Abstracts from Berlin Garlic Symposium of the 6th Annual Phytotherapy Congre

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Re: Abstracts from Berlin Garlic Symposium of the 6th Annual

Phytotherapy Congress

 

Orekhov, Alexander N, et al. Direct Anti-atherosclerosis-related

Effects of Garlic. Annal of Medicine. Vol 27:63-65.

http://www.herbalgram.org/nowfoods/herbclip/review.asp?i=41790

 

Das, Indrajit, Nusrat S. Khan, and Suren R. Sooran. Potential

Activation of Nitric Oxide Synthase by Garlic: A Basis For It's

Therapeutic Applications. Current Medical Research & Opinion. Vol

13, No 5:257-263.

 

Holub, B.J. Effect of Garlic and Fish Oil Supplementation on Serum

Lipid & Lipoprotein Levels in Hypocholesterolaemic Men. Zeitschrift

fur Phytotherapie. :.

 

The following conference report was published in HerbalGram #36

pp.62-63

 

The Garlic Symposium of the 6th annual Phytotherapy Congress was

held in Berlin, Germany in October 1995. Eleven medical researchers

gathered together from the United Kingdom, Germany, Russia, United

States, and Canada to present scientific studies on the health

benefits of garlic supplements. The conference was funded by

Lichtwer Pharma GmbH of Berlin, whose standardized garlic supplement

Kwai® was used in all of the studies. Lichtwer states that Kwai is

standardized for its allicin yield, considered to be one of the key

active constituents of garlic responsible for its pharmacological

activity.

 

Garlic products are the top-selling over-the-counter medicine in

German pharmacies, where the government (Commission E of the Federal

Health Agency) approves claims for cardiovascular benefits. In the

U.S., garlic products are the largest-selling dietary supplement in

pharmacies. Under the Dietary Supplement Health and Education Act of

1994, garlic marketers in the U.S. have begun to advertise and label

their products with " structure and function " claims that indicate

some of garlic's actions on the cardiovascular system, based on the

growing body of scientific research suggesting such benefits. Thus,

the following research presented at the Berlin Garlic Conference

becomes increasingly relevant to public health concerns over the

high incidence of cardiovascular disease in the U.S.

 

Alexander Orekhov, a researcher from the Russian Academy of Medical

Sciences in Moscow, presented his group's study on the direct anti-

atherosclerotic effects of garlic. The positive influence of garlic

on cardiovascular risk factors having previously been reported in

numerous studies, this investigation was conducted to determine

whether the anti-atherosclerotic effect of garlic can be explained

by its direct action on the arterial wall or by indirect influences.

An aqueous extract of garlic powder obtained from Lichtwer Pharma

GmbH was used in a culture of smooth muscle cells derived from

atherosclerotic plaques of human aorta, with an incubation period of

24-hours. During that time, the garlic powder extract significantly

reduced the level of cholesteryl esters and free cholesterol in the

cultured atherosclerotic cells and also inhibited their

proliferation. A similar garlic extract used to incubate a culture

of normal healthy cells incubated for 24 hours significantly reduced

atherogenic manifestations of the blood serum. Thus, the garlic

powder extract caused both directly anti-atherosclerotic-related

action as well as anti-atherogenic-related (preventive) action,

reducing atherogenic manifestations at the cellular level.

 

Researchers Das, Khan, and Sooranna from Charing Cross and

Westminster Medical School in London reported on their investigation

of the platelet aggregation inhibiting effect of garlic, and whether

it was due to activation of nitric oxide synthase (NOS), the enzyme

which produces nitric oxide (NO).2 Both water and alcohol extracts

of garlic are potent inhibitors of platelet aggregation; similar

dilutions have also activated NOS activity in isolated platelets. In

their study, the researchers determined the effects of garlic

extract (prepared from fresh cloves of garlic or from Kwai garlic

tablets) on calcium-dependent NOS activity in two different in vitro

systems. Another parallel experiment was carried out in vivo, with

blood samples being collected before and after from subjects

ingesting fresh garlic cloves. The results of these investigations

showed a correlation between inhibition of platelet aggregation and

activation of NOS by very similar concentrations of garlic extract

Corresponding activation was also observed when garlic cloves were

ingested. The researchers noted that these findings could be

relevant in pregnancy; NOS activity has been found to be decreased

in placental tissues of pregnancies complicated by pre-eclampsia and

growth retardation. Due to its ability to activate NOS, garlic may

be able to alleviate such complications.

 

B.J. Holub, a researcher from the University of Guelph in Canada

presented a study wherein the effects of garlic and fish oil

supplementation, alone and in combination, on serum lipids and

lipoproteins in hypercholesterolemic subjects were examined. The

main purpose of the study was to determine the potential for a

combination garlic and fish oil to control elevated total

cholesterol, LDL cholesterol, and triglyceride levels

simultaneously. The investigator also sought to determine if garlic

could offset the commonly observed rise in LDL cholesterol induced

by fish oil supplementation alone. Fifty male subjects with moderate

hypercholesterolemia were randomized for twelve weeks to one of four

groups: (1) garlic placebo with fish oil placebo (GP/OP); (2) garlic

with fish oil placebo (G/OP); (3) garlic placebo with fish oil

(GP/FO); and (4) garlic with fish oil (G/FO).

 

Garlic supplementation alone (G/OP) significantly decreased both

total cholesterol and LDL cholesterol levels. Fish oil

supplementation alone (GP/FO) significantly decreased triglyceride

levels but increased LDL cholesterol levels. In combination, the

G/FO supplementation prevented the fish oil induced rise in LDL

cholesterol, and gave an overall decrease. The combination exhibited

a beneficial effect on serum lipid and lipoprotein levels by

providing a combined lowering total cholesterol, LDL cholesterol,

and triglyceride levels as well as lowering total cholesterol-HDL

and LDL-HDL ratios in the subjects.

 

R. Gebhardt, an investigator from the University of Tubingen in

Germany interested in the hypocholesteremic effects of garlic,

examined the interactions of garlic-derived organosulfur compounds

such as allicin, ajoene, and diallyldisulfide [DADS] with the

biosynthetic pathway for cholesterol in vitro, using cultured rat

hepatocytes.4 The results of the investigation showed that different

garlic compounds exert various effects on hepatic cholesterol

biosynthesis, and that these effects result in a " fine-tuned

modulation of the physiological regulation of this pathway. " By

interacting with intercellular signaling pathways, the garlic

compounds effectively influence several metabolic functions. The

researcher suggested that these effects may make garlic a unique

therapeutic tool for treatment of mild cases of

hypercholesterolemia.

 

Researchers Siegel and Casper from the Freie Universität in Berlin

investigated the influence of garlic constituents allicin and ajoene

and of an aqueous extract of garlic on the vascular tone of human

coronary vessels. Vascular strips were isolated from heart

transplant operations for use in these experiments. Kwai garlic

powder in aqueous extracts produced a vasodilating effect on the

smooth muscle cells and reduced wall tension in a concentration-

dependent manner. The effects of allicin and ajoene were reported to

be similar to those of the aqueous garlic extract, and to be

sufficient to explain quantitatively the whole vasodilating effect

of the extract.

 

Another group of researchers from Germany (Breithaupt, Ling, Wolf,

and Belz) presented their study on the effects of long-term garlic

intake on pulse wave velocity along the aorta, considered to be a

reliable index of the assessment of the degree of atherosclerosis.

Significant correlations between the degree of atherosclerosis of

the aorta or the coronary arteries and the pulse wave velocity have

been found in epidemiological studies. Aorta elastic properties are

characterized by : (1) pulse wave velocity (PWV); (2) the blood

pressure normalized elastic vascular resistance index (EVR); and (3)

by these parameters adjusted for age. The effects of a chronic

intake of Kwai garlic powder preparation in 100 healthy individuals

(aged 50 to 80 years) were compared to a control group of healthy

individuals reporting garlic intake as not above the usual German

average. The results, based on a fraction of the final group, show a

tendency towards an age dependent increase of PWV and EVR indicating

increased aortic stiffness with progressing age, with the EVR lower

in the garlic group. The researchers concluded that regular, long-

term intake of standardized garlic powder preparations may produce a

decreased stiffness of the aorta, and thereby lower the risk of

atherosclerosis.

 

Results of a randomized, double-blind, placebo-controlled study,

conducted by K.R. Melvin in a Toronto, Canada clinical setting, on

the effects of garlic powder tablets on patients (both male and

female) with hyperlipidemia were presented. A statistically

significant average of 12% reduction in plasma cholesterol was shown

with ingestion of 900 mg/day of Kwai garlic powder tablets over the

120 day trial period, suggesting that garlic powder supplementation

may provide a useful adjunctive therapy to conventional lipid

lowering medication.

 

While there is a great deal of evidence supporting the effectiveness

of allicin potential in standardized garlic supplements, little

clinical data is available for garlic oils, and no reported

comparative studies. These facts render broad generalizations about

garlic preparations difficult. In a randomized investigation, De A

Santos, a researcher in Birmingham, England, compared the effects of

Kwai dried garlic powder and garlic oil (Hofels, Seven Seas) on

blood lipids and blood pressure in patients randomly allocated to

one or the other preparation. Both medications were dosed three

times daily for a period of four months. Total cholesterol,

triglycerides, blood pressure and body mass were measured at entry

and monthly. The two groups were comparable at baseline with respect

to lipid values, but patients randomized to receive garlic powder

had significantly higher blood pressures. Results were tabulated and

summarized, showing significant decreases for cholesterol, LDL, and

systolic and diastolic blood pressure in the Kwai garlic powder

patients. These same levels were not affected significantly in the

patients receiving Hofels garlic oil. The researcher concluded that

if cardiovascular benefits are desired, only Kwai standardized

garlic powder can be expected to produce significant results.

 

In a study presented by researchers Mansell, Leatherdale, Lloyd, and

Reckless from hospitals in both Southampton and Bath in the U.K.,

the effects of dried garlic were investigated in non-insulin

dependent, diabetic male patients. Diabetics have a 2-3 fold

increased incidence of cardiovascular disease. Compared to placebo,

the Kwai garlic tablets had no significant effect on serum total

cholesterol, serum triglycerides, other lipid subfractions, blood

pressure, fasting blood glucose, HbAlo, serum insulin or C-peptide.

The garlic treatment did, however, reduce the LDL cholesterol

levels, and raise the HDL cholesterol level slightly. The authors of

the study concluded that dried garlic tablets have a beneficial

effect on LDL-HDL cholesterol ratios and thereby decrease the risk

factor for cardiovascular disease in " moderately dyslipidemic, non

insulin dependent diabetic patients. " [Ed note - The conclusions

cannot be drawn for all patients but only for male patients of this

description, since women were not included in the study.]

 

Christopher A. Silagy from the University of South Australia and

Andrew W. Neil from the University of Oxford presented their

findings of a meta-analysis of garlic as a lipid-lowering agent.

This study has already been covered in a previous issue; see

Herbalgram #33, page 13, for a more complete review.