Measurement error and results from analytic epidemiology: dietary fat and breast cancer

BACKGROUND: International correlational analyses have suggested a strong positive association between fat consumption and breast cancer incidence, especially among post-menopausal women. However, case-control studies have been taken to indicate a weaker association, and a recent, pooled cohort analysis reported little evidence of an association. Differences among study results could be due to differences in the populations studied, differences in the control for total energy intake, recall bias in the case-control studies, and dietary measurement error biases. Existing measurement error models assume either that the sample data used to validate dietary self-report instruments are without measurements error or that any such error is independent of both the true dietary exposure and other study subject characteristics. However, growing evidence indicates that total energy and, presumably, both total fat and percent energy from fat are increasingly underreported as percent body fat increases. PURPOSE: A relaxed dietary measurement model is introduced that allows all measurement error parameters to depend on body mass index (weight in kilograms divided by the square of height in meters) and incorporates a random underreporting quantity that applies to each dietary self-report instrument. The model was applied to results from international correlational analyses to determine whether the differing associations between dietary fat and postmenopausal breast cancer can be explained by measurement errors in dietary assessment. METHODS: The relaxed measurement model was developed by use of data on total fat intake and percent energy from fat from 4-day food records (4DFRs) and food-frequency questionnaires (FFQs) from the original Women's Health Trial. This trial was a randomized, controlled, feasibility study of a low-fat dietary intervention carried out from 1985 through 1988 in Cincinnati (OH), Houston (TX), and Seattle (WA) among 303 women (184 intervention and 119 control) who were 45-69 years of age. The relaxed model was used to project results from the international correlational analyses onto 4DFR and FFQ fat-intake categories. RESULTS AND CONCLUSIONS: If measurement errors in dietary assessment are overlooked entirely, the projected relative risks (RRs) for breast cancer based on the international data vary substantially across percentiles of total fat intake. The projected RR for the 90% versus the 10% fat-intake percentile is 3.08 with the 4DFR and 4.00 with the FFQ. If random (i.e., noise) aspects of measurement error are acknowledged, the projected RR for the same comparison is reduced to 1.54 with the 4DFR and 1.42 with the FFQ. If both systematic and noise aspects of measurement error are acknowledged, the projected RR is reduced to about 1.10 with either instrument. Acknowledgment of measurement error also leads to a projected RR of about 1.10 for the 90% versus the 10% percentile of percent energy from fat with either dietary instrument. IMPLICATIONS: Dietary self-report instruments may be inadequate for analytic epidemiologic studies of dietary fat and disease risk because of measurement error biases.     

The effects of a low-fat dietary intervention and tamoxifen adjuvant therapy on the serum estrogen and sex hormone-binding globulin concentrations of postmenopausal breast cancer patients

The purpose of the study was to determine the effect of a low-fat dietary intervention, with or without concomitant tamoxifen adjuvant therapy, on serum estrogen and sex hormone-binding globulin (SHBG) levels in postmenopausal patients with resected breast cancer. Ninety-three patients were randomized to either reduce their fat intake to 15-20% of total calories, or to a dietary control group. Serum estradiol, estrone, estrone sulfate, and SHBG concentrations were assayed at baseline, and at 6, 12, and 18 months thereafter. In 19% of patients, the preintervention serum estradiol levels were below the sensitivity of the assay (5 pg/ml). Tamoxifen had no significant effect on serum estrogen levels, but produced an elevation in SHBG. Patients with reliably quantifiable preintervention estradiol concentrations (> or = 10 pg/ml) showed a significant reduction in serum estradiol after 6 months on the low-fat diet (average, 20%; p < 0.005); this was sustained over the 18 month study period. Serum SHBG levels were increased by tamoxifen therapy, but were reduced significantly (p = 0.01) after 12 months on the low-fat diet in patients not receiving tamoxifen. No changes in serum estrone or estrone sulfate resulted from the dietary intervention. While the low-fat diet produced significant weight loss, patients treated with tamoxifen without dietary intervention showed a gain in body weight. These weight changes produced disruptions in the normal positive correlation between body weight and serum estrone sulfate, and the negative correlation with SHBG concentration.     

Effect of high-fat and low-fat diets on voluntary energy intake and substrate oxidation: studies in identical twins consuming diets matched for energy density, fiber, and palatability

There remains controversy over the effects of dietary fat content on voluntary energy intake. Additionally, the question of whether there is a genetic susceptibility to overeating high-fat diets has not been resolved. To address these issues, we designed two diets: a low-fat diet providing approximately 20% of energy as fat and a high-fat diet with approximately 40% of energy as fat. The diets were matched for energy density, fiber, and palatability. In a two-phase, 18-d intervention study, voluntary energy intakes and macronutrient oxidation rates during the fasting and fed states were determined in seven pairs of identical male twins. In contrast with results of previous intervention studies, in which low-fat and high-fat diets were not matched for energy density and other associated variables, we observed no significant difference in voluntary energy intake between the low-fat and high-fat phases, and mean daily intakes were similar (10.3 and 10.7 MJ/d, respectively). Postprandial rates of fat oxidation tended to reflect fat intakes in the two dietary phases, thus helping to explain the lack of a difference in mean energy intakes. There was also a significant twin-pair similarity in differences in energy intakes between dietary phases (P = 0.013). These results suggest that dietary fat content does not have a major influence on voluntary energy intake when dietary variables usually associated with fat are controlled for and that there may be a familial influence on the effects of dietary fat content on energy intake.     

Systematic review of dietary intervention trials to lower blood total cholesterol in free-living subjects

OBJECTIVES: To estimate the efficacy of dietary advice to lower blood total cholesterol concentration in free-living subjects and to investigate the efficacy of different dietary recommendations. DESIGN: Systematic overview of 19 randomised controlled trials including 28 comparisons. SUBJECTS: Free-living subjects. INTERVENTIONS: Individualised dietary advice to modify fat intake. MAIN OUTCOME MEASURE: Percentage difference in blood total cholesterol concentration between the intervention and control groups. RESULTS: The percentage reduction in blood total cholesterol attributable to dietary advice after at least six months of intervention was 5.3% (95% confidence interval 4.7% to 5.9%). Including both short and long duration studies, the effect was 8.5% at 3 months and 5.5% at 12 months. Diets equivalent to the step 2 diet of the American Heart Association were of similar efficacy to diets that aimed to lower total fat intake or to raise the polyunsaturated to saturated fatty acid ratio. These diets were moderately more effective than the step 1 diet of the American Heart Association (6.1% v 3.0% reduction in blood total cholesterol concentration; P<0.0001). On the basis of reported food intake, the targets for dietary change were seldom achieved. The observed reductions in blood total cholesterol concentrations in the individual trials were consistent with those predicted from dietary intake on the basis of the Keys equation. CONCLUSIONS: Individualised dietary advice for reducing cholesterol concentration is modestly effective in free-living subjects. More intensive diets achieve a greater reduction in serum cholesterol concentration. Failure to comply fully with dietary recommendations is the likely explanation for this limited efficacy.     

Do beliefs, knowledge, and perceived norms about diet and cancer predict dietary change?

OBJECTIVES: We hypothesized that belief in an association between diet and cancer, knowledge of dietary recommendations and food composition, and perceived norms would predict healthful dietary changes. METHODS: Data are from a population-based sample of Washington State residents (n = 607). Psychosocial constructs measured at baseline (1989/90) were used to predict changes in dietary practices, fat intake, fiber intake, and weight over 3 years. RESULTS: Adults who strongly believed in a diet-cancer connection decreased the percentage of energy consumed from fat by 1.20 percentage points and increased fiber intake by 0.69 g, compared with decreases of 0.21 percentage points and 0.57 g among those with no belief (P < .05). Adults with knowledge of the National Cancer Institute fat and fiber goals decreased their percentage of energy from fat by 1.70 points compared with an increase of 0.27 points among those with little knowledge (P < .05). Food composition knowledge and perceived pressure to eat a healthful diet were not significant predictors of changes in fat intake, fiber intake, or weight. CONCLUSIONS: Interventions that increase the public's beliefs in diet and health associations and communicate diet recommendations can encourage healthful dietary change.     

Stages of change for reducing dietary fat intake over 18 months

OBJECTIVE: To describe the stages of change that take place over 18 months, using the criterion of fat intake < or = 30% of total energy to define effective action and to investigate the effect of a single dietary feedback report on dietary fat reduction. DESIGN: Subjects were randomly assigned to experimental or control conditions and assessed at 0, 6, 12, and 18 months for fat intake and stage of change. Subjects in the experiment group received 1 feedback report at baseline; all subjects received a report at 12 months. SUBJECTS: Potential subjects (n = 614) were recruited by mail from a random sample of nonsmoking adults (32% response rate). Subjects were excluded if consuming < or = 30% of energy from fat or if pregnant or lactating (n = 145). Although 83% of subjects (n = 389) completed the 18-month study, only 296 provided complete data for all time points. The study was restricted to these 296. INTERVENTION: Dietary feedback reports plus brief educational materials were provided following the experiment design. ANALYSES: Repeated measures analysis of variance with fat intake (percent of energy from fat) as the dependent variable and baseline stage and condition as independent variables. In addition, t tests were used to compare groups at specific time points. RESULTS: There was a main effect for time (F3,286 = 39, P < .0001) and baseline stage (F3,286 = 24, P < .0001), but no effect of feedback. There was a time-by-feedback interaction (F4,286 = 4.7, P < .01). There was a short-term effect of feedback over 6 months (t = 3.8, P < .001), but this effect was not significant at other time points. About 9% to 12% of subjects in the precontemplation or contemplation stages, 24% of subjects in the preparation stage, and 40% of unclassified subjects at baseline progressed to the action stage by 18 months. Between 12 and 18 months, subjects progressing at least 1 stage reduced their fat intake to a greater extent than subjects who failed to progress (t = 5.1, P < .0001). IMPLICATIONS: Interventions targeted to stage of change have the potential for accelerating the rate of change for dietary fat reduction, but reaching the goal of fat intake < or = 30% of total energy may require more intensive interventions than a single dietary feedback report.     

Effects of dietary fat and a vegetable-fruit mixture on the development of intestinal neoplasia in the ApcMin mouse

The variation in colorectal cancer (CRC) incidence worldwide strongly suggests a role for dietary influences. Based on epidemiological data, protective effects of vegetables and fruit intake on CRC are widely claimed, while other data indicate a possible increased CRC risk from (higher) dietary fat intake. Therefore, we have investigated single and interactive effects of dietary fat and a vegetable-fruit mixture (VFM) in the ApcMin mouse, a mouse model for multiple intestinal neoplasia. In this study, four different diets (A-D) were compared, which were either low in fat (20% energy diets A/B) or high in fat (40% energy diets C/D). In addition, 19.5% (wt/wt) of the carbohydrates in diets B and D were replaced by a freeze-dried VFM. The diets were balanced so that they only differed among each other in fat/carbohydrate content and the presence of specific plant-constituents. Because the initiation of intestinal tumors in ApcMin mice occurs relatively early in life, exposure to the diets was started in utero. Without the addition of VFM, mice maintained at a high-fat diet did not develop significantly higher numbers of small or large intestinal adenomas than mice maintained at a low-fat diet. VFM added to a low-fat diet significantly lowered multiplicity of small intestinal polyps (from 16.2 to 10.2/mouse, 15 animals/group), but not of colon tumors in male ApcMin mice only. Strikingly, addition of VFM to female mice maintained on a low-fat diet and to both sexes maintained on a high-fat diet significantly enhanced intestinal polyp multiplicity (from 16.5 to 26.7 polyps/mouse). In conclusion, our results indicate that neither a lower fat intake nor consumption of VFM included in a high-fat diet decreases the development of polyps in mice genetically predisposed to intestinal tumor development.     

Sociodemographic and psychological predictors of changes in dietary fat consumption in adults with high blood cholesterol following counseling in primary care.

The associations between sociodemographic variables, psychological factors, and changes in dietary fat consumption over 4 months were assessed in a randomized controlled trial of behavioral counseling versus standard advice. Patients were 141 men and 150 women, with an average age of 52.1 years and total cholesterol level of 7.27 mmol/l (278 mg/dl). Smokers, younger patients, and those with greater body mass index had higher fat intake at baseline. Behavioral counseling led to greater reductions in fat intake than did standard advice. Self-efficacy and ratings of benefits of low-fat diets were related to fat consumption at baseline, and changes in these measures were correlated with changes in fat intake. Family support, baseline anticipated regret, and (for the behavioral counseling group only) baseline behavioral intentions predicted reductions in fat intake. The results indicated that psychosocial variables associated cross-sectionally with fat consumption do not necessarily predict change and that factors involved in the process of change and the prediction of change need to be differentiated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of two low-fat diets, high and low in polyunsaturated fatty acids, on plasma lipid peroxides and serum vitamin E levels in free-living hypercholesterolaemic men

Diet enriched with polyunsaturated fat may increase the susceptibility of LDL to oxidation. Therefore the effects of two low-fat diets on plasma lipid peroxides in free-living mildly hypercholesterolaemic men (n = 37) were investigated in a randomized single-blind 28-week study. Composition of the diets were (1) American Heart Association (AHA) type 32/10:8:8 (indicating percentages of energy from total fat/saturated fat:monoenes:polyenes in actual diet); (2) low-fat 30/12:8:3. The subjects kept 3-day dietary records five times during the study to estimate the intake of nutrients. Plasma lipid peroxides were measured photometrically as the thiobarbituric-acid reactive substances (TBARS). Levels of serum vitamin E during the study were also determined. Mean change (+/- SD) in serum low density lipoprotein (LDL) cholesterol was similar in both groups (-0.32 +/- 0.76 vs -0.32 +/- 0.87 mmol/l) (AHA type vs low-fat). Level of TBARS decreased (P < 0.05) during the AHA type diet (-8.4 +/- 37.1%) (mean +/- SD) and increased (P = 0.228) during the low-fat diet (+8.7 +/- 27.0%) from 0 to 6 months. The mean intake of total active tocopherols was greater (14.7 +/- 3.7 mg) during the AHA type diet compared to the low-fat diet (7.8 +/- 2.1 mg). Serum vitamin E to LDL cholesterol ratio increased from 8.9 +/- 2.9 to 9.6 +/- 2.4 nmol/mmol (0 vs 6 months) (P = 0.07) during the AHA type diet and from 8.6 +/- 2.6 to 9.3 +/- 2.4 nmol/mmol (P = 0.159) during the low-fat diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dietary fat reduction and increased aerobic exercise on cardiovascular risk factors

1. The combined effect of dietary fat reduction and increased aerobic exercise on coronary heart disease (CHD) risk factors was investigated in healthy, normolipidaemic, normotensive, sedentary individuals. 2. After a baseline period of 2 weeks, 21 subjects were randomly allocated to one of two intervention groups (low fat exercise (LFEX) or low fat control (LFC)) for 8 weeks. Both groups were counselled to reduce their dietary fat intake to 20-25% energy from fat. The LFEX group was also required to commence an aerobic exercise programme (4 x 45 min per week). 3. In both groups, the falls in total cholesterol seen at week 4 were not maintained at the end of the study; however, the LFEX group maintained a fall in low-density lipoprotein (LDL) of 0.21 +/- 0.11 mmol/L. At the end of the study, the LFC group experienced a fall in high-density lipoprotein (HDL)-cholesterol of 0.16 +/- 0.05 mmol/L, due to a 0.19 +/- 0.07 mmol/L fall in the HDL2 subfraction. The LFEX group experienced no change in HDL (-0.09 +/- 0.06 mmol/L) or HDL2 (-0.09 +/- 0.05 mmol/L). 4. At the end of the study the LFEX and LFC groups experienced a 7 +/- 3 and 5 +/- 1 mmHg fall in systolic blood pressure, respectively, while the LFEX group also observed a 4 +/- 2 mmHg fall in diastolic blood pressure. 5. The benefits of a low-fat diet combined with aerobic exercise include a reduction in LDL and blood pressure, while maintaining HDL through the HDL2 subfraction.     

History of patient education in rheumatic diseases in Croatia]

OBJECTIVE: This report examined the acceptability to mothers of a dietary educational and behavioral intervention for preadolescent children with elevated levels of serum low-density lipoprotein cholesterol (LDL-C) who were enrolled in the Dietary Intervention Study in Children (DISC). DESIGN: DISC is a randomized, controlled clinical trial. Subjects were randomly assigned to either an intervention or usual-care (control) group. SUBJECTS/SETTING: To be eligible for the study, participants were required to have the average of 2 fasting LDL-C values fall between the 80th and 98th sex-specific percentiles. Three hundred thirty-four 8-to 10-year-old children and their families were randomly assigned to an intervention group, and 329 were assigned to a usual-care (control) group. This study examined data from 232 subjects in the intervention group. Data were collected at 6 intervention sites around the United States. INTERVENTION: Those assigned to the intervention group participated in a multidisciplinary dietary intervention that included a series of group and individual sessions over a 3-year period. Children and their caretakers were taught to follow a nutritionally adequate diet that was low in total fat, saturated fat, and cholesterol and high in polyunsaturated fat. MAIN OUTCOME MEASURES: Three nonconsecutive 24-hour diet recalls were collected at baseline and at 1 year by trained and certified dietitians. A questionnaire designed to assess diet acceptability was administered at months 4, 8, 11, and 15. Demographic measures were collected at the onset of the study. STATISTICAL ANALYSIS PERFORMED: Statistical procedures included factor analysis and regression analysis. RESULTS: Regression analysis suggested that perceived effectiveness of the dietary intervention and mothers' having few concerns about disadvantages of the diet were significantly related to higher overall fat intake in children in one-parent families. Maternal willingness to implement the diet was significantly related to lower saturated fat intake. APPLICATIONS/CONCLUSIONS: In attempts to change eating behavior of children, interest and cooperation of the parents are essential to achieving successful results. These analyses further suggest that maternal acceptability translates into willingness to implement the diet and may facilitate changes that are associated with reduced saturated fat intake in children.     

Interaction of N-methyl-anthraniloyl-labelled porcine apolipoprotein A-I with porcine lecithin: cholesterol acyltransferase: an energy transfer study

In an 8-month strictly controlled dietary study of 16 healthy young men, the long-term effect of a low-fat (26% of energy) high-fiber (4.5 g/MJ) diet on cardiovascular risk markers of the hemostatic system was assessed. Fasting blood sampling was performed during a 4-week baseline period and then monthly during the intervention. A matched control group of 16 men on habitual diets was also monitored. Median fibrinolytic activity of tissue-type plasminogen activator (t-PA) in plasma was significantly elevated (twofold to fourfold) by the experimental diet. A significant increase in the systemic fibrinolytic activity of the euglobulin fraction of plasma was also observed. Median plasma factor VII coagulant activity (F VIIc) was depressed by 5-10% during the first 2 months and the last month of the study period. The dietary change did not significantly affect plasma levels of fibrinogen, t-PA antigen, or plasminogen activator inhibitor type I antigen. In conclusion, young men who were switched from a typical Danish diet high in saturated fat to a low-fat/high-fiber diet showed a permanent increase in plasma fibrinolytic activity and a biphasic decrease in F VIIc. The dietary change thus had a favorable effect on cardiovascular risk markers of the hemostatic system.     

Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study

We conducted a controlled feeding study to evaluate the effects of fat and fiber consumption on plasma and urine sex hormones in men. The study had a crossover design and included 43 healthy men aged 19-56 y. Men were initially randomly assigned to either a low-fat, high-fiber or high-fat, low-fiber diet for 10 wk and after a 2-wk washout period crossed over to the other diet. The energy content of diets was varied to maintain constant body weight but averaged approximately 13.3 MJ (3170 kcal)/d on both diets. The low-fat diet provided 18.8% of energy from fat with a ratio of polyunsaturated to saturated fat (P:S) of 1.3, whereas the high-fat diet provided 41.0% of energy from fat with a P:S of 0.6. Total dietary fiber consumption from the low- and high-fat diets averaged 4.6 and 2.0 g.MJ-1.d-1, respectively. Mean plasma concentrations of total and sex-hormone-binding-globulin (SHBG)-bound testosterone were 13% and 15% higher, respectively, on the high-fat, low-fiber diet and the difference from the low-fat, high-fiber diet was significant for the SHBG-bound fraction (P = 0.04). Men's daily urinary excretion of testosterone also was 13% higher with the high-fat, low-fiber diet than with the low-fat, high-fiber diet (P = 0.01). Conversely, their urinary excretion of estradiol and estrone and their 2-hydroxy metabolites were 12-28% lower with the high-fat, low-fiber diet (P < or = 0.01). Results of this study suggest that diet may alter endogenous sex hormone metabolism in men.     

Dietary manipulation and energy compensation: does the intermittent use of low-fat items in the diet reduce total energy intake in free-feeding lean men?

OBJECTIVE: The effect of two low-fat treatments on ad libitum energy intake (EI) was investigated in five lean men living within a metabolic facility. DESIGN: Diet was controlled over two consecutive periods of 12 d when either, i) all foods eaten or ii) only a single (lunch) meal, was manipulated to increase the fat content from 20, 40 to 60% of energy, and ad libitum EI measured. RESULTS: All foods: EI increased from 8.6 (2.9 s.d.)-14.8 (3.1 s.d.) MJ/d and energy density (ED) from 4.1 (0.8 s.d.)-7.7 (1.6 s.d.) kJ/g as fat content increased from 20-60% (P < 0.0001). There was no decrease in weight of food eaten across diets (P > 0.05) and hence no energy compensation. Lunch meal: EI (20%:13.1 MJ/d, 40%:13.8 MJ/d, 60%:14.8 MJ/d) and ED (6.03 kJ/g, 5.89 kJ/g, 6.41 kJ/g) increased but not significantly across treatments (P > 0.05). There was partial energy compensation on the low-fat 20% diet (due in part to compensatory increase in fat intake), but no compensation for the high-fat 60% diet. CONCLUSIONS: Changes in total dietary fat and ED result in concomitant changes in EI; low fat diets reducing EI. However, the dietary strategy of intermittent use of low- and high-fat items fail to significantly alter ED, and hence EI, in free-feeding lean men. Whilst there is a trend towards reduction in intake, manipulation of the fat content of a single meal may not be sufficient to induce significant long-term weight loss.     

Carbohydrate versus fat in the dietary treatment of short-bowel syndrome

The importance of the human colon in energy salvage has been documented again in a recent clinical study. Patients with short-bowel syndrome can be divided into two groups: those with colon and those without colon in continuity. While a high-carbohydrate, low-fat diet appears to be of nutritional benefit to the former group, dietary restrictions and reduction of fat intake are not effective in reducing intestinal energy loss in the latter group.     

Spontaneous weight loss in young subjects of normal weight after 11 weeks of unrestricted intake of a low-fat/high-fiber diet

The present study investigated the spontaneous, unintended body weight changes observed during the first 11 weeks of an eight months' ad libitum low-fat/high-fibre diet (25.5 energy-% fat, 58.5 energy-% carbohydrate, 3.9 g dietary fiber/MJ), primarily aimed at investigating changes in blood lipid concentrations. Subjects were normal-weight, young, healthy students, 24 in the intervention group, and 24 in the control group (no diet). After 11 weeks, an overall decrease in body weight (1.3 +/- 0.4 kg) (mean +/- SEM) (p < 0.01) and fat mass (1.6 +/- 0.2 kg, p < 0.001) was observed in the intervention group. Fat-free mass remained unchanged. Initial body weight and fat mass correlated significantly to changes in body weight and fat mass. No changes were observed in the control group. In conclusion, the ad libitum intake of a low-fat/high-fibre diet led to a spontaneous, small loss of body weight and fat mass in young, normal-weight subjects.     

Positive association between dietary fat intake and risk of gastric stump carcinoma in rats

Effect of high- and low-fat diets on gastric stump carcinogenesis was experimentally investigated. A total of 130 Wistar male rats weighing 250-300 g received either sham operation or Billroth II partial gastrectomy, the resection of the distal two-thirds glandular stomach and reconstruction of gastro-jejunostomy. After surgery, each group of rats was switched from a standard diet (CRF-1) to a special diet containing either 15% soybean oil (high-fat) or 0.5% soybean (low-fat), fed ad libitum and tap water, and were killed 50 weeks after surgery. Gastric tumours were observed only in the animals that underwent gastrectomy while no tumours were detected in the animals following the sham operation. Tumours located invariably at the gastrojejunostoma, were carcinomas or adenomas in histology. Carcinomas developed in 12 of 29 gastrectomy animals (41%) fed the high-fat diet and 4 of 27 gastrectomy animals (15%) fed the low-fat diet. The difference was significant (P < 0.05). The incidence of adenoma was also significantly higher in the gastrectomy animals fed the high-fat diet (38%) than that in those fed the low-fat diet (15%) (P < 0.05). A daily faecal output of bile acids was significantly greater in the gastrectomy animals fed the high-fat diet (19.0 +/- 16.4 micromol/day) than that in those fed the low-fat diet (11.2 +/- 6.2 [micromol/day; P < 0.05). This study suggests that increased fat intake is associated with a high risk of gastric stump carcinoma.     

Dietary supplementation at home improves the regain of lean body mass after surgery

Little is known about nutritional intake after discharge though it takes months to regain preoperative weight after gastrointestinal surgery. We studied whether a 4-mo intervention with dietary advice and protein-rich supplements would increase nutritional intake and gain in lean body mass (LBM) in patients who had undergone gastrointestinal surgery. Patients admitted for gastrointestinal surgery were randomized at discharge to serve as control patients (n = 47) or to receive intervention (n = 40). One month after discharge, the control patients had a nutritional intake (3-d diet record) comparable with the intake of the general population that did not increase further. During the 4 m, the intervention patients had an increased intake of protein (+22%) and energy (+16%), and an enhanced gain of LBM after 2 mo (control 0.8 kg versus intervention 2.1 kg; P = 0.009). After the 4-mo intervention, both LBM and fat were gained (control 1.7 kg LBM and 0.2 kg fat versus intervention 3.1 kg LBM and 1.5 kg fat; LBM: P = 0.029 and fat: P = 0.056). At discharge patients should increase protein intake to 1.5 g.kg-1.d-1 for 2 mo, e.g., by taking protein-rich liquid supplements.     

Determinants and nature of dietary underreporting in a free-living population: the Fleurbaix Laventie Ville Santé (FLVS) Study

OBJECTIVE: To study the determinants and nature of dietary underreporting in a free-living population. DESIGN: Cross-sectional study of nutritional and behavioural characteristics. SUBJECTS: 1030 weight-stable subjects, 501 women and 529 men older than 15 y, included in the Fleurbaix Laventie Ville Santé study. MEASUREMENTS: Dietary intake was assessed using a 3 dy dietary record. Self assessed body weight and height were also recorded. Behavioural and socio-economic data were obtained from a questionnaire. Underreporters were defined as people with a reported ratio of energy intake to estimated basal metabolic rate lower than 1.05. RESULTS: Underreporting concerned 16% of the population and was significantly more frequent in obese than in non obese subjects (P < 0.001). Underreporting was significantly associated with a high socio-professional class (P < 0.05), having dieted at least once (P < 0.01) and to be in dietary restraint (P < 0.05). Furthermore, the contribution of protein to energy intake was significantly higher in underreporters than in non underreporters, independently of weight status. CONCLUSIONS: These data underline that underreporting may bias the assessment of energy and macronutrient intake, particularly in studies on obesity and dietary restraint. Questions about weight concern, dieting and dietary restraint may be useful to identify subjects who underestimate their food intake.     

Fat intake: implications of changes in distribution for setting dietary goals in the UK

STUDY OBJECTIVE: To examine (a) changes in the shape of the distribution of dietary fat intake as the mean dietary fat intake of the population shifts and (b) implications for setting national dietary goals. DESIGN: Data on the percentage of energy from total fat, saturates, monounsaturates, polyunsaturates, and the P:S ratio were analysed for two dietary intervention trials and six cross sectional dietary surveys. The nutrient distributions from each study were described in terms of the mean, standard deviation (SD), coefficient of variation (CV), and skewness statistic. For the intervention trials statistical parameters were compared for groups who received and did not receive dietary advice. For the cross sectional studies, statistical parameters were compared across groups with different levels of mean fat intake. The implications of the results for setting dietary goals were considered using statistical models. MAIN RESULTS: For most fat fractions there was a positive association between the mean and the SD, and an inverse association between the mean and the CV, indicating that as the mean shifts upwards the SD increases but not in proportion to the mean. This is intermediate between a constant SD and a constant CV model. For a population nutrient goal of a maximum of 15% saturates, the estimated population mean for British women would be 8.4% using the constant SD model and 10.8% using the constant CV model. For saturates and the P:S ratio, a lower mean intake was associated with a greater positive skew in the distribution of reported intakes. For saturates, this is consistent with a group of high fat consumers who fail to reduce their intake as the population mean shifts downwards: a "rearguard effect". Findings for the P:S ratio are consistent with a group of consumers who produced a strong positive skew at low mean intakes, which reduced in size as the mean population intake increases: a "vanguard effect". CONCLUSIONS: These findings provide evidence that the distribution of fat intake may change with the mean to a degree that the setting and monitoring of nutritional goals may need to take account of changes in variance and shape of the intake distribution.