Why Is Olive Oil So Effective For Our Health When Combined With Green Leafy Salads?
The combination of unsaturated fats in olive oil and nitrite-rich leafy salad or vegetables may be what gives the Mediterranean diet its healthy edge, according to new research.
The study, published in PNAS, suggests that the combination unsaturated fats and nitrite-rich vegetables can lead to the formation of nitro fatty acids that may offer protection against high blood pressure (hypertension). Extra virgin olive oil (EVOO) and olives, key sources of unsaturated fatty acids in the Mediterranean diet, provide health benefits to humans. The diet typically includes unsaturated fats found in olive oil, nuts and avocados, along with vegetables like spinach, celery and carrots that are rich in nitrites and natural nitrates.
When these two food groups are combined, the reaction of unsaturated fatty acids with nitrogen compounds in the vegetables results in the formation of nitro fatty acids, said the team behind the research.
Nitro-fatty acids are formed and detected in human plasma, cell membranes, and tissue, modulating metabolic as well as inflammatory signaling pathways.
"The findings of our study help to explain why previous research has shown that a Mediterranean diet supplemented with extra-virgin olive oil or nuts can reduce the incidence of cardiovascular problems like stroke, heart failure and heart attacks," commented Professor Philip Eaton of King's College London, who led the study.
In their study, which was supported by the British Heart Foundation, the researchers used genetically engineered mice to see what impact nitro fatty acids had on the body.
The team used genetically engineered mice to test whether nitro fatty acids lowered blood pressure via an enzyme known as soluble epoxide hydrolase - which regulates blood pressure. Mice genetically engineered to be resistant to the enzyme process were found to maintain their high blood pressure despite being fed the type of nitro fatty acids that normally form when a Mediterranean diet is consumed.
However, nitro fatty acids were found to lower the blood pressure of normal mice following the same diets.
Eaton and his team therefore concluded that the protective effect of the Mediterranean diet, combining unsaturated fats and vegetables abundant in nitrite and nitrate, comes at least in part from the nitro fatty acids generated, which in turn which inhibit soluble epoxide hydrolase to lower blood pressure.
"These observations reveal that lipid electrophiles such as NO2-OA mediate antihypertensive signalling actions by inhibiting sEH and suggest a mechanism accounting for protection from hypertension afforded by the Mediterranean diet," said the team.