Low-fat Dietary Pattern Research Articles

Re: Low-Fat Dietary Pattern and Cancer Incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial

Re: Low-Fat Dietary Pattern and Cancer Incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial

Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Observational studies, clinical trials, and the women’s health initiative

The complementary roles fulfilled by observational studies and randomized controlled trials in the population science research agenda is illustrated using results from the Women's Health Initiative (WHI). Comparative and joint analyses of clinical trial and observational study data can enhance observational study design and analysis choices, and can augment randomized trial implications. These concepts are described in the context of findings from the WHI randomized trials of postmenopausal hormone therapy and of a low-fat dietary pattern, especially in relation to coronary heart disease, stroke, and breast cancer. The role of biomarkers of exposure and outcome, including high-dimensional genomic and proteomic biomarkers, in the elucidation of disease associations, will also be discussed in these same contexts.

Low-Fat Dietary Pattern and Cancer Incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial

The Women's Health Initiative Dietary Modification (DM) Randomized Controlled Trial evaluated the effects of a low-fat dietary pattern on chronic disease incidence, with breast cancer and colorectal cancer as primary outcomes. The trial protocol also listed ovarian cancer and endometrial cancer as outcomes that may be favorably affected by the intervention. A total of 48,835 postmenopausal women were randomly assigned during 1993-1998 to a DM intervention (n = 19,541) or comparison (usual diet; n = 29,294) group and followed up for an average of 8.1 years. The intervention goal was to reduce total fat intake to 20% of energy and to increase consumption of vegetables, fruits, and grains. Cancer outcomes were verified by pathology report review. We used weighted log-rank tests to compare incidence of invasive cancers of the ovary and endometrium, total invasive cancer, and invasive cancers at other sites between the groups. All statistical tests were two-sided. Ovarian cancer risk was lower in the intervention than in the comparison group (P = .03). Although the overall ovarian cancer hazard ratio (HR) was not statistically significantly less than 1.0, the hazard ratio decreased with increasing intervention duration (P(trend) = .01). For the first 4 years, the risk for ovarian cancer was similar in the intervention and control groups (0.52 cases per 1000 person-years in the intervention group versus 0.45 per 1000 person-years in the comparison group; HR = 1.16, 95% confidence interval [CI] = 0.73 to 1.84); over the next 4.1 years, the risk was lower in the intervention group (0.38 cases per 1000 person-years in the intervention group versus 0.64 per 1000 person-years in the comparison group; HR = 0.60, 95% CI = 0.38 to 0.96). Risk of cancer of the endometrium did not differ between the groups (P = .18). The estimated risk of total invasive cancer was slightly lower in the intervention group than in the control group (HR = 0.95, 95% CI = 0.89 to 1.01; P = .10). A low-fat dietary pattern may reduce the incidence of ovarian cancer among postmenopausal women.

Fat Intake and Breast Cancer Revisited

fat intake, the uncorrected HR was 1.15 (95% CI = 1.05 to 1.26) and the corrected HR was 1.32 (95% CI = 1.11 to 1.58). Thus, even with correction for measurement error, this study provides further evidence that the association between total fat intake and the risk of breast cancer among postmenopausal women is likely to be modest. Analyses of specifi c subtypes of fat yielded increased risks that ranged from 10% to 13% for a doubling of percent energy from fat, an unrealistic scenario except, perhaps, for the small minority of women with the lowest intakes . When all types of fat were considered simultaneously, only the association for saturated fat re mained statistically signifi cant. Thiebaut et al. found a stronger association between saturated and monounsaturated fat intakes and breast cancer risk among current users of menopausal hormone therapy than among never or former users, which suggests that dietary fat intake may have more infl uence on breast cancer risk when it occurs in the context of an estrogen-rich environment (i.e., menopausal hormone therapy users or premenopausal women). Indeed, the pooled analysis of prospective studies ( 4 ) reported positive associations for polyunsaturated fat and vegetable fat among current users of menopausal hormones but not among never or former users. Furthermore, in the Women’s Health Initiative Dietary Modifi cation Trial ( 6 ), women who were randomly assigned to the low-fat group and who were either using postmenopausal hormones at baseline or who were also randomly assigned to the estrogen plus progestin arm of the trial had a 17% (95% CI = 1% to 31%) reduction in breast cancer incidence compared with the control group; by contrast, there was no difference in breast cancer incidence between the low-fat dietary pattern group and the control group among women not using postmenopausal hormones ( P for interaction = .06). Similarly, in the predominantly premenopausal Nurses’ Health

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Exercise and biomarkers for cancer prevention studies.

The International Agency for Research on Cancer estimates that 25% of cancer cases worldwide are caused by overweight or obesity and a sedentary lifestyle. These lifestyle patterns may increase cancer risk by several mechanisms including increased estrogens and testosterone, hyperinsulinemia and insulin resistance, increased inflammation, and depressed immune function. Several randomized clinical trials have shown that physical activity and diet interventions can change biomarkers of cancer risk. In a controlled physical activity trial, we found decreases in serum estrogen, testosterone, and insulin in overweight, sedentary postmenopausal women with a 1-y exercise program consisting of moderate-intensity aerobic exercise, 45 min/d, 5 d/wk. In another controlled trial in middle-aged to older persons, we found that a 1-y exercise intervention of 60 min/d, 6 d/wk, reduced colon crypt cell proliferation in men who adhered closely to the program. Only 1 trial, the Women's Health Initiative Dietary Modification Trial, has published results of a dietary intervention on breast cancer incidence and reported a statistically nonsignificant 9% reduction in invasive breast cancer incidence in postmenopausal women following a low-fat dietary pattern for 8-12 y. Other trials under way are testing effects of weight loss, physical activity, and dietary patterns on other cancer biomarkers. The NCI-funded Transdisciplinary Research on Energetics and Cancer centers are exploring novel research into mechanisms linking energy balance with cancer risk and prevention. The worldwide trends toward increasing overweight and obesity and decreasing physical activity may lead to an increased incidence of several cancers unless other means of risk reduction counteract these effects. Thus, adoption of lifestyle changes by individuals and populations may have a large impact on the future incidence of cancer.

A low fat dietary pattern intervention did not reduce breast cancer, colorectal cancer, or CVD in postmenopausal women

A low fat dietary pattern intervention did not reduce breast cancer, colorectal cancer, or CVD in postmenopausal women

Low-Fat Diet and Risk of Breast Cancer

To the Editor: The Women’s Health Initiative (WHI) randomized controlled trial of a low-fat dietary pattern by Dr Prentice and colleagues found a reduced risk of invasive breast cancer that did not quite reach statistical significance. An important issue is not whether the results are significant but whether any reduction in risk should be attributed to lower fat intake or to the reduction of body weight observed in the intervention group and generated by lower energy intake in that group. As seen in Table 2 of the article, over a 6-year period the average body weight reduction was more pronounced in the intervention group than in the comparison group by 1.4 kg (the mean value of the differences in weight changes of 2.2, 1.3, and 0.8 kg at years 1, 3, and 6, respectively). Huang et al found that among nonusers of hormone therapy, a weight gain of more than 20 kg compared with stable weight was associated with a relative risk of 1.99 for development of breast cancer over 16 years. A crude calculation would suggest that a weight change of 1 kg may be associated with a change in the relative risk of 0.049 (the excess risk of 0.99 divided by 20); if so, a reduction of body weight by 1.43 kg would be associated with a risk reduction of 7%, similar to the 9% reduction found in the intervention group of the WHI trial. This at least merits consideration in the interpretation of the results of this study. The mechanism linking increased body weight to breast cancer risk invokes increased aromatization of androstenedione to estrone in adipose tissue. Estrogens among postmenopausal women are likely to function as growthenhancing compounds with fairly short latency, comparable with that observed after cessation of hormone therapy ( 1 year). If an effect of fat reduction beyond that mediated by weight reduction were to be proposed on the basis of the results of the trial, body weight reduction would have to be controlled for in the analysis.

Low-Fat Dietary Pattern and Risk of Invasive Breast Cancer: The Women???s Health Initiative Randomized Controlled Dietary Modification Trial

Despite a longstanding belief that a low-fat diet can reduce the risk of breast cancer, no controlled intervention trials have been reported. This randomized, controlled, primary prevention trial, based on the Women's Health Initiative cohort, enrolled 48,835 postmenopausal women 50 to 79 years of age at 40 U.S. clinical centers in the years 1993-2005. Forty percent of participants received a diet designed to lower the intake of total fat to 20% of energy, provide at least 5 servings daily of fruit and vegetables, and include at least 6 daily servings of grains. There was no explicit weight loss goal. The remaining 60% of women continued on their usual diets. The intervention group took part in an intensive behavioral modification program administered by a specially trained nutritionist. Participants received an individualized goal of total fat grams based on height and were trained to monitor their dietary intake. The comparison women were given informational materials, including dietary guidelines. At baseline, dietary and other variables, including body weight, were nearly identical in the intervention and control groups. Women in the diet group had a small decrease in energy consumption. The difference between groups in change from baseline in the percentage of energy from fat ranged from 10.7% after 12 months to 8.1% at year 6. The intervention group ate more fruits and vegetables, but there was less difference in grain consumption. The annualized incidence rate of invasive breast cancer during an average follow up of 8.1 years was 0.42% in the intervention group and 0.45% in the comparison group. The hazard ratio was 0.91% with a 95% confidence interval of 0.83 to 1.01. Rates of total cancer (excluding non-melanoma skin cancer), breast cancer mortality, and total mortality all were slightly lower for the intervention group, but the differences were not significant at the 0.05 level. Women who actively participated in the dietary intervention program and those consuming a high-fat diet at baseline had lower hazard ratios. The breast cancer risk also was lower in women with a relatively high baseline percentage of energy from fat. Tumor grade and size, lymph node status, and stage of breast cancers all were similar in the intervention and comparison groups. A lower hazard ratio was noted for progesterone receptor-negative tumors, but there was no apparent association with estrogen receptor status. A low-fat diet failed to lessen the risk of invasive breast cancer in this large trial of postmenopausal women during a follow up averaging approximately 8 years. Nevertheless, the trends observed, although not statistically significant, warrant longer-term studies. Any beneficial effects of reduced fat intake might take years to fully emerge.

A low-fat dietary pattern intervention did not reduce incidence of breast cancer, colorectal cancer, or CVD in postmenopausal women

Source Citation Prentice RL, Caan B, Chlebowski RT, et al. Low-fat dietary pattern and risk of invasive breast cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial...

Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Women???s Health Initiative Randomized Controlled Dietary Modification Trial

Previous studies have failed to document positive effects of a low-fat diet on the risk of colorectal cancer. The risk was examined in relation to the dietary pattern in the Women's Health Initiative Dietary Modification Trial. This randomized, controlled trial enrolled 48,835 postmenopausal women 50 to 79 years of age seen at 40 clinical centers throughout the United States in the years 1993-1998. The interventional diet called for at least 5 daily servings of vegetables and fruits and at least 6 servings of grains with the goal of lowering total fat to 20% of energy intake. An intensive behavioral intervention entailed 18 group sessions in the first year and, subsequently, quarterly sessions led by specially trained and certified nutritionists. Dietary goals were individualized on the basis of height. Motivational interviewing was part of the program. Forty percent of participants were assigned to the intervention and 60% to a comparison group of women who were given dietary guidelines but were not asked to change their diets. The 2 groups had similar risk profiles for colorectal cancer. During a mean follow-up interval of 8.1 years, the reduction in percentage of energy from fat was approximately 70% of that planned. Fewer than one third of women met the goal after 12 months and only 14%' at year 6. Consumption of saturated fat did decline, and women in the intervention group did eat more fruits, vegetables, and grains. Dietary intake of folate and plasma carotenoid levels increased significantly, whereas serum cholesterol levels declined. Rates of invasive colorectal cancer were 0.13% per year in the intervention group and 0.12% in the comparison group. The hazard ratio (HR) was 1.08, with a 95% confidence interval (CI) of 0.90-1.29. The cumulative hazard of colorectal cancer was very similar in the 2 management groups, and no time trend for invasive colorectal cancer was evident. Outcomes were similar in the 2 groups, and there were no significant differences in total cancer incidence, total cancer mortality, or total mortality. Tumor characteristics were similar in the 2 groups. Annualized incidence rates of self-reported colonic polyps or adenomas were lower in the intervention group (HR, 0.91; 95% CI, 0.87-0.95). The risk of colon cancer increased with advancing age, but intervention did not interact with age at baseline. This large trial gave no evidence that, when taken by midlife to late-life postmenopausal women, a low-fat diet decreases the risk of colorectal cancer over 8 years of observation.

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Women???s Health Initiative Randomized Controlled Dietary Modification Trial

There is not yet sufficient information to determine whether a diet that is low in fat and high in fruits, vegetables, and grains can lower the risk of cardiovascular disease (CVD). This hypothesis was tested in the Women's Health Initiative Dietary Modification Trial, a randomized, controlled study enrolling 48,835 postmenopausal women ranging in age from 50 to 79 years. The major dietary goal was to lower the intake of total fat to 20% of energy intake by eating 5 or more servings per day of fruits and vegetables and at least 6 servings of grains. Women assigned to the intervention were asked to attend 18 group sessions in the first year and then quarterly sessions conducted by specially trained, certified nutritionists. The group activities were supplemented by individual interviews. Forty percent of women were assigned to the intervention, whereas 60% in a comparison group were given written dietary guidelines and other health-related materials. The participants, seen at 40 U.S. clinical centers in the years 1993-1998 were followed up for 8.1 years on average. The demographic characteristics of this ethnically diverse study population were comparable in the intervention and comparison groups. After 6 years, the intervention group had an 8.2% lower mean total fat intake and a 2.9% lower mean saturated fat intake than at baseline. They ate less trans, monounsaturated, and polyunsaturated fat and cholesterol, but the ratio of polyunsaturated to saturated fat did not change. The dietary intervention was associated with small but significant reductions in body weight, waist circumference, and diastolic blood pressure. Serum levels of low-density lipoprotein cholesterol declined, but there were no significant changes in high-density lipoprotein cholesterol, triglycerides, or lipoprotein(a). The dietary intervention was not associated with significant changes in major coronary heart disease (CHD), which included myocardial infarction and death from CHD; composite CHD (CHD/coronary revascularization); or total, fatal, or nonfatal strokes. After excluding women with a history of CVD at baseline, the hazard ratio for CHD was 0.94 (95% confidence interval, 0.86-1.02), and that for stroke was 1.02 (95% confidence interval, 0.90-1.17). There was a trend toward greater reductions in CHD risk in participants with lower intakes of saturated fat or trans fat, and in those eating more vegetables and fruits. Hazard ratios did not change after considering adherence criteria based on participation in the interventional activities. The low-fat diet given to postmenopausal women in this study for approximately 8 years on average failed to appreciably reduce the risk of CHD or stroke. It may be that a more focused diet with greater changes in multiple macro-and micronutrients, along with alterations in behaviors that influence CVD risk factors, will be needed to achieve a substantial impact on manifestations of CVD.

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease: The Womenʼs Health Initiative Randomized Controlled Dietary Modification Trial

Obstetrics & Gynecology: May 2006 - Volume 107 - Issue 5 - p 1165 doi: 10.1097/01.AOG.0000209484.37803.c0

Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Womenʼs Health Initiative Randomized Controlled Dietary Modification Trial

Obstetrics & Gynecology: May 2006 - Volume 107 - Issue 5 - p 1164-1165 doi: 10.1097/01.AOG.0000209483.30180.ad

Low-Fat Dietary Pattern and Risk of Invasive Breast Cancer: The Womenʼs Health Initiative Randomized Controlled Dietary Modification Trial

Low-Fat Dietary Pattern and Risk of Invasive Breast Cancer: The Womenʼs Health Initiative Randomized Controlled Dietary Modification Trial

Mammakarzinomrisiko - Fettarme Ernährung ohne Einfluss?

Quelle: Prentice RL, Caan B, Chlebowski RT et al. Low-fat dietary pattern risk of invasive breast cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial. JAMA 2006; 295 (6): 629-642

Low-Fat Dietary Pattern and Weight Change Over 7 Years: The Womenʼs Health Initiative Dietary Modification Trial

Low-Fat Dietary Pattern and Weight Change Over 7 Years: The Womenʼs Health Initiative Dietary Modification Trial