Much of the laboratory studies have been done in the unfortunately usual mode
of pharmacology. This author in no way endorses or supports animal experiments
with herbs. The reasons are discussed at length elsewhere. The reasons for
introducing such tainted research findings here is to illustrate the way in
which such science is "proving" to itself what herbalist's already know.
Of the herbs discussed here Carduus is more often used in Europe and
North America, Glycyrrhiza in Japan, Schizandra in China, and
Bupleurum in Japan and China.
Milk Thistle & Silymarin
The importance of botanical accuracy is highlighted here. In different places
this herb is called Milk Thistle, Mary Thistle and even Sow Thistle.
Historically this herb has been used in Europe as a liver tonic and current
Phytotherapy indicates its use in a whole range of liver and gall bladder
conditions including hepatitis and cirrhosis. It may also have value in the
treatment of chronic uterine problems. A wealth of research done in Germany is
revealing exciting data about reversal of toxic liver damage as well as
protection from potential hepatotoxic agents. A number of chemical
components of herb are now being shown to have this protective effect on liver
cells. They are all flavones and flavo-lignins, the flavones often grouped
together as silymarin.
In laboratory tests a range of effects have been demonstrated
- silymarin reduced the harmful actions on the liver of hepatotoxins
such as carbon tetrachloride, thioacetamide, a-amanitin and phalloidin.
- a protective effect against carbon tetrachloride induced liver damage in
- a reduction of the prolongation of hexobarbital sleeping time produced by
carbon tetrachloride. This is a common method for assessing protective effects
on the liver against the effects of chemical toxins. Hexobarbital causes a
consistent pattern of sleep in the unfortunate experimental animals, and any
change in sleep time reflects some disturbance of the liver ability to
metabolize the sedative. An increase in sleeping time implies impairment of the
livers ability to metabolize the hexobarbital. Carbon tetrachloride produces
such a change. When Milk Thistle is added the increase in sleeping time
normally produced by the carbon tetrachloride is reduced by up to 60%,
suggesting that the herb is protecting liver function from the toxin.
- prevention of the inhibition of hepatic metabolism of
p-oxyphenylpyruvic acid (OH) caused by carbon tetrachloride. This
chemical is metabolized exclusively in the liver during the degradation of
tyrosine. Any unmetabolized OH is excreted in the urine, thus, its level in
the urine increases following the administration of a liver toxin. Substances
that counteract the toxin bring urine OH levels back to normal. Histological
studies of the liver reveal how much structural damage has occurred. The
histological finds from carbon tetrachloride poisoning is very similar to that
of hepatitis, and it increases OH levels in the urine dramatically. Milk
Thistle significantly counteracts the effects of the carbon tetrachloride, so
much so, that the results are almost indistinguishable from controls.
- carbon tetrachloride raises serum levels of enzymes such as
glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT)
and sorbitol dehydrogenase (SDH), but under treatment with silymarin these
increases were significantly diminished.
- i.p. injection of D-galactosamine (GalN) to rats causes an acute hepatitis
that is similar to viral hepatitis in humans. Silymarin has a protective action
against such liver lesions.
- poisoning with DL-ethionine leads to accumulation of triglycerides in the
liver of rats. Silymarin inhibited such increases.
- it counteracted the effects of cadmium, an pollutant that accumulates in
human tissues over time, causing hypertension, liver, kidney & neural
damage, and hemorrhagic necrosis of the liver and testes. Milk Thistle
pretreatment almost completely prevented death and necrosis whilst reducing
- the hepatotoxic salts of such rare earth metals as praseodymium, indium and
cerium cause necrosis and fatty degeneration in the liver. Pretreatment with
Milk Thistle reduces or prevented this altogether. The researchers suggest a
number of possible mechanism:
- that it facilitates a more rapid elimination of the metals from the body
- it stimulates the formation of metal-binding proteins which detoxify the
- it may inhibit the binding of these metals with cells at receptor sites
- thioacetamide is a hepatotoxin which causes a development of conditions in
rats that are similar to human liver. When silymarin was given with the poison
in the feed, animals lost less weight and their survival times increased.
Injecting thioacetamide increases the serum levels of the enzymes GPT, GOT,
SDH, and glutamate dehydrogenase, which were also prevented by silymarin.
- it partially counteracts alcohol damage to the liver.
- mitochondrial changes caused by ethanol are almost completely prevented by
- ethanol increases malondialdehyde formation and spontaneous chemiluminescence
in the rat liver. Silymarin given prior to the ethanol suppresses both effects
- Milk thistle has an extraordinary hepato-protective effect, blocking damage
from the toxins of the Avenging Angel mushroom Amanita phalloides,
phalloidin and a-amanitin. It has both protective and curative effects on
survival time and death rate of mice after administration of a-amanitin, also
antagonizing the toxicity of phalloidin. It inhibits the loss of weight
observed in poisoned animals. Animals fed sub-lethal doses of amanitine lose
weight very rapidly and gain it back very slowly. Animals fed a combination of
amanitine and Milk Thistle lose weight much more slowly and gain it back much
more rapidly. It greatly increased life-span in the poisoned animals. When
administered later than 20 minutes after poisoning, it was no longer possible
to detect any anti-hepatotoxic effect, suggesting that silymarin prevents
penetration of the toxins by competing for the same receptor sites on cell
- it has blocked the hepatotoxic effects of some viruses on laboratory
- silybin enhances ribosomal RNA synthesis as a result of the
stimulation of DNA-dependent RNA-polymerase A.
Such impressive effect upon toxic damage to liver cells is probably due
to a combination of two main mechanisms:
Mechanisms that may explain the inhibition of ethanol induced changes by
silymarin include scavenging of free radicals and increases levels of both
reduced and oxidized glutathione.
- an alteration of cell membranes, such that only small amounts of toxins may
penetrate into the cell
- an acceleration of protein synthesis, thus stimulating cell
This remarkable herb has therapeutic effects, not only in toxic and
metabolic liver damage, but also in liver diseases. Clinical trials have
replicated the laboratory evidence of its ability to reverse many liver
disorders from acute viral hepatitis to cirrhosis. It stimulates hepatocytes to
replace diseased tissue. The liver can regenerate but this innate ability slows
or stops altogether when infected or damaged by alcohol or other drugs.
About The Author
Whilst working in conservation and lecturing in ecology and the eco-crisis for the University of Wales, David Hoffman became convinced that to heal the world, to embrace planetary wholeness and responsibility for it with hope, he as an individual had to be whole within himself....more