Perception of parents' physical activity as a positive model on physical activity of adolescents.

Physical activity (PA) promotes an adequate level of health in adolescents. The PA behaviors moderation is led by the adolescents' perception of their parents. We suppose that higher adolescents' perception of their parents' physical activity influences the physical activity spent in adolescents. The objective of this study was to determine the association between adolescents' perception of their parents' PA practice with adolescent's PA in a sample of public schools in the Morelos state of Mexico. We analyzed the information of 4625 adolescents from the baseline of a cohort study of students in public schools in Mexico. We evaluated adolescents' perceptions of their parents PA and PA practice of the adolescents. A logistic regression analysis stratified by sex was carried out to evaluate the association between adolescents' perceptions of their parents PA, and adolescents' PA. We found that the PA of female adolescents was associated with their perceptions' of both parents' PA (OR = 2.48; IC95% 1.84-3.35). Adolescents' perceptions of their mother's PA was associated with their PA (daughters OR = 1.69; IC95% 1.33-2.15; sons OR = 1.87 IC95% 1.41-2.45). In conclusion, adolescents' perceptions of their parents' PA practice were associated with higher adolescents' PA. Higher adolescents' perception of their parents PA may play an important role as a positive model for the adolescent's PA practice (p < 0.001). Finally, parental PA and the perceptions that adolescents have of their parents' PA must be considered in devising general PA programs.

Dietary intake of polyphenols, nitrate and nitrite and gastric cancer risk in Mexico City.

N-nitroso compounds (NOC) are potent animal carcinogens and potential human carcinogens. The primary source of exposure for most individuals may be endogenous formation, a process that can be inhibited by dietary polyphenols. To estimate the risk of gastric cancer (GC) in relation to the individual and combined consumption of polyphenols and NOC precursors (nitrate and nitrite), a population-based case-control study was carried out in Mexico City from 2004 to 2005 including 257 histologically confirmed GC cases and 478 controls. Intake of polyphenols, nitrate and nitrite were estimated using a food frequency questionnaire. High intakes of cinnamic acids, secoisolariciresinol and coumestrol were associated with an approximately 50% reduction in GC risk. A high intake of total nitrite as well as nitrate and nitrite from animal sources doubled the GC risk. Odds ratios around 2-fold were observed among individuals with both low intake of cinnamic acids, secoisolariciresinol or coumestrol and high intake of animal-derived nitrate or nitrite, compared to high intake of the polyphenols and low animal nitrate or nitrite intake, respectively. Results were similar for both the intestinal and diffuse types of GC. Our results show, for the first time, a protective effect for GC because of higher intake of cinnamic acids, secoisolariciresinol and coumestrol, and suggest that these polyphenols reduce GC risk through inhibition of endogenous nitrosation. The main sources of these polyphenols were pears, mangos and beans for cinnamic acids; beans, carrots and squash for secoisolariciresinol and legumes for coumestrol.

Gastric cancer in relation to the intake of nutrients involved in one-carbon metabolism among MTHFR 677 TT carriers.

BACKGROUND: DNA methylation is an important epigenetic process for transcriptional control of human genome including those genes involved in cancer initiation and progression. Clinical studies have suggested that biological explanation to the protective effect of some nutrients could be linked with the DNA methylation. Folate is a primary methyl donor nutrient; it has been shown to play a key role in DNA methylation, repair and synthesis, by acting as co-factors and/or substrates in this metabolic pathway. Likewise, activity of a key enzyme, the methylenetetrahydrofolate reductase (MTHFR) has also been shown to influence DNA methylation. Overall, these findings support the notion that dietary intake as well as genetic factors play a role in one-carbon metabolism. AIM OF THE STUDY: This study is to evaluate the dietary intake of nutrients involved in one-carbon metabolism and the genotype of MTHFR 677 C > T with respect to GC risk. METHODS: We carried out in January 2004 a population-based case-control study in the metropolitan area of Mexico City. A total of 248 histological confirmed GC patients were recruited from nine tertiary hospitals, along with 478 age and sex-matched controls. Nutrient intake was estimated from food frequency questionnaire; the MTHFR 677C > T genotype was determined by PCR-RFLP analysis. RESULTS: A significant reduction in diffuse GC risk was observed for MTHFR 677 TT genotype among individuals with high consumption of folate (OR = 0.23; 95% CI 0.06-0.84), choline (OR = 0.55; 95% CI 0.33-0.9) and Vitamin B(6) (OR = 0.59; 95% CI 0.36-0.96) compared to MTHFR 677 CC + CT carriers. Among subjects with low consumption of methionine, a reduced risk of diffuse GC was also detected (OR = 0.40; 95% CI 0.16-0.97). In contrast, carriers of the MTHFR 677 TT genotype with a low consumption of folate had a significant increased risk of intestinal GC (OR = 1.88 95% CI 1.02-3.47). A folate-MTHFR 677 C > T interaction in the borderline of significance (P = 0.055) was detected. CONCLUSIONS: It is probable that GC prevention requires dietary recommendations according to the individual genotype; nevertheless, the available information to this respect is still very limited.

Dietary folate and vitamin B12 intake before diagnosis decreases gastric cancer mortality risk among susceptible MTHFR 677TT carriers.

OBJECTIVE: To assess gastric cancer survival in relation to dietary intake of methyl donors and the methylenetetrahydrofolate reductase 677C>T (MTHFR 677C>T) polymorphism. METHODS: A prospective cohort of 257 incidental, histologically confirmed gastric cancer cases was assembled in January 2004 and followed until June 2006. Patients were recruited from the main oncology and/or gastroenterology units in Mexico City and were queried regarding their sociodemographic information, clinical history, and dietary habits 3 y before the onset of their symptoms. The intake of methyl donors was estimated with a food-frequency questionnaire and the MTHFR 677C>T polymorphisms were determined by polymerase chain reaction/restriction fragment length polymorphism analysis. Cox's multivariate regression models were used to estimate the mortality risk of gastric cancer. RESULTS: MTHFR 677TT carriers with low folate and vitamin B12 intakes had the lowest survival rate in cases of gastric cancer. High intakes of folate and vitamin B12 before diagnosis was associated with decreased gastric cancer mortality risk in susceptible MTHFR 677TT carriers (mortality risk for folate 0.14, 95% confidence interval 0.04-0.46, P for trend=0.001; mortality risk for vitamin B12 0.23, 95% confidence interval 0.08-0.66, P for trend=0.008). CONCLUSION: Folate and related B vitamins may be used as an intervention strategy to improve the survival outcome of gastric cancer.

Assessing phytochemical intake in a group of Mexican women.

OBJECTIVE: Identify the content of selected phytochemicals (PHYs) in Mexican foods and evaluate the reliability of a food frequency questionnaire (FFQ) in assessing PHYs intake among Mexican women. MATERIAL AND METHODS: Values for PHYs content were obtained from four different data sets. PHYs intake was assessed in 50 women of reproductive age enrolled in a longitudinal cohort study. Values were obtained from a FFQ administered twice, one year apart in order to evaluate its reliability. Selected PHYs included flavonol (FOL), flavones (FES), flavanol (FAL), secoisolariciresinol (SE), matairesinol (MA), lariciresinol (LA), pinoresinol (PI), cynamic acid (CA) and coumestrol (CU). RESULTS: Daily PHYs intake ranged from 1.3 microg +/- 0.9 for MA to 116.3 +/- 43.8 mg for CA. The adjusted correlation coefficients ranged from 0.17 for FAL to 0.47 for LA. Pinto beans, oranges, hot sauce, broccoli, apples and onions were the main sources of the selected PHYs daily intake. DISCUSSION: The results of this study contribute to our understanding of the consumption of PHYs in the Mexican diet, and would help evaluate their potential health impact.

Assessing phytochemical intake in a group of Mexican women

OBJECTIVE: Identify the content of selected phytochemicals (PHYs) in Mexican foods and evaluate the reliability of a food frequency questionnaire (FFQ) in assessing PHYs intake among Mexican women. MATERIAL AND METHODS: Values for PHYs content were obtained from four different data sets. PHYs intake was assessed in 50 women of reproductive age enrolled in a longitudinal cohort study. Values were obtained from a FFQ administered twice, one year apart in order to evaluate its reliability. Selected PHYs included flavonol (FOL), flavones (FES), flavanol (FAL), secoisolariciresinol (SE), matairesinol (MA), lariciresinol (LA), pinoresinol (PI), cynamic acid (CA) and coumestrol (CU). RESULTS: Daily PHYs intake ranged from 1.3 µg ± 0.9 for MA to 116.3 ± 43.8 mg for CA. The adjusted correlation coefficients ranged from 0.17 for FAL to 0.47 for LA. Pinto beans, oranges, hot sauce, broccoli, apples and onions were the main sources of the selected PHYs daily intake. DISCUSSION: The results of this study contribute to our understanding of the consumption of PHYs in the Mexican diet, and would help evaluate their potential health impact.

OBJETIVO: Crear una base de datos con el contenido de nueve fitoestrógenos (FIT) presentes en alimentos mexicanos y calcular su ingestión y reproducibilidad en 50 mujeres participantes en un estudio de cohorte en México. MATERIAL Y MÉTODOS: Los FIT seleccionados incluyeron flavonol (FOL), flavones (FES), flavanol (FAL), secoisolariciresinol (SE), matairesinol (MA), lariciresinol (LA), pinoresinol (PI), ácido cinámico (CA) y coumestrol (CU). El contenido de estos compuestos se obtuvo de cuatro diferentes fuentes de datos. La ingestión diaria se estimó a través de un cuestionario de frecuencia de consumo de alimentos, aplicado en dos oportunidades con una diferencia de un año a cada participante. La reproducibilidad en el reporte de cada FIT se estimó mediante coeficientes de correlación intraclase ajustados por residuales de energía. RESULTADOS: La media de consumo de los FIT seleccionados varió de 1.3 ± 0.8 µg/d de MA hasta 116.3 ± 43.8 mg/d de CA. La reproducibilidad varió desde 0.17 para FAL hasta 0.47 para LA. Las principales fuentes de FIT fueron frijoles, naranja, salsa picante, brócoli, manzana y cebolla. DISCUSION: Este es el primer estudio que calcula la ingestión de FIT en México y podría constituir una herramienta útil para la futura evaluación de su efecto en la salud.