In a series of recent clinical studies approved by the Sapienza University of Rome ethics committee, an Italian research group provided preliminary evidence on the short-term beneficial effect of extra virgin olive oil (EVOO), the hallmark of the Mediterranean diet, on postprandial glycemic and lipid profile in healthy and pre-diabetic adults. In parallel, this group discovered incretin regulation as a plausible underlying mechanism for EVOO antioxidant and cardioprotective effects.
Despite robust clinical evidence associating the Mediterranean diet, especially its key component extra virgin olive oil (EVOO), with a lower risk of vascular disease, until now there has been no clear indication how it can exert its vascular protective effects. Furthermore, postprandial glycemia has been linked to higher prevalence of cardiovascular outcomes in the general population.
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In the first series of studies published in Atherosclerosis, the Italian group demonstrated not only the “protective effect of EVOO on a number of oxidative stress markers,” but also “showed for the first time that extra virgin olive oil down-regulated NOX2 activity, pointing to this enzymatic pathway as a mechanism accounting for the antioxidant activity of extra virgin olive oil.”
The authors pointed out the possibility that EVOO may exert its effect by other enzymatic pathways in the control of postprandial oxidative stress.
Last year, the research group took a step further and demonstrated in healthy adult volunteers that a meal with added EVOO is associated with reduced postprandial oxidative stress and improved postprandial glycemia via incretin regulatory mechanism.
Incretin hormones such as Glucagon-like peptide-1 (GLP1) and glucose-dependent insulinotropic peptide (GIP) are known to induce insulin secretion and significantly influence postprandial glycemic control. These incretins are rapidly deactivated by dipeptidyl-peptidase-4 (DPP-4) ubiquitous enzyme thus lowering insulin secretion.
The findings of the latest research published in Clinical Nutrition further revealed that the addition of small amount of EVOO (10g) to a meal enhanced postprandial glycemic and lipid profile this time in pre-diabetic patients. Compared to control, meals containing EVOO resulted in an almost 20 percent decrease in postprandial blood glucose and 40 percent increase in insulin production.
Similar to their previous findings, the evidence supported incretin hormone involvement specifically GLP1 in the regulation of postprandial glucose. The in vitro studies demonstrated EVOO resulted in activation of both incretin hormones with concomitant inhibition of DPP-4 activity.
The authors concluded that inclusion of EVOO in meals improves postprandial glucose and lipid profile in pre-diabetic patients reducing damaging effects of high sugar and cholesterol on the vascular system. They also recognize that further research in this impaired glucose metabolism group is warranted to evaluate long-term effects of EVOO supplementation.
The message from these studies reinforces the notion that prevention against a host of chronic ailments is as simple as the addition of a tablespoon of EVOO to meals on a daily basis.
- Carnevale, Roberto, et al. “Extra virgin olive oil improves post-prandial glycemic and lipid profile in patients with impaired fasting glucose.” Clinical Nutrition (2016)
- Carnevale, Roberto, et al. “Extra virgin olive oil blunt post-prandial oxidative stress via NOX2 down-regulation.” Atherosclerosis 235.2 (2014): 649-658
- Carnevale, Roberto, et al. “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