Dietary Variables (dietary + variable)

Distribution by Scientific Domains


Selected Abstracts


Comparison of risk factors for colon and rectal cancer

INTERNATIONAL JOURNAL OF CANCER, Issue 3 2004
Esther K. Wei
Abstract Predictors of colorectal cancer have been extensively studied with some evidence suggesting that risk factors vary by subsite. Using data from 2 prospective cohort studies, we examined established risk factors to determine whether they were differentially associated with colon and rectal cancer. Our study population included 87,733 women from the Nurses' Health Study (NHS) and 46,632 men from the Health Professionals Follow Up Study (HPFS). Exposure information was collected via biennial questionnaires (dietary variables were collected every 4 years). During the follow-up period (NHS: 1980 to May 31, 2000; HPFS: 1986 to January 31, 2000), we identified 1,139 cases of colon cancer and 339 cases of rectal cancer. We used pooled logistic regression to estimate multivariate relative risks for the 2 outcomes separately and then used polytomous logistic regression to compare these estimates. In the combined cohort, age, gender, family history of colon or rectal cancer, height, body mass index, physical activity, folate, intake of beef, pork or lamb as a main dish, intake of processed meat and alcohol were significantly associated with colon cancer risk. However, only age and sex were associated with rectal cancer. In a stepwise polytomous logistic regression procedure, family history and physical activity were associated with statistically significant different relative risks of colon and rectal cancer. Our findings support previous suggestions that family history and physical activity are not strong contributors to the etiology of rectal cancer. Future investigations of colon or rectal cancer should take into consideration risk factor differences by subsite. © 2003 Wiley-Liss, Inc. [source]


Maternal diets, nutritional status, and zinc in contemporary Mexican infants' teeth: Implications for reconstructing paleodiets

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009
Alexis E. Dolphin
Abstract Despite attempts to use zinc (Zn) concentrations in hard tissues to comment upon the degree of carnivory in past populations, zinc has yielded inconsistent trophic level effects. The question of what, if anything, zinc in human enamel reveals regarding past diets is the focus of this research. We test whether the zinc content of deciduous tooth enamel from contemporary Mexican infants varies by maternal dietary variables such as zinc intake, proportion of animal products consumed, and dietary components that are known to impact zinc absorption. Deciduous teeth were collected from former participants in a longitudinal study of maternal and infant diet and function in highland Mexico. The Zn/Ca ratios of both prenatal and postnatal regions of 37 anterior teeth representing 26 individuals were assessed via laser ablation,inductively coupled plasma,mass spectrometry. Maternal dietary data collected during lactation were not correlated with zinc levels in the early postnatal enamel of infants' teeth, which were forming at the same time. In the case of prenatal enamel, zinc values were correlated with the consumption of foods known to influence Zn bioavailability, most notably tortillas (P = 0.008; r = 0.510), but not with meat consumption. Unexpectedly, women who consumed diets with poor zinc bioavailability during pregnancy gave birth to infants whose prenatal enamel demonstrated the highest Zn/Ca ratios, possibly due to enhanced zinc absorption during pregnancy for those mothers suffering most from long-term micronutrient deficiency. These results would suggest that zinc is not a reliable trophic level indicator. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]


A multivariate approach to optimization of macronutrient composition in weaning diets for cod (Gadus morhua)

AQUACULTURE NUTRITION, Issue 1 2006
K. HAMRE
Abstract Atlantic cod, initial weight 0.26 g, were fed diets varying in added protein from 530 to 830 g kg,1, lipid from 50 to 300 g kg,1 and carbohydrate from 0 to 150 g kg,1 of dry weight, according to a three-component mixture design. Analysed values of protein and lipid were 500,770 g kg,1 and 30,270 g kg,1, respectively. Analysed carbohydrate levels were as added. Increasing levels of both lipid and carbohydrate had a positive effect on fish growth (P < 10,3), whereas protein levels above 600 g kg,1 gave a reduction in growth (P < 10,4). The effects on growth were evident in fish less than 4 g, whereas fish growth between 4 and 6 g was unaffected by the dietary variation. It is hypothesized that the reduction in growth at high protein levels in fish of less than 4 g could be owing to incomplete utilization of protein, as the stomach of cod is not fully developed before the fish is approximately 1 g. Mortality and cannibalism were high in fish less than 4 g but low when the fish grew from 4 to 6 g. There was a significant decrease in cannibalism with increasing dietary lipid during the first half of the experiment (P < 0.05) and cannibalism was consistently high in fish fed less than 150 g kg,1 lipid. The lipid level in whole fish increased with increasing dietary levels of lipid (P < 10,6) and carbohydrate (P < 10,4), whereas the liver lipid level increased with increasing dietary lipid up to 200 g kg,1 (P < 10,6) and decreased thereafter (P < 10,4). Whole body glycogen increased slightly with increasing levels of dietary carbohydrate (P < 0.05) and was not affected by the other dietary variables. Liver glycogen increased in response to increasing dietary carbohydrate (P < 10,5) and decreasing levels of dietary lipid (P < 10,5). An abrupt increase in liver glycogen was seen with the reduction in dietary lipid from 100 to 50 g kg,1. The hepatosomatic index increased in response to both dietary lipid and carbohydrate (P < 10,6). It is concluded that the protein requirement of young cod is less than 500 g kg,1 of dry diet. Fish of less than 4 g should not be given more than 620 g kg,1 protein and should be supplemented with 150,200 g kg,1 lipid. Carbohydrate up to 150 g kg,1 of dry diet promoted growth and did not seem to affect the fish negatively. Fish above 4 g can be given diets varying in protein and carbohydrate over the wide range of concentrations used in the present study, but lipid supplementation should be restricted to between 100 and 200 g kg,1. [source]


Lack of association between television viewing, soft drinks, physical activity and body mass index in children

ACTA PAEDIATRICA, Issue 6 2008
Kelly Laurson
Abstract Objective: To examine the cross-sectional and longitudinal associations of physical activity, screen time and dietary habits on the body mass index (BMI) of children. Methods: A cohort of 122 girls and 146 boys (age at entry 10 years) from three rural states in the western USA was studied over an 18-month period. Subjects were measured for height and weight. Habitual physical activity, screen time (television viewing, video games and computer use) and dietary variables were assessed by a questionnaire. Cross-sectional and longitudinal analyses were conducted to examine the associations between physical activity, screen time and diet with BMI at baseline and follow-up and change in BMI. Results: At baseline, approximately 10% of boys and girls were obese and 17.8% of boys and 14.8% of girls were overweight. BMI showed a high degree of stability for boys and girls (r = 0.90), whereas physical activity, screen time and dietary habits showed moderate stability (r = 0.31,0.50) across the 18-month period. Cross-sectional and longitudinal correlations between physical activity, screen time, diet and BMI were low and non-significant (r < 0.15). The regression models explained between 8% and 22% of the variance in the change in BMI; however, none of the predictor variables were statistically significant. Conclusion: Physical activity, screen time and dietary habits were not significantly related to the BMI in cross-sectional or longitudinal analyses. Further research is warranted to better understand the complex, multifactorial phenotype of the BMI in growing and maturing children. [source]