Antioxidant enzyme activity and coronary heart disease: meta-analyses of observational studies

Area of Science:

• Biochemistry
• Cardiovascular Medicine
• Preventive Cardiology

Background:

• Conflicting data exist regarding the association between scavenger antioxidant enzyme activity and coronary heart disease (CHD) risk.
• Antioxidant enzymes play a crucial role in cellular defense against oxidative stress, a known contributor to cardiovascular pathology.

Purpose of the Study:

• To conduct updated meta-analyses evaluating the relationship between the activities of glutathione peroxidase, superoxide dismutase, and catalase and CHD risk.
• To synthesize evidence from existing studies to clarify the role of these enzymes in CHD pathogenesis and prevention.

Main Methods:

• Comprehensive literature searches (January 1966-January 2008) using computer-based and manual methods.
• Inclusion of case-control and prospective studies measuring antioxidant enzyme activities and clinical CHD outcomes.
• Calculation of pooled odds ratios using an inverse-variance-weighted random-effects model to assess CHD risk associated with enzyme activity levels.

Main Results:

• Inclusion of 42 case-control and 3 prospective studies.
• Significant inverse associations were found: a 1-SD increase in activity was linked to reduced CHD risk (GPx: OR 0.51, SD: OR 0.48, CAT: OR 0.32).
• High between-study heterogeneity (I(2) > 90%) was observed, though findings remained robust in sensitivity analyses.

Conclusions:

• The meta-analyses support a significant inverse association between circulating levels of superoxide dismutase, glutathione peroxidase, and catalase activities and CHD.
• These findings highlight the potential cardioprotective role of these antioxidant enzymes.
• Further high-quality prospective studies are warranted to confirm these associations and explore underlying mechanisms.