When oxygen free-radicals overwhelm the antioxidant defenses of
the body, oxidative stress occurs, producing inflammation. In
one study, two groups of people with higher chances of heart
disease took 4,000 mg of EPA (eicosapentaenoic acid) or DHA
(docosahexaenoic acid) per day, or a placebo. The first group
was overweight and had abnormal blood fat levels. The second
group had type 2 diabetes and was taking medication for high
blood pressure. After six weeks, compared to placebo,
researchers found about 20 percent fewer signs of oxidative
stress in those who took EPA and about 17 percent fewer signs in
those who took DHA. Doctors believe that the anti-inflammatory
action of omega-3s lowers oxidative stress and chances of
cardiovascular disease.