Worldwide, type 2 diabetes is at epidemic proportions, with over 300 million already having the condition with an estimated rise to 600 million diagnosed cases by the year 2030.
Information regarding reduced risk of type 2 diabetes is fairly common. However, finding information regarding treatment and management for an individual who already has type 2 diabetes can be somewhat more difficult.
Therefore, this article is designed as a mini literature review of sorts, pointing to some of the recent research around olive oil and its potential benefits for use as a dietary intervention in type 2 diabetes treatment.
Endoplasmic reticulum stress (ER) is a central mediator for pancreatic beta-cell dysfunction in type 2 diabetes. An in vitro study published in Biochemical and Biophysical Research Communications, 2016, investigated if tyrosol, an antioxidant polyphenolic compound found in olive oil, could protect against beta-cell dysfunction. Researchers found that tyrosol did in fact protect against beta-cell ER stress-induced cell death, suggesting that it should be explored as a therapeutic agent for improving insulin resistance and diabetes.
Insulin resistance (IR) is one of the major contributors to difficulties in maintaining blood glucose control. A study published in Diabetologia, 2015, randomized 642 patients to either an olive oil enriched Mediterranean diet (MedDiet) (35 percent fat; 22 percent from monounsaturated fat) or a low-fat diet (less than 28 percent fat) to determine whether dietary intervention effects tissue-specific IR and beta-cell function. The study found that both diets improved IR, however, liver IR is improved more through a low-fat diet, while muscle IR and muscle+liver IR could benefit more from the olive oil enriched MedDiet.
At this point there are no clinical trials evaluating the role of dietary patterns on the incidence of microvascular complications such as retinopathy and nephropathy in type 2 diabetes. A post hoc analysis of a cohort of type 2 diabetic participants, published in Diabetes Care, 2015, shows that a MedDiet supplemented with EVOO may protect against diabetic retinopathy, a complication leading to blindness, but not nephropathy.
According to a detailed review of 2824 studies, published in the British Medical Journal, 2015, consuming a MedDiet is associated with better glycaemic control and cardiovascular risk factors, even compared to a lower fat diet.
Clinical conditions associated with obesity, such as type 2 diabetes, show improvements with daily intake of conjugated linoleic acid (CLA) or extra virgin olive oil (EVOO). A study on mice published in The Journal of Nutritional Biochemistry, 2015, investigated whether dietary supplementation of CLA or EVOO could change body metabolism associated with mitochondrial energetics. The study found that while EVOO alone did not change any metabolic parameter, combined with CLA it protects against IR and liver enlargement, while the CLA improves mitochondrial action and body metabolism.
According to research published in Biochimia et Biophysica Acta, 2014, oleic acid, a major biological component in olive oil, is a primary component of membrane lipids and helps to regulate membrane structures by having the ability to incorporate into phospholipids, which has various advantages to cell composition. It is also thought that membranes rich in oleic acid have increased flexibility to promote GLUT4 glucose transport into cells and help reverse saturated fatty acid-induced IR.
An 8.1-year follow-up of a 4 year randomized trial, published in Diabetes Care, 2014, evaluated the long-term effects of two dietary interventions on 215 overweight participants with newly diagnosed type 2 diabetes. A low-carbohydrate MedDiet (LCMD) (less than 50 percent carbohydrate) was compared to a typical low-fat diet (less than 30 percent fat) on the need for antihyperglycemic medication. The LCMD resulted in a significantly greater reduction in HBA1c levels, a higher rate of diabetes remission, and a 2-year difference in the need for diabetic medication compared to the low-fat diet.
Dyslipidemia is a consequence of metabolic syndrome and is common in individuals with type 2 diabetes. An in vitro study on rat liver cells, published in The Journal of Nutritional Biochemistry, 2014, showed that hydroxytyrosol, tyrosol, and oleuropein, phenols present in EVOO, inhibit fatty acid and triglyceride synthesis, supporting other research that shows olive oil exerts positive benefits on cholesterol levels.
A study published in Clinical Nutrition, 2013, randomized 110 patients with metabolic syndrome to either MedDiet+EVOO; MedDiet+nuts; or low-fat diet to investigate the effect of the MedDiet on systemic oxidative biomarkers. The results showed that compared to a low-fat diet, the MedDiet reduced oxidative damage to lipids and DNA in individuals with metabolic syndrome.
This is not an exhaustive list of the research examining the benefits of olive oil in the treatment and management of type 2 diabetes, just a brief review of recent evidence. However, the research does appear to show that olive oil, it’s phenols, polyphenols, and properties can help improve some of the key mechanisms involved in the development and progression of type 2 diabetes, being a suitable recommendation as part of a healthy dietary intervention.
- Biochemical and Biophysical Research Communications (2016): Tyrosol, an olive oil polyphenol, inhibits ER stress-induced apoptosis in pancreatic β-cell through JNK signaling.
- Diabetologia (2015): The insulin resistance phenotype (muscle or liver) interacts with the type of diet to determine changes in disposition index after 2 years of intervention: the CORDIOPREV-DIAB randomized clinical trial
- Diabetes Care (2105): Mediterranean Diet, Retinopathy, Nephropathy, and Microvascular Diabetes Complications: A Post Hoc Analysis of a Randomized Trial
- British Medical Journal (2015): A journey into a Mediterranean diet and type 2 diabetes: a systematic review with meta-analyses
- The Journal of Nutritional Biochemistry (2015): The combination of conjugated linoleic acid (CLA) and extra virgin olive oil increases mitochondrial and body metabolism and prevents CLA-associated insulin resistance and liver hypertrophy in C57Bl/6 mice.
- Biochimica et Biophysica Acta (2014): Membrane composition and dynamics: A target of bioactive virgin olive oil constituents.
- Diabetes Care (2014): The Effects of a Mediterranean Diet on Need for Diabetes Drugs and Remission of Newly Diagnosed Type 2 Diabetes: Follow-up of a Randomized Trial
- The Journal of Nutritional Biochemistry (2014): Extra virgin olive oil phenols down-regulate lipid synthesis in primary-cultured rat-hepatocytes
- Clinical Nutrition (2013): The Mediterranean diet improves the systemic lipid and DNA oxidative damage in metabolic syndrome individuals. A randomized, controlled, trial.