This could be old news but very credible. It has been published in credible medical journals. I was planning on making Starfruit wine, as it took best of show awards in Australia local wine contest, and already have the materials but then came across this old news article. I have no problem eating starfruit or carambola fruits when I was younger, but growing old, most problems come up like high cholesterol, diabetes which can lead to renal problems, and now this:
Starfruit,
Averrhoa carambola
Star Fruit Warning
Eating Star Fruit May be Fatal in Uremic Patients
Westport 2-11-00 Reuters Health - Am J Kidney Dis 2000; 35: 189-193
Patients with renal failure, even those not yet undergoing dialysis, can develop severe and potentially fatal neurologic complications after eating star fruit.
Dr. Yung-Hsiung Lai and colleagues at Kaohsiung Medical University, in Kaohsiung, Taiwan, explain in the February issue of the American Journal of Kidney Diseases that "substances safely ingested by healthy persons can be deleterious for uremic patients." Because of its high potassium content, star fruit may be considered to be one such substance that uremic patients should exclude from their diets.
In a review of hospital records, Dr. Lai and colleagues identified 20 uremic patients with star fruit-related toxicity in the past 10 years, of whom eight died within 5 days of ingestion despite intensive medical care and emergency hemodialysis. One patient who died had a serum creatinine level of 6.4 mg/dL and had not yet begun dialysis.
"Their initial presentations included sudden-onset limb numbness, muscle weakness, intractable hiccups, consciousness disturbance of various degrees and seizure,"the researchers say. No clinical characteristics appeared to differentiate survivors from patients who died after star fruit ingestion, with the exceptions of consciousness disturbance and seizure on presentation.
Analysis of patients' blood biochemistry and the electrolyte concentrations of star fruit "eliminated the possibility that hyperkalemia was responsible for the syndrome,"according to the report. The authors also identified uremic patients from their records who had eaten star fruit but developed none of these manifestations, suggesting that host characteristics or different types or formulations of star fruit may affect clinical outcomes.
While nephrologists in Taiwan have been aware of the dangers of star fruit consumption by uremic patients for more than 10 years, the first formal report on this issue was published only 2 years ago. Based on their experience and past reports, Dr. Lai and colleagues "warn practicing nephrologists that star fruit intoxication must be considered when uremic patients present with consciousness disturbance or other unexplained neurological symptoms."
http://starbulletin.com/2003/04/28/features/health.html
Kidney patients
should avoid star fruit
Star fruit is a decorative and refreshing treat and, for most of us, a healthy delicacy. But for some people with impaired kidney function, the star fruit (also known as carambola) can be deadly.
Researchers from Brazil and Taiwan are studying why star fruit causes serious life-threatening reactions to some kidney patients.
Question: What are the symptoms of star fruit intoxication?
Answer: Typical symptoms occur within one to five hours and include persistent hiccups, nausea, vomiting, agitation, insomnia, mental confusion and convulsions. Death sometimes results. A study conducted at the University of Sao Paulo found that hiccups were experienced in 30 of 32 cases, and vomiting in about two-thirds. Even though mental confusion and convulsions were less common, these symptoms are more likely to be associated with death.
Q: Does star fruit cause kidney problems?
A: No. Star fruit intoxication only occurred if some degree of kidney failure already existed. For most of those affected, kidney decline was extensive enough that they were being treated by blood dialysis, although in four cases kidney problems had not reached that severity. There is no evidence of any problem for people with normal kidney function.
Q: What substance in star fruit causes this problem?
A: The tangy tartness in star fruit comes from high levels of oxalic acid (or oxalate). Weakened kidneys can be damaged if high levels of oxalate accumulate in the organ. But it is likely that another toxin in star fruit is also problematic since common foods such as spinach contain even greater levels of oxalic acid and do not seem to be associated with this severe problem.
The Brazilian researchers think that star fruit contains a substance toxic to nerves (a neurotoxin). People with healthy kidneys probably clear this toxin from the blood quickly and experience no problem. Without efficient kidney function, the combined effect of oxalate and a neurotoxin may deliver a double whammy.
Q: How much star fruit needs to be consumed to produce toxic effects in kidney patients?
A: As little as one half of a fruit and less than eight ounces of star fruit juice has caused serious symptoms. One person died from eating just one fruit.
Current medical treatment for star fruit intoxication is prompt kidney dialysis. Anyone who experiences hiccups, vomiting or other unusual symptoms after eating star fruit should seek medical attention as soon as possible.
On the positive side, star fruit lovers with normal kidneys should be able to continue enjoying the delectable treat without concern.
http://www.uninet.edu/cin2003/conf/mmoyses/mmoyses.html 
