What the evidence says. Early or small human trials; promising but not yet conclusive.
Nutrition per serving 1 medium (91 g)
Water83.2 g92%
Sugars3.6 g4%
Fibre2.5 g3%
Protein1 g1%
Fat0.3 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.
Starfruit (Carambola) (Averrhoa carambola) is a fruit used for low-calorie, high-water fruit useful for weight-conscious and hydration-focused diets. NutriDex grades the human evidence as Preliminary. Starfruit is a low-calorie, water-dense tropical fruit that delivers a useful dose of vitamin C (about a third of the Daily Value per fruit) and insoluble fiber, plus a broad mix of flavonoids and phenolic acids with antioxidant activity in laboratory assays. The most robust human evidence about starfruit, however, concerns harm rather than benefit: dozens of case reports and case series document severe nephrotoxicity and neurotoxicity—intractable hiccups, vomiting, confusion, seizures, status epilepticus, and death—after ingestion by people with chronic kidney disease, and occasionally those with normal or only mildly impaired renal function. A 2013 chemistry study isolated caramboxin, a phenylalanine-like toxin that activates glutamatergic (AMPA/kainate) receptors and inhibits the GABAergic system, explaining the neurological effects, while high soluble oxalate drives oxalate nephropathy. The widely cited metabolic and anti-diabetic \"benefits\" come almost exclusively from in-vitro and rodent experiments; there are essentially no controlled human trials confirming any therapeutic effect. Overall the weight of human evidence is preliminary for benefits and clearer for risk. For most people with healthy kidneys, normal culinary amounts are considered safe and nutritious. Anyone with reduced kidney function or on dialysis should avoid it completely.
Purported Benefits
✓Low-calorie, high-water fruit useful for weight-conscious and hydration-focused diets
✓Meaningful vitamin C contribution (about a third of the Daily Value per fruit) supporting antioxidant defense and collagen synthesis
✓Dietary fiber (largely insoluble) that may aid satiety and bowel regularity
✓Rich source of polyphenols and flavonoids with antioxidant activity in lab models
✓Preclinically studied anti-hyperglycemic and anti-hyperlipidemic actions (animal/in-vitro only)
✓Traditionally used as a cooling, thirst-quenching food in tropical cuisines
Dosing & Compounds
Typical Dose
1 medium fruit (~91 g) or ~100 g sliced; avoid entirely in chronic kidney disease
Active Compounds
Vitamin C (L-ascorbic acid)Soluble oxalate / oxalic acid (anti-nutrient and nephrotoxin)Caramboxin (phenylalanine-like excitatory neurotoxin)Flavonoid glycosides (apigenin C-glycosides, quercetin, rutin)Proanthocyanidins / condensed tanninsBenzoquinone derivatives (e.g. 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione)Insoluble dietary fiber (cellulose, lignin)Gallic acid and other phenolic acidsPotassium and copper
Safety & Cautions
⚠
CONTRAINDICATED in chronic kidney disease, end-stage renal disease, and dialysis patients—even a single fruit or glass of juice can trigger hiccups, vomiting, confusion, seizures, status epilepticus, and death (caramboxin neurotoxin plus oxalate nephropathy). Toxicity has also been reported with normal-to-moderate renal function, especially when consumed on an empty stomach, dehydrated, or in large quantity/concentrated juice. High oxalate content poses a kidney-stone risk in susceptible individuals and can cause acute oxalate nephropathy. Like grapefruit, starfruit inhibits CYP3A4 and can raise blood levels of interacting drugs (e.g. statins, certain calcium-channel blockers). If neurological symptoms appear after ingestion in a renal patient, urgent hemodialysis/hemofiltration is the recommended treatment. Educational only — always check with your doctor or pharmacist before combining Starfruit (Carambola) with any medicine.
Starfruit (Carambola) is most often taken for Low-calorie, high-water fruit useful for weight-conscious and hydration-focused diets, Meaningful vitamin C contribution (about a third of the Daily Value per fruit) supporting antioxidant defense and collagen synthesis, Dietary fiber (largely insoluble) that may aid satiety and bowel regularity, Rich source of polyphenols and flavonoids with antioxidant activity in lab models. Crisp tropical star, safe only with healthy kidneys
Does Starfruit (Carambola) work — what does the evidence say?
Preliminary evidence. Early or small human trials; promising but not yet conclusive. Starfruit is a low-calorie, water-dense tropical fruit that delivers a useful dose of vitamin C (about a third of the Daily Value per fruit) and insoluble fiber, plus a broad mix of flavonoids and phenolic acids with antioxidant activity in laboratory assays. The most robust human evidence about starfruit, however, concerns harm rather than benefit: dozens of case reports and case series document severe nephrotoxicity and neurotoxicity—intractable hiccups, vomiting, confusion, seizures, status epilepticus, and death—after ingestion by people with chronic kidney disease, and occasionally those with normal or only mildly impaired renal function. A 2013 chemistry study isolated caramboxin, a phenylalanine-like toxin that activates glutamatergic (AMPA/kainate) receptors and inhibits the GABAergic system, explaining the neurological effects, while high soluble oxalate drives oxalate nephropathy. The widely cited metabolic and anti-diabetic \"benefits\" come almost exclusively from in-vitro and rodent experiments; there are essentially no controlled human trials confirming any therapeutic effect. Overall the weight of human evidence is preliminary for benefits and clearer for risk. For most people with healthy kidneys, normal culinary amounts are considered safe and nutritious. Anyone with reduced kidney function or on dialysis should avoid it completely.
What is the typical dose of Starfruit (Carambola)?
1 medium fruit (~91 g) or ~100 g sliced; avoid entirely in chronic kidney disease
Is Starfruit (Carambola) safe? Any cautions or side effects?
CONTRAINDICATED in chronic kidney disease, end-stage renal disease, and dialysis patients—even a single fruit or glass of juice can trigger hiccups, vomiting, confusion, seizures, status epilepticus, and death (caramboxin neurotoxin plus oxalate nephropathy). Toxicity has also been reported with normal-to-moderate renal function, especially when consumed on an empty stomach, dehydrated, or in large quantity/concentrated juice. High oxalate content poses a kidney-stone risk in susceptible individuals and can cause acute oxalate nephropathy. Like grapefruit, starfruit inhibits CYP3A4 and can raise blood levels of interacting drugs (e.g. statins, certain calcium-channel blockers). If neurological symptoms appear after ingestion in a renal patient, urgent hemodialysis/hemofiltration is the recommended treatment.
How many studies support Starfruit (Carambola)?
NutriDex cites 11 sources for Starfruit (Carambola), graded "Preliminary".
Cite this page
APA
Peh, D. (2026). Starfruit (Carambola) (Averrhoa carambola): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/starfruit-carambola
BibTeX
@misc{nutridex_starfruit_carambola,
author = {Peh, Daryl},
title = {Starfruit (Carambola) (Averrhoa carambola): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/starfruit-carambola},
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.