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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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Fish consumption and markers of colorectal cancer risk: a multicenter randomized controlled trial.
Pot, GK, Majsak-Newman, G, Geelen, A, Harvey, LJ, Nagengast, FM, Witteman, BJ, van de Meeberg, PC, Timmer, R, Tan, A, Wahab, PJ, et al
The American journal of clinical nutrition. 2009;90(2):354-61
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Colorectal cancer (CC) risk is strongly related to dietary habits, with 65–75% of the incidence of CC attributed to dietary factors. This RCT studied the effects of fish consumption on markers of CC risk. 242 patients, either at high risk of developing CC or with a healthy bowel, were randomly assigned to 3 groups - 2 portions of oily fish per week, 2 portions of lean fish per week, or a control group who received dietary advice only for 6 months. 216 patients completed the trail. No statistically significant effect on CC risk markers was found between the fish groups and controls at 6 months. These results did not support the hypothesis that additional fish consumption over a 6-month period changes the number of colonic precancerous cells. The authors call for further studies to include non-fish eaters to further test their hypothesis.
Abstract
BACKGROUND Diet is a major factor in the etiology of colorectal cancer, with high fish consumption possibly decreasing colorectal cancer risk, as was shown in several observational studies. To date, no intervention trials have examined the possible beneficial effects of fish intake on colorectal cancer risk. OBJECTIVE The objective was to investigate the effects of a 6-mo intervention with oil-rich or lean fish on apoptosis and mitosis within the colonic crypt. DESIGN In a multicenter, randomized, controlled intervention trial, patients with colorectal polyps, inactive ulcerative colitis, or no macroscopic signs of disease were recruited (n = 242) and randomly allocated to receive dietary advice plus either 300 g oil-rich fish (salmon) per week (n = 82), 300 g lean fish (cod) per week (n = 78), or only dietary advice (DA) (n = 82). Apoptosis and mitosis were measured in colonic biopsy samples collected before and after intervention (n = 213). RESULTS The total number of apoptotic cells per crypt did not increase in the salmon or cod group: -0.10 (95% CI: -0.36, 0.16) and -0.06 (95% CI: -0.32, 0.20), respectively, compared with the DA group. The total number of mitotic cells per crypt decreased nonsignificantly in the salmon group (-0.87; 95% CI: -2.41, 0.68) and in the cod group (-1.04; 95% CI: -2.62, 0.53) compared with the DA group. Furthermore, the distribution of mitosis within the crypt did not significantly change in either group. CONCLUSION An increase in the consumption of either oil-rich or lean fish to 2 portions weekly over 6 mo does not markedly change apoptotic and mitotic rates in the colonic mucosa. This trial was registered at www.clinicaltrials.gov as NCT00145015.