What the evidence says. Several controlled trials; effects real but modest or context-dependent.
Nutrition per serving 1/2 medium (123 g)
Water108.3 g88%
Sugars8.5 g7%
Fibre2 g2%
Other carbs2.6 g2%
Protein0.9 g1%
Fat0.2 g0%
What's in one serving, by weight — average composition (USDA).One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
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.
✓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.
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.
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 8 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 16 Sept 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 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.