.37 mg/L; P < 0.001; high certainty), and iron balance (1 trial; MD = 2.4; low certainty). ... No impact on iron absorption (3 studies; MD = 3.36%; P = 0.07, low certainty), plasma ferritin (4 studies; MD = -0.11 μg/L, P = 0.82; high certainty), or plasma transferrin receptor (3 studies; MD = 1.53 mg/L; very low certainty).
   Am J Clin Nutr, 2026 · checked 2026-09-25
6. clemor-daily-r2-13 · nutrient retention factor table
   FRUITS,CITRUS,CKD, Retn_Code 270, group Fruits and Fruit Juices (code 9): vitamin_c_mg 95% remains / 5% loss, folate_total_ug 70% remains / 30% loss, calcium_mg 100% / 0%, potassium_mg 100% / 0%
   USDA Table of Nutrient Retention Factors, Release 6, 2007 · checked 2026-09-25
7. clemor-daily-r2-01 · systematic review and meta-analysis of RCTs
   Three RCTs involving 252 participants were included in our analysis. The extract significantly reduced body weight (mean difference (MD) -2.08 kg; 95% confidence interval (CI) -3.50, -0.67; I2 = 0%; p < 0.01) and fat mass (MD -1.53 kg; 95% CI -2.92, -0.15; I2 = 0%; p = 0.03), the pooled analysis of waist circumference presented heterogeneous point estimates (MD -3.25 kg; 95% CI -6.44, -0.07; I2 = 99%; p = 0.05).
   Nutr Health, 2026 · checked 2026-09-25
8. clemor-daily-r2-03 · systematic review and meta-analysis
   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 2026-09-25
9. clemor-daily-r2-04 · agency fact sheet
   In general, vitamin C has low toxicity, and high intakes of vitamin C do not cause serious adverse effects. However, high doses of vitamin C can lead to diarrhea, nausea, abdominal cramps, and other gastrointestinal disturbances. ... The Tolerable Upper Intake Level for vitamin C ranges from 400 to 2,000 mg, depending on age.
   NIH Office of Dietary Supplements, Vitamin C Fact Sheet for Health Professionals · checked 2026-09-25
10. clemor-daily-r2-06 · EU health claim register entry
    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 2026-09-25
11. clemor-daily-r2-07 · EU health claim register entry
    POL-HC-7000 Cryptoxanthin from orange juice (Cryptoxanthin from) orange juice participate to strengthen immune system. Clarification provided (Cryptoxanthin from) orange juice ensure antioxidant action / ensure protective effect on the organism. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7000, snapshot 2026-09-21 · checked 2026-09-25
12. clemor-daily-r2-05 · agency fact sheet
    High vitamin C intakes also have the potential to increase urinary oxalate and uric acid excretion, which could contribute to the formation of kidney stones, especially in individuals with renal disorders [8].
    NIH Office of Dietary Supplements, Vitamin C Fact Sheet for Health Professionals · checked 2026-09-25
13. clemor-daily-r2-08 · systematic review and multilevel meta-analysis of observational studies
    Twenty-five studies, including 147 patients, were analyzed. Patients diagnosed with scurvy frequently presented with involvement of multiple organ systems, with a pooled mean of 2.29 affected organ systems per patient (95% CI: 1.62-2.96; I2 = 66.8%), highlighting clinically relevant heterogeneity in presentation. ... Across studies, cases predominantly clustered in pediatric patients with neurodevelopmental disorders, restrictive dietary patterns, medically complex conditions, and psychosocial vulnerability.
    Nutrients, 2026 · checked 2026-09-25