Abstract

At the level of arterial wall, the trigger step in atherogenesis is the deposition of intracellular cholesterol that is followed by foam cell formation, and induces excessive production of connective tissue matrix components, migration of hematogenic cells, cellular proliferation and inflammatory reactions. So, the prevention of lipid deposition in vascular wall may inhibit further formation of atherosclerotic lesions. 
To test this hypothesis, the 2-years double-blinded placebo-controlled randomized clinical trial has been performed in 196 asymptomatic men aged 40-74. Time-released garlic powder tablets Allicor were used to inhibit patients' serum ability to induce intracellular cholesterol accumulation, the effect being monitored in cultured human monocyte-derived macrophages. The primary outcome was the rate of atherosclerosis progression, measured by high-resolution B-mode ultrasonography as the increase in intima-media thickness (IMT) of common carotid arteries. 
The mean rate of IMT changes in Allicor-treated group (-0.022±0.007 mm per year) differed significantly (p=0.002) from the placebo group in which there was a moderate yearly progression of 0.015±0.008 mm. Within Allicor-treated group, IMT significant reduction was observed in 47.3% patients vs 30.1% in placebo group (p<0.05). The further significant IMT increase was registered in 32.2% patients in Allicor-treated group vs 47.3% in placebo group (p<0.05). The ability of patients' serum to induce cholesterol accumulation in cultured cells was lowered in Allicor-treated patients by 30% on an average. In the placebo group, serum atherogenic potential did not change significantly during the study. A significant correlation has been revealed between the changes in serum atherogenicity during the study and the changes in IMT of common carotid arteries (r=0.144, p=0.045). 
Garlic is known to possess a wide range of cardioprotective effects, including cholesterol lowering, blood pressure regulation, anti-platelet action and fibrinolysis activation. The novel mechanism of action of garlic based on the reduction of serum atherogenic potential provides the direct antiatherosclerotic effect.