Garlic Q&As
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Allicin: Not Found in Top Garlic Products
Research has shown that garlic supplements actually contain no allicin. -
"Allicin Potential" of Questionable Value. Intestinal Conditions Hinder the Generation of Allicin.
Allicin production in the body (from naturally occurring alliin and alliinase in garlic) is inhibited by various body fluids. Most supplements can only produce allicin in water but not in the body. Stomach fluids have been shown to destroy the enzyme, alliinase, in raw garlic powders which is necessary to generate allicin. -
What About Enteric Coatings?
Enteric-coated supplements can potentially produce allicin in the intestinal tract, but....
— much of the allicin production is inhibited by intestinal fluids (only 60% of the amount produced in water can be produced in intestinal fluids).
— the remaining allicin may destroy not only bad, but also good bacteria. Allicin is a harsh oxidizing agent and high amounts have been shown to aggravate the intestinal lining as well as the stomach.
— if the allicin is absorbed by the liver in small amounts, it is completely metabolized or detoxified, however, absorbed in large amounts it may damage liver tissue.
— if it makes it past the liver to the blood, it may oxidize red blood cells. -
Allicin Is Not Bioavailable:
No allicin found in the body following oral intake. Allicin is not biologically active inside of the body Allicin has not been conclusively proven to be responsible for garlic's known health benefits. Allicin was not found in the blood or urine after consumption of approximately 90,000 mcg (roughly 10 cloves). It is lost en route and therefore is unlikely to be the active compound in garlic. -
Other Compounds Must Be Responsible for the Benefits of Garlic
Allicin:
Not Found in Top Garlic Products
For years, allicin has been deemed as the compound responsible for the
benefits of garlic. It has shown an ability to kill bacteria and fungus in
test tubes and topically crushed raw garlic has been used in wars to fight
infections. However, no clinical trials have been performed with allicin
and it has not become a commercial product, mainly because of its chemical
instability but also because of its pungent odor and irritating nature.
Allicin is produced by an enzymatic reaction when raw garlic is either crushed or somehow injured. The enzyme, alliinase, combines with a compound called alliin in raw garlic and produces allicin. Because allicin is so unstable, once it is generated it readily changes into other compounds. Thus cooking, aging, crushing and otherwise processing garlic causes the allicin to be decomposed into other compounds. According to two studies of garlic preparations, allicin decreased to nondetectable amounts within one to six days (20-144 hours) This could explain why a study of various products on the market showed that they all contained an undetectable amount (<1 ppm) of allicin.
"Allicin
Potential" of Questionable Value
To prevent the typical loss of allicin, some manufacturers have attempted
to stabilize alliin and alliinase so that these compounds would not come
together until after they enter the body in hopes of producing allicin
inside of the body. Such "allicin potential" is measured by
adding water to garlic products which contain both alliin and alliinase to
determine how much allicin can be produced. However, the actual production
of allicin inside the body is not the same as that produced in a test tube
for the following reasons:
Intestinal Conditions Hinder the Generation of
Allicin:
— Stomach
acid destroys alliinase, preventing allicin production.
— Intestinal
fluids further diminish the amount of allicin that can be produced.
Simulated stomach fluids and simulated intestinal fluids have commonly
been used to determine the effects of typical digestion on nutrients or
chemicals in question. Interestingly, alliinase, the enzyme which
catalyzes the conversion of alliin to allicin, has been shown to be
irreversibly deactivated at pH 3 or below, an acidic environment typically
found in the stomach.Further, a 99% loss in allicin
production was observed following consecutive exposure to simulated
stomach fluids and simulated intestinal fluids which would occur when one
takes a garlic powder orally.Therefore, it appears that
unless a garlic powder bypasses the stomach, the amount of allicin
produced is negligible.
What About
Enteric Coatings?
Some manufacturers have enteric-coated their garlic powder so that it
would bypass the stomach. Assuming the best, that a high quality garlic
powder is used initially (one that is not exposed to high temperatures
which can deactivate alliinase), this form of garlic could potentially
deliver alliin and alliinase to the intestinal tract. However, simulated
intestinal fluids have been shown to inhibit 40% of the allicin
production. The remaining allicin may exert anti-microbial
effects on bad bacteria, however, it may also destroy friendly bacteria.
Both allicin and raw garlic preparations which contain allicin have been
shown to decrease the bacteria flora. Further, being a
strong oxidizing agent allicin may irritate the sensitive
cells which line the intestinal tract as it has been shown to
irritate the cells lining the stomach. Finally, if
organically grown garlic is not used as a starting material,
enteric-coatings may assist in delivering pesticides and other
contaminants in the garlic directly into the intestinal tract for
absorption.
Allicin Is
Not Bioavailable:
No allicin found in the body following oral intake.
A study in which participants consumed a large amount of allicin
(approximately 90,000 mcg) via crushed raw garlic (25 grams; roughly 10
cloves) revealed that neither allicin nor 16 of its daughter compounds
could be detected in blood or urine from one to 24 hours after
consumption. Due to its high reactivity allicin was shown to
be completely metabolized in the liver. If allicin could
even make it to the blood (to be delivered throughout the body), studies
have shown that it changes into other compounds within five minutes and in
the process may oxidize the blood cells causing them to lose their ability
to carry oxygen.
"Allicin
is not biologically active inside of the body"
Yukihiro Kodera, at the Designer Foods III Symposium: Research Update on
Phytochemicals in Garlic, Soy and Licorice held in May, 1994 in
Washington, D.C. found the following:
"Under simulated digestive conditions, little allicin was released
from a garlic powder which contained both alliin and alliinase. When
allicin was mixed with blood, it disappeared very rapidly, and the
formation of trace amounts of allylmercaptan and diallyl disulfide were
observed. Allicin also converted the hemoglobin in red blood cells to
methemoglobin. Furthermore, allicin has been shown to disappear upon
contact with the liver; no allicin could be detected in the effluent when
allicin was perfused into an isolated liver."
"Though allicin was considered to be a key compound in garlic in the
past, recent scientific findings, including the pharmacokinetics and
metabolism of organosulfur compounds in garlic, have revealed that allicin
is not biologically active inside of the body…"
Allicin has not been conclusively proven to be responsible for garlic's
known health benefits.
Following are some conclusions drawn about allicin from garlic scientists
at the "First World Congress on the Health Significance of Garlic and
Garlic Constituents" held in August 1990 in Washington, D.C.:
Contrary to the popular myth that a garlic product must contain allicin to
be beneficial, allicin has not been conclusively proven to be responsible
for garlic's known health benefits. Most of the garlic or garlic products
that have been based to demonstrate garlic health effects do not contain
significant amounts of allicin. (Allicin is an odorous and transient
garlic compound.)
· Equally untrue is the myth that if garlic or a garlic product does not
have a garlic odor it does not provide benefits. A major part of the data
on the benefits of garlic is derived from studies of cooked garlic,
pickled garlic, aged garlic, and aged garlic extract. All of them have
little typical garlic odor.
Other
Compounds Must Be Responsible for the Benefits of Garlic
Various forms of garlic, which contain no allicin (e.g., cooked, steamed,
microwaved and aged garlic extract), have demonstrated an array of
benefits in studies. Therefore, it is logical that compounds other than
allicin are responsible for such benefits. To date, well over 100
compounds have been identified in garlic preparations.
Presently, S-allyl cysteine appears to be a very promising compound with
good absorption. Again, according the research of Kodera et al:
"The pharmacokinetic studies of S-allyl cysteine demonstrated rapid
absorption and almost 100% bioavailability after oral administration. In
addition, since both the safety and effectiveness of S-allyl cysteine have
been reported, this compound appears to play an important role in garlic's
medicinal effects."
Though individual compounds, such as S-allyl cysteine, have shown activity
in studies and are absorbed by the body, it is likely that a synergism of
various compounds provide the benefits of garlic. This is in agreement
with Dr. Koch, a renowned Austrian scientist who stated that the activity
of various sulfur compounds could not alone be responsible for the
benefits of garlic and fixation on a single group of components can lead
to mistakes and wrong conclusions.
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