Friday Favorites: Neurotoxicity Effects of Star Fruit

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Someone walks into the ER with intractable hiccups. One of the questions the emergency room physician should ask is, “Have you been eating star fruit?”

In my video cautioning about oxalate-rich foods, I talked about star fruit nephrotoxicity—kidney toxicity. “…[E]xcessive consumption of star fruit has been associated with the development of oxalate [kidney damage].” Less than a cup of star fruit juice or three whole fruits—they’re not that big—can result in “acute star fruit nephrotoxicity.” “…[I]ngestion of even modest quantities of star fruits can produce” kidney problems;  so, it is essential to educate the public to avoid consuming star fruit, “especially on an empty stomach or in a dehydrated state” to prevent star fruit nephrotoxicity.

But what about the neurotoxicity? We’ve known for more than a quarter century now about the neurotoxic effects, but few seem to be familiar with the syndrome. It starts, most commonly, with hiccups, but then can rapidly worsen, especially in those with compromised kidney function to start out with. Why? Because the “fruit contains a powerful neurotoxin that can accumulate in blood, cross the blood–brain barrier…, and eventually cause irreversible [brain] damage.” The toxin itself, named caramboxin, is normally excreted by the kidneys; and so, is especially toxic to those with renal insufficiency—compromised kidney function—so much so that for those with severe chronic kidney disease, a single star fruit can put someone in seizures within three hours, a coma, and then death within three days.

In a series of about a hundred cases of toxicity, consumption ranged between just a half of a star fruit up to 50, with an average of about four, but most of those had some sort of pre-existing kidney disease. The average number of star fruits eaten by the normal kidney function group before their toxic dose was more like 15. So, people with normal kidney function may be more likely to suffer from kidney damage than brain damage, which starts at down around four star fruit.

The bottom line is that those with chronic kidney disease should avoid star fruit to avoid severe intoxication. In Brazil, where the fruit is popular, there are actually laws to alert people about the risks.  Because of the neurotoxins, star fruit should be prohibited for patients with chronic kidney disease, and even those with normal kidney function may want to avoid the fruit. Just something to think about, before you reach for the stars.

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• Wijayaratne DR, Bavanthan V, De Silva MVC, Nazar ALM, Wijewickrama ES. Star fruit nephrotoxicity: a case series and literature review. BMC Nephrol. 2018;19(1):288.
• Niticharoenpong K, Chalermsanyakorn P, Panvichian R, Kitiyakara C. Acute deterioration of renal function induced by star fruit ingestion in a patient with chronic kidney disease. J Nephrol. 2006;19(5):682-6.
• Garcia-Cairasco N, Moyses-Neto M, Del Vecchio F, et al. Elucidating the neurotoxicity of the star fruit. Angew Chem Int Ed Engl. 2013;52(49):13067-70.
• Tsai JT, F TC, Wang CH, Chung TH, Hsu BG. Fatal Outcome After Ingestion of Star Fruit in a Severe Chronic Kidney Disease Patient. 2009;38(3):1-3.
• Auxiliadora-Martins M, Alkmin Teixeira GC, Da Silva GS, et al. Severe encephalopathy after ingestion of star fruit juice in a patient with chronic renal failure admitted to the intensive care unit. Heart Lung. 2010;39(5):448-52.
• Barretti P. Star fruit intoxication in chronic kidney disease patients: from the first clinical description to caramboxin. J Bras Nefrol. 2015;37(4):429-30.
• De Oliveira ES, De Aguiar AS. Why eating star fruit is prohibited for patients with chronic kidney disease? J Bras Nefrol. 2015;37(2):241-7.
• Neto MM, Silva GE, Costa RS, et al. Star fruit: simultaneous neurotoxic and nephrotoxic effects in people with previously normal renal function. NDT Plus. 2009;2(6):485-8.
• Chua CB, Sun CK, Tsui HW, et al. Association of renal function and symptoms with mortality in star fruit (Averrhoa carambola) intoxication. Clin Toxicol (Phila). 2017;55(7):624-628.
• Neto MM, Robl F, Netto JC. Intoxication by star fruit (Averrhoa carambola) in six dialysis patients? (Preliminary report). Nephrol Dial Transplant. 1998;13(3):570-2.
• Alessio-Alves FF, De Souza CP, Da Silva LK, Moyses-Neto M, Pontes-Neto OM. Starfruit neurotoxicity mimicking an acute brainstem stroke. Clin Neurol Neurosurg. 2012;114(6):684-5.

Video includes graphics from Vecteezy.com

Motion graphics by Avocado Video