Supplementing the diet with hydroxytyrosol-enriched sunflower oil was associated with higher activity levels of the enzyme arylesterase, said to be an antioxidant biomarker, as well as lower levels of oxidized LDL cholesterol, believed to be a major player in terms of promoting atherosclerosis, the build up of fatty plaques in the arteries, and in cardiovascular disease in general.
Researchers from the Universidad Complutense de Madrid report their results in the British Journal of Nutrition.
Hydroxytyrosol is thought to be the main antioxidant compound in olives, and believed to play a significant role in the many health benefits attributed to olive oil. Previous research has linked the compound to cardiovascular benefits, with reductions in LDL or 'bad' cholesterol. Data has also suggested the compound may boost eye health and reduce the risk of against macular degeneration.
The Madrid based researchers recruited 22 healthy volunteers aged between 20 and 45 years and with a BMI between 18 and 33 kg/m2. Volunteers were randomly assigned to received the 10 to 15 grams per day of hydroxytyrosol-enriched sunflower oil or non-enriched sunflower oil for three weeks. The former provided a daily hydroxytyrosol dose of between 45 and 50 mg. After the initial three weeks, the volunteers had two weeks of no intervention before crossing over to receive the other intervention.
Results showed no changes in total, LDL-, and HDL-cholesterol between the groups. However, consumption of the hydroxytyrosol-enriched sunflower oil produced significant reductions in oxidised LDL from 79.8 units per liter at the start of the study to 64.1 U/l after three weeks, compared to an increase from 72.7 to 86.4 U/l during the control phase.
Furthermore, the activity of arylesterase increased from 235.2 to 448.9 U/l during the hydroxytyrosol phase, compared with an increase from 204.1 to 310.3 U/l during the control phase.
“Although hydroxytyrosol-enriched sunflower oil was unable to reduce LDL-cholesterol or increase HDL-cholesterol, it acts as a functional food by increasing arylesterase activity and reducing oxidised LDL,” report the researchers. “This oil can therefore be used as a dietary complement to reduce CVD risk.
“Further studies are needed to understand the mechanisms by which hydroxytyrosol affects arylesterase activity and influences the arylesterase activity:HDL-cholesterol ratio,” they concluded.
Source: British Journal of Nutrition
Published online ahead of print, FirstView Articles, doi:10.1017/S0007114510005015
“Effects of hydroxytyrosol-enriched sunflower oil consumption on CVD risk factors”
Authors: M. Vazquez-Velasco, L. Esperanza Diaz, R. Lucas, S. Gomez-Martínez, S. Bastida, A. Marcos, F.J. Sanchez-Muniz