| Researchers have identified
a number of other ways in which consuming soy protein
may help reduce the risk CVD. One area of study concerns
the ability of soy protein with naturally occurring isoflavones
and other bioactives to decrease the extent of plaque
formation in arteries. Some researchers are investigating
the effect of soy protein and/or bioactives on the normal
functioning of your blood vessels.
Another approach is to look at the effects of individual
isoflavones on the formation of blood clots. Another
exciting area of study is the potential ability of soy
protein to reduce the oxidation of LDL-cholesterol.
Antioxidant Effect of Soy Protein
The discovery that oxidized LDL-cholesterol is more
damaging to your arteries has spurred research interest
in antioxidants, substances that can delay or prevent
oxidation. Some research has shown that the isoflavone
genistein inhibits the oxidation of LDL-cholesterol
in the laboratory.
Other researchers conducted a small study in healthy
volunteers who consumed three bars containing soy protein
with naturally occurring bioactives every day for two
weeks. LDL-cholesterol was isolated from blood samples
taken both during soy intake and again while the participants
weren't consuming soy. When the various LDL-cholesterol
samples were exposed to an oxidizing agent, oxidation
of the samples taken during soy intake was delayed by
20 minutes, indicating that this LDL-cholesterol was
resistant to oxidation.
Effect on Blood Coagulation
of Soy Protein
Blood clots are often responsible for totally blocking
an artery already narrowed by atherosclerosis. Laboratory
studies suggest that soy isoflavones, especially genistein,
have a favorable effect on blood clot formation. Several
mechanisms appear to be involved, all of which alter
the processes that typically result in the formation
of blood clots associated with atherosclerotic plaque.
Soy Protein and Its Effect on
Blood Vessel Health
Normal, healthy arteries expand when exposed to acetylcholine,
a neurotransmitter naturally occurring in the body.
Arteries damaged by atherosclerosis, on the other hand,
constrict in response to acetylcholine. This reduction
in vascular reactivity is highly associated with fatal
heart attacks.
In one study, male and female monkeys were given soy
protein either containing naturally occurring isoflavones
and other bioactives (Soy+) or with the bioactives removed
(Soy-). Next, their coronary arteries were exposed to
acetylcholine. The arteries of both groups of male monkeys
constricted in response to acetylcholine although the
monkeys in the Soy+ group had less constriction. The
female monkeys in the Soy+ group experienced a dilation
of their arteries in response to acetylcholine. The
arteries of the female monkeys in the Soy- group constricted
in response to acetylcholine. However, when these monkeys
were later given the isoflavone genistein in the purified
form intravenously, their arteries dilated.
Effect of Soy Protein on Atherosclerotic
Plaque
In another study researchers actually measured the amount
of atherosclerotic plaque present in the arteries of
monkeys consuming either casein, soy protein with containing
naturally occurring isoflavones and other bioactives
(Soy+), or soy protein with the bioactives removed (Soy-).
They found that the monkeys in the Soy+ group had 90%
less atherosclerosis than monkeys receiving casein and
50% less than monkeys in the Soy- group.
When the researchers measured the size of the atherosclerotic
areas that were present, they found that monkeys in
the Soy+ group had the smallest areas of atherosclerosis,
monkeys receiving casein had the largest areas, and
monkeys in the Soy- group fell somewhere in between.17
The researchers concluded that the beneficial effects
of soy protein on atherosclerosis appeared to be due
to the isoflavones that were present.
References
View cardiovascular
disease references list.
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