Carambola

Botanical

What is it

Carambola (Averrhoa carambola), also called star fruit, is a tropical fruit native to Southeast Asia. The fruit is eaten fresh or dried and is occasionally used in supplements as a source of vitamin C and antioxidants.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Vitamin C and polyphenol intake

Mixed Evidence

Carambola contributes to vitamin C and polyphenol intake as a fruit. Specific clinical outcomes for star fruit supplementation are not well established.

How it works

Carambola provides vitamin C, fiber, and polyphenols. It also contains soluble and insoluble oxalates and a compound called caramboxin, which is neurotoxic in people with reduced kidney function. In most people, carambola is digested without issue. People with kidney impairment can experience serious neurologic symptoms (hiccups, confusion, seizures) after eating it, due to caramboxin accumulation.

Dosage

There is no specific dose. Typical food serving is one medium fruit (about 90 g).

When and how to take it

Carambola fruit and juice should be separated from CYP3A4-metabolized medications, similar to grapefruit.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Fresh fruit

Traditional consumption.

Vitamin C and polyphenols available; oxalates and caramboxin present

Fruit powder or extract

Used in some functional foods.

Concentrated nutrients and oxalates

Safety

Safe for most people at typical food intake. People with chronic kidney disease should not eat carambola due to risk of caramboxin neurotoxicity. The fruit also contains oxalates that can affect people prone to oxalate kidney stones.

Who should be cautious

Avoid completely if you have any kidney disease. Use cautiously if you have kidney stones (oxalate). Check with a clinician if you take medications metabolized by CYP3A4.

Interactions

Carambola juice and fruit can inhibit cytochrome P450 3A4 in a manner similar to grapefruit and can elevate levels of statins, calcium channel blockers, and other CYP3A4 substrates.

Food sources

Star fruit (carambola), fresh

Amount
1 medium
%DV
—

Frequently asked questions

Why is carambola dangerous for kidney patients?⌄

It contains caramboxin, which is neurotoxic and normally cleared by the kidneys. People with kidney disease cannot eliminate it efficiently.

Does carambola interact with drugs like grapefruit?⌄

Yes, it inhibits CYP3A4 similarly. Separate from sensitive medications.

References

Carambola on Wikidata — Wikidata link

Carambola on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Carambola (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.