The Neurotoxin Caramboxin is what I’m concerned about, Oxalic Acid is not a big problem as it can be reduced to safe levels easily.
I’ve also read the Oxalic Acid makes the Neurotoxin Caramboxin more effective at poisoning you. Normally a healthy Kidney is able to process Caramboxin safely. Oxalic acid damages the kidney & thus when combined together, the Oxalic acid compromises the kidneys ability to process the Neurotoxin Caramboxin.
How much Oxalic Acid does it take to damage healthy kidneys to cause poisoning? I don’t know, it probably depends on ripeness of fruit, Cultivar or species of Starfruit & the person eating starfruit.
IIRC I’ve eaten 2 starfruits in my lifetime, both times from overripe Starfruit on clearance & both times the edges bit off. I did notice starfruit gives me the apple/grape mouth feel afterwards, whatever is causing the that mouthfeel (it’s probably Oxalic Acid) is probably what makes starfruit taste sour. I like it’s flavor, I don’t mind the mouth feel but I wonder if it is in fact the Oxalic Acid I’m actually tasting?
Very interesting… I thought the poisonous Prunus was the Bitter Oregon Cherry (P. emarginata) no?
Prunus besseyi is in the Prunus subgenus, meaning same subgenus as Plums & Peaches. I wasn’t aware any of those were toxic when the fruit is fully ripe.
What do you mean you can taste the toxins when fresh? By Fresh you mean rockhard Green Unripe, Not Fully Ripe, or Fully ripe?
And just to clraify it’s not sour taste but toxic taste? Because Chokecherries (Prunus virginiana) also taste astrigent sour but isn’t toxic. Altho I’ve heard cool weather makes the cherries loose asrignency, same might apply to Prunus besseyi? Idk
I’ve never tried one, I hope to one day. It has to be properly cooked from what I hear. I don’t think there is a mushroom you can eat raw is there? Nor would it be advisable I think.
Very interesting, I’ve never heard of this. By Tonka you mean Tonka Beans (Dipteryx odorata) a member of the Bean Family & not True Vanilla (Vanilla planifolia Complex) which is a monocot of the Orchid Family.
It’s quite alarming to see the dismissive responses here to your question. It’s not alarmist to point out that star fruit has verifiable toxicological risks.
Regarding Prunus pumila (which I believe P. besseyi is a synonym of), I haven’t found any reports during my cursory search of toxicity from the ripe fruit itself. Like most Prunus species, the seeds contain cyanogenic glycosides that can release small amounts of cyanide if chewed, but the fruit pulp is considered safe to eat as far as I know. If you could show us where you’ve read otherwise, Clark, I’d appreciate that.
Tonka beans are indeed hepatoxic in excessive quantities because of coumarin. But coumarin is an entirely different compound and mechanism than what’s seen in star fruit. It’s found naturally in trace amounts in foods like strawberries, cherries, and currants and, at sane dietary levels, is not a concern. Caramboxin on the other hand is a potent neurotoxin unique to star fruit and bilimbi.
Caramboxin is structurally related to phenylalanine and acts as an excitatory amino acid, a glutamate receptor agonist. In certain susceptible individuals (e.g. those with impaired kidney function) it can accumulate and cause intractable hiccups, confusion, paresthesia, seizures and even FATAL neurotoxicity. This isn’t something to shrug off as fine as numerous peer reviewed case reports from Brazil, India, Malaysia and other places document these effects in detail.
The second issue with star fruit is its high oxalic acid content which can crystallize within thr body as calcium oxalate and cause acute kidney injury even in previously healthy individuals after excessive intake. Certainly the most severe cases occur in patients with preexisting renal disease, but several well documented cases describe acute renal failure and neurological symptoms in otherwise healthy folks.
Star fruit consumption in the US and Europe is relatively low, so these cases are under reported here. However, it’s in tropical regions where the fruit is more commonly eaten or juiced where nephrotoxic and neurotoxic cases are more well recognized in clinical practice.
I also really, REALLY want to stress the point that toxic damage is often cumulative and subclinical. Just because one appears “fine” after years of consumption doesn’t necessarily mean the body is unaffected. Chronic low grade neurotoxicity or nephrotoxicity can remain “silent” for decades before manifesting as cognitive decline or kidney dysfunction. This pattern is certainly not exclusive to star fruit as it’s also seen with long term exposure to annonaceae fruits (such as pawpaw) where chronic ingestion has been epidemiologically linked to atypical parkinsonism and progressive supranuclear palsy.
My broader point is that awareness is not the same as fear mongering, so thank you for this thread, Prof. Porcupine. It’s really about understanding that some totally natural foods contain biologically active compounds that can have very real consequences under certain conditions. If certain foods can have physiologically beneficial effects (which we know is true), then the opposite is also true that foods can very well be physiologically detrimental.
I’m personally no health Saint as I’m a two-pack-a-day smoker since my teens and fully aware of the risks I’m taking. I don’t pretend cigarettes are risk free just because I haven’t yet developed a cough. Or that there are worse habits to have, like heroin, so that makes smoking okay. I’m well aware that my senior years (if I am lucky to live that long) will likely be spent in poorer health than I otherwise would because of my lifestyle and dietary choices. So really, acknowledging the toxicity of certain fruits does not necessarily mean we must give them up entirely, but it means thst being fully informed is wiser than blind ignorance, and frankly, I no longer eat nor do I recommend people try star fruit because of what I know. The science is out there for all to read regardless of if you stick your head in the sand or not.
I literally mean i can taste it. There are many sources that agree. Same is true of star fruit i can feel the toxicity of some i have eaten. I highly advice as i said being careful with any food your not used to consuming. I have friends who consume false morels and they were shocked i wont touch them. The same is true of them they would not touch poke greens. When plants such as poke are highly toxic i can taste a metal taste to the greens. The same is true of large amounts of coffee it can become toxic in large quantities.
" Sand cherry contains potentially dangerous cyanogenic compounds that can be toxic or fatal in larger quantities.
Symptoms of cyanide poisoning include gasping, weakness, excitement, pupil dilation, spasms, convulsions, coma, and respiratory failure leading to death."
“No standardized medicinal dosages have been established for sand cherry. Traditional use typically involved consuming small amounts of the fruit or preparing mild teas. Any medicinal use should be approached with extreme caution due to the presence of cyanogenic compounds.”
" Historically, Prunus species including sand cherry have been used in traditional medicine for:
Edible fruit – consumed fresh, dried, or made into jellies and pies
Natural dye production – green dye from leaves, gray-green dye from fruits
Rootstock for fruit trees including plums, peaches, and apricots
Soil stabilization and erosion control
Wildlife habitat and food source
Ornamental landscaping"
" Sand cherry contains cyanogenic glycosides, particularly amygdalin and prunasin, which break down in water to form hydrocyanic acid (cyanide or prussic acid). In small, controlled amounts, these compounds have been shown to:
Stimulate respiration
Improve digestion
Promote a sense of well-being
Potentially provide benefits in cancer research (though claims are largely refuted)
Traditional uses by Native American tribes included treatments for coughs, colds, and as a general antibiotic. However, scientific documentation of specific medicinal applications for this species is limited."
“Coffee can contain low levels of mycotoxins, which are toxins produced by molds, as well as pesticides and other harmful chemicals. However, these levels are generally below safety limits and are not typically harmful to most people.”
My mother got excessively ill from elderberries. She ate them raw when she was a child and they also are poison raw.
"
Annonacin is present in the fruit, leaves, and bark of plants belonging to the Annonaceae family, which includes Annona muricata (soursop) and Asimina triloba (pawpaw).4 Pawpaw is native to the eastern United States and southern Canada and is the only fruit-bearing annonaceous plant widely distributed in North America. A recent regional increase in pawpaw’s popularity is concerning in light of studies demonstrating the neurotoxicity of annonacin as well as possible associations with the development of neurodegenerative disease."
I proably shouldn’t tell everyone all of these but im going to give full disclosure
We know to avoid mysterious mushrooms, but some unassuming crops also pack a wallop of harmful toxins when eaten under certain conditions.
Plants are wonderfully wise and have devised all sorts of schemes to ensure their survival. Among other strategies, some entice pollinators to provide an assist in the romance department,1 some employ the elements to disperse their seeds, and some have developed small arsenals of chemical weapons to avoid being eaten by predators. It’s the last one that should concern us plant-eaters the most.
“The idea that all natural things are good for you is rubbish. We are eating [fruits and] vegetables that potentially contain bad things,” Peter Spencer, professor of neurology and occupational health sciences at Oregon Health and Science University, tells CNN. Many plants "were not put here for our benefit but to protect themselves from predators,” he adds.
While not all of the following fruits and vegetables may be on everyone’s grocery list, they each have particular considerations to keep in mind.
1. Lychee
Pierre-Yves Babelon / Getty Images
Sweet, floral beautiful lychee fruit seems as innocent as can be, but no. When eaten before they are ripe, toxins in the fruit can lead to extremely low blood sugar; for those with already low blood sugar or suffering from malnourishment, the toxins can lead to a host of problems from fever to encephalopathy to death.2 If you remember hearing about a mystery disease striking down Indian children every year, researchers finally tracked down the cause to, yes, unripe lychees.3 The area affected was near the country’s largest lychee-farming region and the children were eating unripe fruit all day.
2. Raw Cashews
Treehugger / Lesly Junieth
Raw cashews come complete with a resin called urushiol, which is the same compound that makes poison ivy so awful.4 It can cause pretty serious skin rashes and can be toxic when ingested or even fatal for anyone with higher sensitivity to urushiol. Now if you’re wondering why you’ve been eating cashews labeled “raw” and not had any problems, it’s because all commercial cashews are actually cooked to remove the shell. They’re sold as raw because they have not been roasted or further processed, but they have been cooked, and that’s a good thing.
3. Ackee
Roderick Chen / Getty Images
The national fruit and symbol of Jamaica, the ackee contains hypoglycin, the same toxin found in lychee.5 The threats from this native West African fruit are well-known amongst those who eat it and it’s rarely eaten uncooked or before it’s ripe. Unfortunately, not all children are aware of the danger and risk poisoning when they consume unripe ackee.6
4. Cassava
Treehugger / Lesly Junieth
One of the most important sources of calories in Africa, South America and parts of Asia, cassava fuels almost half a billion people around the world each day.7 But if not processed properly, cassava can release hydrogen cyanide, which can wreak havoc on thyroid hormones as well as affecting parts of the the brain relating to movement.8 Not to mention irreversible paralysis. That such an important source of nutrition is also so potentially toxic is vexing.
5. Starfruit
Narintorn Pornsuknimitkul / EyeEm / Getty Images
For some people, starfruit is decidedly not a lucky star, as it contains a potentially deadly neurotoxin for those with kidney disease. For people with properly functioning kidneys, the toxin caramboxin is handled without a problem.9 But for people with kidney problems, the toxic accumulates and can lead to everything from hiccups, vomiting, weakness, mental confusion, and psychomotor agitation, to unusually long-lasting epileptic seizures, coma, and death, according to a study on caramboxin.10
6. Stone Fruit Pits
Treehugger / Lesly Junieth
The pits of some stone fruits like cherries, apricots, plums, and peaches have a little secret surprise is hidden inside: Cyanogenic compounds! (In other words, the makings for cyanide.) Swallowed hole the pit will pass on through without a problem, but were you to chew it first or eat it already pulverized, things could get ugly. How much would do the trick? Anywhere between .5 and 3.5 milligrams per kilogram of body weight can be lethal. Experts at the European Food Safety Authority estimate that it is not safe for adults to eat more than three small apricot seeds in one sitting.11 For a toddler it only takes one small kernel to risk getting poisoned.
7. Potatoes
Treehugger / Lesly Junieth
For all of our talk around here about not wasting food and not fearing a lack of perfection in produce – when it comes to potatoes, a little waste might be ok. If your spuds have taken on a greenish cast or have sprouted, step away, as it’s here that the toxic alkaloid solanine is particularly concentrated.12 Even so, one would need to eat a lot of green potatoes to get to the point of vomiting, stomach pain, hallucinations or even paralysis, but still.
8. Raw Kidney Beans
Treehugger / Lesly Junieth
Thankfully, raw kidney beans are not that appealing. But I know that people on a raw food diet are often looking for novel ways to eat things without heat. Still, they shouldn’t try to get creative with beans. A lot of beans come with the toxin phytohemagglutinin, which comes in especially high concentrations in raw red kidney beans; and while cooking is enough to render the toxin harmless, just a handful of raw beans can kick symptoms into gear.13 On the bright side, recovery is pretty quick.
All of that said, this isn’t meant to be a miserable message from the Doyenne of Doom, just a reminder to be careful. Please continue eating plants, and lots of them.
"
2.5% of people are highly allergic to peanuts
One of the most dangerous foods can be sprouts.
Yes bananas can kill you too
"“It is a fact. Potassium levels are dangerously high if you have six bananas… I saw a bowl of bananas. There’s six bananas there. You know why there’s only six? Seven would be dangerous.”
So how dangerous is potassium? Actually, it is crucial for survival and can be found “within every single cell of the body,” says Catherine Collins, a dietitian at St George’s Hospital in London.
“We use it to help generate an electrical charge which helps the cell function properly. It helps keep your heart rate steady, it helps trigger insulin release from the pancreas to help control blood sugars, and more importantly keeps blood pressure in check.”
On the other hand, if the level of potassium in the body is too low or too high it can result in an irregular heartbeat, stomach pain, nausea and diarrhoea. Potassium chloride is even one of the chemicals used in lethal injections in the US, as extremely high doses can cause cardiac arrest."
Likewise, Fully Ripe Fruit flesh of Prunus spp. are not toxic. Generally I like to think most plants are not trying to poison their seed distributor but there are always few exceptions.
This explains a lot of the Almond flavor people describe in Apple Seeds & Cherry pits or leaves having an “Almondy” smell.
I don’t think a by accidently swallowed cherry bit is gonna kill you (Especially if you didn’t crush it with your teeth to release toxins) but most are definitely toxic. Altho as always sweet almonds are the exception IIRC, they have to still be cooked/processed?
Yew Berry pits on the other hand are very toxic, I’m scared to swallow even just 1 seed.
Plus I’ve carefully eaten Yew Berry flesh, they taste okay-ish but gave me horrible diarrhea afterwards, never again!
I don’t even think other members of the same family (Oxalidaceae) have this toxin right? I don’t recall Woodsorrels & Oca (Oxalis spp.) have Caramboxin.
I agree, even tho I really just want to shrug it off . But this is the reality so it’s why I really want to learn how to render this toxin safe to eat.
For now, its just eating very small amounts of Fully Ripe Starfruit (Like maybe 1 a day or 2).
Indeed, but can’t this specific toxin be reduced? I know fully ripe even overripe fruits contain less Oxalic Acid, cutting off edges/wings where Oxalic Acid Concentrates means less Oxalic Acid Consumed & cooking does help destroy Oxalic Acid, rendering it much safer.
Hmm… maybe Starfruit should be used more as a cooked fruit? Like Pineapples on Pizza except with Starfruit?
This is the sneaky Toxin I don’t like… this is what also concerns me about Pawpaw & Cherimoya. Even more so because I want to Breed different more wild versions of Pawpaw & Annona fruits thus I will be eating more of then & more crazy wilder versions of them which may be even worse for the Nuerotoxins.
This breeding goal puts me right in the cross hairs of this toxin. I need to better understand it if I’m serious about Pawpaw & Starfruit plant breeding.
Side note about Pawpaws & another Annona fruits.
I couldn’t find a definitive study showing that the flesh of fully ripe fruits without the skin & seed contain Annonacin, the Neurotoxin causing Parkinson type symptoms.
I know it’s found in Leaves, Seeds, Unripe Fruit & Skin, but all of those are exactly the parts of the fruit I don’t eat anyways so… Yea. More research is needed but I feel eating just the fully ripe flesh of pawpaws & nothing else is less risky.
It could also be the fully ripe flesh contains neglegtable amounts of Annonacin.
Lots of fruits follow this trend where fully ripe fruit flesh is safe to eat while seed or unripe fruit is toxic. Of course this is not a rule, as there’s always exception but the trend is notable.
This is also something I need to learn more about in Mayapples (Podophyllum spp.).
It also follows this trend where only the fully ripe fruit pulp is edible, unripe fruit, leaves & seeds are toxic. IIRC Podophylloxin is concentrated in the root, not the ripe fruit.
But there’s almost no studies on fruit edibility of Mayapples, just tradition & foraging culture. I’ve eaten it many times, no issues what so ever (Hopefully it ain’t one of those sneaky long term shits).
Mayapples like Pawpaws & Starfruits are another breeding project that will envolve eating lots of fruits to select which taste the best.
You’re welcome! This is why I started this tread, I want to learn more. I love starfruit, so I want to dismantle their toxins so I can enjoy them safely. No Fear mongering for a fruit you love!
I hope we can learn more so we can change that. Starfruit does have other very good health benefits, it just comes with nasty toxins , sheesh…
I like to think of beans for example, very toxic raw but oh man when cooked they are a powerhouse of nutrition. Beans have taught me not to dismiss a food because it has some toxins in it, especially if we can find a way to safely neutralize the toxins.
Keyword is safely. In starfruit I can mostly neutralize the Oxalic Acid but I haven’t found a confirmed way to neutralize the Caramboxin yet. If we find an easy way to neutralize this toxin, than I think it’s safe to recommend starfruit with those methods.
I also eat woodsorrel (Oxalis spp.) raw occasionally as a trailside nibble. If I’m gonna eat larger qunaities, I will boil them. Thankfully there is no Caramboxin in Woodsorrels.
What does it taste like? Sour or leaves that apple mouth feel but for starfruit?
Indeed! If you eat the seed especially. Thankfully Cyanide is destroyed by cooking but I still feel off eating the seed. I still wouldn’t eat any Prunus spp. ripe fruit that taste bitter.
Also should note Cyanide in very small qunaities can also have some health benefits. I occasionally eat an apple seed, cooking it however neutralizes the Cyanide.
Of course for many spices, exactly what makes the spice taste good is exactly the part that is also toxic. However in small quantities such as a spice/flavoring, they can be safe to eat & have unique health benefits.
Rhubarb leaves are toxic for high concentrations of Oxalic Acid. I wonder how much cooking would it take to reduce the Oxalic Acid to safe levels? Is it even worth it?
Yes but the distinction of ripe vs unripe fruits certainly makes a big difference! Especially if the pulp is eaten & not the skin or seed.
Many studies & articles fail to make this distinction, why? Is this because a study addressing which parts of fruit & ripeness affect the toxicity hasn’t been done yet?
That study you linked about Pawpaw grower dying from eating the fruit is indeed scary!
“Subsequently, his wife disclosed that he had habitually consumed pawpaw fruit from their family-owned nursery, starting 5 years prior to symptom onset and continuing until his death (10 years total). She estimated that he had consumed up to 13.6 kg of raw fruit annually over the five-year period prior to death.”
Especially since this is someone who as a grower of Pawpaw trees would’ve probably known to only the flesh of fully ripe fruits, not the seed, skin or leaves.
Also all this talk about toxicity in fruits really highlights the importance of good Kidney Health.
I grow sweet pit apricots as well. Poison is always bitter, almond like or objectionable in flavor. Aronias have high tannins making them healthy in very small amounts. I mix my aronia 40 parts apple juice to 1 part aronia. It tastes like grapejuice when mixed.
I’m glad we call them Aronias now, instead of their old name, “Chokeberries”
I wonder if frost changes them? I know frost works very well on Crabapples which are another wise too sour & nasty to enjoy but come first frost, they taste like delicious sour apple sauce.
My simple response to all the very in depth analysis is this. I think I can likely eat the amount of star fruit I would want to, and have no issues. The key element here is it just simply isn’t irresistible to me, and one bite is about all I want every so often. I would however definitely have not purchased a tree had I known what I know now, and also I don’t eat much of it, nor do I entice many people to try it. I do think it’s best to proceed with caution and really limit your intake. Again, for me this is easy and it’s refreshing but not something that I would call a delicious fruit.
If this was about mangoes or mandarins then I’d have a real business decision to make, but with carambola it’s an easy decision to mostly avoid them entirely.
I didn’t really mean to be dismissive of the OP’s concerns, just dismissive about myself. I’m not concerned at all about starfruit but my kidney’s are in good shape.
[quote=“Professor_Porcupine, post:24, topic:76040”]
Altho as always sweet almonds are the exception IIRC, they have to still be cooked/processed?
[/quote]Sweet almonds were selectively bred for thousands of years to get the concentration of cyanogenic glycosides down to miniscule levels.
Like i said, all food is somewhat toxic. As @ribs1 said very well, that does not mean we are not concerned for everyone else or ourselves. Most apple juice has some lead in it. The fda is who most of us have historically trusted for food and drug regulation. I have to accept some risk to stay alive.
Personally I wouldn’t ever really look for anything that could be done to reduce the toxins in starfruit as cooked starfruit isn’t very good. I would either eat it fresh or not eat it.
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but there are always few exceptions.
never again!
This is the sneaky Toxin I don’t like… this is what also concerns me about Pawpaw & Cherimoya. Even more so because I want to Breed different more wild versions of Pawpaw & Annona fruits thus I will be eating more of then & more crazy wilder versions of them which may be even worse for the Nuerotoxins.
, sheesh…