Issue:
98
Page: 30
Artichoke Leaf Extract Improves HDL Cholesterol Levels in Patients with Hypercholesterolemia
by Amy C. Keller
HerbalGram.
2013; American Botanical Council
Reviewed: Rondanelli M, Giacosa A, Opizzi A, et al. Beneficial effects of artichoke
leaf extract supplementation on increasing HDL-cholesterol in subjects with primary
mild hypercholesterolaemia: a double-blind, randomized, placebo-controlled
trial. Int J Food Sci Nutr. February
2013;64(1):7-15.
Cardiovascular
disease (CVD) is a prevalent worldwide threat to health. Nutritional
modifications, such as low-fat diets, typically are used to prevent or lessen
CVD risk. However, diets targeting the reduction of harmful low-density
lipoprotein (LDL) cholesterol also may reduce the concentration of beneficial
high-density lipoprotein (HDL) cholesterol. Thus, interventions that reduce LDL
while promoting higher concentrations of HDL are necessary for the alleviation of CVD. Artichoke (Cynara scolymus,
Asteraceae) leaf extract (ALE) has been shown to lower cholesterol in previous
studies. This randomized, double-blind, placebo-controlled study investigated
the effects of eight weeks of ALE supplementation on HDL, LDL, and total
cholesterol concentrations in subjects with hypercholesterolemia.
The 92 study participants were “mildly” hypercholesterolemic (5.4-7.0 mmol/l), 18 to 60
years of age, had a body mass index (BMI) range from 19 to 30 kg/m2,
and were recruited from the University of Pavia in Pavia, Italy. They did not
have CVD or chronic diseases and were not on medicine that targeted cholesterol
concentrations. The study excluded those who smoked tobacco, consumed excessive
amounts of alcohol or weight-loss drugs, or were pregnant, lactating, or in
menopause. Subjects were instructed to maintain their normal level of exercise
and a three-day baseline dietary assessment was taken. This information was
used to standardize subjects’ diets to total caloric levels similar to American
Heart Association recommendations; diet also was evaluated at the end of the
study.
Blood pressure,
body weight, and BMI, as well as skinfold thickness and abdominal diameter,
were measured both at the beginning and at the end of the study. Treatments
consisted of 250 mg tablets of either ALE or “a matching placebo” (excipients
without ALE) administered before lunch and dinner (500 mg total daily dosage)
for eight weeks. ALE was standardized to contain more than 20% caffeoylquinic
acids, 5% flavonoids, and 5% cynaropicrin. [Note: No description of the placebo
is given.] Both the ALE and placebo tablets were supplied by Indena SpA; Milan,
Italy. Leftover tablets were used to gauge compliance.
Fasting LDL,
HDL, total cholesterol, and glucose concentrations were measured from blood
samples taken at baseline and the study endpoint. Fasting HDL cholesterol also
was assessed eight weeks after the study’s conclusion. Tolerability of the
treatments was estimated by blood pressure and blood chemistry at baseline and
at the end of the study. Any adverse side effects were inquired about by
investigators and reported by subjects.
Of the subjects
enrolled, there were no dropouts reported and all participants — 46 in each
group — completed the study. Blood pressure measurements of both groups were
within a normal range at baseline and endpoint, and BMI did not significantly
change in either group during the study. Beneficial HDL cholesterol levels, the
primary endpoint, significantly increased in the ALE group (P<0.001), but
remained unchanged in the placebo group. No significant changes were observed
in blood glucose concentrations in either group. Total cholesterol was
significantly lower in both the supplemented (P<0.001) and control
(P<0.010) groups; the change in this parameter in the supplemented group was
significantly greater than in the control group (P=0.012).
In addition,
the total cholesterol-to-HDL cholesterol ratio at the end of the study was
significantly lowered in the supplemented group as compared to baseline
(P<0.001); no change was observed in the placebo group. The LDL cholesterol
concentrations also were significantly lowered in both the supplemented and
placebo groups (P<0.001 and P<0.05, respectively). In the supplemented
group, the LDL cholesterol-to-HDL cholesterol ratio significantly decreased
(P<0.001), but remained unchanged in the placebo group. Triglycerides were
not significantly altered in either group. Compliance was rated as “excellent,”
and no adverse side effects were reported. In addition, blood chemistry was
normal in all subjects both at baseline and endpoint of the study.
In conclusion,
this study reports a significant increase in HDL cholesterol with a concurrent
decrease in LDL cholesterol in patients with hypercholesterolemia after eight
weeks of supplementation with ALE. The authors note that an inverse
relationship exists between HDL cholesterol and CVD risk, with a three percent
reduction in death risk or myocardial infarction for every one percent increase
in HDL cholesterol. Therefore, the clinical applications of ALE for this
purpose may be beneficial, but warrant further study.
Possible
mechanisms for the observed bioactivity include the modulation of various
enzymatic activities by ALE compounds. For example, previous studies have shown
that the ALE compounds chlorogenic acid and luteolin possibly attenuate LDL
cholesterol oxidation and related damage. Luteolin, in addition, inhibits
coenzyme A reductase activity, which is a key enzyme in the liver cholesterol
synthesis pathway. Finally, chlorogenic acid could favor the HDL cholesterol
increase through the agonistic effect on paraxonase-1, which is involved in the
protection of HDL cholesterol from oxidation.
One important
avenue of future research into ALE is the investigation of gender-related
effects, as certain parameters measured — HDL cholesterol, in particular — have
shown differences when data is stratified by gender. This suggests potential
variable responses to ALE supplementation. Furthermore, given the marked
sensory properties of cynaropicrin (bitter) and cynarin (sweet aftertaste),
more information on the nature of the placebo should have been included in the
publication.
—Amy
C. Keller, PhD
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