Effect of virgin and refined olive oil consumption on gut microbiota. Comparison to butter M. Hidalgo a , I. Prieto b , H. Abriouel a , A. Cobo a , N. Benomar a , A. Gálvez a , M. Martínez-Cañamero a, ⁎ a Área de Microbiología, Departamento de Ciencias de la Salud, Universidad de Jaén, Spain b Área de Fisiología, Departamento de Ciencias de la Salud, Universidad de Jaén, Spain abstract article info Article history: Received 27 April 2014 Accepted 20 July 2014 Available online 28 July 2014 Keywords: DGGE Gut microbiota Olive oil Butter There is increasing evidence of the health benefits of olive oil consumption in the diet. Some authors have studied the effect of high fat/high calorie diets and have detected changes on the microbiota. However, these studies are mainly based on saturated fats. Here we present a study on the specific effect on gut bacterial populations of extra virgin olive oil, rich in monounsaturated fatty acids and phenolic compounds, in comparison to refined olive oil, rich in monounsaturated fatty acids but low in phenolic compounds, and to butter, rich in saturated fatty acids and cholesterol. Four groups of animals were studied: one group of mice received a standard chow diet, and the other received three high fat diets, rich in extra virgin olive oil, refined olive oil or butter. Evolution of sym- biont population in feces was studied using culture-dependent and culture-independent methods. In the latter, the V3 region of 16S rDNA was amplified and separated by denaturing gradient gel electrophoresis; followed by sequencing of the most representative bands. Culture-dependent studies and comparison of the different DGGE profiles throughout the experiment demonstrated that different dietary fats had different effects on gut microbial composition. Butter-induced changes in the microbial counts resembled those previously described in obese individuals. Interestingly, a different behavior between extra virgin and refined olive oil was also ob- served, extra virgin olive oil being most different from butter. To our knowledge, no studies have analyzed gut microbiota depending on diets with different fatty acid saturations including different types of olive oil. This may offer new data supporting the benefits for health of extra virgin olive oil, so important in the Mediterranean diet. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Currently, the popularity of the Mediterranean diet is increasing not only because of its organoleptic properties but also, and mainly, due to the health benefits it confers. A major component of the Mediterranean diet is virgin olive oil, which has been related to a decrease in the incidence of cardiovascular disease and hypertension (Williams, Fortmann, & Terry, 1987) as well as to other positive effects, including a possible role in modulating cognitive functions (Segarra et al., 2011). Concordantly, the Mediterranean diet, which is characterized by a high intake of vegetables, fruits, legumes, nuts, cereals, and monounsat- urated fat (e.g., olive oil), has also been associated with positive effects such as improved cardiovascular health, reduction in the cognitive decline and a lower risk of development of Alzheimer's disease (Ye et al., 2013). Olive oil can be produced and distributed mainly as four different products: extra virgin olive oil (EVOO), which is a high quality juice extracted from olives only by mechanical means with no chemical inter- vention; virgin olive oil (VOO), which is a good quality juice extracted from olives only by mechanical means with no chemical intervention; refined olive oil (ROO), which is a low quality oil that undergoes chem- ical intervention to become edible and olive oil (OO), which is ROO with a low percentage (10–15%) of VOO to improve palatability. Usually, OO is the only way refined olive oil reaches the consumer, since organolep- tic properties of ROO are very poor. Fatty acid composition is similar in the four types of products but minor components, mainly phenolic com- pounds, are depleted in refined olive oil as they are lost during the chemical extraction procedure (Ramírez-Tortosa et al., 1999). It should be noted that phenolic compounds are assumed to be one of the health- iest fractions of olive oil (Cicerale, Lucas, & Keast, 2012; Owen et al., 2000; Pérez-Martínez, García-Ríos, Delgado-Lista, Pérez-Jiménez, & López-Miranda, 2011). During the last few years there has been a high number of reports about the effect of diet on the composition of the intestinal microbiota, defining different enterotypes according to the diet (Arumugam et al., 2011) and even proposing a mathematical model that allows us to pre- dict the intestinal microbiota depending on this variable (Faith, McNulty, Rey, & Gordon, 2011). Within this field, there is a marked in- terest on high fat diets due to the negative effects on the population, Food Research International 64 (2014) 553–559 ⁎ Corresponding author at: Universidad de Jaén, Área de Microbiología, Facultad de Ciencias Experimentales (Edf. B-3), Campus Las Lagunillas s/n., 23071 Jaén, Spain. Tel.: +34 953 212701. E-mail address: canamero@ujaen.es (M. Martínez-Cañamero). http://dx.doi.org/10.1016/j.foodres.2014.07.030 0963-9969/© 2014 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres