Dietary-fat intake in the US population.

OBJECTIVE: This article looks at the food group choices by individuals grouped based on fat intake, saturated fat intake, and use of lowfat foods. METHODS: Food consumption data from USDA's National Food Consumption Surveys (NFCS) and the Continuing Survey of Food Intakes by Individuals (CSFII) were used to look at changes in the mean energy, percent calories from fat and saturated-fat and total-fat intakes over time. USDA's 1995 CSFII data were used to evaluate the diets of individuals grouped based on percent calories from fat and use of low-fat foods. Individuals six to 50 years old who had complete food intake records were included and five age-gender classifications were used. RESULTS: The percent of calories from total fat and saturated fat have steadily declined over the last 30 years, and the amount of fat in the diet has increased from 1989 to 1995. Those whose diets met the Dietary Guidelines Recommendations for fat and saturated fat had lower fat intakes. Except for adult males, those with low-fat diets had higher intakes of total-food amount. Also, lower saturated-fat intakes were associated with lower energy intakes. In general, high-fruit-and-grain-products consumption were seen in groups with low-fat intake. For those who included low-fat foods in their diets and also had low-fat intakes, rice and pasta were the major foods of choice for calories. Fried potatoes were one of the main sources of calories for high-fat groups. CONCLUSION: The study showed individuals whose diets included low-fat foods are more likely to have a diet that meets the dietary guidelines recommendations for fat and saturated fat.     

Comparison of dietary assessment methods in a low-fat dietary intervention program

The food frequency questionnaire (FFQ) is commonly utilized for assessment of dietary fat intake, but its validity among individuals following a low-fat diet is unclear. We evaluated the agreement of nutrient estimates derived from FFQ, 24-h recall, and 3-day food records obtained from 104 participants in a randomized trial of a low-fat dietary intervention for women at elevated breast cancer risk. Comparisons were made for total calories, percent calories from fat, and total fat after 1 yr. Correlation was assessed using standard methods based on a null hypothesis of no agreement between instruments as well as by a methodology based on a null hypothesis that the instruments should be in agreement. With the use of standard methods, FFQ estimates for women on the low-fat diet were significantly correlated to records only for percent calories from fat (r = 0.39), whereas recall and record estimates were significantly correlated for all three dietary variables. Using the new method, we found no significant correlation between FFQ and either recalls or records for women following a low-fat diet but significant correlation between recall and record estimates for total calories (r = 0.67). Traditional correlation testing may overestimate the extent of agreement in dietary instruments among women on a low-fat diet. We found empirical support for the nontraditional method.     

The Stanford Nutrition Action Program: a dietary fat intervention for low-literacy adults.

OBJECTIVES: This study was undertaken to test the effectiveness of the Stanford Nutrition Action Program, an experimental trial to reduce dietary fat intake among low-literacy, low-income adults. METHODS: Twenty-four paired adult education classes (351 participants, 85% women, mean age = 31 years) were randomly assigned to receive a newly developed dietary fat curriculum (the Stanford Nutrition Action Program) or an existing general nutrition curriculum. Food frequency and nutrition-related data, body mass index, and capillary blood cholesterol were collected at baseline and at two postintervention follow-ups. RESULTS: The Stanford Nutrition Action Program classes showed significantly greater net improvements in nutrition knowledge (+7.7), attitudes (/0.2), and self-efficacy (-0.2) than the general nutrition classes; they also showed significantly greater reductions in the percentage of calories from total (-2.3%) and saturated (-0.9%) fat. There were no significant differences in body mass index or blood cholesterol. All positive intervention effects were maintained for 3 months postintervention. CONCLUSIONS: The Stanford Nutrition Action Program curriculum, tailored to the cultural, economic, and learning needs of low-literacy, low-income adults, was significantly more effective in achieving fat-related nutritional changes than the general nutrition curriculum.     

Do flavonoid intakes of postmenopausal women with breast cancer vary on very low fat diets?

In the Women's Intervention Nutrition Study (WINS), a very low-fat eating pattern decreased breast cancer recurrence. We assessed whether the women's flavonoid intakes varied on the very low fat diet. A total of 550 randomly selected WINS participants who had been treated with conventional therapy (surgery, chemotherapy, and/or radiation) for primary breast cancer were randomized to either a very low fat diet (15% of calories from fat, N = 218) or their usual diets (30% calories from fat, N = 332). We compared their intakes of total flavonoids and 6 flavonoid classes (isoflavones, flavones, flavanones, flavonols, flavan-3-ols, and anthocyanins) for these 2 groups using the U.S. Department of Agriculture food flavonoid database and a flavonoid dietary supplement database on three 24-h dietary recalls at baseline and 12 mo after randomization. At baseline, neither mean fat intakes (31.7% +/- 6.8 SD of calories, n = 332 in the usual diet group and 31.6% +/- 6.8 SD of calories, n = 218 in the very low fat diet group; P = NS) nor flavonoid intakes (218 +/- 283 SD mg/day, n = 332 in the usual diet group and 236 +/- 393 SD mg/day, n = 218 in the very low fat diet group; P = NS) differed. Over half of the women's flavonoid intakes were from the flavan-3-ols. After 12 months of intervention, with 39 participants lost to follow-up, dietary fat intakes were 30.7 +/- 8.4 SD calories (n = 316) among those on their usual diets but were significantly lower among those on the very low fat diet intervention: 21.4 +/- 8.3 SD calories (n = 195), P = <0.05. However, flavonoid intakes remained similar in both groups (201 +/- 252 SD mg/day, n = 316 in the usual diet group vs. 235 +/- 425 SD mg/day, n = 195 in the very low fat group; P = NS). In this random sample of WINS participants, neither total flavonoid intakes nor intakes of subclasses of flavonoids differed between those who had dramatically decreased their fat intakes and those who had not. Flavonoid intakes are therefore unlikely to account for WINS results on differences between the groups in cancer recurrence.     

The Effects of a Low-Carbohydrate Diet vs. a Low-Fat Diet on Novel Cardiovascular Risk Factors: A Randomized Controlled Trial

Increasing evidence supports a low-carbohydrate diet for weight loss and improvement in traditional cardiovascular disease (CVD) markers. Effects on novel CVD markers remain unclear. We examined the effects of a low-carbohydrate diet (<40 g/day; n = 75) versus a low-fat diet (<30% kcal/day from total fat, <7% saturated fat; n = 73) on biomarkers representing inflammation, adipocyte dysfunction, and endothelial dysfunction in a 12 month clinical trial among 148 obese adults free of diabetes and CVD. Participants met with a study dietitian on a periodic basis and each diet group received the same behavioral curriculum which included dietary instruction and supportive counseling. Eighty percent of participants completed the intervention. At 12 months, participants on the low-carbohydrate diet had significantly greater increases in adiponectin (mean difference in change, 1336 ng/mL (95% CI, 342 to 2330 ng/mL); p = 0.009) and greater decreases in intercellular adhesion molecule-1 concentrations (−16.8 ng/mL (−32.0 to −1.6 ng/mL); p = 0.031) than those on the low-fat diet. Changes in other novel CVD markers were not significantly different between groups. In conclusion, despite the differences in weight changes on diets, a low-carbohydrate diet resulted in similar or greater improvement in inflammation, adipocyte dysfunction, and endothelial dysfunction than a standard low-fat diet among obese persons.     

Effect of low-fat and/or low-energy diets on anthropometric measures in participants of the women's diet study

OBJECTIVE: To compare the effects of low-fat, low-energy and combination low-fat/low-energy intervention on changes in six anthropometric measures in Caucasian and African-American free-living women. METHODS: The effects of dietary counseling strategies for fat and/or energy reduction were examined on anthropometric measures in 86 pre-menopausal women, average BMI of 28 kg/m2, who participated in a 12-week intervention trial called the Women's Diet Study. The dietary goals were 15% of energy from fat and/or 25% reduction in energy intake, relative to reported baseline intake, using a 2 x 2 factorial design. Analysis of covariance models were constructed to evaluate changes in anthropometric measures over the 12 weeks of study. RESULTS: The biggest difference by race was in women who were relatively heavier at baseline, in which case African-American women lost significantly less weight but decreased their waist:hip ratio to a significantly greater extent than Caucasian women. With regard to the effects of diet arm, weight loss varied depending on baseline weight, and in women with higher baseline weights, the combination low-fat/low-energy diet resulted in the most weight loss (6.7 kg, p < 0.05). Decreases in the other anthropometric measures at week 12 were more uniform across diet arms and did not depend on baseline values. After controlling for previous weight history and race, the decreases in BMI, percent body fat and waist circumference after 12 weeks were statistically equivalent with the low-fat, low-energy or combination low-fat/low-energy diets. The relatively greater decreases in percent body fat and waist circumference with the combination diet versus the low-fat or low-energy diets were not statistically significant. CONCLUSION: The low-fat, low-energy and combination diets all resulted in similar and statistically significant decreases in BMI, percent body fat and waist circumference over 12 weeks of intervention. The extent of weight loss, however, varied depending on baseline weight, and the combination diet was the only intervention to result in significant weight loss for women who were heavier at baseline. This indicates that, although there may be an advantage for reducing dietary fat in initially heavier women, any of these counseling strategies could be effective for improving anthropometric predictors of health risks associated with overweight status. This is useful since flexibility in dietary choices may facilitate adherence to dietary counseling in some individuals.     

Is dietary fat intake related to liking or household availability of high- and low-fat foods?

OBJECTIVE: Despite the increasing availability of low- and reduced-fat foods, Americans continue to consume more fat than recommended, which may be a contributing factor to the obesity epidemic. This investigation examined relationships between liking and household availability of high- and low-fat foods and their association with dietary fat intake. RESEARCH METHODS AND PROCEDURES: A food frequency questionnaire assessed percent calories from fat consumed over the past year in 85 men and 80 women. Participants reported their degree of liking 22 "high-fat foods" (>45% calories from fat) and 22 "low-fat foods" (<18% calories from fat), and the number and percentage (number of high- or low-fat foods/total number of foods x 100) of these high- and low-fat foods in their homes. RESULTS: Hierarchical regression analyses examined the ability of liking and household availability of low- and high-fat foods to predict percent dietary fat intake. After controlling for age, sex, and BMI, liking ratings for high- and low-fat foods and the interaction of liking for low-fat foods by the percentage of low-fat foods in the household were significant predictors of percent dietary fat consumed. Greater liking of high-fat foods and lower liking of low-fat foods, both alone and combined with a lower percentage of low-fat foods in the home, were predictive of higher dietary fat intake. DISCUSSION: Interventions designed to reduce dietary fat intake should target both decreasing liking for high-fat foods and increasing liking for low-fat foods, along with increasing the proportion of low-fat foods in the household.     

Patterns of dietary behavior associated with selecting diets low in fat: reliability and validity of a behavioral approach to dietary assessment

This report describes the development and evaluation of a behavioral measure of dietary patterns related to selecting low-fat diets. An 18-item questionnaire, based on an anthropological theory of dietary change, was developed to assess four relevant dimensions of dietary behavior: (a) excluding high-fat ingredients and preparation techniques, (b) modifying high-fat foods, (c) substituting specially manufactured low-fat foods for their higher-fat counterparts, and (d) replacing high-fat foods with low-fat alternatives. In this study, 99 women completed the diet behavior questionnaire twice and, to characterize precisely their dietary fat intake, also completed two 4-day food records and a food frequency questionnaire. Participants were aged 45 to 59 years and were selected to have a wide range of fat intakes (19.4% to 49.4% of calories from fat). Confirmatory factor analysis identified five scales that corresponded to those hypothesized, except for exclusion, which split into avoiding meat and avoiding fat as a seasoning. The scales had high test-retest and internal consistency reliabilities, and correlations with percent of calories from fat ranged from 0.34 to 0.57 (p less than .01). The correlation of the sum of the five scales (18 items) with percent of calories from fat was 0.68 (p less than .001) and, in multiple regression models, the multiple R2 using all factors to predict percent of calories from fat was 0.47. Overall, these findings supported the validity of the theoretical model of dietary patterns related to selecting diets low in fat. We conclude that a standardized, behavioral approach to measuring fat-related dietary behavior may be useful for designing and evaluating nutrition intervention programs.     

Effects of advice on dietary intake and/or physical activity on body composition,blood lipids and insulin resistance following a low-fat,sucrose-containing,high-carbohydrate,energy-restricted diet

Aim To determine the effect of dietary advice in conjunction with advice to increase physical activity on the body composition, blood lipid and insulin profiles in overweight women.

Design A 12-week randomized controlled intervention study. Subjects were assigned to one of four groups: (1) no advice, (2) low-fat, high-carbohydrate (including sucrose) energy-reduced diet, (3) 60 min/day brisk walking, and (4) diet and activity advice as previous.

Subjects Sixty-nine overweight women (mean age 41 years).

Measurements Dietary compliance was assessed by 4-day diet diaries. Activity levels were assessed by Caltrac? accelerator monitors. Anthropometric changes were recorded at baseline, 6 and 12 weeks. Fasting blood samples measuring glucose, insulin, and blood lipids were recorded at baseline and 12 weeks.

Results Group 4 achieved greatest weight loss of 4.2 kg and greatest reduction in waist circumference of 6.5 cm. Groups 2 and 4 decreased the percentage energy from fat by 5.2%. Group 3 increased the percentage energy from fat by 4.0%. Group 4 significantly reduced total cholesterol by 0.45 mmol/l and low-density lipoprotein-cholesterol by 0.53 mmol/l.

Conclusion A low-fat, high-carbohydrate, sucrose-containing diet combined with increased physical exercise resulted in greater health benefits than diet or physical activity advice alone.     

The influence of a low-fat diet on incidence and severity of migraine headaches

Migraine headaches are a common, debilitating syndrome causing untold suffering and loss of productivity. A review of the literature indicates that high levels of blood lipids and high levels of free fatty acids are among the important factors involved in triggering migraine headaches. Under these conditions, platelet aggregability, which is associated with decreased serotonin and heightened prostaglandin levels, is increased. This leads to vasodilation, the immediate precursor of migraine headache. A high-fat diet is one factor that may directly affect this process. This study, undertaken to evaluate the impact of dietary fat intake on incidence and severity of migraine headache, was conducted over a 12-week period on 54 previously diagnosed migraine headache patients. During the first 28 days, the study subjects recorded all food consumption in a diet diary and maintained a headache diary. At the conclusion of this 28-day baseline period, subjects were individually counseled to limit fat intake to no more than 20 g/day. A 28-day run-in period was allowed for adaptation to the low-fat diet. Results are reported on the final 28-day postintervention period. Subjects significantly decreased the ingestion of dietary fat in grams between baseline (mean 65.9 g/day, p < 0.0001) and the postintervention period (mean 27.8 g/day). The decreased dietary fat intervention was associated with statistically significant decreases in headache frequency, intensity, duration, and medication intake (all p < 0.0001). There was a significant positive correlation between baseline dietary fat intake and headache frequency (r = .44, p = 0.02). This study indicates that a low-fat diet can reduce headache frequency, intensity, and duration and medication intake.     

Do Flavonoid Intakes of Postmenopausal Women With Breast Cancer Vary on Very Low Fat Diets?

In the Women's Intervention Nutrition Study (WINS), a very low-fat eating pattern decreased breast cancer recurrence. We assessed whether the women's flavonoid intakes varied on the very low fat diet. A total of 550 randomly selected WINS participants who had been treated with conventional therapy (surgery, chemotherapy, and/or radiation) for primary breast cancer were randomized to either a very low fat diet (15% of calories from fat, N = 218) or their usual diets (30% calories from fat, N = 332). We compared their intakes of total flavonoids and 6 flavonoid classes (isoflavones, flavones, flavanones, flavonols, flavan-3-ols, and anthocyanins) for these 2 groups using the U.S. Department of Agriculture food flavonoid database and a flavonoid dietary supplement database on three 24-h dietary recalls at baseline and 12 mo after randomization. At baseline, neither mean fat intakes (31.7% ± 6.8 SD of calories, n = 332 in the usual diet group and 31.6% ± 6.8 SD of calories, n = 218 in the very low fat diet group; P = NS) nor flavonoid intakes (218 ± 283 SD mg/day, n = 332 in the usual diet group and 236 ± 393 SD mg/day, n = 218 in the very low fat diet group; P = NS) differed. Over half of the women's flavonoid intakes were from the flavan-3-ols. After 12 months of intervention, with 39 participants lost to follow-up, dietary fat intakes were 30.7 ± 8.4 SD calories (n = 316) among those on their usual diets but were significantly lower among those on the very low fat diet intervention: 21.4 ± 8.3 SD calories (n = 195), P = < 0.05. However, flavonoid intakes remained similar in both groups (201 ± 252 SD mg/day, n = 316 in the usual diet group vs. 235 ± 425 SD mg/day, n = 195 in the very low fat group; P = NS). In this random sample of WINS participants, neither total flavonoid intakes nor intakes of subclasses of flavonoids differed between those who had dramatically decreased their fat intakes and those who had not. Flavonoid intakes are therefore unlikely to account for WINS results on differences between the groups in cancer recurrence.     

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.     

Persons Successful at Long-term Weight Loss and Maintenance Continue to Consume a Low-energy, Low-fat Diet

Objectives To describe the dietary intakes of persons who successfully maintained weight loss and to determine if differences exist between those who lost weight on their own vs those who received assistance with weight loss (eg, participated in a commercial or self-help program or were seen individually by a dietitian). Intakes of selected nutrients were also compared with data from the third National Health and Nutrition Examination Survey (NHANES III) and the 1989 Recommended Dietary Allowances (RDAs).Subjects Subjects were 355 women and 83 men, aged 18 years or older, primarily white, who had maintained a weight loss of at least 13.6 kg for at least 1 year, and were the initial enrollees in the ongoing National Weight Control Registry. On average, the participants had lost 30 kg and maintained the weight loss for 5.1 years.Methods A cross-sectional study in which subjects in the registry completed demographic and weight history questionnaires as well as the Health Habits and History Questionnaire developed by Block et al. Subjects’ dietary intake data were compared with that of similarly aged men and women in the NHANES III cohort and to the RDAs. Adequacy of the diet was assessed by comparing the intake of selected nutrients (iron; calcium; and vitamins C, A, and E) in subjects who lost weight on their own or with assistance.Results Successful maintainers of weight loss reported continued consumption of a low-energy and low-fat diet. Women in the registry reported eating an average of 1,306 kcal/day (24.3% of energy from fat); men reported consuming 1,685 kcal (23.5% of energy from fat). Subjects in the registry reported consuming less energy and a lower percentage of energy from fat than NHANES III subjects did. Subjects who lost weight on their own did not differ from those who lost weight with assistance in regards to energy intake, percent of energy from fat, or intake of selected nutrients (iron; calcium; and vitamins C, A, and E). In addition, subjects who lost weight on their own and those who lost weight with assistance met the RDAs for calcium and vitamins C, A, and E for persons aged 25 years or older.Applications Because continued consumption of a low-fat, low-energy diet may be necessary for long-term weight control, persons who have successfully lost weight should be encouraged to maintain such a diet. J Am Diet Assoc. 1998;98:408–413.     

A Low-Fat Diet Supplemented With Monounsaturated Fat Results in Less HDL-C Lowering Than a Very-Low-Fat Diet

Objective The purpose of this study was to compare the effects of a very-low-fat diet with a low-fat diet supplemented with monounsaturated oil on plasma lipid levels in subjects with hypercholesterolemia.Design The 8-week study was divided into one 2-week baseline diet and two 3-week intervention periods in a randomized crossover design.Setting The study was conducted in an outpatient setting at the Deakin Institute of Human Nutrition, Deakin University, Geelong, Australia.Subjects Twenty-four free-living subjects with hypercholesterolemia participated in and completed the study.Intervention After a 2-week baseline period of a self-selected diet, subjects were assigned to one of two dietary interventions: a very-low-fat (10% of energy from fat), high-carbohydrate diet or a low-fat (26% of energy from fat) diet supplemented with olive oil and an olive oil-based margarine.Main outcome measures Lipid measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride concentrations. Plasma cholesteryl esters were measured to monitor compliance.Statistical analyses A paired t test was used to assess differences between treatment periods for each subject. The dependence of the difference between treatment periods on the covariates of age, sex, initial cholesterol concentration, and energy intake was analyzed using repeated measures and analysis of covariance.Results The low-fat diet supplemented with monounsaturated fat resulted in significantly less high-density lipoprotein cholesterol lowering than the very-low-fat diet (P=.005). Both interventions resulted in significant reductions in both low-density lipoprotein cholesterol and total cholesterol compared with the baseline diet.Applications This study suggests that a low-fat diet enriched with olive oil provides advantages over a very-low-fat diet in the control of serum lipoproteins among persons with hypercholesterolemia. J Am Diet Assoc. 1997; 97:151–156.     

Nutrient and food intake in obese women on a low-fat or low-calorie diet

The low-fat group consumed significantly fewer calories from fat and more calories from carbohydrate at both 6 and 12 months than the low-calorie group, but their fat intake was still about twice their goal at both 6 months (39 gm per day) and 12 months (46 gm per day). The low-calorie group achieved their fat goal of 30% of calorie intake, but they consumed from 300 to 700 kcal more than their calorie goal. Caloric intake, physical activity, palatability, satiety, quality of life, and weight loss were not significantly different by treatment. Two studies, which gave patients hypocaloric diets of varying fat and carbohydrate content (fat calories 10% to 45%) for from 10 to 12 weeks, found no effect of diet composition on weight loss. In addition, one study, which gave patients a low-fat, energy-unrestricted diet (fat calories 19%), reported a weight loss of 10.1 lb at 16 to 20 weeks and 5.7 lb at 9 to 12 months, which is similar to that seen in the low-fat group in the this study. Most of the decrease in fat intake (90%) in the low-fat group resulted from a reduction in intake of fat from fat and oils; meat, fish, and poultry; dairy products; and sweets. The dietary changes in the low-fat group are consistent with those found in one study, which prescribed a 15% fat calorie diet to women with breast cancer. Intake of vitamin C increased in the low-fat group and decreased in the low-calorie group. This difference was significant and was caused by an increased intake of fruits and vegetables in the low-fat group and a decreased consumption of fruits in the low-calorie group. Calcium intake decreased significantly more in the low-calorie group because of a decreased intake of dairy foods.     

Dietary fat and natural-killer-cell activity

An intervention trial designed to lower the amount of fat in the diet was conducted to test the effect of reduced fat consumption (LF diet) on activity of natural killer (NK) cells in humans. Of 26 men enrolled initially, 17 successfully completed the intervention and lowered their fat intake to less than 30% of calories as fat. Data were analyzed in two ways. The paired t test showed a marked increase in NK-cell activity from baseline to the end of the LF-diet intervention (t = 4.77, p = 0.0002). Results of a general linear model showed an effect of lowering total dietary fat on increased NK-cell activity (approximately 0.53% increase for each absolute percent of calories as fat, p = 0.14) for all men and a highly significant effect in a subset of men who ate greater than 25% of calories as fat at baseline (approximately 1.22% increase, p = 0.009). These results were obtained after changes in total caloric intake, weight, exercise, and other fat-related covariates were accounted for.     

Dietary adherence in the Women's Health Initiative Dietary Modification Trial

This article describes adherence to a low-fat dietary pattern (less than 20% energy from fat, five or more fruit/vegetable and six or more grain servings daily) in Years 1 and 5 of the Women’s Health Initiative Dietary Modification Trial, which was designed to examine the effects of a low-fat dietary pattern on risk of breast and colorectal cancers and other chronic diseases in postmenopausal women. Participants were randomly assigned to a low-fat dietary intervention arm (40%, n=19,542) or a usual diet control arm (60%, n=29,294). Women in the intervention arm completed 18 group sessions during the first year, followed by quarterly annual maintenance sessions. Adherence was assessed as control minus intervention (C−I) group differences in percent total energy from fat as estimated by a food frequency questionnaire. Based on these self-reported dietary data, mean C−I was 10.9 percentage points of energy from fat at Year 1, decreasing to 9.0 at Year 5. Factors associated with poorer adherence were being older, being African American or Hispanic (compared with white), having low income, and being obese. Group session attendance was strongly associated with better dietary adherence. There are many limitations of self-reported dietary data, particularly related to social desirability and intervention-associated bias. Nonetheless, these data indicate that long-term dietary change was achieved in this clinical trial setting and reinforce the potential of the ongoing trial to answer questions of public health importance.     

Methods to increase fruit and vegetable intake with and without a decrease in fat intake: compliance and effects on body weight in the nutrition and breast health study

Dietary patterns that involve a decrease in fat and an increase in fruit and vegetable (FV) intake have been suggested to decrease cancer risks. In this study, intervention methods to selectively modify dietary fat and/or FV intakes were developed. Compliance to the diets and the effects on body weight are shown, because both of these dietary changes can impact on and be confounded by changes in energy intake. A total of 122 women with a family history of breast cancer were randomized onto one of four diets for 12 mo. Counseling methods were devised to increase amount and variety of FV consumed with or without a decrease in fat intake using modified exchange list diets. Women on the low-fat and combination low-fat/high-FV diet arms decreased their fat intakes to approximately 16% of energy. Women on the high-FV and the combination low-fat/high-FV diet arms increased FV intakes to approximately 11 servings/day. Despite counseling efforts to maintain baseline energy intakes, mean body weight increased significantly by 6 pounds in women in the high-FV diet arm and decreased significantly by 5 pounds in women in the low-fat diet arm. Percent body fat also was increased in the high-FV diet arm and decreased in the low-fat diet arm. Body weight and percent body fat in the combination diet arm did not change significantly. Control of energy intake, therefore, appears to have been achieved only when the addition of FV to the diet was balanced by a decrease in fat intake and both dietary components were enumerated daily. Maintenance of energy intake, therefore, did not appear to be attained intrinsically when individuals were counseled to make changes in the composition of their diets.     

A brief dietary screen for high fat intake

A 13-item questionnaire has been developed to identify groups of individuals with a high (or low) fat intake. It is intended as a rapid screening tool to identify those who may benefit from counseling or who could then be subjected to a more definitive dietary assessment. It may be either self-or interviewer-administered. A correlation of r = 0.58 was observed between grams of total fat as estimated by the 13-item screener and grams of total fat as calculated from the mean of three four-day diet records, among 101 women aged 45 years and older. By dividing the screener fat distribution at its midpoint, two groups are identified which have a percent of calories from fat, by diet records, of 41 and 35 percent. The 13-item screener does nearly as well as a four-day diet record in correctly identifying those above and below the group's midpoint in percent of calories from fat.