Clinical conditions associated with
obesity can be improved by daily intake of
conjugated linoleic acid (CLA) or extra virgin
olive oil (EVOO). Here we investigated whether dietary supplementation with CLA and EVOO, either alone or in combination, changes body metabolism associated with mitochondrial energetics. Male C57Bl/6 mice were divided into one of four groups: CLA (1:1 cis-9, trans-11:trans-10, cis-12; 18:2 isomers), EVOO, CLA plus EVOO or control (
linoleic acid). Each mouse received 3 g/kg
body weight of the stated oil by gavage on alternating days for 60 days. Dietary supplementation with CLA, alone or in combination with EVOO: (a) reduced the white adipose tissue gain; (b) increased body VO2 consumption, VCO2 production and energy expenditure; (c) elevated
uncoupling protein (UCP)-2 expression and UCP activity in isolated liver mitochondria. This organelle, when energized with
NAD(+)-linked substrates, produced high amounts of H2O2 without inducing oxidative damage. Dietary supplementation with EVOO alone did not change any metabolic parameter, but supplementation with CLA itself promoted
insulin resistance and elevated weight,
lipid content and
acetyl-CoA carboxylase-1 expression in liver. Interestingly, the in vivo
antioxidant therapy with
N-acetylcysteine abolished the CLA-induced rise of body metabolism and liver UCP expression and activity, while the in vitro
antioxidant treatment with
catalase mitigated the CLA-dependent UCP-2 expression in hepatocytes; these findings suggest the participation of an oxidative-dependent pathway. Therefore, this study clarifies the mechanisms by which CLA induces liver UCP expression and activity, and demonstrates for the first time the beneficial effects of combined CLA and EVOO supplementation.