Yo-Yo Diets and Olestra
Boost Toxic Excretion
Perhaps Ukrainian opposition leader Viktor Yushchenko should
try an "Olestra diet" to rid his body of dioxin.
It wouldn't be the first time that the "fake fat" product was
used as an emergency agent to flush out dioxin, one of a group
of chlorinated hydrocarbons that are toxic, lipophilic (attracted
to fat) – and persistent in the environment and animal tissues.
About five years ago, two Austrian women suffering from dioxin
poisoning were given olestra snacks, which resulted in removal
of dioxin at 10 times the normal rate, according to some reports.
In an as-yet-unpublished study, researchers at the University
of Cincinnati School of Medicine, along with Trevor Redgrave at
the University of Western Australia, treated a patient with PCB
toxicity over a two-year period with olestra in the form of fat-free
Pringles. The patient's chloracne disappeared and the PCB level
in fat tissue dropped dramatically.
The same University of Cincinnati School of Medicine team is
reporting new research that sheds light into how diet affects
retention and re-distribution through the weight gain-loss-regain
cycle of chlorinated hydrocarbons, which include DDT, PCBs and
dioxins. They also looked at the effects of the additive olestra,
which is made by Procter & Gamble, on this redistribution and
perhaps more importantly, on excretion of toxins from the body.
Indeed, "combined dietary olestra and caloric restriction caused
a 30-fold increase in the rate of excretion" of a test toxin,
while the toxin's distribution "into the brain resulting from
the restricted diet was reduced by 50% by dietary olestra," the
study found.
The study, "Effects of yo-yo diet, caloric restriction, and
olestra on tissue distribution of hexachlorobenzene," was conducted
by Ronald J. Jandacek, Nicole Anderson, Min Liu, Shuqin Zheng,
Qing Yang and Patrick Tso of the Department of Pathology and Laboratory
Medicine, University of Cincinnati School of Medicine, Cincinnati,
Ohio. The research appears in the online edition of the American
Journal of Physiology-Gastrointestinal and Liver Physiology, published
by the American Physiological Society.
They're everywhere, and with long half-lives
Toxic lipophilic substances like PCBs and dioxins are so widespread
globally, and are known to ascend the food chain, that virtually
"all people tested have measurable levels of some of these compounds,"
the Jandacek et al. report notes. Because the compounds and many
of their metabolites are lipophilic (attracted to fat) they are
stored in adipose (fat) tissue where they remain stable, usually
without adverse affect in moderate amounts for their long half-lives.
Jandacek and his colleagues designed a multi-branch, multi-endpoint
study that showed with weight loss (with and without olestra)
toxins redistribute around the body, but with differing affinity
to various organs.
Method and results: brain, adipose and liver tissue differences
The Cincinnati researchers used 14C-hexachlorobenzene (14C-HCB),
a radioactively-marked toxin that is only partly metabolized by
mice, to measure how its distribution changed in various organs
during the weight gain-loss yo-yo process.
They found that continued "weight loss resulted in a three-fold
increase of 14C amount and concentration in the brain. After weight
regain, 14C in the brain decreased but then increased again after
a second weight loss." In adipose tissue, weight loss resulted
in an increase in the concentration of 14C without changing the
total amount in the fat tissue. "Weight loss and regain resulted
in an increase of 14C in the liver that reflected an increase
of fat in the liver," Jandacek et al. reported.
At this point, the regimen of weight gain and loss was repeated
in mice gavaged (direct-fed to the stomach) with 14C-HCB, with
one group receiving the "non-absorbable fat, olestra" in their
diet. The results were striking: "Combined dietary olestra and
caloric restriction caused a 30-fold increase in the rate of excretion
of 14C, relative to an ad lib diet or a reduced caloric (diet)
alone. The distribution of 14C into the brain resulting from the
restricted diet was reduced by 50% by dietary olestra," Jandacek
et al. reported.
Next steps
The results of the current study have indicated several avenues
to pursue, among them being:
- Plasma HCB increased with prolonged caloric restriction,
indicating the need for future studies into the possible role
of carriers of HCB.
- HCB was cleared more rapidly from chylomicrons than triacylglycerol,
"suggesting an affinity of organochlorines for the fatty acids
generated during fat metabolism."
- "How plasma carriers facilitate HCB entry into the brain
is an interesting question with potential physiological implications."
- Jandacek's laboratory is currently studying the relationship
of fasting and refeeding to liver lipid deposition.
- The exact role of olestra and its mechanism of action in
the excretion process.
- Whether and how different organochlorine compounds (PCBs,
dioxins, etc.) undergo redistribution in yo-yo diet situations.
- Testing a lipase inhibitor such as orlistat (Xenical, Roche)
"will also result in partial blockage of the enterohepatic circulation
of lipophiles by providing an undigested intestinal triacylglycerol
phase that will solubilize these compounds."
Source and funding
The study, "Effects of yo-yo diet, caloric restriction, and
Olestra on tissue distribution of hexachlorobenzene," by Jandacek
et al. appears online in the American Journal of Physiology-Gastrointestinal
and Liver Physiology, published by the American Physiological
Society.
Reference
Source 125
December 20, 2004
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