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Health News Archive 63 - Heart (continued)
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to structure/function index
L-Arginine Helps The Heart
L-arginine has
made many health headlines purporting the amino acid's ability to reduce
blood pressure, prevent plaque buildup, lower cholesterol, and increase
coronary circulation. Now, research shows that the nonessential amino acid
may also reduce the risk of heart disease and other cardiac events.
The study,
published in a recent issue of the Journal of Nutrition, found that
supplemental arginine lowers homocysteine,
a toxic amino acid found in the blood that is a cardiac risk marker (2005,
vol. 135, no. 2). Researchers administered 12 grams of supplemental
arginine a day to 16 middle-age men suffering from hypercholesterolemia.
After each dose, scientists measured blood variables of the participants
at rest and during two stress tests.
At the end of
the three-week study, researchers discovered that high blood levels of l-arginine
were positively correlated with a reduction in homocysteine. Arginine
supplementation also produced a modest decrease in blood pressure, but the
reduction was not significant enough to preclude blood-pressure
medication.
L-Arginine is
found in a number of common foods, including meat, poultry, fish, dairy,
and nuts. However, Sheila West, PhD, the study's lead author, cautions
that some arginine-rich foods, such as beef, also contain high levels of
saturated fats and methionine, a homocysteine-raising amino acid, and so
these foods are not recommended for heart patients. Instead, increase your
arginine intake by eating beans, soy, nuts, or supplements.
Pomegranate Juice Fights Heart Disease
A glass of
pomegranate juice a day could be just what your cardiologist ordered.
Scientists writing in the Proceedings of the National Academy of Sciences
reported three key findings on the consumption of pomegranate juice:
-
Pomegranate
Juice helped reduce the fatty deposit buildup from the artery walls in
mice
-
Pomegranate
Juice kept the cells of the human heart healthier
-
Pomegranate
Juice significantly reduced the progression of atherosclerosis by 30
percent in the mice that consumed it
Pomegranates
are a Middle Eastern fruit that contain crunchy seeds surrounded by juicy
pulp. It is becoming increasingly popular in the United States. One
nutritionist noted that while eating pomegranates is a fun experience it
is also be a messy one. For this reason she claimed that pomegranate juice
may be the more practical option.
Other studies
have uncovered the antioxidants in pomegranate juice might be responsible
for plaque reduction on artery walls and play a part in reducing oxidative
stress on endothelial cells (the cells that line the blood vessels),
producing a substance called nitric oxide, which helps the blood vessels
relax. It was discovered that the heart cells of mice that were given
pomegranate juice had a 50 percent increase in nitric oxide and nearly a
30 percent reduction in plaque.
SOURCE:
Beneficial effects of pomegranate juice on oxidation-sensitive genes and
endothelial nitric oxide synthase activity at sites of perturbed shear
stress. de Nigris et al. PNAS.2005; 0: 50099810
Atherosclerosis
is enhanced in arterial segments exposed to disturbed flow. Perturbed
shear stress increases the expression of oxidation-sensitive responsive
genes (such as ELK-1 and p-JUN) in the endothelium. Evidence suggests that
polyphenolic antioxidants contained in the juice derived from the
pomegranate can contribute to the reduction of oxidative stress and
atherogenesis. The aim of the present study was to evaluate the effects of
intervention with pomegranate juice (PJ) on oxidation-sensitive genes and
endothelial NO synthase (eNOS) expression induced by high shear stress in
vitro and in vivo. Cultured human coronary artery endothelial cells (EC)
exposed to high shear stress in vitro and hypercholesterolemic mice were
used in this study. PJ concentrate reduced the activation of redox-sensitive
genes (ELK-1 and p-JUN) and increased eNOS expression (which was decreased
by perturbed shear stress) in cultured EC and in atherosclerosis-prone
areas of hypercholesterolemic mice. Moreover, oral administration of PJ to
hypercholesterolemic mice at various stages of disease reduced
significantly the progression of atherosclerosis. This experimental study
indicates that the proatherogenic effects induced by perturbed shear
stress can be reversed by chronic administration of PJ. This approach may
have implications for the prevention or treatment of atherosclerosis and
its clinical manifestations.
Alpha-linolenic
Acid Reduces Risk of Cardiovascular Disease
Alpha-linolenic acid
(ALA) reduces cardiovascular disease (CVD) risk, possibly by inhibiting
vascular inflammation and endothelial activation, according to a study
published in the November issue of The Journal of Nutrition (134,
11:2991-2997, 2004) (www.nutrition.org).
The researchers
assessed inflammatory markers and lipid and lipoprotein levels in 23
hypercholesterolemic subjects fed two diets low in saturated fat and
cholesterol and high in polyunsaturated fatty acids compared with the
average American diet (AAD). The first of these two diets--the alpha-linolenic
acid diet (ALA Diet)--provided 17 percent of its energy from
polyunsaturated fatty acids (PUFAs) (10.5 percent LA; 6.5 percent ALA),
while the second of the two diets--the linolenic acid diet (LA
Diet)--provided 16.4 percent of its energy from PUFA (12.6 percent LA; 3.6
percent ALA); the AAD provided 8.7 percent of its energy from PUFAs (7.7
percent LA; 0.8 percent ALA). The ALA Diet decreased the serum
concentration of a protein indicative of acute inflammation, whereas the
LA Diet tended to decrease this concentration. Although both high-PUFA
diets similarly decreased intercellular cell adhesion, the ALA Diet
decreased vascular cell adhesion and endothelial activation more than the
LA Diet. Both high-PUFA diets similarly decreased serum total cholesterol,
low-density lipoprotein (LDL) cholesterol and triglycerides. The ALA Diet
decreased high-density lipoprotein (HDL) cholesterol and the primary
protein constituent of HDL, compared with the AAD.
The researchers
concluded ALA appears to decrease CVD risk beyond its lipid-lowering
effects by inhibiting vascular inflammation and endothelial activation.
Omega-3
Alpha-linolenic Acid Helps Protect Women from Cardiac Death
The American Heart
Association's Scientific Sessions 2004 was the site of a presentation on
November 8 of the findings of Harvard researchers that higher dietary
levels of alpha-linolenic acid appear to help protect women from dying of
heart disease and sudden cardiac death. Alpha-linolenic acid (ALA) is an
omega-3 fatty acid found in flaxseed, canola oil, green leafy vegetables
and other foods.
The team studied
dietary information obtained from the Nurse's Health Study, which included
76,763 women. During the study's sixteen year follow-up, 1,325 women
experienced a nonfatal heart attack, 169 underwent sudden cardiac death
and 564 died from coronary artery disease.
Alpha-linolenic acid
intake was found to range from 0.7 grams per day to 1.5 grams per day.
Women whose intake was in the top one-fifth of participants were
discovered to have a 46 percent lower risk of dying from sudden cardiac
death compared to those in the lowest fifth. Their risk of dying
from coronary heart disease was 21 percent lower.
Dr Christine M.
Albert, MD, assistant professor of medicine at Harvard University Medical
School, and the study's lead author, explained the team's findings: "In
this study, we examined whether ALA was associated with a lower risk of
dying from heart disease or sudden cardiac death, which is death resulting
from an abrupt loss of heart function. Sudden cardiac death is usually the
result of a fatal rhythm disturbance. So, if this fat were to prevent
sudden cardiac death, it would support the hypothesis that these oils were
preventing fatal arrhythmias.“
"A clinical trial
that randomly assigns people to ALA supplements or to a diet high in ALA
would be needed to know for sure that ALA lowers risk of coronary heart
disease and sudden cardiac death," Dr Albert added.
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