Baseline data and design for a randomized intervention study of dietary change in religious organizations.

BACKGROUND: Reducing dietary fat has been identified as a potential means of preventing chronic disease. Several studies have identified methods of changing dietary fat consumption in small, intensive intervention settings. Fewer studies have examined how to improve dietary habits of individuals in the general public. METHODS: The Eating for a Healthy Life (EHL) project was a randomized trial [n = 40 religious organizations (ROs) and 2175 individuals, 1099 in intervention]. The study tested an intervention package of self-help books, motivational messages, and social interactions designed to change dietary behaviors (lowering fat, increasing fruit and vegetable consumption) among members of religious organizations aged 18 and over. The primary outcomes are fat- and fruit- or vegetable-related behaviors measured using the Fat and Fiber Behavior (FFB) Questionnaire. RESULTS: Religious organizations and their members participated fully in the initial study activities. CONCLUSIONS: This study will support a rigorous test of the intervention package.

Is religious orientation associated with fat and fruit/vegetable intake?

We explored associations of religious orientation with dietary behavior among participants in the Eating for a Healthy Life Study (EHL), a randomized low-fat, high-fruit/vegetable dietary intervention trial in religious organizations. Data in this report are from baseline telephone surveys of 2,375 people, which assessed dietary behaviors (Fat- and Fiber-Related Diet Behavior Questionnaire) and religiosity (Allport-Ross Religious Orientation Scale). After adjusting for demographic characteristics, higher extrinsic (socially motivated) religious orientation was positively associated with low-fat dietary fat behaviors (P=.0438). No associations were observed for dietary behaviors and intrinsic (life based on religious beliefs) religious orientation. These results support further exploration of religious orientation's potential influence on dietary behaviors and its applicability to dietary interventions.

Food groups and colon cancer risk in African-Americans and Caucasians.

The disparities in colon cancer incidence between African-Americans and other U.S. ethnic groups are largely unexplained. This report examines associations of various food groups with colon cancer in African-Americans and Caucasians from a case-control study. Incident cases of histologically confirmed colon cancer, age 40-80 years, (n = 613) and matched controls (n = 996) were interviewed in-person to ascertain potential colon cancer risk factors. Diet over the year before diagnosis or interview date was assessed using a validated food frequency questionnaire adapted to include regional foods. Multivariate logistic regression models estimated energy-adjusted and non-energy adjusted odds ratios (OR). Controls generally reported higher consumption (daily amount and weekly frequency) of fruits, vegetables and dark green, deep yellow fruits/vegetables, whereas cases consumed more refined carbohydrates and fats, oils and snacks. Regardless of ethnic group or energy adjustment, high and frequent vegetable consumption (particularly dark green vegetables) was protective, consistent with 20-50% reductions in risk. In Caucasians, high refined carbohydrate and red meat consumption (amount and frequency) was associated with a statistically significant 2-fold increased risk in non-energy adjusted models. In African-Americans, frequent intake of dairy foods was associated with a doubling in risk (OR = 1.9, 95% CI = 1.1-3.4) in non-energy-adjusted models, whereas frequent fruit consumption correlated with a non-significant 30% lower risk. These findings add to growing evidence that plant foods may protect against colon cancer; however, the effects of the other food groups varied by ethnic group and energy adjustment. These results may also explain some of the ethnic differences in colon cancer incidence.

Assessment of a one-page questionnaire on long-term recreational physical activity.

BACKGROUND: Physical activity is associated with a reduced risk of several chronic diseases. Although there is considerable published research on methods to assess current or recent recreational physical activity, there are few short, self-administered questionnaires designed to assess long-term physical activity. METHODS: We developed a one-page questionnaire to capture data on usual recreational physical activity during the preceding 10 years. This questionnaire was used in a cohort study of adults age 50 to 75 years residing in western Washington state. To examine the measurement characteristics of this questionnaire, we compared metabolic equivalent task (MET)-hours derived from this short questionnaire to MET-hours estimated from a detailed comparison interview in a subsample (n = 217) and to current body mass index (BMI; weight in kilograms/height in square meters) in the full sample of 57,811 persons. RESULTS: The age- and sex-adjusted partial Pearson correlation coefficient for total recreational activity between the 2 instruments was 0.68. In the full cohort, BMI was inversely correlated with physical activity as assessed by the one-page questionnaire (r = -0.22). CONCLUSIONS: This short questionnaire measures long-term physical activity at a level of precision appropriate to the examination of associations in studies of physical activity and disease.

VITamins And Lifestyle cohort study: study design and characteristics of supplement users.

Vitamin and mineral supplements are among the most commonly used drugs in the United States, despite limited evidence on their benefits or risks. This paper describes the design, implementation, and participant characteristics of the VITamins And Lifestyle (VITAL) Study, a cohort study of the associations of supplement use with cancer risk. A total of 77,738 men and women in western Washington State, aged 50-76 years, entered the study in 2000-2002 by completing a detailed questionnaire on supplement use, diet, and other cancer risk factors, and 70% provided DNA through self-collected buccal cell specimens. Supplement users were targeted in recruitment: 66% used multivitamins, 46% used individual vitamin C, 47% used individual vitamin E, and 46% used calcium, typically for 5-8 of the past 10 years. Analyses to identify confounding factors, the main study limitation, showed that regular nonsteroidal anti-inflammatory drug use, intake of fruits and vegetables, and recreational physical activity were strongly associated with supplement use (p < 0.001). The authors describe a follow-up system in which cancers, deaths, and changes of residence are tracked efficiently, primarily through linkage to public databases. These methods may be useful to other researchers implementing a large cohort study or designing a passive follow-up system.

Associations of total energy and macronutrients with colon cancer risk in African Americans and Whites: results from the North Carolina colon cancer study.

The higher incidence of colon cancer in African Americans compared with other US racial/ethnic groups is largely unexplained. This report describes associations of total energy and macronutrients with colon cancer risk in African Americans and Whites from a case-control study in North Carolina between 1996 and 2000. Incident cases of histologically confirmed colon cancer, aged 40-80 years (n = 613), and matched controls (n = 996) were interviewed in person to elicit information on potential colon cancer risk factors. A validated food frequency questionnaire adapted to include regional foods was used to assess diet over the year prior to diagnosis or interview date. Cases generally reported higher mean daily intakes of total energy and macronutrients and lower dietary fiber consumption than did controls. Total energy intake was positively associated with colon cancer risk in both racial groups and, although there were some differences by race, high intakes of individual energy sources were also generally associated with two- to threefold increases in risk in models not controlled for total energy. However, these associations largely disappeared when total energy was taken into account. A high level of dietary fiber was associated with a statistically significant 50-60% risk reduction in African Americans and a nonsignificant 30% decreased risk in Whites. Alcohol intake was not statistically significantly associated with colon cancer in either racial group. Total energy intake was consistently associated with colon cancer risk, but associations with individual macronutrients varied somewhat by race and by adjustment for energy intake. These findings may provide an explanation for some of the racial differences in colon cancer incidence.

Is olestra consumption associated with changes in dietary intake, serum lipids, and body weight?

OBJECTIVES: There is considerable controversy regarding the effects of fat substitutes (such as the non-caloric fat substitute, olestra) on Americans' diet and health. This report gives associations of olestra consumption (in savory snacks) with changes in nutrient intake, serum lipid concentrations, and body weight 1 y after these snacks became available nationally in the United States. METHODS: Participants were 1178 adults recruited from three large U.S. cities. At baseline (before the availability of olestra), participants attended a clinic visit and completed questionnaires (including a food-frequency questionnaire), provided fasting blood samples, and had height and weight measured. The clinic visit was repeated about 1 y later, after the introduction of olestra-containing snacks in the marketplace. Olestra consumption was categorized as "none," "very low" (>0 to <0.4 g/d), "low" (>/=0.4 to <2.0 g/d), and "moderate/high" (>/=2.0 g/d). RESULTS: Twenty-five percent of participants reported consuming olestra-containing savory snacks in the preceding month, but only 2% were categorized as moderate/high consumers. Men reported nearly twice as much olestra consumption as women (1.22 versus 0.68 g/d, P = 0.01). Among moderate/high olestra consumers, total energy and carbohydrate intakes increased by 209 kcal/d and 37 g/d, compared with decreases of 87 kcal/d and 14 g/d, respectively, among non-consumers (both Ps for trend = 0.01), corresponding to non-significant changes in percentages of energy from carbohydrate and total fat. Olestra consumption was not associated with statistically significant changes in serum lipids or body weight. CONCLUSIONS: This study found very modest changes in total diet, but no changes in serum lipids or body weight, associated with consumption of olestra-containing savory snacks. However, the low use of olestra by the study sample limited the ability of this study to detect significant effects.

Associations of micronutrients with colon cancer risk in African Americans and whites: results from the North Carolina Colon Cancer Study.

African Americans have the highest incidence of colon cancer among United States racial/ethnic groups, but these disparities are largely unexplained. This report describes associations of micronutrients with colon cancer risk in African Americans and whites using data from a case-control study in North Carolina. Incident cases of histologically confirmed colon cancer, age 40-80 years (n = 613), and matched controls (n = 996) were interviewed in person to elicit information on potential colon cancer risk factors. A previously validated food frequency questionnaire adapted to include regional foods was used to assess diet over the year prior to diagnosis or interview date. Micronutrient exposure included food sources and dietary supplements. Multivariate logistic regression models estimated energy-adjusted and non-energy-adjusted odds ratios (ORs). African Americans reported lower mean micronutrient intakes than whites, primarily due to larger contributions from dietary supplements in whites. Controls generally reported higher micronutrient intakes than cases; however, these differences were only statistically significant for whites. In whites, high beta-carotene, vitamin C, and calcium intakes were associated with 40-60% reductions in colon cancer risk when contrasting highest to lowest quartiles in both energy-adjusted and non-energy-adjusted models, e.g., OR = 0.4 (95% confidence interval, 0.3-0.6) for the highest quartile of calcium in the energy-adjusted model. In African Americans, vitamins C and E were strongly inversely associated using both statistical approaches: high vitamin E intake was associated with a 70% reduced risk for colon cancer, and the OR comparing the highest to lowest quartiles of vitamin C was 0.5 (95% confidence interval, 0.3-0.8). Folate and lutein were not statistically significantly associated with colon cancer risk in either racial group. These results suggest that at high intakes, micronutrients commonly found in plant and other foods (in particular, beta-carotene, vitamin C, and calcium in whites and vitamins C and E in African Americans) exhibit independent associations consistent with 30-70% reductions in colon cancer risk.

Vitamin C intake and apoptosis in normal rectal epithelium.

Apoptosis, or programmed cell death, may lower the risk of neoplasia by removing genetically damaged or mutated cells. A high rate of apoptosis has been linked to a reduced risk of colorectal adenomas; therefore, it is important to understand factors that impact apoptosis. Antioxidants (e.g., vitamin C) protect cells from harmful oxidation processes but may interfere with apoptosis by protecting genetically damaged cells from reactive oxygen species-dependent cell death. The objective of this study was to evaluate the association between vitamin C intake and apoptosis in normal rectal mucosa. Study participants were part of a large, cross-sectional study, the Diet and Health Study III. Participants were recruited from consecutive, consenting patients who underwent colonoscopy at University of North Carolina Hospitals between August 1, 1998 and March 4, 2000. Vitamin C intake, obtained from a food frequency questionnaire, included both dietary sources and vitamin supplements. Apoptosis was measured by morphological evaluation of H&E-stained sections obtained from pinch biopsy samples of normal rectal mucosa in consenting participants (n = 503). The relationship between vitamin C and apoptosis varied by adenoma status. Among individuals with adenomas, there was an inverse linear association between apoptosis and total vitamin C intake. Similarly, individuals with adenomas in the highest quintile of total vitamin C intake were substantially less likely than those in the lowest quintile to have increased colonic apoptosis (odds ratio, 0.05; 95% confidence interval, 0.01-0.46). Vitamin C was not significantly associated with apoptosis in adenoma-free patients. High vitamin C intake was associated with reduced colorectal apoptosis among individuals with adenomas in this study population. Given that high apoptosis may lower colorectal cancer risk, vitamin C supplements may be contraindicated for patients with a history of adenomas.

Reliability and validity of self-report of vitamin and mineral supplement use in the vitamins and lifestyle study.

In the United States, dietary supplements contribute a large proportion of micronutrient intakes. Therefore, it is important to collect accurate information on supplement use for studies of micronutrients and disease risk. This report describes the test-retest reliability and validity of a detailed, self-administered mailed questionnaire on vitamin and mineral supplement use. Participants (n = 220) completed the questionnaire at baseline and 3 months later. During an in-person interview, participants provided spot urine and blood samples, and interviewers transcribed nutrient information from their supplement bottle labels. The questionnaire had very good test-retest reliability for mean supplement intake over the past 10 years, with intraclass correlations ranging from 0.69 for beta-carotene to 0.87 for vitamin E. Pearson's correlation coefficients comparing current supplemental intakes from the questionnaire and interviews/label transcriptions were high, ranging from 0.58 for beta-carotene to 0.82 for chromium; however, for some nutrients, median intakes from the questionnaire were slightly lower than from the interviews. Beta-carotene, vitamin C, and vitamin E (alpha-tocopherol) showed clear linear trends of increasing blood concentrations with higher self-reported supplemental intakes (Pearson's correlation coefficients adjusted for potential confounding factors and diet = 0.31, 0.29, and 0.69, respectively; all p < 0.0001). Creatinine-adjusted spot urinary calcium values were not associated with supplemental calcium intakes (Pearson's r = -0.07). This self-administered questionnaire demonstrated high reproducibility and validity for collecting detailed information on supplement use.

Dietary supplement use and medical conditions: the VITAL study.

BACKGROUND: Over half of U.S. adults use vitamin or mineral supplements, and some are likely using supplements to treat chronic diseases or risk factors for disease. Information on the relationship between supplement use and medical conditions is useful to health professionals to understand the self-medication behavior of their patients, and important for researchers because medical conditions may be potential confounding factors in observational studies of supplement use and disease risk. METHODS: The cross-sectional data in this report are from 45,748 participants, aged 50 to 75 years, who completed a self-administered, mailed questionnaire on current dietary supplement use (multivitamins plus 16 individual vitamins or minerals), medical history (cancer, cardiovascular-related diseases, and other self-reported medical conditions), and demographic characteristics. RESULTS: Supplement use (mean number used at least once a week) was higher among respondents who were older, female, highly educated, Caucasian, and of normal body mass index (all p<0.001). After controlling for these covariates, supplement use was higher among those with the condition for 13 of the 21 conditions examined (p<0.01); only having diabetes or high stress was associated with using fewer supplements. For specific supplements, the strongest associations were for cardiovascular disease and its risk factors with vitamin E, niacin, and folate, and for calcium with indigestion and acid reflux disease. For several conditions, the relative odds of using specific supplements were consistently higher for men than for women. CONCLUSIONS: Supplement use was associated with many medical conditions in this cohort. However, these cross-sectional data do not permit inferences about the temporal sequence. Some associations appeared to be based on evidence for efficacy (e.g., folate with coronary artery disease), and others could be based on misinformation (e.g., selenium with benign prostatic hyperplasia).

Buccal cell DNA yield, quality, and collection costs: comparison of methods for large-scale studies.

There is considerable interest in noninvasive and cost-effective methods for obtaining DNA in large-scale studies. In this randomized crossover study of 22 participants, we compared the DNA yield, quality, and associated costs of buccal cell DNA collected using cytobrushes (three brushes per collection) and swish (i.e., mouthwash) in self-administered procedures. There was a nonstatistically significant higher yield from the mouthwash compared with cytobrush collections (15.8 microg versus 12.0 microg, respectively; P = 0.53). PCR reactions that required short (0.3 kb) or intermediate (1.1 kb) DNA fragments were 100% successful for DNA from brush and mouthwash, whereas PCRs for reactions that required long fragments (7.8 kb) failed for all of the participants from cytobrush DNA and were 81% successful for DNA from the mouthwash source. The brush collections provided sufficient DNA for an estimated 150-225 PCR reactions requiring short and intermediate DNA fragments. The estimated per person costs for buccal brush DNA collections in large studies were less then half (8.50 dollars) those for the mouthwash method (18 dollars). In addition, we tested whether cytobrush instructions to rub cheeks before collection or collect cells only in the morning increased DNA yield and whether repeat brushings of the same cheek reduced DNA yield. These variations resulted in no significant differences in DNA yields. We conclude that the collection of DNA with cytobrushes using simple instructions is cost effective in large-scale studies, and yields sufficient quantity and quality of DNA for genotyping.

Dietary acculturation: applications to nutrition research and dietetics.

The US immigrant population is growing dramatically, making the health status of racial/ethnic minorities an increasingly important public health issue. Immigration to the United States is usually accompanied by environmental and lifestyle changes that can markedly increase chronic disease risk. In particular, adoption of US dietary patterns that tend to be high in fat and low in fruits and vegetables is of concern. The process by which immigrants adopt the dietary practices of the host country--called "dietary acculturation"--is multidimensional, dynamic, and complex; in addition, it varies considerably, depending on a variety of personal, cultural, and environmental attributes. Therefore, to intervene successfully on the negative aspects of dietary acculturation, it is important to understand the process and identify factors that predispose and enable it to occur. In this report, we give an overview of acculturation, define dietary acculturation and present a model for how it occurs, discuss measurement issues related to dietary acculturation, review the literature relating acculturation to eating patterns, and provide a case study illustrating how information on acculturation can be used to design dietary interventions in 2 markedly different immigrant groups. Finally, we give applications for nutrition researchers and dietetic practitioners. Studies investigating associations of acculturation with disease risk should identify and intervene on those steps in the acculturation process that are most strongly associated with unhealthful dietary changes. Practitioners working with immigrants should determine the degree to which dietary counseling should be focused on maintaining traditional eating habits, adopting the healthful aspects of eating in Western countries, or both.

Psychosocial predictors of diet and acculturation in Chinese American and Chinese Canadian women.

OBJECTIVE: To examine the influence of diet-related psychosocial constructs on the dietary practices of Chinese populations living in North America. DESIGN: Data are from a cross-sectional survey of 244 women of Chinese ethnicity living in Seattle, WA, USA and Vancouver, BC, Canada. Using an interviewer-administered questionnaire and PRECEDE/PROCEED as our model, we collected information on diet-related psychosocial (predisposing, enabling, and reinforcing) factors; consumption of foods reflecting Western and Chinese dietary practices; and past and current consumption of fruits, vegetables and fat. RESULTS: Participants generally believed that there were strong relationships between diet and health, but only about a quarter were aware of nutrition information from the government. Food cost, availability, and convenience did not appear to be major concerns among these participants. Respondents' older relatives and spouses tended to prefer a Chinese diet and also had a strong influence on the household diet. Associations of the psychosocial factors with demographic characteristics, adoption of Western dietary practices, and consumption of fruits and vegetables were informative. For example, older, less educated respondents considered it very important to eat a low fat, high fruit and vegetable diet; while younger, more educated participants who were employed outside the home did not think the Chinese diet is healthier than a typical Western diet (all p < 0.05). Western acculturated respondents were more likely to believe in a relationship between diet and cancer/heart disease and report that preparing Chinese meals is inconvenient (p < 0.05). Respondents with in-family normative pressure to maintain Chinese eating patterns ate more fruits and vegetables (4.4 vs 3.7 servings), while knowledge of nutrition information from the government was associated with increased fruit and vegetable consumption after immigration (all p < 0.05). CONCLUSIONS: Chinese cultural beliefs play an important role in the dietary practices of Chinese living in North America. Therefore, traditional health beliefs, as well as socioeconomic and environmental factors related to diet should be incorporated into the design and implementation of culturally appropriate health promotion programs for Chinese immigrants.

Energy from fat is associated with obesity in U.S. men: results from the Prostate Cancer Prevention Trial.

BACKGROUND: Diets high in fat have been proposed as one cause of obesity, primarily because fat is more energy-dense than other macronutrients. However, the literature on fat consumption and human obesity is inconclusive. This research examines associations between dietary fat intake and obesity in men participating in the Prostate Cancer Prevention Trial. METHODS: Data in this cross-sectional study are from 15,266 men (55-79 years) who completed questionnaires on usual diet, physical activity, and health-related characteristics. Height and weight were collected by clinic personnel. Obesity was defined as body mass index (BMI) greater than or equal to 30 kg/m2. RESULTS: In this healthy cohort, 23.3% were obese. Younger age, a sedentary lifestyle, lower education, and black race were positively associated with obesity (all P < 0.001). Using two statistical approaches, both total energy and energy from fat, but not total energy from other macronutrients, increased linearly and significantly with increasing BMI. Mean fat intake increased from 691 kcal (31.4% energy) among normal-BMI men to 797 kcal (34.3% energy) among the obese (P for trend <0.001). After controlling for demographic and health-related characteristics in regression models, BMI increased by 0.53 and 0.14 kg/m(2) for every 500 kcal of fat and total energy consumed, respectively. Energy underreporting, based on estimated basal metabolic rate and physical activity, was fourfold higher among obese compared to normal-weight men. CONCLUSIONS: In this large cohort of healthy older men, energy from fat was associated with obesity, suggesting that high-fat dietary patterns are contributing to the high rates of obesity in U.S. men.