A Mediterranean diet is considered to be ideal for healthy nutrition. It is typically composed of fruits, vegetables, cereals, fish, moderate wine consumption, and limited intake of dairy products and red meat. Furthermore, there are several studies showing that this type of diet is connected with reduced risk of cardiovascular events. Therefore, a Mediterranean-style diet may be preferred in certain individuals with cardiovascular risk due to the associated potential benefits. Specifically, research has been conducted to identify the effects on post-prandial glucose with the use of extra virgin olive oil in this type of cuisine.
At Sapienza University of Rome, professor Francesco Violi, MD, and his partners conducted research where they analyzed glucose and cholesterol findings from healthy subjects consisting of 12 men and 13 women. These individuals were randomly assigned to a Mediterranean-style meal with or without 10 grams of extra virgin olive oil. One month after the end of the study, the research was conducted again with the same participants, but this time with either 10 grams of extra virgin olive oil or 10 grams of corn oil. Investigators acquired blood tests prior to meals and two hours after meals. The parameters measured were glucose, insulin, DPP4 protein and activity, GLP-1, glucose-dependent insulinotropic polypeptide (GIP) and lipid profiles.
In the first phase of the study, a significantly lower blood glucose, DPP4 protein and activity, LDL cholesterol, and oxidized LDL were identified in subjects that ate meals with extra virgin olive oil. In addition, these subjects also displayed higher insulin, GLP-1 and GIP in comparison to subjects who ate meals without extra virgin olive oil (P<0.001 for all except GIP; P= 0.025 for GIP). Extra virgin olive oil consuming subjects had an average blood glucose baseline of 79.7 mg/dL prior to meals, and a two-hour postprandial average of 105.9 mg/dL. Subjects who consumed meals without extra virgin olive oil had average blood glucose baseline of 77.8 mg/dL, and a two-hour postprandial average of 131.4 mg/dL.
In the second phase of the study, subjects who consumed meals with extra virgin olive oil instead of corn oil displayed similar results. These participants showed improved levels of glucose (P= 0.01), insulin (P<0.001), GLP1 (P<0.001), DPP4 (P<0.001) and activity (P= 0.001) and LDL cholesterol (P<0.05). Subjects who consumed extra virgin olive oil had an average blood glucose baseline of 77 mg/dL, and a two-hour postprandial average of 98.2 mg/dL. Subjects who consumed meals with corn oil had an average blood glucose baseline of 79 mg/dL, and two-hour postprandial average of 119.7 mg/dL. Other parameters for cholesterol such as HDL and triglycerides were not significant; however, showed an improvement in trend.
The authors conclude that this is the first study demonstrating that a Mediterranean-type meal supplemented with extra virgin olive oil has beneficial effect on postprandial glycemic and lipid profile by decreasing blood glucose, LDL-C, and ox-LDL. However, no data exists on insulin secretion since these incremental parameters were not available or measured. Furthermore, it cannot be excluded that corn oil has a positive effect compared to the control since this hypothesis was not the prime focus of investigation. Lastly, the study was performed on healthy individuals; therefore, it is important to determine if the same benefits apply to patients with diabetes or dyslipidemia.
- A Mediterranean diet supplemented with extra virgin olive oil compared to corn oil or no consumption of oil may have some benefit in controlling postprandial blood glucose and cholesterol.
- Extra virgin olive oil consumption may have a protective effect against cardiovascular disease as indicated by short-term findings of improvement in glucose and cholesterol levels; however, further studies need to be performed to identify long-term consistency.
- Improvement in the lipid profile with the consumption of extra virgin olive oil is an unexpected finding that requires further research in addition to identifying the mechanism for better postprandial glucose control.
Violi, F., et al. “Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects.” Nutrition & diabetes 5.7 (2015): e172.