NutriDex

The Supplement Research Compendium
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Grapefruit

Citrus × paradisi

Tart citrus rich in vitamin C and lycopene

Moderate evidence 🍎Fruits

✚ Updated · How we grade evidence

Evidence tier
Moderate
Research weight
Citations
7 verified / 7
Classification
Fruits
❝
What the evidence says. Several controlled trials; effects real but modest or context-dependent.

Nutrition per serving 1/2 medium (123 g)

123gSERVING
  • Water 108.3 g88%
  • Sugars 8.5 g7%
  • Fibre 2 g2%
  • Other carbs 2.6 g2%
  • Protein 0.9 g1%
  • Fat 0.2 g0%
What's in one serving, by weight — average composition (USDA).
Vitamin C43%Fibre7%Vitamin A8%Potassium3.5%Folate4%
One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
52 kcal0.9 g protein2 g fiber0.2 g fat
NutrientPer serving% daily value
Vitamin C38 mg43%
Fibre2 g7%
Vitamin A71 µg RAE8%
Potassium166 mg3.5%
Folate16 µg DFE4%
Lycopene1745 µg0%
Beta-carotene844 µg0%
Calcium27 mg2.1%

Composition data: USDA FoodData Central ↗

What is Grapefruit?

Grapefruit (Citrus × paradisi) is a fruit used for may modestly lower systolic blood pressure (small effect, limited trials). NutriDex grades the human evidence as Moderate. Human evidence for grapefruit is moderate and largely indirect. A 2017 systematic review and meta-analysis (Onakpoya) of just three small RCTs (n=250) found a statistically significant but small reduction in systolic blood pressure (~2.4 mmHg) and no significant effect on body weight. A small 30-day controlled feeding study (Gorinstein, n=57 coronary-atherosclerosis patients) reported reductions in total and LDL cholesterol and triglycerides, with red grapefruit outperforming blond/white; the trial was small and not blinded. Broader citrus-intake cohorts (Yamada; Cassidy) associate frequent consumption with lower stroke and cardiovascular risk, consistent with general fruit-and-vegetable dose-response meta-analyses (Aune), though the citrus-specific association in Cassidy was not statistically significant. Limitations are substantial: few grapefruit-specific RCTs, short durations, small samples, and confounding in observational data. Benefits are best viewed as part of an overall fruit-rich diet rather than from grapefruit alone.

Purported Benefits

✓May modestly lower systolic blood pressure (small effect, limited trials)
✓May help reduce LDL-cholesterol and triglycerides (esp. red varieties), based on small trials
✓High vitamin C supports immune and antioxidant function
✓Low energy density may aid satiety, though trials show no significant weight change
✓Citrus/flavanone intake linked to lower stroke and CVD risk in cohorts

Dosing & Compounds

Typical Dose
A typical serving is half a medium grapefruit (~123 g) or one whole fruit, eaten fresh as part of a varied fruit intake. Metabolic trials showing modest benefit used roughly half a fresh grapefruit before meals (3x/day) for 6-12 weeks.
Active Compounds
Vitamin C (ascorbic acid)Lycopene (pink/red varieties)Beta-caroteneFlavanones (naringin, naringenin)Furanocoumarins (bergamottin, 6',7'-dihydroxybergamottin)Pectin (soluble fibre)PotassiumFolate

Safety & Cautions

Clinically important: grapefruit furanocoumarins irreversibly inhibit intestinal CYP3A4, raising blood levels of many drugs (certain statins e.g. simvastatin/atorvastatin, some calcium-channel blockers, immunosuppressants like tacrolimus/cyclosporine, some benzodiazepines, amiodarone, and others) — effects can persist ~24 h, so separating timing does not avoid them; check medication labels and consult a pharmacist. Acidic and naturally sugary, so moderate intake if managing blood glucose or acid reflux/dental erosion. True citrus allergy is uncommon but possible. Educational only — always check with your doctor or pharmacist before combining Grapefruit with any medicine.

Grapefruit drug interactions

Known or theoretical interactions between Grapefruit and common medications — educational, not exhaustive. Always check with your doctor or pharmacist before combining Grapefruit with any medicine.

Avoid
Statins, some CCBs, immunosuppressants & other CYP3A4 drugs
Grapefruit can sharply raise levels of simvastatin/atorvastatin and other CYP3A4 drugs — toxicity risk.
Furanocoumarins irreversibly inhibit intestinal CYP3A4, reducing first-pass metabolism. FDA — Grapefruit Juice and Some Drugs Don't Mix

Key Studies

Meta-analysis Frontiers in Nutrition 2023 ✓ Full text
Dose-response meta-analysis of hesperidin supplementation on cardiovascular risk factors in adults, providing pooled estimates for blood pressure and lipid outcomes from randomized trials.
Meta-analysis Onakpoya 2017 ✓ PubMed
Systematic review/meta-analysis of 3 small RCTs (n=250, overweight/obese): grapefruit lowered systolic BP by ~2.43 mmHg but had no significant effect on body weight; authors note paucity of trials and short durations.
Meta-analysis Aune 2017 ✓ PubMed
Dose-response meta-analysis of 95 prospective studies: each 200 g/day of fruit & veg lowered CHD (RR 0.92), stroke (0.84) and all-cause mortality (0.90); benefit plateaued ~800 g/day. Citrus among protective subtypes.
Controlled trial Gorinstein 2006 ✓ PubMed
In 57 hyperlipidemic coronary-atherosclerosis patients, 30 days of fresh red grapefruit reduced total cholesterol (~15.5%), LDL (~20.3%) and triglycerides (~17.2%); red outperformed blond. Small, unblinded controlled trial.
Review European Psychiatry 2025 ✓ Full text
Review documenting that grapefruit juice substantially raises plasma drug levels via intestinal CYP3A4 inhibition (buspirone 4.3-fold, diazepam ~3-fold AUC), with effects lasting ~24 hours, underscoring clinically important grapefruit-drug interaction risk.
Cohort Yamada 2011 ✓ PubMed
Jichi Medical School cohort (n=10,623): almost-daily citrus intake associated with lower CVD incidence (HR ~0.51 women, ~0.57 men), notably for stroke/cerebral infarction but not myocardial infarction.
Cohort Cassidy 2012 ✓ PubMed
Nurses' Health Study (n=69,622): highest flavanone intake associated with 19% lower ischemic stroke risk (RR 0.81); the citrus-specific association trended protective but was not statistically significant.
7 sources cited · 7 verified Search all studies on PubMed ↗

Common questions about Grapefruit

What is Grapefruit used for?

Grapefruit is most often taken for May modestly lower systolic blood pressure (small effect, limited trials), May help reduce LDL-cholesterol and triglycerides (esp. red varieties), based on small trials, High vitamin C supports immune and antioxidant function, Low energy density may aid satiety, though trials show no significant weight change. Tart citrus rich in vitamin C and lycopene

Does Grapefruit work — what does the evidence say?

Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Human evidence for grapefruit is moderate and largely indirect. A 2017 systematic review and meta-analysis (Onakpoya) of just three small RCTs (n=250) found a statistically significant but small reduction in systolic blood pressure (~2.4 mmHg) and no significant effect on body weight. A small 30-day controlled feeding study (Gorinstein, n=57 coronary-atherosclerosis patients) reported reductions in total and LDL cholesterol and triglycerides, with red grapefruit outperforming blond/white; the trial was small and not blinded. Broader citrus-intake cohorts (Yamada; Cassidy) associate frequent consumption with lower stroke and cardiovascular risk, consistent with general fruit-and-vegetable dose-response meta-analyses (Aune), though the citrus-specific association in Cassidy was not statistically significant. Limitations are substantial: few grapefruit-specific RCTs, short durations, small samples, and confounding in observational data. Benefits are best viewed as part of an overall fruit-rich diet rather than from grapefruit alone.

What is the typical dose of Grapefruit?

A typical serving is half a medium grapefruit (~123 g) or one whole fruit, eaten fresh as part of a varied fruit intake. Metabolic trials showing modest benefit used roughly half a fresh grapefruit before meals (3x/day) for 6-12 weeks.

Is Grapefruit safe? Any cautions or side effects?

Clinically important: grapefruit furanocoumarins irreversibly inhibit intestinal CYP3A4, raising blood levels of many drugs (certain statins e.g. simvastatin/atorvastatin, some calcium-channel blockers, immunosuppressants like tacrolimus/cyclosporine, some benzodiazepines, amiodarone, and others) — effects can persist ~24 h, so separating timing does not avoid them; check medication labels and consult a pharmacist. Acidic and naturally sugary, so moderate intake if managing blood glucose or acid reflux/dental erosion. True citrus allergy is uncommon but possible.

How many studies support Grapefruit?

NutriDex cites 7 sources for Grapefruit, graded "Moderate".

Does Grapefruit interact with any medications?

Yes — known or theoretical interactions include: CYP3A4 drugs (some statins, CCBs, immunosuppressants) (avoid). This is educational and not exhaustive; always check with your doctor or pharmacist before combining Grapefruit with any medicine.

Cite this page
APA

Peh, D. (2026). Grapefruit (Citrus × paradisi): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/grapefruit

BibTeX
@misc{nutridex_grapefruit,
  author       = {Peh, Daryl},
  title        = {Grapefruit (Citrus × paradisi): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/grapefruit},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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