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Impact of Consuming Extra-Virgin Olive Oil or Nuts within a Mediterranean Diet on DNA Methylation in Peripheral White Blood Cells within the PREDIMED-Navarra Randomized Controlled Trial: A Role for Dietary Lipids.
Arpón, A, Milagro, FI, Razquin, C, Corella, D, Estruch, R, Fitó, M, Marti, A, Martínez-González, MA, Ros, E, Salas-Salvadó, J, et al
Nutrients. 2017;10(1)
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Our genes are not fixed. They interact constantly with the environment through dietary and lifestyle factors, which affect whether genes are expressed or not. This is often referred to as epigenetic modulation. DNA methylation is an epigenetic mechanism that adds a methyl group to DNA, thereby modifying the function of the genes and affecting gene expression. Epigenetic alterations have been associated with conditions, such as obesity, type 2 diabetes, cardiovascular disease and immunological conditions. It is suggested that epigenetic marks are reversible and can be modulated by nutrient status and certain dietary components. The aim of the current study was to explore methylation changes in genes of peripheral white blood cells in a subset of participants from the PREDIMED-Navarra randomised controlled trial. 36 participants were allocated to three groups, all consuming a Mediterranean diet. In the first group, the diet was supplemented with extra virgin olive oil (EVOO), in the second group, with mixed nuts, and the third group, which served as the control group, were advised to consume a low-fat diet. Changes in DNA methylation were analysed from blood samples at baseline and at five-year follow-up. The authors observed methylation changes in several genes, related to metabolism, glucose and energy regulation, diabetes and inflammation, after the consumption of EVOO and nuts. They concluded that the beneficial effects of Mediterranean diets that include EVOO and nuts, may, at least in part, be mediated via epigenetic mechanisms. As these foods are high in monounsaturated and polyunsaturated fats, the quality of fat may be playing an important role in this mediation.
Abstract
DNA methylation could be reversible and mouldable by environmental factors, such as dietary exposures. The objective was to analyse whether an intervention with two Mediterranean diets, one rich in extra-virgin olive oil (MedDiet + EVOO) and the other one in nuts (MedDiet + nuts), was influencing the methylation status of peripheral white blood cells (PWBCs) genes. A subset of 36 representative individuals were selected within the PREvención con DIeta MEDiterránea (PREDIMED-Navarra) trial, with three intervention groups in high cardiovascular risk volunteers: MedDiet + EVOO, MedDiet + nuts, and a low-fat control group. Methylation was assessed at baseline and at five-year follow-up. Ingenuity pathway analysis showed routes with differentially methylated CpG sites (CpGs) related to intermediate metabolism, diabetes, inflammation, and signal transduction. Two CpGs were specifically selected: cg01081346-CPT1B/CHKB-CPT1B and cg17071192-GNAS/GNASAS, being associated with intermediate metabolism. Furthermore, cg01081346 was associated with PUFAs intake, showing a role for specific fatty acids on epigenetic modulation. Specific components of MedDiet, particularly nuts and EVOO, were able to induce methylation changes in several PWBCs genes. These changes may have potential benefits in health; especially those changes in genes related to intermediate metabolism, diabetes, inflammation and signal transduction, which may contribute to explain the role of MedDiet and fat quality on health outcomes.
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Vegetarian dietary patterns and mortality in Adventist Health Study 2.
Orlich, MJ, Singh, PN, Sabaté, J, Jaceldo-Siegl, K, Fan, J, Knutsen, S, Beeson, WL, Fraser, GE
JAMA internal medicine. 2013;173(13):1230-8
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Vegetarian diets have been associated with reduced risk of several chronic cardiometabolic diseases. The aim of this cohort study was to evaluate the effect of vegetarian diets on mortality. The study followed 73,308 male and female Seventh-day Adventists for a mean of 5.79 years. At baseline, just under half were non-vegetarians. Vegetarians had a lower mortality than non-vegetarians: death rates (deaths per 1000 person-years) were 5.4 for vegans, 5.61 for ovo-lacto vegetarians and 5.33 for pesco-vegetarians, which were significantly lower than that of non-vegetarians (6.61). After adjustment for a variety of factors, the lowered hazard ratio seen with vegetarian diets only remained statistically significant in pesco-vegetarians (compared to non-vegetarians). The non-vegetarians had on average higher rates of other risk factors, such as smoking, they consumed more alcohol, exercised less and had lower educational level. The authors concluded that vegetarian dietary patterns were associated with lower mortality.
Abstract
IMPORTANCE Some evidence suggests vegetarian dietary patterns may be associated with reduced mortality, but the relationship is not well established. OBJECTIVE To evaluate the association between vegetarian dietary patterns and mortality. DESIGN Prospective cohort study; mortality analysis by Cox proportional hazards regression, controlling for important demographic and lifestyle confounders. SETTING Adventist Health Study 2 (AHS-2), a large North American cohort. PARTICIPANTS A total of 96,469 Seventh-day Adventist men and women recruited between 2002 and 2007, from which an analytic sample of 73,308 participants remained after exclusions. EXPOSURES Diet was assessed at baseline by a quantitative food frequency questionnaire and categorized into 5 dietary patterns: nonvegetarian, semi-vegetarian, pesco-vegetarian, lacto-ovo-vegetarian, and vegan. MAIN OUTCOME AND MEASURE The relationship between vegetarian dietary patterns and all-cause and cause-specific mortality; deaths through 2009 were identified from the National Death Index. RESULTS There were 2570 deaths among 73,308 participants during a mean follow-up time of 5.79 years. The mortality rate was 6.05 (95% CI, 5.82-6.29) deaths per 1000 person-years. The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs nonvegetarians was 0.88 (95% CI, 0.80-0.97). The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73-1.01); in lacto-ovo-vegetarians, 0.91 (95% CI, 0.82-1.00); in pesco-vegetarians, 0.81 (95% CI, 0.69-0.94); and in semi-vegetarians, 0.92 (95% CI, 0.75-1.13) compared with nonvegetarians. Significant associations with vegetarian diets were detected for cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality, and endocrine mortality. Associations in men were larger and more often significant than were those in women. CONCLUSIONS AND RELEVANCE Vegetarian diets are associated with lower all-cause mortality and with some reductions in cause-specific mortality. Results appeared to be more robust in males. These favorable associations should be considered carefully by those offering dietary guidance.