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Prevention of Hypercholesterolemic Atherosclerosis by Garlic, an Antixoidant
1Departments of Physiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Abstract:
BACKGROUND: Investigations of the effects of high cholesterol diet in the presence and absence of garlic on the genesis of atherosclerosis, the blood lipid profile, aortic tissue lipid peroxidation product malondialdehyde, chemiluminescence, a marker for antioxidant reserve and activity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase were made in rabbits. METHODS AND RESULTS: Four groups of 10 rabbits each were studied: group 1 was given regular rabbit chow, group 2 was given rabbit chow diet supplemented with garlic powder (300 mg twice daily orally), group 3 was given 1% cholesterol diet, group 4 was given 1% cholesterol diet supplemented with garlic powder (300 mg twice daily orally). Blood concentration of triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol were measured before and after 4 and 10 weeks of experimental diets. The aorta was removed at the end of protocol (10 weeks) for assessment of atherosclerotic changes (gross and microscopic), malondialdehyde concentration, chemiluminescence, and activity of antioxidant enzymes. Total cholesterol, low density-lipoprotein cholesterol and ratio of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol and ratio of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol increaserd in group 3 and 4; the increase was smaller in group 4 than in in group 3 although not significant. Serum high-density lipoprotein cholesterol decreased to a similar extent in groups 3 and 4. Serum triglyceride and very low-density lipoprotein cholesterol remained unchanged in group 3 but increased in group 4. These values were significantly higher than those in group 1. Garlic in rabbits with control diet decreased the levels of triglyceride and very low density lipoprotein but did not affect the levels of total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol and the ratio of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol. There was an increase in aortic tissue malondialdehyde, chemiluminescence, and activities of catalase and glutathione peroxidase in group 3 compared with those in group 1. Levels of aortic malondialdehyde, chemiluminescence, catalase, and glutathione peroxidase were lower in group 4 compared with group 3; however, values for malondialdehyde and chemiluminescence were lower and that of catalase and glutathione peroxidase were higher in group 4 compared with group 1. Superoxide dismutase activity was similar in all the four groups. Malondialdehyde, chemiluminescence, and activity of catalase of aortic tissue decreased while activity of glutathione peroxidase increased in group 2. Atherosclerotic changes were lower in group 4 compared with group 3. Histologic changes were practically similar in groups 3 and 4. CONCLUSIONS: Increased levels of malondialdehyde, chemiluminescence, and antioxidant enzymes associated with development of atherosclerosis suggests a role for oxygen free radicals in the pathogenesis of hypercholesterolemic atherosclerosis. The protection afforded by garlic was associated with decrease in aortic malondialdehyde and chemiluminescence inspite of no change in serum cholesterol. These findings suggest that oxygen free radicals are involved in the genesis and maintenance of hypercholesterolemic atherosclerosis and that use of garlic can be useful in preventing the development of hypercholesterolemic atherosclerosis.
Insights
Garlic may help prevent atherosclerosis by reducing oxidative stress in aortic tissue, even without significantly altering blood cholesterol levels. This study in rabbits suggests garlic
Area of Science:
- Cardiovascular Research
- Nutritional Science
- Biochemistry
Background:
- Atherosclerosis is a complex disease influenced by diet and oxidative stress.
- High cholesterol diets are known risk factors for atherosclerosis.
- Garlic's potential cardioprotective effects are under investigation.
Purpose of the Study:
- To investigate the effects of a high-cholesterol diet, with and without garlic, on atherosclerosis development in rabbits.
- To assess the impact on blood lipid profiles and oxidative stress markers in aortic tissue.
Main Methods:
- Rabbits were divided into four groups: control, garlic-supplemented control, high-cholesterol diet, and high-cholesterol diet with garlic.
- Blood lipid profiles were measured over 10 weeks.
- Aortic tissues were analyzed for atherosclerotic changes, malondialdehyde (MDA), chemiluminescence, and antioxidant enzyme activities.
Main Results:
- High-cholesterol diet increased aortic MDA and chemiluminescence, indicating increased lipid peroxidation and oxidative stress.
- Garlic supplementation in the high-cholesterol group reduced aortic MDA and chemiluminescence compared to the high-cholesterol group alone.
- While serum cholesterol levels were not significantly altered by garlic in the high-cholesterol diet, aortic oxidative stress markers were improved.
- Garlic alone (control diet) reduced triglyceride and very low-density lipoprotein levels and aortic oxidative stress markers.
Conclusions:
- Oxygen free radicals play a significant role in the pathogenesis of hypercholesterolemic atherosclerosis.
- Garlic demonstrates protective effects against atherosclerosis, likely through its antioxidant properties, reducing aortic oxidative stress.
- Garlic may be a useful dietary intervention for preventing hypercholesterolemic atherosclerosis.