The sources of the two articles please. Thanks.

I have a honeyheart in my backyard and don't want to feed my kids toxic fruits:(

Well, that is quite a lot of fruits you are talking about. Just in Brazil, where I lived for a time, there are a dozen cherimoya-like fruits. Fortunately, I never liked the fruit much, it is much too sweet for me. I may have eaten five, certainly less than ten in my whole life. I loved the graviola ice cream though, made with a larger, less sweet annonacea fruit.

The link below (in German) describes the PhD thesis that studied the phenomenon.

Here are the two articles:

1) Lannuzel, A; et al. (6 October 2003). "The mitochondrial complex i inhibitor annonacin is toxic to mesencephalic dopaminergic neurons by impairment of energy metabolism". Neuroscience (International Brain Research Organization) 121 (2): 287Â296. doi:10.1016/S0306-4522(03)00441-X.

2) Champy, Pierre; Hoeglinger, Guenter U.; Feger, Jean; Gleye, Christophe; Hocquemiller, Reynald; Laurens, Alain; Guerineau, Vincent; Laprevote, Olivier; Medja, Fadia; Lombes, Anne; Michel, Patrick P.; Lannuzel, Annie; Hirsch, Etienne C.; Ruberg, Merle (2004). "Annonacin, a lipophilic inhibitor of mitochondrial complex I, induces nigral and striatal neurodegeneration in rats: Possible relevance for atypical parkinsonism in Guadeloupe". Journal of Neurochemistry 88 (1): 63Â69

Note that the journals are Neuroscience and the Journal of Neurochemistry, both respected, peer reviewed journals.

Note also that they've identified the mode of action of the neurotoxin--it impairs the mitochondria in certain nerve cells. So, this is hard science here, and should not be dismissed.

As regards your children, their brains are still developing, and thus they are likely to me more sensitive to neurological damage than adults.

Note also that a friend of mine stopped drinking espresso at home when a link was found between Alzheimer and aluminum. He had one of those italian stovetop things, made of Al. He just missed on a lot of espressos, and did no favors to his brain (he has resumed using it since). Epidemiological studies are the hardest evidence there is, but I did not see much dementia anywhere in South America. Why only in Guadeloupe?

(sorry for changing the header, gardenweb is acting up on me)

That's why I've been hesitant to try the pawpaw -- even though there are zero epidemiological studies on pawpaw. If it makes up a small part of the diet, it's probably alright, since there has to be extensive damage to get parkinsonism symptoms and a few fruit would be unlikely to cause that much damage. However, Parkinson Disease runs in my husband's family, so I am more cautious in case the cumulative damage from all sources might increase the risk for PD. Otherwise I might well plant a pawpaw tree.

Thanks for posting.

Mary, I read somewhere that the pawpaw has negligible levels of the toxin. Better check that out for yourself, however.

Scott, thanks for the link to the cloudforest discussion board. I'm going to have to disagree that there's no reliable data. The article presented on cloudforest was sufficiently good for me to stay away from these fruits. Yes, a full-fledged epidemiological study would be necessary to nail the issue once and for all, but honestly, why would you consume a fruit that had ANY level of a neurotoxin? For the record, there is no such thing as a safe level of a chemical that inhibits mitochonrial complex I.

I think ScottSmith said it best -- moderate consumption probably isn't a danger to anyone. It's one of those things where more research is needed.

In the meantime, I certainly wouldn't dwell on it. A lot of people get overly stressed about things that MIGHT get them, and don't even worry about the things they do all the time that are ALREADY destroying their health. Case in point, I used to know this lady who lived next door to some high voltage transmission lines. She obsessed about whether the EMF was going to give her brain cancer. The three packs a day she smoked are what did her in in the end.

OK, I'll get off the soapbox now.

Let us also keep in mind that if you eat one pound of parsley in one sitting you will die right there. Obviously, we have all eaten pounds of the stuff in our lives. I saw it listed in a list of the 500 most toxic plants in temperate climates. It is a close relative of hemlock, of Socrates' fame.

Asparagus and pokeweed are the shoots of a lethal and toxic plant respectively. Carrot tops are listed as toxic, but they are sold in farmer markets in Europe as a stock green, and I use them myself by the pound to make stock. Going to rarer situations, there are the potentially lethal consequences of eating favas, which does not stop the city of Rome, Italy, from eating them twice a week for 3 months in spring (all 4 millions of them).

I would have a tree, if it is care-free and productive. And you can't eat many of them, they are just too rich. Even one is too much, and I routinely eat half a watermelon in a sitting in the summer.

I've known about this issue for several years now. Given that I have a pretty significant garden investment in annonas (a dozen cherimoya trees, a dozen pawpaw trees, and a few exotic annonas from Brazil), and given that cherimoyas are so incredibly delicious, before ripping out my trees, I decided to wait it out that some things get cleared up. Here's what's not very consistent:

Soursop juice and pulp is consumed in great quantities throughout the tropics, and the only population that has shown the parkinson's like symptoms is the one in Guadeloupe. Go to any chinese, vietnamese, or other Asian market, and you will not only find tonns of fresh cherimoyas, but also lots of processed soursop products. Not to mention the Andes, where cherimoyas are consumed in great quantities and processed into ice cream and other items. None of these populations have shown any issues around annona consumption.

There are a number of theories around:

1) It turns out that annonacin becomes non-toxic in the presence of sugar.

2) The pulp used in the studies may contain the skin as well as the fruit pulp. It's well known that all the plant parts of annona trees are highly toxic except for the fruit.

3) The Guadelupe population uses other parts of the annona tree as tea and other medicinal purposes. Seems that is where the trouble is.

So until someone shows that eating JUST the pulp of annonas and not any other plant parts also causes illness, I will not be so quick as to dump all my annona trees. However, I will eat the fruit in moderation.

I grew up in South America eating guanabanas and cherimoyas. I think I am fine. However, I think the California growers need a better representative. I attended a University of California Agriculture Department cherimoya testing in February and found that one of the Cherimoya Association was a very rude person, accusing a respectful gardener that attended the testing of STEALING the cherimoyas. When indeed, everyone who paid $10 got a small sack to take as many cherimoyas as he/she could put in the sack (usually 4 or 5). This persona screamed STEALING loud in front of everyone, not noticing that the person was or asiatic origina and did not understand English well. All he needed to do say was: do not take fruits from this table, please go to that table to get the ones you PAID for. I immediately quit eating cherimoyas and left. This mans is short, with a receding line, and dyes his hair black. He is very loud and seems of Indian or Mexican descend.

There is a very famous saying among toxicologists; "The dose makes the poison." Even water is lethal at too high a dose. It is very unlikely that consuming cherimoya pulp is dangerous, but of course one should avoid the skin and seeds (since they don't taste good). Of course I'm sure if you eat enough of the pulp (or anything else on Earth) you could make yourself sick.

When I eat too many plums I get diarrhea. Must be toxic too?

Graviola, Cherimoya and Paw Paw also have strong anti-cancer benefits. Maybe the benefits outweigh the risks, considering chances of getting cancer are like 50% in a lifetime.

We are typically unaware of all the potential toxins in our food. In one study years ago, the brain development of young monkeys was seriously disrupted by feeding them lots of alfalfa sprouts (raw). Other raw leguminous foods also contain some pretty serious toxic elements when eaten in quantity.

In many fruits and vegetables (also seeds), toxins are concentrated in or just under the skin -- the part we are told contains the most nutrients. Makes sense for a plant's defenses against insects and animals to be near the surface. When the purpose of fruit is to attract animals in order to spread seeds, toxins often decrease dramatically as the fruit ripens. Vegetables which have been under cultivation for a long, long time and thus have human protection from animals and insects are typically lower in toxins than wild relatives of those vegetables.

Bruce Ames, who led the development of the Ames tests for potential mutagenicity and carcinogenicity, was shocked to discover how many foods have carcinogenic potential. But when asked what changes he had made as a result of what he had learned he said that the only rules he had were to avoid smoking and to take the skin off barbecued chicken. I think he would be opposed to the trend toward "blackened" cuisine, too.

Carolyn made a really great observation here.....

It turns out that *Most* fruits and vegetables do contain "Toxic" things or poisons of one sort or another..... Some in fairly small doses and others in fairly large doses.....

BUT... Over the course of Human existance - we have managed to work out many of these issues by picking at the proper point of ripening, proper preparation and/or cooking....

Examples of this abound....

For example... I made Jelly out of wild pears.... The pears were incredibly bitter raw... Eating even a small quantity would give you a terrible stomach ache..... but when cooked - delicious with no issues at all... The bitter chemicals go away during cooking.... Quince and Cider apples are similar in this regard...

Another good example is that while Cherries, peaches, and plums are delicious - you don't eat the pits... because they are generally inedible and bitter....

Crack open a walnut, pecan, or hickory nut and make the mistake of eating some of the pith and you will be unhappy....

Thanks

thisbud4u(San Diego) thanks for this valuable info. Seeds and skin of these fruits are poisonous for humans, so it's quite logical for the flesh to be poisonous too. Maybe only a little, but still. Again, thank you for the info.