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Biomedical subjects

J R Hebert

Publications and source records attributed to J R Hebert.

At least 73 records · Page 4Linked to original sources
PubMed1994

Social and environmental factors and life expectancy, infant mortality, and maternal mortality rates: results of a cross-national comparison.

Using data from United Nations sources we conducted an international comparison study of infant and maternal mortality rates and life expectancy at birth. We examined these three dependent variables in relation to a range of independent variables including dietary factors, medical resource availability, gross national product (GNP/capita), literacy rates, growth in the labor force, and provision of sanitation facilities and safe water. Based on exploratory stepwise regression models, we fitted a series of general linear models for each of the three dependent variables. For the models with the highest explanatory ability, the percent of households without sanitation facilities showed the strongest association with all three dependent variables: life expectancy at birth (R2 = 0.83, B = -0.088, P = 0.0007); infant mortality rate (R2 = 0.87, B = +0.611, P < 0.0001); and maternal mortality rate (R2 = 0.54, B = +8.297, P = 0.002). Additional significant predictors of life expectancy at birth and infant mortality rate included the quantity of animal products consumed, the percent of households without safe water, excess calories consumed as fat, and the total literacy level. Maternal mortality rate was significantly associated with total energy consumption and excess energy consumed as fat. Using residuals from the general linear models we chose three outlying countries: Costa Rica, Sri Lanka and Egypt, on which to do case studies. These country case studies are discussed briefly in regard to characteristics that could account for their differing statistical relationships.

Adult↗
PubMed1994

A cross-national investigation of diet and bladder cancer.

The existence of a large unexplained portion of attributable risk, and the marked variation in bladder cancer rates globally, have stimulated an interest in the role of nutrition in cancer of the urinary bladder. For this cross-national comparison study, we had complete data available for 50 countries. Using stepwise regression followed by general linear modelling, age-truncated (45-74 years), world-standardised, sex-specific bladder cancer mortality rates were regressed on an array of nutritional and socioeconomic independent variables in an effort to identify important predictors of bladder cancer mortality. Separate principal components analyses were used to summarise the nutritional and the socioeconomic (SES) variables. In the stepwise analyses, using food scores expressed in kcal/day per capita (as opposed to the nutritional components), total fat consistently entered the model first, and explained the greatest share of variability (R2) for both males and females. General linear models were fitted that included total fat, tobacco, alcohol, the three SES components (comprising seven socioeconomic predictors) and two food categories found significant in stepwise modelling, roots/tubers and vegetable oil. The R2 values were 0.84 for male rates and 0.77 for female rates, meaning that these study factors account for 84% of bladder cancer mortality in men and 77% in women. Substitution of the nutritional components for the foods resulted in general linear models with slightly higher R2 values (0.85 for males, 0.77 for females), but with attenuated fat effects. Results are discussed in light of biological plausibility.

Aged↗
PubMed1994

The physician-delivered smoking intervention project: can short-term interventions produce long-term effects for a general outpatient population?

Patterns of smoking cessation using 6- and 12-month follow-up data are reported for 1,261 primary care patients randomized to 3 physician-delivered smoking interventions: advice only (AO), counseling (CI), and counseling plus availability of nicotine-containing gum (CI + NCG). One-week-point-prevalence cessation rates at 12 months did not differ among the interventions: AO (15.2%), CI (12.9%) and CI + NCG (16.7%). However, maintained cessation rates (abstinent at both 6 and 12 months) increased with intervention intensity: AO (6.0%), CI (7.8%) and CI + NCG (10.0%): Test of trend chi 2 = 5.06, p = .02. CI + NCG was significantly higher than AO (p = .02). The findings support the following conclusions: Brief physician-delivered intervention with availability of nicotine-containing gum can have a beneficial long-term effect on smoking cessation, and cohort data as well as point-prevalence rates are important when assessing the long-term impact of lifestyle interventions.

Adolescent↗
PubMed1994

Use of mentholated cigarettes and oropharyngeal cancer.

We used data from a hospital-based case-control study of tobacco-related cancers to test the hypothesis that smoking mentholated cigarettes increases the risk of cancer of the oral cavity and pharynx, a cancer with a 50% higher incidence in black Americans compared with whites. Detailed information on smoking habits and other variables, obtained in personal interviews, was available for 194 male and 82 female newly diagnosed, histologically confirmed cases of oropharyngeal cancer and 845 male and 411 female controls, all of whom were current smokers. In univariate, stratified, and multivariable analyses involving all cases and controls, menthol was not a risk factor for cancer. The odds ratio, adjusted for covariates, for smoking mentholated cigarettes for > = 15 years relative to smoking nonmentholated cigarettes only was 0.9 (95% confidence interval = 0.5-1.6) in males, and 0.7 (95% confidence interval = 0.5-1.7) in females. In analyses by subsite, menthol use was positively associated only with cancer of the pharynx in males, although the magnitude of the association was small. These results indicate that use of mentholated cigarettes is unlikely to be an important independent factor in oropharyngeal cancer.

Aged↗
PubMed1993

A comparison of serum retinol concentration between human and different species of normo and hypercholesterolemic nonhuman primates fed semi-purified diets with defined amounts of vitamin A.

1. Serum retinol and total cholesterol concentrations were determined in several species of nonhuman primates fed semipurified diets. Two species of Old World and three species of New World nonhuman primates were examined. 2. Retinol levels were significantly lower (up to four-fold) in the serum of the smaller New World than the larger Old World animals and the difference could not be explained by differences in dietary make-up. 3. Cholesterol levels were not different between the groups but differed within a species when type of dietary fat was altered. 4. Differences in circulating levels of retinol may reflect differences in levels of retinol binding protein between the groups.

Animals↗
PubMed1993

Measuring the effect of a worksite-based nutrition intervention on food consumption.

Although current dietary guidelines focus on a combination of specific nutrients and food items, most effective dietary interventions focus on patterns of dietary intake and take into account the relationships among nutritional factors. In a controlled nutrition intervention conducted at 16 workplaces, a self-administered health habits questionnaire (HHQ) including a 67-item version of a semiquantitative food frequency questionnaire (FFQ) was distributed prior to a 15-month intervention and again after it. Principal components analysis (PCA) was used to reduce this large set of highly correlated FFQ food items to a smaller set of maximally uncorrelated components (PCs). Of the eight discrete food-based eating patterns targeted in the Treatwell intervention, six were highly correlated ([r[ > or = 0.48) with at least one PC each. This indicates a high level of concordance between a priori intervention targets and actual behavior. Based on log-transformed preintervention FFQ measures, our results showed that a very high proportion (0.55) of the variance in the FFQ data was explained by the PCs. A significantly greater increase in consumption of total vegetables and a larger decrease in dietary intake of ground and processed meats were observed among intervention companies. A comparison PCA conducted on intervention and control companies after the intervention indicated that patterns of intake were very stable over time.

Eating↗
PubMed1993

Consumption of meat and fruit in relation to oral and esophageal cancer: a cross-national study.

Using data from 59 countries, we conducted an international comparison study to identify nutritional predictors of age-adjusted oral and esophageal cancer mortality rates. Statistical models accounted for per capita tobacco disappearance data, alcohol consumption, and various measures of socioeconomic status. For oral cancer, stepwise regression results showed protective effects for milk/dairy products (B = -0.030, p < 0.0001) and cabbage consumption (B = -0.391, p = 0.01) and increased risk from vegetable oil (B = 0.072, p = 0.04) and excess animal fat calories (B = 0.344, p < 0.0001) as well as marginally increased risk from cereals (B = 0.008, p = 0.08). Results were obtained after accounting for all background factors, including sex (model R2 = 0.52). For esophageal cancer, stepwise results indicated protective effects for fruit (B = -0.046, p = 0.0006) and total caloric intake (B = -0.013, p < 0.0001) and increased risk from vegetable oil (B = 0.061, p = 0.04) and meat (B = 0.031, p < 0.0001) consumption (model R2 = 0.55). When analyzed separately by sex, results were similar, indicating that the risk factors are probably the same in both sexes, even though women consistently have fewer deaths, on average, from these cancers. On the basis of results from stepwise regression models, we also fitted general linear models for mortality rates of each cancer site, and results were similar in terms of magnitude and direction of effects. Although the evidence provided by this type of analysis using data aggregated by country is limited in terms of control for potential confounding effects and modeling of possible effect modification, an effect of high meat, animal product, or vegetable oil and low fruit and cabbage consumption is consistent with the known biology of these tumors.

Aged↗
PubMed1993

A work-site nutrition intervention: its effects on the consumption of cancer-related nutrients.

OBJECTIVES: In a work-site nutrition intervention targeting fat and fiber, we examined the intervention's effect on specific nutrients implicated in carcinogenesis, including trace metals, vitamins, and categories of fatty acids. The rationale was based on the association observed in a variety of epidemiologic studies between these nutrients and epithelial cancers. METHODS: Data were taken from eight control companies and five intervention companies that fully implemented the Treatwell intervention. Analyses of variance were used preserving the study's nested design. RESULTS: Significant intervention-related associations were observed for increased total vitamin A and carotene. Marginal intervention effects were observed for relative decreases in the percentage of calories from both saturated and monounsaturated fatty acids, a relatively smaller increase in the percentage of calories from polyunsaturated fatty acids, and an increase in the consumption of vitamin B6. CONCLUSIONS: Results indicate a broader effect of the intervention than on fat and fiber only. Increased intake of carotene, the single most important of these other nutrients, is plausibly related to a variety of epithelial cancers.

Diet↗
PubMed1992

Patient characteristics and the effect of three physician-delivered smoking interventions.

BACKGROUND: This paper investigates individual patient characteristics predicting differential response to each of three physician-delivered smoking interventions after 6 months. METHODS: Participants were 1,286 currently smoking patients seen by 196 medical and family practice residents in five primary care clinics affiliated with the University of Massachusetts Medical School. Of the participants, 57% were female, 92% were white, their average age was 35 years, and they smoked an average of 23 cigarettes per day. Physicians were trained to provide the following interventions: advice only (AO), a brief (< 10 min) patient-centered counseling intervention (CI), and counseling plus prescription of the nicotine-containing gum Nicorette (CI+NCG). The CI+NCG condition included NCG only when appropriate and if acceptable to the patient. Patients were randomized to one of these three physician-delivered intervention conditions. RESULTS: Overall, stratified univariate analyses revealed that AO produced consistently lower cessation rates across most subgroups (generally 9-13%) but was somewhat more effective for certain groups of lighter smokers. Relative to AO, CI was somewhat more effective (about 20-24%) for less addicted smokers, for those with more previous quit attempts, and for those with fewer close associates who smoke, but generally failed to produce higher quit rates for harder core smokers or for women. CI+NCG had an overall pattern of greater effectiveness for both more addicted and less addicted smokers, with the highest absolute levels of cessation (about 27-30%) among less dependent smokers. Women in this group had cessation rates (20.6%) comparable to those of men (23.6%). Condition-stratified logistic regression analyses, controlling for a wide range of covariates, revealed associations similar to those observed in the univariate analyses: An overall logistic model in which intervention conditions were fitted as dummy variables produced the following significant main effects: sex, years smoked, contact with other smokers, symptoms, and CI+NCG condition. Significant interactions were observed for both CI and CI+NCG and smoking when feeling too ill to continue normal activities and CI+NCG and amount smoked. CONCLUSIONS: We observed significant main effects on cessation of variables related to addiction, sex, social factors, and physician counseling interventions. Specific interactions were observed between reported smoking when feeling ill and each of the counseling interventions as well as by amount smoked in the CI+NCG condition.

Adult↗
PubMed1992

Vitamin supplement use and risk for oral and esophageal cancer.

In a hospital-based case-control study, 290 oral cancer cases and 133 esophageal cancer cases were queried as to smoking status, alcohol consumption, and dietary exposures, including vitamin supplement history. Among oral cancer cases, vitamin E use appeared to exert a protective effect. Vitamins C and E had protective effects among esophageal cancer cases. When stratified by smoking status, the protective effect of vitamin C use in esophageal cancer was significant only among current smokers, as was vitamin B use. A reduced risk of oral cancer was correlated with multivitamin use and increasing vegetable consumption, as was vegetable/fruit consumption and vitamin C supplementation. Among esophageal cancer cases, increasing meat consumption and vitamin C use were associated with a significantly reduced cancer risk.

Adult↗
PubMed1992

Work-site nutrition intervention and employees' dietary habits: the Treatwell program.

In a randomized, controlled study of the Treatwell work-site nutrition intervention program, which focused on promoting eating patterns low in fat and high in fiber, 16 work sites from Massachusetts and Rhode Island were recruited to participate and randomly assigned to either an intervention or a control condition. The intervention included direct education and environmental programming tailored to each work site; control work sites received no intervention. A cohort of workers randomly sampled from each site was surveyed both prior to and following the intervention. Dietary patterns were assessed using a semiquantitative food frequency questionnaire. Adjusting for work site, the decrease in mean dietary fat intake was 1.1% of total calories more in intervention sites than in control sites (P less than .005). Mean changes in dietary fiber intake between intervention and control sites did not differ. This study provides evidence that a work-site nutrition intervention program can effectively influence the dietary habits of workers.

Adolescent↗
PubMed1991

Use of mentholated cigarettes and lung cancer risk.

Black males have higher age-adjusted lung cancer incidence rates compared to white males, and blacks of both sexes have higher rates of increase in lung cancer incidence over past decades. The majority of black smokers smoke mentholated cigarettes. These observations prompted us to assess the effect of smoking mentholated cigarettes on lung cancer risk, using data from a hospital-based case-control study of tobacco-related cancers. Analysis was restricted to current cigarette smokers and was carried out on 588 male lung cancer cases and 914 male control patients and on 456 female lung cancer cases and 410 female controls interviewed between 1985 and 1990. The prevalence of menthol usage did not differ between cases and controls of either sex. No significant association was observed between either short-term (1-14 years) or long-term (15+ years) menthol use and lung cancer in logistic regression analyses adjusting for covariates. For specific histological types of lung cancer there was no indication of an association with menthol usage.

Adult↗
PubMed1991

The inappropriateness of conventional use of the correlation coefficient in assessing validity and reliability of dietary assessment methods.

Accuracy and precision of nutritional data are crucial in estimating effects in nutritional epidemiology. Because it is known that such data are usually flawed, studies have been designed to estimate both the validity of diet assessment methods in measuring "true" diet and the reliability of these methods in providing nutrient data that are at least reproducible. In these studies, validity and reliability have often been gauged by computing correlation coefficients between two or more estimates of diet and testing the coefficient's departure from 0. We propose that the correlation coefficient may be inappropriate in these studies as a measure of association. If correlation coefficients are presented, we suggest that one should also present confidence intervals and test the departure of the coefficient from approximately 1 rather than 0. We have examined this approach using dietary data from various studies. We have computed 95% confidence intervals of the correlation coefficients and have tested H0:rho = 0.95 as an approximation of rho = 1.00. In all of the studies selected, comparisons produced correlation coefficients statistically significantly different from both 0.95 and 0. Due to the dependence of the correlation coefficient on factors unique to individual studies, it is recommended that other techniques be used to assess agreement between nutrient scores derived in reliability or validation studies. Viable options include linear regression, analyses of the standard deviations of the differences between scores, and examinations of the intraclass correlation coefficient.

Diet↗
PubMed1991

Implications for cancer epidemiology of differences in dietary intake associated with alcohol consumption.

Several dietary factors are thought to modify risk for cancers that are known to be associated with alcohol intake. In this study, we sought to identify and describe alcohol-related differences in dietary and nutritional factors that are potential independent predictors of cancer risk or effect modifiers or confounders of alcohol-cancer relationships. Data were obtained from a large hospital-based case-control study that was designed to estimate the cancer risk from various tobacco products. Study subjects consisted of 465 male and 300 female incident lung cancer cases and 870 male and 556 female hospitalized patient controls matched on age (+/- 5 yrs). Nutritional data were analyzed as log-transformed frequencies of 30 food items, 9 factor scores generated to describe overall patterns of dietary intake, and nutrient scores estimating daily intake of fat, vitamin A, fiber, and cholesterol. We observed many more significant differences in nutritional exposures by alcoholic beverage intake than would be expected merely by chance. For males, the most striking relationships included increased meat and egg consumption with increasing alcohol consumption and higher intake of cantaloupe and cold cereal among lighter drinkers. For females, we observed strong inverse relationships between alcohol consumption and reported intake of fruit, cold cereal, and ice cream. We also observed a direct association between alcohol and meat consumption, though it was weaker than that found among men. Findings based on factors and nutrients followed the pattern observed for the individual food items, with highest fat scores and lowest fruit scores among the heaviest drinkers. Implications for nutrient-alcohol interactions and statistical considerations are discussed.

Alcohol Drinking↗
PubMed1990

Intra and inter-person sources of variability in fat intake in a feeding trial of 14 men.

An impediment to analyzing the effect of nutritional factors on biologic processes or health status in human populations arises from the relatively small dietary differences that exist between individuals in relation to large periodic fluctuations in dietary intake and the imprecision with which diet is normally assessed. We report here on characteristics of dietary variability in a group of 14 young men who successfully completed an intervention study specifically designed to create large differences in fat intake between baseline and two dietary intervention-periods each lasting two months (during which safflower and coconut oil supplements were given). We found that in the second supplemental phase of the intervention inter-person sources of variability were greatly increased over the low-fat baseline values. For proportion of calories as fat it increased to 64.2% of total variance from 21.6% without supplementation; for saturated fatty acids, 47.3% from 17.7%; for polyunsaturated fatty acids, 62.4% from 22.8%; and for the P:S ratio, 71.5% from 21.6%. During the first intervention phase we observed only moderate changes. Reasons for the intervention phase differences in effect, implications for feeding trials designed to look at dietary fat effects, and the need for future studies aimed at clarifying these results are discussed.

Adult↗
PubMed1990

Natural killer cell activity in a longitudinal dietary fat intervention trial.

It has been hypothesized that dietary fat may affect natural killer (NK) cell activity, a factor of potential importance in early tumor surveillance. Fourteen men successfully completed an intervention trial designed to test the effect of dietary fat on NK activity in humans. Study subjects lowered their fat intake to an average of 22% of calories as fat and consumed two dietary supplements (of coconut and safflower oils), in a cross-over design. These supplements resulted in large changes in the ratio of polyunsaturated to saturated fatty acids (1.73 to 0.34, on average). Results of a general linear model in which we fitted covariates on exercise, body mass, intervention sequence, and various dietary predictors revealed a significant effect of decreased total dietary fat intake on increased NK activity at an E/T ratio of 100:1 (about 0.79% increase for each absolute percent of calories as fat, P = 0.04). Similar results were obtained at E/T ratios of 50:1 and 25:1. No other nutritional predictor was significantly associated with NK activity at any E/T ratio.

Adult↗