ATLANTA, GEORGIA. As the incidence of metabolic syndrome grows rapidly in the Western world, many avenues of research are being pursued with the aim of limiting its damaging effects. Metabolic syndrome consists of a cluster of symptoms including insulin resistance, abdominal obesity, hypertension (high blood pressure), high triglyceride levels, and low levels of "good" cholesterol (HDL cholesterol). It increases risk of diseases related to atherosclerosis (hardening of the arteries), such as stroke and heart attack.
Findings suggest that pro-inflammatory and pro-oxidative processes play a significant role in the syndrome, so a team from Emory University School of Medicine investigated the effects of an anti-inflammatory drug and an antioxidant supplement. The anti-inflammatory they used was irbesartan, which blocks angiotensin II, a central molecule in inflammation, atherosclerosis, and the functioning of endothelial cells, which line the blood vessels. The antioxidant used for the study was lipoic acid, a widely-available nutritional supplement which increases levels of coenzyme Q10 and acts as a free-radical scavenger.
For four weeks, 58 participants with metabolic syndrome were randomly allocated to irbesartan (at 150 mg per day), lipoic acid (at 300 mg per day), both, or placebo. The dose of irbesartan was chosen because it had previously reduced inflammation in coronary artery disease patients, and the lipoic acid dose had reduced oxidative stress in healthy participants. Each of the treatment groups showed improved blood flow in the main artery of the upper arm, due to dilation of the blood vessels. Dilation increased by 67 per cent in the irbesartan group, 44 per cent in the lipoic acid group, and 75 in the combined group, compared with those on placebo. The treatments also reduced oxidative stress and markers of inflammation that are linked to atherosclerosis. They did not affect blood pressure.
The authors conclude that giving these treatments to patients with metabolic syndrome benefits endothelial
function and triggers anti-inflammatory changes which together protect against the development of
atherosclerosis and its related diseases.