Source
Department of Nutrition and Food Sciences, Physiology and Toxicology, University of Navarra, Pamplona, Spain. anabelencrujeiras@hotmail.com
Abstract
BACKGROUND:
Postprandially induced oxidative stress can cause damage to mitochondrial components and initiate cellular degradative processes; which are related to obesity comorbidities.
AIM OF THE STUDY:
This trial sought to determine whether weight loss induced by caloric restriction provides antioxidant protection to reduce the postprandial response of mitochondrial function and oxidative stress markers.
METHODS:
A group of overweight/obese volunteers (n = 17; 39 +/-7 years, 32.5 +/- 4.8 kg/m(2)) followed an 8-week hypocaloric diet. Volunteers provided blood samples at fasting and 2-h after a test drink (CHO: 95% E, PROT: 5% E and containing antioxidants) and these were examined for postprandial oxidative stress responses, before and after the nutritional intervention. The expression of four mitochondrial-related genes, COX15, NDUFS2, MGST2 and TNF-alfa, was measured in peripheral blood mononuclear cells (PBMC) by quantitative RT-PCR. Lipid peroxidation and nitrosative stress biomarkers, total antioxidant capacity (AOP), uric acid and glutathione peroxidase were also determined.
RESULTS:
Before nutritional treatment, the test drink induced a postprandial increase in lipid peroxidation and nitrosative stress biomarkers with a concomitant increase in the AOP. The increase in postprandial oxidative stress biomarkers was accompanied by a decrease in PBMC COX15 mRNA levels. Interestingly, after the weight loss period (-5.8 +/- 2.3%), the postprandial-induced changes were lower than at the beginning of the study and involved oxidative stress biomarkers and the COX15 and MGST2 transcripts. This finding suggests the occurrence of a tachyphylactic process.
CONCLUSIONS:
We demonstrate for the first time that the well-known effect of energy restriction on oxidative stress is accompanied by a tolerance mechanism on the postprandial oxidative stress response and mitochondrial function-related genes. Indeed, the COX15 and MGST2 gene expression assays in PBMC emerged as valuable nutrigenomic biomarkers of the oxidative response under energy-restriction conditions.