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Isoflavones may not be responsible for soy’s anticancer
effect
Research conducted at the University of Illinois suggests that
the isoflavones in soy protein may not be the constituents responsible
for soy’s anticancer effect, as previously thought. Female
rats were treated with purified isoflavones or a soy protein mix
with or without isoflavones. The mix without isoflavones was the
most effective in reducing the incidence and number of mammary
tumors in female rats, though all the treatments had some anti-tumor
activity. The researchers suggested that other soy constituents—such
as lignans, dietary fiber, or phytic acid—may be acting as
antioxidants to inhibit the tumors. The findings were presented
April 3 at the American Association for Cancer Research meeting
in San Francisco.
Nutraceuticals International, June 2000.
Beta-carotene shown to reduce LDL oxidation
In a clinical study sponsored by Nutrilite, a 4.5 mg
daily supplement of beta-carotene significantly reduced low-density
lipoprotein (LDL) oxidation in adults considered to be at risk
for heart disease. The study involved 200 male and female subjects
aged 35-68 years who were divided into three at-risk groups—smokers,
diabetics, and obese—and a healthy control group. All subjects
were tested for LDL oxidation susceptibility, given the beta-carotene
along with their normal diet for 45 days, then tested again. At
the end of the study, oxidized LDLs were reduced by 18, 22, and
21 percent in the smoker, diabetic, and obese groups, respectively.
While this difference was significant, LDL oxidation susceptibility
for the at-risk subjects at the end of the study was still higher
than that of the healthy control group at the beginning of the
study. Researchers from the Rambam Medical Center and National
Institute of Oceanography in Haifa, Israel conducted the study.
Their findings were presented at the International Conference
on Dietary Medicine in April.
Nutrilite Press Release, May 17, 2000.
Extra-virgin is the oil of choice to protect against LDL oxidation
Olive oil
Olea europea
Many Mediterranean populations that consume large amounts of
olive oil as part of their diets enjoy a decreased incidence of
coronary heart disease. The presence of monounsaturated fatty
acids and antioxidants in the diet is directly related to the
ability of low-density lipoprotein (LDL) cholesterol to resist
oxidation. Oxidative damage of LDL cholesterol has been linked
to development of atherosclerosis and other cardiovascular diseases.
The present study was conducted to investigate whether differences
in olive oil processing methods yield any measurable health benefits.
Extra-virgin olive oil (VO) is characterized by very low acidity
and retains the fatty acids and antioxidants present in the olives.
Refined olive oil (RO), by contrast, has the same fatty acid composition,
but because of additional processing lacks the antioxidants present
in VO. In this randomized, crossover study, one group of patients
with peripheral vascular disease received VO to use in cooking
for three months, followed by a three-month washout period, then
received RO for the final three months. The other group consumed
the oils in the opposite order. Intake of alpha-tocopherol, considered
to be a “first line of defense” against LDL oxidation,
was higher for patients consuming VO. LDL oxidation rate was lower
for patients consuming VO than RO, and during periods when patients
consumed VO, a decreased uptake of oxidized LDL by macrophages
was also noted. Significant differences in the susceptibility
of LDL to oxidation during VO consumption periods led researchers
to conclude that the antioxidant composition of VO appears to
be more protective against LDL oxidation than RO.
Ramirez-Tortosa M, Urbano G, López-Jurado M, et al.
Extra-virgin olive oil increases the resistance of LDL to oxidation
more than refined olive oil in free-living men with peripheral
vascular disease. J Nutr 1999; 129: 2177-2183.
St. John’s wort
Hypericum perforatum
Another possible mechanism of action for St. John’s wort’s
antidepressant activity
St. John’s wort has demonstrated favorable results in the
treatment of mild to moderate depression in clinical studies,
but the herb’s mechanism of action remains unclear. Previous
research has shown that the extract inhibits synaptosomal uptake
of serotonin, leading some to suspect that it works in the same
manner as the synthetic antidepressant drugs known as selective
serotonin reuptake inhibitors (SSRIs). In the present study, researchers
verified that St. John’s wort extract did, in fact, inhibit
serotonin accumulation in rat brain cortical synaptosomes. However,
its mechanism of action appeared to be more closely related to
that of reserpine-like compounds than to classic SSRIs in that
it depletes storage vesicles of serotonin, thereby raising serotonin
concentrations and resulting in apparent reuptake inhibition.
Gobbi M, Dalla Valle F, Ciapparelli C, et al. Hypericum
perforatum L. extract does not inhibit 5-HT transporter in
rat brain cortex. Arch Pharmacol 1999; 360: 262-269.
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