Natural antioxidants and atherosclerosis.

Area of Science:

• Biochemistry
• Cardiovascular Research
• Nutritional Science

Background:

• Atherosclerosis begins with fatty streaks, involving lipid-laden macrophages derived from blood monocytes.
• Low-density lipoprotein (LDL) uptake by macrophages is enhanced when LDL is oxidatively modified.
• Oxidative modification of LDL in the subendothelial space is hypothesized as a key factor in atherosclerosis development.

Purpose of the Study:

• To investigate the role of antioxidants, specifically ubiquinol, in protecting LDL from oxidation.
• To explore the relationship between antioxidant levels, LDL oxidation, and coronary heart disease (CHD) incidence.
• To assess the impact of ubiquinone supplementation on LDL's resistance to oxidation.

Main Methods:

• Epidemiological study of 12 European populations with varying CHD incidence but similar cholesterol levels.
• Analysis of plasma antioxidant levels (alpha-tocopherol, ubiquinol, carotenoids) and their correlation with CHD.
• In vitro experiments assessing LDL oxidation resistance with and without antioxidants (ascorbate, ubiquinol).
• Clinical trial involving ubiquinone supplementation to volunteers and subsequent measurement of LDL oxidation resistance.

Main Results:

• A significant inverse correlation was found between plasma alpha-tocopherol and CHD incidence.
• Small amounts of ubiquinol in LDL significantly protect it against oxidation.
• Ubiquinol, unlike vitamins C and E, is biosynthesized by humans and found in fatty fish.
• Supplementation with ubiquinone increased plasma LDL ubiquinol content fourfold, making LDL more resistant to oxidation.

Conclusions:

• Ubiquinol plays a crucial role in protecting LDL from oxidative damage, a key process in atherosclerosis.
• Dietary or supplemental ubiquinone may enhance LDL's resistance to oxidation, potentially mitigating CHD risk.
• Antioxidant status, particularly ubiquinol levels, is an important factor in cardiovascular health.