Know2eat

Carambola (star fruit)

Averrhoa carambola

What carambola (star fruit) has been studied for

2 associations assessed — none with dependable human evidence behind them yet. Strongest first.

  • 2 Insufficient
3 things to know first — allergies, interactions and intake limits

About carambola (star fruit)

A ridged, waxy yellow-green tropical fruit that cuts into star-shaped slices. Sweet and tart cultivars are both sold; the tart type is more acidic and higher in oxalate.

Also known as Star fruit, Starfruit, Five-corner fruit, Belimbing

Blood Sugar & Metabolic HealthKidney & Urinary Health

The evidence in depth

Best supported: Insufficient

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how impressive the food is. How we rate evidence.

Blood glucose response

Blood Sugar & Metabolic Health
Insufficient evidence

Carambola fibre has been examined in a few small studies for effects on glucose and lipids, but the human evidence base is negligible. Given the documented kidney risks, there is no basis for eating it with a health outcome in mind.

Insufficient evidence. Not enough human research to say anything useful yet.

No source is attached to this association yet, so it is rated insufficient by default. It is listed because people commonly ask about it — not because there is evidence for it.

Kidney and urinary function

Kidney & Urinary Health
Insufficient evidence

The human literature on carambola and the kidney is almost entirely a harm literature: case series of neurotoxicity in kidney disease and of oxalate injury in healthy people. There is no evidence of benefit to set against it.

Insufficient evidence. Not enough human research to say anything useful yet.

1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Ask about Carambola (star fruit)

Ask about Carambola (star fruit)

Answers are written only from the entries on this page — the same nutrients, compounds, claims and citations you can read above. Nothing is added from outside the database, and every answer lists what it was built from.

AI explanations are not switched on for this site, so there is nothing to ask here. Everything above is read straight from the database and does not need them.

Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories31 kcal2%
Protein1.04 g2%
Total fat0.33 g0%
Carbohydrate6.73 g2%
Fibre2.8 g10%
Total sugars3.98 g—
Water91.4 g—
Fats
Saturated fat0.019 g0%
Monounsaturated fat0.03 g—
Polyunsaturated fat0.184 g—
Cholesterol0 mg0%
EPA (omega-3)0 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)0.157 g—
Vitamins
Vitamin A3 µg0%
Vitamin C34.4 mg38%
Vitamin D0 µg0%
Vitamin E0.15 mg1%
Vitamin K0 µg0%
Thiamin (B1)0.014 mg1%
Riboflavin (B2)0.016 mg1%
Niacin (B3)0.367 mg2%
Pantothenic acid (B5)0.391 mg8%
Vitamin B60.017 mg1%
Folate12 µg3%
Vitamin B120 µg0%
Choline7.6 mg1%
Minerals
Calcium3 mg0%
Iron0.08 mg0%
Magnesium10 mg2%
Phosphorus12 mg1%
Potassium133 mg3%
Sodium2 mg0%
Zinc0.12 mg1%
Copper0.137 mg15%
Manganese0.037 mg2%
Selenium0.6 µg1%
Other measured compounds
Beta-carotene25 µg—
Alpha-carotene24 µg—
Lycopene0 µg—
Lutein + zeaxanthin66 µg—
Caffeine0 mg—
Ash0.52 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Carambola, (starfruit), raw (USDA FoodData Central, FDC ID 171715).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

Nothing dependable is recorded about how preparation changes this food’s nutritional properties. Rather than guess, this section stays empty.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Avoid

    Dangerous in chronic kidney disease

    Carambola contains caramboxin, a neurotoxin normally cleared by the kidneys. In people with reduced kidney function it accumulates and has caused hiccups, vomiting, confusion, seizures, coma and death, sometimes after a single fruit or a glass of juice. Anyone with chronic kidney disease or on dialysis is advised to avoid it entirely.

  • Worth knowing

    Acute oxalate nephropathy in healthy kidneys

    Large amounts of carambola juice, particularly taken on an empty stomach or while dehydrated, have caused acute kidney injury in people with previously normal kidneys through calcium oxalate deposition. Reported cases cluster around fasting juice cleanses.

  • Interaction

    Inhibits drug-metabolising enzymes

    Carambola juice inhibits cytochrome P450 3A4 in the gut wall, the same pathway involved in the grapefruit effect. It can raise blood levels of medicines that depend on that enzyme.