Olive oil is one of the major ingredients in the Mediterranean diet. We see this oil in salad dressings, and as a bulk liquid or carrier for a variety of savoury food products. It has long been associated with offering protective effects against heart disease (cardiovascular disease or CVD) although it is not clear why. Traditionally, the Mediterranean diet itself is characterized by a regularly high intake of fruits and vegetables, various cereals, fish and moderate wine consumption, with reduced intake of dairy products and red meat. Not only does this particular diet have positive associations with reducing heart disease but also with reducing type-2 diabetes (Salvas-Salvado et al., 2014) and possibly improving mental acuity in the elderly.
Cardiovascular diseases account for more deaths around the globe than any other cause including cancer. It is estimated that 17.5 million people died from heart diseases in 2012, most often from heart disease or stroke, according to the World Health Organization (WHO).
Italian researchers based at the Sapienza University of Rome researched the value of olive oil in the diet of 25 healthy subjects who were randomly allocated in a crossover design to a Mediterranean-type meal to which was added either 10 g of extra virgin olive oil or not. A second study involved consumption of a Mediterranean-type meal with 10 g of extra virgin olive oil or 10 g of corn oil.
In the first study, two hours after their meal, subjects who assumed a meal with olive oil had significantly lower blood glucose, DPP-4 protein and activity, low-density lipoprotein (LDL) cholesterol and oxidized LDL, and higher insulin, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), compared with those without olive oil. The second study showed that compared with corn oil, olive oil improved both glycaemic and lipid profile. Thus, a significantly smaller increase of glucose, DPP4 protein and activity, and higher increase of insulin and GLP-1 were observed. Furthermore, compared with corn oil, olive oil showed a significantly less increase of LDL and oxidized LDL.
The results of this study, for the first time, show that extra virgin olive oil improves post-prandial glucose and LDL cholesterol, an effect that may account for the anti-atherosclerotic effect of the Mediterranean diet. Possible explanations as to why olive oil rather than other forms of oil are beneficial are still being formulated.
Nutrition & Diabetes (2015) 5, e172; doi:10.1038/nutd.2015.23
Salas-Salvado, J., Bullo, M., Estruch, R., Ros, E., Covas, M.I., Ibarrola-Jurado, N. et al. (2014) Prevention of diabetes with mediterranean diets: a subgroup analysis of a randomized trial. Ann. Intern. Med. 160 pp.1–10.
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