Comparison of baseline dietary intake of Hispanic and matched non-Hispanic white breast cancer survivors enrolled in the Women's Healthy Eating and Living study

OBJECTIVE: To assess the reported baseline dietary intake of Hispanic and non-Hispanic white breast cancer survivors in the Women's Healthy Eating and Living study, a randomized plant-based dietary intervention clinical trial. DESIGN: Dietary data from 4 days repeated 24-hour recalls within 3 weeks included daily total intake of energy, protein, carbohydrates, cholesterol, total fat, monounsaturated fat, saturated fat, polyunsaturated fat, fruit/vegetable servings, carotenoids, alcohol, caffeine, and percentage of energy from protein, carbohydrates, alcohol, and fats. SUBJECTS: One hundred sixty-five Hispanic breast cancer survivors age-matched to 165 non-Hispanic white breast cancer survivors diagnosed with Stage I, II, or IIIA primary operable breast cancer. STATISTICAL ANALYSES: Two-sample t tests and Wilcoxon rank sum tests to compare dietary intake, and logistic and ordinal logistic regression analyses to examine the association between ethnicity, alcohol, and lycopene consumption, while controlling for place of birth, education, body mass index, and time since diagnosis. RESULTS: Hispanics were more likely to be foreign-born (P<0.001), less educated (P<0.0001) and to consume higher amounts of lycopene (P=0.029), while non-Hispanic whites were more likely to consume alcohol (P=0.001). However, no differences were observed in the average amounts of alcohol consumed or total percents of energy from alcohol. Both groups consumed more than five servings of fruits and vegetables daily. Being Hispanic remained a significant predictor of lower alcohol use (P=0.004) and higher lycopene consumption (P=0.005) after controlling for place of birth, education, body mass index, and time since diagnosis. CONCLUSIONS: There are more similarities than differences in the dietary intake of Hispanic and non-Hispanic white breast cancer survivors in the Women's Healthy Eating and Living study. Further analysis is needed to determine if higher lycopene consumption shown among the Hispanic participants will translate to greater protection against breast cancer recurrence or increased survival.     

Validity and systematic error in measuring carotenoid consumption with dietary self-report instruments

Vegetables and fruits are rich in carotenoids, a group of compounds thought to protect against cancer. Studies of diet-disease associations need valid and reliable instruments for measuring dietary intake. The authors present a measurement error model to estimate the validity (defined as correlation between self-reported intake and "true" intake), systematic error, and reliability of two self-report dietary assessment methods. Carotenoid exposure is measured by repeated 24-hour recalls, a food frequency questionnaire (FFQ), and a plasma marker. The model is applied to 1,013 participants assigned between 1995 and 2000 to the nonintervention arm of the Women's Healthy Eating and Living Study, a randomized trial assessing the impact of a low-fat, high-vegetable/fruit/fiber diet on preventing new breast cancer events. Diagnostics including graphs are used to assess the goodness of fit. The validity of the instruments was 0.44 for the 24-hour recalls and 0.39 for the FFQ. Systematic error accounted for over 22% and 50% of measurement error variance for the 24-hour recalls and FFQ, respectively. The use of either self-report method alone in diet-disease studies could lead to substantial bias and error. Multiple methods of dietary assessment may provide more accurate estimates of true dietary intake.     

Feasibility of a randomized trial of a high‐vegetable diet to prevent breast cancer recurrence

Epidemiologic evidence supports the concept that diet influences risk for breast cancer and suggests that prognosis after the diagnosis of breast cancer may also be related to modifiable nutritional factors. The purpose of this study was to investigate the feasibility of a randomized trial of a high‐vegetable, reduced‐fat, and increased‐fiber diet intervention to reduce risk for recurrence among breast cancer survivors. This major change in dietary pattern was promoted through intensive telephone counseling. Participants were 93 women who had been diagnosed with breast cancer (stages I, II, and IIIA) within the previous four years and who had completed their initial treatment. We assessed adherence to the study diet using repeated 24‐hour dietary recalls at 6 and 12 months and measurement of circulating carotenoid concentrations. Six months after randomization, the intervention group had significantly increased their mean intake of vegetables (+4.6 servings/day), fruit (+0.7 servings/day), and fiber (+6.4 g/1,000 kcal) and significantly reduced their intake of dietary fat (‐9.9% of energy) compared with the control group. Circulating concentrations of carotenoids also increased in the intervention group. These changes persisted at the 12‐month visit. Results of this study demonstrate that telephone counseling can be a useful approach in diet intervention and that breast cancer survivors can adopt and maintain a high‐vegetable, reduced‐fat dietary pattern.     

On the importance of using multiple methods of dietary assessment

BACKGROUND: Plasma carotenoid concentrations reflect intake of vegetables and fruits, the major food sources of these compounds. This study compared the ability of 2 measures of dietary intake (24-hour diet recalls and food frequency questionnaires [FFQs]) to corroborate plasma carotenoid concentrations in a subset of women participating in a diet intervention trial. METHODS: Plasma carotenoid concentrations and dietary intakes, estimated from 24-hour diet recalls and FFQs, were examined at baseline and 1 year later in a subset of 395 study participants (197 intervention and 198 comparison group). We used longitudinal models to examine associations between estimated intakes and plasma carotenoid concentrations. These analyses were stratified by study group and adjusted for body mass index (BMI), plasma cholesterol concentration, and total energy intake. We conducted simulations to compare mean-squared errors of prediction of each assessment method. RESULTS: In mixed-effects models, the estimated carotenoid intakes from both dietary assessment methods were strongly associated with plasma concentrations of alpha-carotene, beta-carotene, and lutein. Furthermore, modeling the 2 sources of intake information as joint predictors reduced the prediction error. CONCLUSION: These findings underscore the importance of using multiple measures of dietary assessment in studies examining diet-disease associations.     

Telephone counseling helps maintain long-term adherence to a high-vegetable dietary pattern

Achieving long-term adherence to a dietary pattern is a challenge in many studies investigating the relationship between diet and disease. The Women's Healthy Eating and Living Study was a multi-institutional randomized trial in 3088 women at risk for breast cancer recurrence. At baseline, the average participant followed a healthy dietary pattern of 7 vegetable and fruit servings, 21 g/d of fiber, and 28.7% energy from fat, although fat intake increased over the enrollment period. Using primarily telephone counseling, the intervention group was encouraged to substantially increase intakes of vegetables, fruits, and fiber while decreasing fat intake. Sets of 24-h dietary recalls were completed on 90% of eligible participants at 1 y and 86% at 4 y. Using a conservative imputation analysis, at 1 y, the intervention group consumed 38% more vegetable servings (100% when including juice) than the comparison group, 20% more fruit, 38% more fiber, 50% more legumes, and 30% more whole grain foods, with a 20% lower intake of energy from fat. At 4 y, the between-group differences were 65% for vegetables (including juice), 25% fruit, 30% fiber, 40% legumes, 30% whole grain foods, and 13% lower intake of energy from fat. The intervention effect on fat intake was similar for early vs. late enrollees. Plasma carotenoid concentrations on a random 28% sample validated self-reported vegetable and fruit intake, with a between-group difference of 66% at 1 y and over 40% at 4 y. This large change will allow testing of hypotheses on the role of dietary change in preventing additional breast cancer events.     

The Diet Quality Index-Revised: a tool to promote and evaluate dietary change among older cancer survivors enrolled in a home-based intervention trial

OBJECTIVE: To utilize the Diet Quality Index-Revised (DQI-R) as a framework for delivering and evaluating an intervention to improve overall diet quality among older cancer survivors. DESIGN: As part of a randomized controlled trial to improve lifestyle behaviors among older cancer survivors, we sought a dietary measure that could serve as both an intervention framework and a means to evaluate global dietary quality. The DQI-R measures overall diet quality by summing 10 subscales that relate to national guidelines. At baseline, DQI-R scores were generated from three multi-pass 24-hour dietary recalls. The 6-month intervention delivered tailored feedback on individual DQI-R subscales. Dietary recalls were repeated at 6 and 12 months. SUBJECTS: Elderly (aged >or=65 years) individuals within 18 months of diagnosis of breast or prostate cancer (n=182) were randomized postbaseline measures to intervention vs attention control arms. RESULTS: Significant differences in overall diet quality were observed between arms at 6 months, with the intervention arm improving (67.6+/-12.2 to 69.8+/-13.9), and controls declining (67.5+/-12.5 to 64.6+/-14.7) (P=0.003). Significant differences were observed between arms over time in dietary diversity subscale scores: baseline and 6-month follow-up means among intervention and control arms were 4.8+/-1.3 to 4.8+/-1.4, and 4.7+/-1.2 to 4.1+/-1.1, respectively (P=0.001). CONCLUSIONS: The DQI-R served as an effective guide and evaluation tool for this diet-related randomized controlled trial. Like many interventions, our effect diminished after the intervention was complete. Future research should consider testing interventions that use the DQI-R, or other global diet-related indexes, as guides and evaluation tools over longer study periods, as well as in other populations.     

The impact of a long-term reduction in dietary energy density on body weight within a randomized diet trial

We examined the effect of dietary energy density change on body weight in participants of a randomized trial. Intervention participants markedly increased fruit and vegetable intake while reducing energy intake from fat. Participants were 2,718 breast cancer survivors, aged 26-74 yr, with baseline mean body mass index of 27.3 kg/m(2) (SD = 6.3). We assessed dietary intake by sets of four 24-h dietary recalls and validated with plasma carotenoid concentrations. Weight and height were measured at baseline, 1 yr, and 4 yr. Dietary energy density was calculated using food but excluding beverages. Intervention participants significantly reduced dietary energy density compared to controls and maintained it over 4 yr -- both in cross-sectional (P < 0.0001) and longitudinal (Group x Time interaction, P < 0.0001) analyses. Total energy intake or physical activity did not vary between groups. The intervention group had a small but significant weight loss at 1 yr (Group x Time interaction, P < 0.0001), but no between-group weight difference was observed at 4 yr. Our study showed that reducing dietary energy density did not result in a reduction in total energy intake and suggests that this strategy alone is not sufficient to promote long-term weight loss in a free-living population.     

Relative validity of a food frequency questionnaire used to assess food intake during a dietary intervention study

To develop a cost-effective alternative for evaluating dietary intake in large-scale intervention trials of cancer and cardiovascular disease outcomes, we designed and validated a semiquantitative food frequency questionnaire (FFQ). We collected 6 to 8 of the 24-hr dietary recalls from 87 adults (ages 30-72 yr) who were randomly assigned to a walnut-supplemented diet or a control diet in a 6-mo dietary intervention trial. Relative validity of a 171-item FFQ in assessing intake of selected foods and the prescribed intervention (intake > or =25 g/day or intake < 2 g of walnuts) was determined using 24-h dietary recalls as the reference. De-attenuated correlations between FFQ and dietary recalls were .82 for walnuts, .80 for fruits, .79 for grains, .77 for vegetables, .63 for water, .44 for sweets, and .36 for dairy/eggs. High within-person variation did not allow de-attenuation for the remaining foods, but uncorrected correlations were high (> .7) for the beverage variables. The FFQ correctly classified 86 out of 87 subjects in the 2 prescribed intervention groups. The FFQ can provide an accurate measure of a food-based intervention (i.e., walnut supplementation) in a trial setting and can also accurately estimate a number of other food groups consumed during the trial.     

Predictors of dietary change in Mexican American families participating in a health behavior change program

Previous research indicates that Mexican Americans have dietary patterns related to cardiovascular disease risk factors. Research on health beliefs in this ethnic group suggests that Mexican Americans may be less amenable to interventions based on cognitive-behavioral change models. Our study derives from the experience in a community trial, the San Diego Family Health Project, in which Mexican American families were recruited for a structured heart health intervention program. We examined correlations between one-year dietary change scores (three-day sodium, three-day fat, 24-hour sodium, 24-hour fat) and a set of predictor variables derived from social learning theory. Both adults and children had lower intake scores after the intervention, except for children's 24-hour sodium scores. Our correlational analysis found only weak and somewhat inconsistent relationships between theoretically based predictor and outcome variables for adults. The children's results showed statistically significant correlations between two theoretical variables (self-efficacy and supporting others' dietary change) and three-day fat and 24-hour sodium intake. We discuss the implications for cardiovascular disease risk reduction interventions with Mexican Americans.     

Interindividual and intraindividual variation in repeated measures of 24-hour dietary recall in the elderly

While several studies have examined the validity of the 24-hour recall as a method for assessment of dietary intake in older people, none has examined the components of variability of dietary data obtained from the 24-hour recalls of older adults. The ability to detect differences in group means, and estimates of correlation and regression coefficients, are all reduced when intraindividual (within-subject) variability in a measure is large in comparison to interindividual (between-subject) variability. The present study considered the components of variance of four 24-hour diet recalls taken bimonthly, for 220 adults whose mean age was 72 years. Two components of variability were estimated for 23 nutritional variables: an interindividual (between-subjects) variance component and an intraindividual (within-subjects) variance component. The ratio of intraindividual to interindividual variance differed substantially as a function of the nutritional parameter being assessed. Methods are presented for determining the number of dietary recalls needed to keep the attenuation of correlation and regression coefficients within a specified level. Power calculations for the test of equal means in two independent groups are also presented.     

Usual Dietary Intake among Female Breast Cancer Survivors Is Not Significantly Different from Women with No Cancer History: Results of the National Health and Nutrition Examination Survey, 2003-2006

Dietary intake is a modifiable behavior that may reduce the risk of recurrence and death among breast cancer survivors. Cancer survivors are encouraged to consume a diet rich in fruit, vegetables, and whole grains and limit red meat, processed meat, and alcohol intake. Using data from the National Health and Nutrition Examination Survey (2003-2006), this study examined whether breast cancer survivors and women with no history of cancer differed in the distribution of usual intake of foods included in the dietary recommendations for preventing cancer and recurrences. Participants completed one or two 24-hour dietary recalls. The food groups included in this analysis were whole fruit; total vegetables; dark green and orange vegetables; whole grains; red meat; processed meat; alcohol; and calories from solid fat, alcohol, and added sugar. The National Cancer Institute Method was used to estimate the distribution of usual intake and to compare breast cancer survivors (n=102) to noncancer respondents (n=2,684). Using age and cancer survivor as covariates, subgroup estimates of usual intake were constructed. No significant group differences were found, except that survivors reported a greater intake of whole grains. More than 90% of both groups did not meet recommendations for fruits, vegetables, and whole grains; 75.4% and 70.2%, respectively, consumed less than the red meat recommendation; and <10% of either group met the recommendation for percent energy from solid fat, alcohol, and added sugar. The diet of breast cancer survivors was not significantly different from women with no history of cancer.     

Comparison of adipose tissue fatty acids with dietary fatty acids as measured by 24-hour recall and food frequency questionnaire in Black and White Adventists: the Adventist Health Study

PURPOSE: To calibrate and compare intake of different fats and individual fatty acids as assessed with a food frequency questionnaire (FFQ) against that estimated with (i) a series of dietary recalls and; (ii) the relative fat concentration in an adipose tissue biopsy. The FFQ was specially designed for use in a cohort of Seventh-day Adventists. In preparation for a large cohort study investigating the effect of diet on risk of colon, prostate and breast cancer. METHODS: The association of adipose tissue fatty acids and dietary fat intake was assessed in 49 black and 72 white Seventh-day Adventists subjects using 8 different 24-hour recalls, a 200-item food frequency questionnaire (FFQ) and adipose tissue biopsies from each subject. RESULTS: Pearson correlation between fatty acids in adipose tissue and dietary intake as assessed by multiple 24-hour recalls were as follows: Linoleic acid: 0.77 in black and 0.71 in white subjects, respectively; Linolenic acid: 0.68 (blacks) and 0.62 (whites); Total Polyunsaturated fat (PUFA): 0.78 (blacks) and 0.70 (whites); Total Monounsaturated fat (MUFA): 0.35 (blacks) and 0.03 (whites); Total Saturated fat (SFA): 0.46 (blacks) and 0.56 (whites). Correlations between fatty acids in adipose tissue and dietary intake as assessed by FFQ were: Linoleic acid: 0.61 (blacks) and 0.52 (whites), respectively; Linolenic acid: 0.29 (blacks) and 0.49 (whites); PUFA: 0.62 (blacks) and 0.53 (whites); MUFA: 0.07 (blacks) and 0.31 (whites), SFA: 0.21 (blacks) and 0.31 (whites). CONCLUSIONS: Our study confirms findings of others that 24-hour recalls are valid for assessing dietary intake of different types of fat. The FFQ we developed and used in this study gave reasonably valid measures of fatty acid intake in our population and is thus suitable for use in large cohort studies. It had validity comparable to that observed for other FFQs.     

Comparing biological measurements of vitamin C, folate, alpha-tocopherol and carotene with 24-hour dietary recall information in nonhispanic blacks and whites.

PURPOSE: To assess intake of several vitamins in preparation for a large cohort study investigating the effect of diet on risk of colon and prostate cancer. METHODS: The dietary intake of several vitamins were assessed using eight different 24-hour recalls and a 200-item food frequency questionnaire (FFQ) from each subject. Participants also attended a clinic where blood was drawn and body composition, weight, height, and blood pressure were measured. A total of 97 black and 96 nonhispanic white subjects participated. The levels of alpha-tocopherol, carotene, folate, and vitamin C in the blood were correlated with the dietary intakes as measured by both 24-hour recalls and FFQ. RESULTS: Correlations between blood levels and energy-adjusted dietary intake assessed by 24-hour recalls (with supplements) were as follows: carotene (adjusted for serum cholesterol): 0.47 and 0.55 in black and white subjects, respectively; alpha-tocopherol (adjusted for serum cholesterol): 0.61 (blacks) and 0.50 (whites); vitamin C: 0.22 (blacks) and 0.17 (whites); folate: 0.54 (blacks) and 0.55 (whites). Correlations between blood levels and FFQ indices were smaller in magnitude: 0.34 and 0.28 for carotene in black and white subjects, respectively, 0.37 and 0.56 for alpha-tocopherol (adjusted for serum cholesterol), 0.20 and 0.03 for vitamin C and 0.24 and 0.32 for folate. CONCLUSIONS: The correlations observed were generally of modest to moderate size and were similar to or larger than those reported by others. This is despite variations in absorption, metabolism, and excretion of the vitamins and suggests that both the 24-hour recalls and the FFQ contain valid information.     

Longitudinal changes in body weight and body composition among women previously treated for breast cancer consuming a high-vegetable, fruit and fiber, low-fat diet

Summary Background Excess adiposity has been shown to be associated with increased risk for breast cancer recurrence, and a plant-based eating pattern has been hypothesized to be protective. Whether a plant-based diet without specific energy goals will result in weight loss or changes in body composition in women who have been diagnosed with breast cancer has not been fully explored. Aim of the study This study was conducted to identify changes in body weight, anthropometric measures, and body composition over a four year period in a sub-sample of breast cancer survivors participating in a dietary intervention targeting increased intake of vegetables, fruit and fiber and decreased dietary fat intake. Methods This randomized, controlled dietary intervention study compared longitudinal changes in intakes, body weight, waist:hip ratio (WHR), body mass index (BMI) and body composition by treatment group among fiftytwo women previously treated for Stage I, II, or IIIA breast cancer from the Arizona site of the Womens Healthy Eating and Living Study. The dietary intervention aimed for eight servings of fruit and vegetables, 30 g fiber, 20% total energy from fat per day, as well as daily intake of vegetable juice. The comparison group was advised to follow general dietary guidelines for cancer prevention. Results The dietary intervention resulted in a significant and sustained increase in fiber, fruit, vegetable, and vegetable juice consumption (p < 0.05) among intervention group subjects as compared to comparison group subjects. The first 6 months resulted in a reduction in body weight and body fat among the intervention group subjects while the comparison group subjects remained stable. Subsequent measurements, at 12, 24 or 36, and 48 months, showed no significant differences in mean body weight, BMI, WHR, or body composition by study group. Also, no significant changes in these measures were demonstrated for either study group between baseline and 48 months. Conclusions The dietary intervention efforts resulted in significant changes in diet toward an increase in plant foods and a decrease in dietary fat. Changes in weight, WHR, BMI, and body composition were not different over time or by study group assignment. Interventions that promote a plantbased diet without specific energy restriction do not appear to promote changes in body weight or body composition in women who have been diagnosed with breast cancer. To adequately examine the role of energy restriction in reducing obesity-associated breast cancer recurrence, future interventions should include prescribed energy imbalance either through reduced intake and/or increased expenditure.     

The use of telephone interview methodology to obtain 24-hour dietary recalls

OBJECTIVE: To compare 24-hour dietary recalls collected over the telephone to in-person recalls collected in the 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII). DESIGN: Trained interviewers collected 24-hour dietary recalls over the telephone using the multiple-pass approach. These results were compared to in-person interviews from a pooled subsample of CSFII respondents. SUBJECTS/SETTING: List-assisted random-digit dialing was used to identify 700 women between the ages of 20 and 49 years. One eligible woman per household was selected to participate. STATISTICAL ANALYSES: Approximate t tests to examine differences in average nutrient and energy intakes were conducted on weighted data. RESULTS: The reported intakes of most nutrients in the current 24-hour dietary recalls collected over the telephone were significantly higher than those reported in the 1994 and 1995 CSFII, but there were no significant differences between the telephone survey and 1996 CSFII results. The 24-hour dietary recalls collected over the telephone yielded consistently greater mean nutrient intake per respondent compared with a comparable pooled subsample from the 1994, 1995, and 1996 CSFII. Generally, no significant differences were found in the food group data between the telephone survey and the CSFII survey. Mean dietary intakes reported by the comparable CSFII subsample increased from 1994 to 1996. APPLICATIONS: Collecting 24-hour dietary recalls over the telephone is a practical and valid data collection tool for use in national food consumption surveys.     

Validity of 24-hour dietary recalls by adolescent females.

The validity of 24-hour dietary recalls was tested by comparing the recalled intake of adolescent girls to their actual intake during a metabolic study. Diet recalls were a valid bases of estimating the dietary intake of energy, protein, calcium, and zinc by this group of adolescents. However, the majority of the subjects were unable to recall their food intake with enough accuracy so that their intake of vitamins A and C, thiamin, riboflavin, niacin, and iron could be calculated within the range of two-thirds to four-thirds of their actual intake.     

Three measures show high compliance in a soy intervention among premenopausal women

OBJECTIVE: To evaluate adherence to a soy-based diet among premenopausal women. DESIGN: First year of a 2-year, randomized dietary intervention. SUBJECTS: 220 healthy premenopausal women who reported low baseline soy intake. INTERVENTION: 5 counseling visits, 7 follow-up phone calls, and 12 group meetings. Main outcome measures Self-reported soy intake logs; food frequency questionnaires; repeated, randomly timed 24-hour recalls; and analysis of urinary isoflavone excretion by high-pressure liquid chromatography. Statistical analyses Frequency distributions, means, t tests, and mixed effects models. RESULTS: At baseline, the 2 groups did not differ in dietary soy intake (P=.51) or urinary isoflavone excretion (P=.16). According to the 24-hour recalls and the food frequency questionnaires, the intervention group's estimated isoflavone intake increased more than 10 times compared with baseline and with the control group (P<.0001). During follow-up, urinary isoflavone excretion results showed no change in the control group, but a 6-fold increase for intervention subjects (P<.0001). Intake logs showed a strong preference for soymilk and tofu over the other foods and indicated that intervention participants consumed at least 12 servings of soy foods per week during 84 out of 100 follow-up contacts. CONCLUSIONS: These data indicate a high level of compliance with the study regimen, which we attribute to the following strategies: repeated contact with the study subjects, personal relationships with the dietitians, wide choice of soy foods, easy access to soy foods at no cost, and recipes that allowed substitution of previously eaten foods with soy products.     

Monitoring Dietary Change in a Low-Fat Diet Intervention Study: Advantages of Using 24-Hour Dietary Recalls vs Food Records

Objective The purpose of the study was to evaluate two methods of dietary assessment for monitoring change in fat intake in a low-fat diet intervention study.Design The two dietary assessment methods were a 4-day food record (4DFR) and an unannounced 24-hour dietary recall conducted by telephone interview (referred to as a telephone recall [TR]). Subjects were assigned randomly to either a low-fat diet intervention group or a control group that received no counseling about fat intake. Dietary data were collected at baseline, 6 months, and 12 months.Subjects Two hundred ninety postmenopausal women with localized breast cancer were recruited at seven clinical centers in the United States.Statistical analysis Analysis of variance was used to test for significant differences in mean fat and energy intakes.Results Three sources of error were identified: (a) an instrument effect, suggesting underreporting at baseline of approximately 8% in mean energy intake and 11% in mean fat intake in the TR group compared with the 4DFR group (P=.0001); (b) a repeated measures effect observed for the 4DFR, suggesting underreporting of approximately 7% for energy intake and 14% for fat intake in the control group at 6 and 12 months compared with baseline values (P<.001); and (c) an adherence effect (or compliance bias), suggesting greater compliance to the low-fat intervention diet when subjects were keeping food records than when estimates were based on the unannounced TR. Compared with the TR, the 4DFR overestimated the extent of fat reduction in the low-fat diet intervention group by 41% (P=.08) and 25% (P=.62) at 6 and 12 months, respectively.Application Multiple days of unannounced 24-hour recalls may be preferable to multiple-day food records for monitoring dietary change in diet intervention studies. J Am Diet Assoc. 1996; 96:574-579.     

A population-based dietary intervention trial in a high-risk area for stomach cancer and stroke: changes in intakes and related biomarkers

BACKGROUND: Dietary intervention is one of the important fields in cancer and cardiovascular disease prevention. The Hiraka Dietary Intervention Study is a community-based randomized cross-over trial designed to develop an effective dietary modification tool and system in an area with high mortality of stomach cancer and stroke. METHODS: The subjects were 550 healthy volunteers and were randomized into two groups with tailored dietary education to decrease sodium intake and to increase vitamin C and carotene intakes either in the first year (intervention group) or in the second year (control group). Dietary changes were assessed using a validated self-administered diet history questionnaire, fasting blood samples, and 48-hour urine samples, which were obtained before and after the one year period. RESULTS: During the first year, changes differed significantly between the intervention and control group for both dietary sodium intake (-384 and +255 mg/day, intervention and control respectively, p < 0.001) and urinary sodium excretion (-1003 and -84 mg/day, p < 0.001). Although favorable net changes were also observed in dietary carotene (+418 and +220 mug/day, p < 0.05) and vitamin C (+13 and +2 mg/day, p < 0.05), the serum level differences were modest (+13 and -25 mg/L, p = 0.09 for carotene, +0.1 and -0.5 mg/L, p = 0.07 for ascorbic acid). CONCLUSION: The present dietary intervention strategy effectively decreased sodium and increased carotene and vitamin C intakes, although the former was more distinct.