ADVERSE EFFECTS OF METALS
ON THE GUT FLORA
derivatives from metals such as mercury, arsenic,
bismuth, tellurium ect... can exert their toxic
effects on human health not only by direct
interaction with host cells but also by disturbing
the physiological gut microflora.
Meyer J, Michalke K,
Kouril T, Hensel R. Votalisations of metals and
metalloids: an inherent feature of methanoarchea ?
Syst Applied Microbiol. 2008, June; 31(2):81-7. Epub
2008 April 18.
- Oral lead exposure
induces dysbacteriosis in rats: For
the first time it was shown that oral lead
exposure causes drastic changes in the gut
microbial community. Proportional
to the lead dose received, the relative number of
lactose-negative E.coli cells increased
dramatically (up to 1,000-fold) in comparison to
the other microbial groups during 2 wk of
exposure. Considering the number of microbes in
the intestine, such a shift in intestinal
microflora (dysbacteriosis) is very significant.
Adhesion studies showed certain stimulating
effects of lead on E. coli attachment to rat
intestinal epithelium as compared to
Lactobacillus attachment. This study may
provide important clues for understanding the pathological
effects of metal dietary toxins in human beings.
I,Artmann AT,Porst D,Linder P,Kayser P,Artmann
G,Savitskaya I,Zhubanova A. Oral Lead Exposure
Induces Dysbacteriosis in Rats. J Occup
Health.2009;51(1):64-73. Epub 2008 Dec 19
- "...cinnabar* induced
disturbance in energy metabolism,
amino acid metabolism and gut
microflora environment as
well as slight injury in liver and kidney,
which might indirectly result from cinnabar*
induced oxidative stress."
Wei L, Liao P, Wu H,
Li X, Pei F, Li W, Wu Y. Toxicological effects of
cinnabar in rats by NMR-based metabolic profiling of
urine and serum. Toxicol Appl Pharmacol. 2008 Mar
15;227(3):417-29. Epub 2007 Nov 28.
Cinnabar is the ore of mercury.
dental amalgam is known to be a source of human
exposure to mercury. We have explored
the use of electron yield Hg L(III) X-ray
absorption spectroscopy to characterize the
chemical nature of dental amalgam surfaces. We
find that the method is practical and that it shows
extensive mercury depletion in the surface of the
aged amalgam with significant differences between
old and fresh amalgam surfaces. Whereas
the fresh amalgam gives spectra that are typical
of metallic mercury, the
aged amalgam is predominantly beta-mercuric
toxicological implications of these results are
GN, Singh SP, Hoover J, Pickering IJ. The chemical
forms of mercury in aged and fresh dental amalgam
surfaces. Chem Res Toxicol. 2009 Nov;22(11):1761-4.
sulfide (HgS) is a major component of cinnabar,
which has been used as a sedative drug in China
for more than 2000 years. Because its
toxicological effects are still unclear, we
attempted to verify the toxic effects of
HgS,focused on liver and immune organs such as
the spleen and thymus. Male ICR mice were
administered HgS (0.02, 0.2, 2.0 g/kg/day) by
gavage for 4 weeks. During the administration
period, HgS-treated mice did not reveal overt
signs of clinical toxicity. HgS had no
significant effect on body weight, food
consumption, water consumption, and organ
weights. In spite of its known insolubility, HgS
was absorbed by the gastrointestinal tract and
accumulated in the liver, spleen and thymus in a
dose-dependent manner. In the biochemical and
histological examination, HgS did not cause
hepatotoxicity. However, HgS significantly
increased both CD8(+) T lymphocytes and
CD4(+)CD8(+) lymphocyte populations in the spleen
without changing in the thymus. In the
histological evaluation, HgS induced enlargement
with marked hyperplasia and increase of lymphoid
follicles in the spleen. In addition, HgS induced
the gene expression of pro-inflammatory cytokines
in the spleen and thymus. Our
results suggest that insoluble HgS
was absorbed by the gastrointestinal tract,
accumulated in the spleen and thymus, and thus
could affect immune systems.
HY, Lee S, Park SB, Kim MS, Choi EJ, Singh TS, Bae Y,
Kwack SJ, Kang TS, Shin HI, Baek MC, Kim SH. Toxic
effects of mercuric sulfide on immune organs in mice.
Immunopharmacol Immunotoxicol. 2010 Jun;32(2):277-83.
- This study compared
the neurobehavioral toxicities of three
mercurial compounds: methyl mercury
(MeHg) which is soluble and organic. and mercuric
sulfide (HgS) and cinnabar
(naturally occurring HgS), which are insoluble
and inorganic. Cinnabar, a Chinese mineral
medicine, is still used as a sedative in some
countries, but there is relatively little
toxicological information about it. These
mercurial compounds were administered
intraperitoneally (MeHg, 2 mg/ kg) or orally (HgS
and cinnabar, 1.0 g/kg) to male rats once every
day for 13 consecutive days with assays conducted
during or after discontinuous administration for
1 h, 2, 8 and 33 weeks. Neurotoxicity was
assessed based on the active avoid-ance response
and locomotor activity. The
results obtained showed that MeHg and cinnabar
prominently and irreversibly caused a decrease in
body weight, prolongation of latency for escape
from electric shock, a decrease in the percentage
for the conditioned avoidance response (CAR) to
electric shock, impairment of spontaneous
locomotion and inhibition of Na+/K+-ATPase
activity of the cerebral cortex. In contrast. HgS
reversibly inhibited spontaneous locomotion and
Na+/K+-ATPase activity. It was noted that HgS
significantly decreased the latency of escape
from electric shock during the ad-ministration
period, which lasted for 33 weeks after
discontinuous administration. In fact that
pretreatment with arecoline (a cholinergic
receptor agonist) but not fipexide (a
dopaminergic receptor agonist) could
significantly shorten the prolonged latency for
escape caused by MeHg and cinnabar, suggested
that the deficit in the active avoidance response
was perhaps, at least in part, mediated by the
dysfunction of the cholinergic rather than the
dopaminergic system. Determination of the Hg
levels of the whole blood and cerebral cortex
revealed that the tissue mercury content was
highly correlated with the degree of
neurobehavioral toxicity of these Hg compounds.
These findings suggest
that insoluble HgS and cinnabar can be absorbed
from the G-I tract and distributed to the brain. The possibility that
contamination due to other minerals in the
cinnabar is responsible for the greater
neurotoxic effects compared to HgS is under
Chuu JJ, Liu SH,
Lin-Shiau SY. Effects of methyl mercury, mercuric
sulfide and cinnabar on active avoidance
responses, Na+/K+-ATPase activities and tissue
mercury contents in rats. Proc Natl Sci Counc Repub
China B. 2001 Apr;25(2):128-36.
Ag-Cu alloy, fluoride and zinc from dental
amalgam showed antibacterial activity
Morrier JJ at al.
Antimicrobial activity of amalgams, alloys and their
elements and phases. Dent Mater. 1998
- Candida Albicans
and Tropicalis are more resistant to the
toxic effects of mercury, cadmium, lead
and arsenic than Saccharomyces Cerevisiae.
Berdicevsky I, Duek
L, Merzbach D, Yannai S. Susceptibility of different
yeast species to environmental toxic metals. Environ
- Mercury can
be methylated by oral and intestinal bacteria.
Edwardsson S, Derand T, Birkhed D. Methylation of
mercury from dental amalgam and mercuric chloride by
oral streptococci in vitro. Scand J Dent Res. 1983
Rowland IR, Grasso
P, Davies MJ. The methylation of mercuric chloride by
human intestinal bacteria. Experientia. 1975 Sep
- The gastrointestinal
uptake of mercury from dental amalgam is
of quantitative importance during dental
Sandborgh-Englund G, Jonsson F, Ekstrand J. Mercury
uptake and kinetics after ingestion of dental
amalgam. J Dent Res. 2001 Sep;80(9):1793-6.
- Mercury is
absorbed through the gut lining.
Einarsson C, Sandstrom M, Ekstrand J.
Gastrointestinal absorption of metallic mercury. Arch
Environ Health. 2004 Sep;59(9):449-54.
- Mercury released
from dental "silver" fillings provokes
an increase in mercury- and antibiotic-resistant
bacteria in oral and intestinal floras of
Summers AO et al.
Mercury released from dental "silver"
fillings provokes an increase in mercury- and
antibiotic-resistant bacteria in oral and intestinal
floras of primates. Antimicrob Agents Chemother. 1993
Mercury,copper, cadmium, indium and zinc are released into the gastrointestinal tract from dental amalgam.
The release of mercury and copper was fifty times higher from high copper amalgam than from other amalgams.
Brune D, Gjerdet N,
Paulsen G. Gastrointestinal and in vitro release of
copper, cadmium, indium, mercury and zinc from
conventional and copper-rich amalgams. Scand J Dent
Res. 1983 Feb;91(1):66-71.