Tuesday, October 28, 2008

Toxin definition

A toxin is a poisonous substance produced by living cells or organisms that is active at very low concentrations. Toxins can be small molecules, peptides, or proteins and are capable of causing disease on contact or abso with body tissues by interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute to almost immediately deadly (as in botulinum toxin).

Toxins are often distinguished from other chemical agents by its method of production- the word toxin does not specify method of delivery (compare with venom and (the narrower meaning) of poison). It simply means it is a biologically produced poison. There was an ongoing dispute between NATO and the Warsaw Pact over whether to call a toxin a biological or chemical agent, in which the former opted for the latter, and vice versa.

Biotoxins vary greatly in purpose and mechanism, and can be highly complex (the venom of the cone snail contains dozens of small proteins, each targeting a specific nerve channel or receptor), or relatively small protein.


Biotoxins in nature have two primary functions:
Justify Full
* Predation (spider, snake, scorpion, jellyfish, wasp)
* Defense (bee, poison dart frog, honeybee, wasp)

Some of the more well known types of biotoxins include:

* Cyanotoxins, produced by cyanobacteria
* Hemotoxins target and destroy red blood cells, and are transmitted through the bloodstream. Organisms that produce hemotoxins include:
o Pit vipers, such as rattlesnakes
* Necrotoxins cause necrosis (i.e., death) in the cells they encounter and destroy all types of tissue. Necrotoxins spread through the bloodstream. In humans, skin and muscle tissues are most sensitive to necrotoxins. Organisms that possess necrotoxins include:

o The brown recluse or "fiddle back" spider
o The "Puff Adder" - Bitis arietans
o Necrotizing fasciitis (the "flesh eating" bacteria)
* Neurotoxins primarily affect the nervous systems of animals. Organisms that possess neurotoxins include:
o The Black Widow and other widow spiders
o Most scorpions
o The box jellyfish
o Elapid snakes
o The Cone Snail
* Cytotoxins are toxic at the level of individual cells, either in a non-specific fashion or only in certain types of living cells:
o Ricin is a plant toxin found in the castor bean plant

When used non-technically, the term "toxin" is often applied to any toxic substances. Toxic substances not of biological origin are more properly termed poisons. Many non-technical and lifestyle journalists also follow this usage to refer to toxic substances in general, though some specialist journalists at publishers such as the BBC and The Guardian maintain the distinction that toxins are only those produced by living organisms.

In the context of alternative medicine the term is often used non-specifically to refer to any substance claimed to cause ill health, ranging anywhere from trace amounts of pesticides to common food items like refined sugar or additives like artificial sweeteners and MSG.

* Apitoxin
* Exotoxin
* Hemotoxin
* Mycotoxin
* Neurotoxin
* Phototoxin
* Cardiotoxin III
* Toxicophore
* Toxoid
* Venom

Food poisoning is a general term for health problems arising from eating contaminated food. Food may be contaminated by bacteria, viruses, environmental toxins, or toxins present within the food itself, such as the poisons in some mushrooms or certain seafood. Symptoms of food poisoning usually involve nausea, vomiting and/or diarrhea. Some food-borne toxins can affect the nervous system.

Natural toxins in food

Food contains natural chemicals that are essential for growth and health, including carbohydrates, sugars, proteins and vitamins. But some foods contain potentially harmful natural toxins.
The reason for the presence of natural toxins is not always known. In some foods, a toxin is present as a naturally occurring pesticide to ward off insect attack. Or a toxin may be formed to protect the plant from spoilage when damaged by weather, handling, UV light or microbes.
Your own sensitivity to a natural toxin, as well as the concentration (strength) of the toxin present, will determine whether you have an adverse reaction and the strength of symptoms you experience.
The commonly eaten foods listed below may contain natural toxins. You can limit your exposure to natural toxins by following the simple practices outlined below.

Fruit seeds and pits

Apple and pear seeds and the inner stony pit of apricots and peaches contain a naturally occurring substance called amygdalin.
Amygdalin can turn into hydrogen cyanide in the stomach causing discomfort or illness. It can sometimes be fatal.
Accidental swallowing of an occasional seed or pip is not a concern. However, do not make a habit of eating the seeds from these fruits. For a young child, swallowing only a few seeds or pits may cause illness and in rare cases can be fatal.


Parsnips commonly contain a group of natural toxins known as furocoumarins. These are probably produced as a way of protecting the plant when it has been stressed. The concentration of the toxin is usually highest in the peel or surface layer of the plant or around any damaged areas.
One of the furocoumarin toxins can cause stomach ache and may also cause a painful skin reaction when contact with the parsnip plant is combined with UV rays from sunlight.
It is important to peel the parsnip before cooking and remove any damaged parts. The levels of toxin drop when the parsnip is cooked by baking, microwaving or boiling. Discard any cooking water.


All potatoes contain natural toxins called glycoalkaloids. The levels are usually low but higher levels are found in potato sprouts, and the peel of potatoes that taste bitter. The toxins are produced by the plant in response to stress such as micro-organisms, UV light, and damage such as bruising. The amount of toxin depends on the type of potato and the growing conditions.
Severe stomach ache and even death from glycoalkaloid poisoning has been reported overseas, but is very unusual. Glycoalkaloids are not destroyed by cooking, so it is important to avoid eating the sprouts and to remove any green or damaged parts before cooking. Do not eat cooked potatoes that still taste bitter. If you come across a green potato crisp, it’s probably best not to eat it. Remember to store potatoes in a dark, cool and dry place.

Kidney beans

Many types of beans contain toxins called lectins. The highest concentrations are found in kidney beans, especially red kidney beans. As few as four or five raw beans can cause severe stomach ache, vomiting and diarrhoea.
To destroy the toxins, soak the beans for at least five hours and then boil them briskly in fresh water for at least 10 minutes. Do not cook beans at a low temperature, for example in a slow cooker, as it may not destroy the toxin. Improperly cooked beans can be more toxic than raw ones. Tinned beans can be used without further cooking.

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