Plant Toxins

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Oxalic Acid and Oxalates in plants

Plants containing Oxalic acid form a high proportion of the Mongolian gerbil and other gerbil species natural diet, and they seem to have developed a good level of tolerance to it. Plants such as Atriplex, Salsola, and even buckwheat and oats (All desert staple plants of the Mongolian gerbil) have a high Oxalic acid content. Oxalic Acid has the ability to bind with several important nutrients making them inaccessible to the body. So we can assume that regular consumption of large amounts of these plants over a long period may result in nutrient deficiencies, the most notable of these nutrients is Calcium. Apart from Calcium, Oxalic acid is known to combine with, iron, sodium, magnesium, or potassium to form less soluble salts known as oxalates. Oxalates can also occur naturally in plants. Oxalates form tiny insoluble crystals with sharp edges, and just like Oxalic acid it can be irritating to internal tissue. In many species, including humans, long-term problems can occur with high ingestion of both Oxalic acid and Oxalates, which can include irritation to the digestive system, stomach and also the kidneys. It is also thought they may promote the formation of kidney stones.

Some main Plant foods with high concentrations of oxalic acid (over 200 ppm) include: buckwheat, star fruit, purslane, poppy seeds, rhubarb, spinach, plantains, ginger, almonds, cashews, peanuts, sorrel, mustard greens, bell peppers, sweet potatoes, soybeans, beets and beet greens, oats, pumpkin, cabbage, green beans, mango, eggplant, tomatoes, lentils, most berries, especially strawberries and cranberries) Parsley, Swiss Chard, Summer squash, and parsnips.

As I mention earlier, foodstuffs very high in oxalates are present in the gerbil's native staple diet.  Typically, most of their native plants have extremely high amounts.  So how would they tolerate, or even thrive on these foods? The answer to this intriguing question may be bacteria!  The Mongolian gerbil, may have adapted to their high oxalate diet similar to several other rodents, the Guinea pig and other herbivores, who have specific intestinal oxalate degrading bacteria.  This bacteria has recently been given a name, Oxalobacter formigenes.  The bacteria is capable of degrading significant amounts of dietary oxalate into harmless metabolites (formates and CO2)  This enables these species to make use of the high nutrients in their staple foods, while at the same time nullifying the harmful toxins contained in them. 

I find it logical to assume that this bacteria is also present in the Mongolian gerbil and other gerbil/jird species that share similar diets, and consume large quantities of foods containing Oxalic acid.

Some interesting scientific research papers to find out more about this subject are;

Intestinal Oxalate-Degrading Bacteria Reduce Oxalate
Absorption and Toxicity in Guinea Pigs

Oxalate degradation by microbes of the large bowel of herbivores: the effects of dietary oxalate.- ALLISON, M. J. &. COOK,H. M. (1981)  Science (Washington, DC) 212: 675-676.

Also the next paper is interesting as the researchers include the specialised leaf eating gerbil, psamommys obesus, aka, the fat sand rat, in their study.  The sand rat consumes huge quantities of Atriplex Halimus (known to be high in Oxalic acid) on a daily basis -

Oxalate metabolism in the pack rat, sand rat, hamster, and white rat.- SHIRLEY E.K. &.SCHMIDT-NIELSEKN. , (1967)  /. Nutr.

Cyanides in plants

About 800 species of higher plants from 70 to 80 families, including agriculturally important species contain cyanogenic compounds. Some of these plant species include sorghum species, white clover, vetch, hydrangea, arrow grass, corn, flax, alfalfa, bamboo, lima beans, leaves and pits of Prunus species (cherries, apricots, peaches) and apple seeds. Cassava is a starchy tuber (like the potato) which, like the plants listed above, can contain cyanide. Some varieties of cassava contain more cyanide than others. Cyanide poisoning of livestock by forage sorghums and other cyanogenic plants is well documented (Mudder 1997). Many members of the sorghum family contain dhurrin. Which is a glucaside which breaks down to release hydrocyanic acid which is also known as Prussic Acid. Sudden disruption of growth in the plant, such as frost, drought or cutting can considerably increase the amount of Prussic acid. It is these elevated levels of Prussic acid that maybe lethal to cattle and livestock. Prussic acid will eventually break down in one to two weeks, so material made into hay or silage is perfectly safe to use.

However to bring things into perspective it should be noted that Coffee and table salt also contain small quantities of cyanide. Laetrile (a scam anti-cancer preparation made from apricot kernels) and sodium nitroprusside (a drug used to reduce high blood pressure), release cyanide upon metabolism.

With respect to adverse effects other than acute toxicity, there is no evidence that cyanide is teratogenic, mutagenic, carcinogenic, or bio-accumulative in humans, animals, or aquatic life (Smith & Mudder 1994). Moreover, there have been no reports of cyanide bio-magnification or cycling in living organisms, probably owing to its rapid detoxification (Hagelstein 1997). The majority of any absorbed cyanide reacts with thiosulphate in the presence of enzymes to produce thiocyanate, which is excreted in the urine over several days. Owing to this rapid detoxification, animals can ingest high sub-lethal doses of cyanide over extended periods without any harm (Eisler 1991). The biggest environmental concern relates to minimising short-term exposures to cyanide levels that would be considered to be acutely toxic (Mudder 1997).

Mould toxins

Various natural toxins, which have been present throughout vertebrate evolutionary history, can cause problems to rodents, and despite their presence throughout evolution, mammals have developed no toxic harmony with them, and they have been shown to cause cancer in man and animals. Mould toxins, such as aflatoxins, have been shown to cause liver cancer in rodents and other species including humans. Aspergillus flavus and Aspergillus parasiticus can be common on animal foodstuffs such as peanuts, etc, that are stored in warm, humid silos. Aflatoxins have also been found in pecans, pistachios and walnuts, grains, soybeans spices and even milk. Governments regularly test crops for aflatoxins and do not permit them to be used for human or animal food if they contain levels over 20 parts per billion. However to be on the safe side I find it's best to get human grade nuts whenever possible. Once this mould starts to develop it will appear white and in time turn will eventually turn black. At this stage the fungus will send off airborne spores into the rodent's environment that can severely damage the rodent's health. Symptoms of poisoning are lethargy, breathing problems/wheezing, blood in the urine, inflamed skin, and chronic diarrhoea. Aspergillus can rapidly grow on any fruits or vegetables that are left to rot in the rodent's environment. It should also be noted that the use of corncob bedding appears to promote the growth of this fungus far faster than any other beddings.


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