Interaction between genes and lifestyle factors on obesity.

Obesity originates from a failure of the body-weight control systems, which may be affected by changing environmental influences. Basically, the obesity risk depends on two important mutually-interacting factors: (1) genetic variants (single-nucleotide polymorphisms, haplotypes); (2) exposure to environmental risks (diet, physical activity etc.). Common single-nucleotide polymorphisms at candidate genes for obesity may act as effect modifiers for environmental factors. More than 127 candidate genes for obesity have been reported and there is evidence to support the role of twenty-two genes in at least five different populations. Gene-environment interactions imply that the synergy between genotype and environment deviates from either the additive or multiplicative effect (the underlying model needs to be specified to appraise the nature of the interaction). Unravelling the details of these interactions is a complex task. Emphasis should be placed on the accuracy of the assessment methods for both genotype and lifestyle factors. Appropriate study design (sample size) is crucial in avoiding false positives and ensuring that studies have enough power to detect significant interactions, the ideal design being a nested case-control study within a cohort. A growing number of studies are examining the influence of gene-environmental interactions on obesity in either epidemiological observational or intervention studies. Positive evidence has been obtained for genes involved in adiposity, lipid metabolism or energy regulation such as PPARgamma2 (Pro12Ala), beta-adrenoceptor 2 (Gln27Glu) or uncoupling proteins 1, 2 and 3. Variants on other genes relating to appetite regulation such as melanocortin and leptin receptors have also been investigated. Examples of some recently-identified interactions are discussed

Low-fat dairy consumption and reduced risk of hypertension: the Seguimiento Universidad de Navarra (SUN) cohort

BACKGROUND: Some observational studies have shown a beneficial effect of dairy consumption on blood pressure, especially in overweight and relatively young (<40 y) persons. However, no results from prospective studies conducted in a free-living population exist that show this association in middle-aged adults. OBJECTIVE: The aim of the present study was to assess whether total, low-fat, and whole-fat dairy consumption was associated prospectively with the risk of hypertension. DESIGN: This was a prospective study conducted in 5880 university graduates in Spain, aged >20 y in 2000 (mean age: 37 y), free of hypertension and cardiovascular disease at baseline, and followed-up with mailed questionnaires for a median of 27 mo. Dairy consumption was assessed with a previously validated semiquantitative food-frequency questionnaire. RESULTS: One hundred eighty new cases of hypertension were identified. The hazard ratio of hypertension between extreme quintiles of low-fat dairy product consumption was 0.46 (95% CI: 0.26, 0.84; P for trend = 0.02) after adjustment for the main known risk factors for hypertension and several dietary factors. No significant association between whole-fat dairy products or total calcium intake and incident hypertension was seen. CONCLUSION: In this Mediterranean cohort, low-fat dairy consumption, but not whole-fat dairy consumption, was associated with a lower risk of incident hypertension

Incidence of Hypertension in a Cohort of Spanish University Graduates:The SUN Study

Hypertension is a major public health problem. However, no estimates of age- and sex-specific incidences are available for the Spanish population. Our objective was to estimate the incidence of hypertension in a cohort of university graduates in Spain. We followed up 5648 individuals aged 25-65 years who were initially free of hypertension, diabetes, and cardiovascular disease for a median of 30 months. New diagnoses of hypertension were identified using mailed questionnaires. We validated the self-reported diagnosis of hypertension. In 18 250 person-years of follow-up, we identified 248 new cases of hypertension. The unadjusted incidences of hypertension in women and men were 8.2 per 1000 person-years (95% CI, 6.7-10.1) and 21.8 per 1000 person-years (95% CI, 18.6-25.4), respectively. The cumulative probability of receiving a medical diagnosis of hypertension by the age of 65 years was 50% among women and 72% among men. In conclusion, we have provided new evidence confirming that hypertension is one of the most important public health problems in Spain

Determinants of the adherence to an "a priori" defined Mediterranean dietary pattern

Background: A prospective cohort study with university level participants was initiated to study the effect of Mediterranean diet on health. Aims: The objective of this study was to identify possible lifestyle and socioeconomic variables associated with the consumption of a Mediterranean dietary pattern (MDP). Method: This analysis includes 1587 males and 2260 females. MDP was defined “a priori” by summing the standardized residuals of nutrients and foods after adjusting a regression model using total energy intake as the independent variable. Multiple regression and non-parametric locally weighted regression models were adjusted with the relative adherence to the MDP as the dependent variable in males and females. Results: Women were more compliant than men with the MDP (Coefficient regression (b) = 4.1; Confidence Interval (CI) 95 % = 3.2 to 4.9). The compliance with the MDP was significantly poorer among younger participants both in men and women (p < 0.001 in men and in women). Participants who were more physically active were more likely to fulfill the traditional MDP (p = 0.01 in men and p < 0.001 in women). Conclusions: Our findings provide evidence supporting the progressive departure from the traditional MDP in younger and highly educated subjects of the Mediterranean area. A more active life-style is associated with a better compliance with the MDP

Dieta mediterránea y enfermedad cardiovascular: resultados del estudio piloto del proyecto SUN

Fundamento: La dieta mediterránea ha sido propuesta como modelo de patrón dietético para la prevención de la cardiopatía isquémica. El proyecto SUN (“Seguimiento Universidad de Navarra”) es un estudio epidemiológico prospectivo de cohortes, que se inició en el año 2000 y que va dirigido a identificar determinantes dietéticos y no dietéticos implicados en estas enfermedades. La viabilidad del proyecto, se comprobó con un estudio piloto en dos fases. Métodos: La primera fase del estudio piloto contó con la participación de voluntarios en los que se valoraron las exposiciones dietéticas y no dietéticas mediante un cuestionario autoadministrado y por entrevista personal. Para la segunda fase, se seleccionó una muestra aleatoria de 600 graduados y se les envió el cuestionario por correo. Para estimar la variabilidad inter-sujetos se calcularon los percentiles 10, 25, 50, 75 y 90 de consumo para los principales alimentos y nutrientes considerados. Resultados: Los participantes entendieron y respondieron adecuadamente los cuestionarios. El tiempo medio empleado en contestar el cuestionario fue de 55,0 minutos (IC 95%=50,7-59,3). Se encontró una amplia variabilidad inter-sujetos entre los percentiles 10 y 90 en el consumo de los principales alimentos que pueden considerarse indicadores de la dieta mediterránea, como son el aceite de oliva, las frutas, las verduras y el vino. Conclusiones: La submuestra presentó una participación relativamente aceptable. Se halló un patrón de dieta mediterránea con una variabilidad inter-sujetos suficientemente amplia como para poder encontrar asociaciones entre el consumo de alimentos y la incidencia de las principales enfermedades cardiovasculares

Daily physical activity and macronutrient distribution of low-calorie diets jointly affect body fat reduction in obese women.

Inadequate dietary patterns and sedentary lifestyles are believed to be important factors in predisposing people to obesity. This study analyzed the potential interaction between habitual physical activity and the carbohydrate (CHO)-fat distribution in 2 hypocaloric diets and the impact of such interplay on body composition changes. Forty healthy obese women, 20–50 years old, were randomly assigned to a high- or low-CHO energy-restricted diet, which was low or high in fat, respectively, during 10 weeks. Baseline and final measurements were performed to assess dietary habits, resting metabolic rate, and body composition changes. Physical activity was measured with a triaxial accelerometer and with a questionnaire. There were no significant differences in anthropometric and metabolic variables between both dietary groups at baseline. However, there was a positive correlation between total free-living physical activity and arm muscle preservation after 10 weeks (r = 0.371; p = 0.024). Interestingly, an interaction between macronutrient (CHO–fat distribution) intake and physical activity was found, since less-active subjects with a high-CHO–low-fat diet showed a greater fat loss than those more active with a lower-CHO–high-fat diet, whereas more-active subjects with a high-CHO–low-fat diet showed a smaller fat loss than those receiving a low-CHO–high-fat diet. Physical activity and the macronutrient content of energyrestricted diets, when designed to promote body fat mass reduction, should be considered together to better predict the outcome

Obesity risk is associated with carbohydrate intake in women carrying the Gln27Glu beta2-adrenoceptor polymorphism.

Interindividual differences in the response to dietary intake are, in some cases, genotype dependent. Moreover, genotype-environment interactions may appear when the impact of lifestyle factors (e.g., diet) on a phenotype (e.g., BMI > 30 kg/m2) differs by genotype. A case-control study (obese subjects vs. normal weight controls) was conducted to assess a possible effect modification on obesity risk of the Gln27Glu polymorphism for the ß2-adrenoceptor gene depending on dietary intake. The sample included 159 subjects with BMI > 30 kg/m2 and 154 controls with BMI 49% energy (E)] had a higher obesity risk (OR = 2.56, P = 0.051). The product-term introduced in the logistic model to assess effect modification revealed a marginally significant interaction (P = 0.058) between both factors. Furthermore, a high intake of CHO (E > 49%) was associated with higher insulin levels among women carrying the Gln27Glu polymorphism (P < 0.01). This gene-nutrient interaction emphasizes the importance of examining the outcome of some obesity-related mutations depending on lifestyle (including diet) and may explain the heterogeneity of findings from previous studies

Dietary total antioxidant capacity is associated with leukocyte telomere length in a children and adolescent population

Background & Aims: Oxidative stress and inflammation seem to be potential underlying mechanisms for telomere attrition. A lack of specific antioxidants is believed to increase free radical damage and a greater risk for telomere shortening. Our aim was to evaluate the relationship between diet and leukocyte telomere length in a cross-sectional study of children and adolescents. We hypothesized that dietary total antioxidant capacity would be positively associated with telomere length. Methods: Telomere length was measured by quantitative real-time polymerase chain reaction in 287 participants (55% males, 6–18 years), who were randomly selected from the GENOI study. Results: A positive correlation between dietary total antioxidant capacity and telomere length (r=0.157, p=0.007) was found after adjustment for age and energy intake. However, higher white bread consumption was associated with shorter telomeres (β=-0.204, p=0.002) in fully-adjusted models. Interestingly, those individuals who had simultaneously higher dietary total antioxidant capacity and lower white bread consumption significantly presented the longest telomeres. Moreover, the multivariable-adjusted odds ratio for very short telomeres was 0.30 for dietary total antioxidant capacity (p=0.023) and 1.37 for white bread (p=0.025). Conclusion: It was concluded that longer telomeres were associated with higher dietary total antioxidant capacity and lower white bread consumption in S2panish children and adolescents. These findings might open a new line of investigation about the potential role of an antioxidant diet in maintaining telomere length

Influencia del polimorfismo -3826 A Æ G en el gen de la UCP1 sobre los componentes del síndrome metabólico

Fundamento. La proteína desacoplante UCP1 se ha relacionado con el desarrollo y/o mantenimiento de la obesidad a través de su implicación en la regulación del balance energético. El papel de esta proteína mitocondrial en humanos es incierto por la escasa presencia del tejido adiposo pardo en el individuo adulto. El polimorfismo -3826 A/G de la UCP1 solo o conjuntamente con la mutación Trp64Arg del receptor adrenérgico β3 se ha asociado con obesidad, diabetes mellitus y enfermedades relacionadas aunque con resultados contradictorios. Con objeto de conocer la influencia del polimorfismo -3826 A/G de la UCP1 sobre los componentes clásicos del síndrome metabólico en nuestra población, se han estudiado 159 individuos obesos y 154 en normopeso, con un diseño de casos y controles. A todos ellos se les ha determinado IMC, índice cintura/cadera, % de grasa corporal, TA, perfil lipídico, leptina, glucemia e insulinemia basales. Asimismo se les ha analizado la presencia de la mencionada mutación en el gen de la UCP1. Resultados. Se obtuvieron diferencias significativas en todas las variables estudiadas entre obesos (casos) y normopeso (controles) Dentro del grupo de obesos, el polimorfismo –3826 A/G del gen de la UCP1 (n=53) se asoció con un mayor IMC (p=0,03), mayor % de grasa corporal (p=0,04) y TA más elevada tanto sistólica (p=0,009) como diastólica (p=0,02) No hubo diferencias estadísticamente significativas en ninguno de los demás índices evaluados. Conclusión. El factor fundamental que influye sobre los componentes del síndrome metabólico es la obesidad. No obstante, el polimorfismo –3826 A/G del gen de la UCP1 se asocia con un mayor grado de obesidad y unas cifras más elevadas de TA

Impact of global and subjective mini nutritional assessment (MNA) questions on the evaluation of the nutritional status: The role of gender and age

Undernutrition is a quite common condition in the elderly, often identified using the mini nutritional assessment (MNA) test. The aim of this research was to study the independent value of the global and the subjective MNA questions to predict the undernutrition according to the full MNA score, and to analyze the influence of gender and age on such items. A total of 22,007 Spanish people 65 years of age or older were evaluated using the MNA test. These data were obtained by trained community pharmacists by using receiver Operating Characteristic (ROC) curves. About 4.3% of the studied population were classified as undernourished according to the full MNA test. The subjective subscore (two questions) presented better predictive value than the global one (six questions). Indeed, 99.5% of subjects detected as well nourished using the MNA test were also correctly classified using the two subjective questions. In the present study, it was identified that the two subjective MNA questions can be an efficient tool for a quick screening to rule out non undernourished subjects