The Impact of Dietary Fiber on Gut Microbiota in Host Health and Disease.

Objective: The purpose of this review is to provide guidance on the development, validation and use of food-frequency questionnaires (FFQs) for different study designs. It does not include any recommendations about the most appropriate method for dietary assessment (e.g. food-frequency questionnaire versus weighed record). Methods: A comprehensive search of electronic databases was carried out for publications from 1980 to 1999. Findings from the review were then commented upon and added to by a group of international experts. Results: Recommendations have been developed to aid in the design, validation and use of FFQs. Specific details of each of these areas are discussed in the text. Conclusions: FFQs are being used in a variety of ways and different study designs. There is no gold standard for directly assessing the validity of FFQs. Nevertheless, the outcome of this review should help those wishing to develop or adapt an FFQ to validate it for its intended use.

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Development, validation and utilisation of food-frequency questionnaires - a review.

Dietary fat intake does affect obesity

Purpose Cancer survivors are at increased risk for several comorbid conditions, and many seek lifestyle change to reduce dysfunction and improve long-term health. To better understand the impact of cancer on adult survivors' health and health behaviors, a review was conducted to determine (1) prevalent physical health conditions, (2) persistent lifestyle changes, and (3) outcomes of previous lifestyle interventions aimed at improving health within this population. Methods Relevant studies from 1966 and beyond were identified through MEDLINE and PubMed searches. Results Cancer survivors are at increased risk for progressive disease but also for second primaries, osteoporosis, obesity, cardiovascular disease, diabetes, and functional decline. To improve overall health, survivors frequently initiate diet, exercise, and other lifestyle changes after diagnosis. However, those who are male, older, and less educated are less likely to adopt these changes. There also is selective uptake of messages, as evidenced ...

Riding the Crest of the Teachable Moment: Promoting Long-Term Health After the Diagnosis of Cancer

Women (n 160) aged 50 to 65 years were asked to weigh their food for 4 d on four occasions over the period of 1 year, using the PETRA (Portable Electronic Tape Recorded Automatic) scales. Throughout the year, they were asked to complete seven other dietary assessment methods: a simple 24 h recall, a structured 24 h recall with portion size assessments using photographs, two food-frequency questionnaires, a 7 d estimated record or open-ended food diary, a structured food-frequency (menu) record, and a structured food-frequency (menu) record with portion sizes assessed using photographs. Comparisons between the average of the 16 d weighed records and the first presentation of each method indicated that food-frequency questionnaires were not appreciably better at placing individuals in the distribution of habitual diet than 24 h recalls, due partly to inaccuracies in the estimation of frequency of food consumption. With a 7 d estimated record or open-ended food diary, however, individual values of nutrients were most closely associated with those obtained from 16 d weighed records, and there were no significant differences in average food or nutrient intakes.

/pdf/comparison-of-dietary-assessment-methods-in-nutritional-1ee0yapd3g.pdf

Comparison of dietary assessment methods in nutritional epidemiology: weighed records v . 24 h recalls, food-frequency questionnaires and estimated-diet records

https://www.gastrojournal.org/article/0016-5085(92)91704-8/pdf

Effect of dietary fiber on colonic bacterial enzymes and bile acids in relation to colon cancer

Several epidemiological studies suggest an inverse relationship between fiber intake and colon cancer risk. Animal model studies indicate that this inhibitory effect depends on the source of dietary fiber. Because of the potential significance of certain colonic mutagens and secondary bile acids in the pathogenesis of colon cancer, the effect of types of supplemental fiber on fecal mutagens and bile acids was studied in human volunteers. Seventy-two healthy individuals consuming high-fat/moderately low-fiber diets were screened for fecal mutagenic activity using the Ames Salmonella typhimurium/microsomal assay system. Twenty-one of them were found to excrete high levels of mutagens, and 19 of them were recruited for the diet intervention study. All participants provided two 24-h stool specimens and a 4-day food record while consuming their normal (control) diet. They were then asked to consume the control diet plus 10 g of dietary fiber from wheat bran, oat fiber, or cellulose for 5 wk. After each fiber period, they were asked to consume their control diet. At the end of each fiber and control diet period, each subject provided two 24-h stool specimens. Stool samples were analyzed for bile acids and mutagens using the Ames strains TA98 and TA100 with or without S9 (microsomal) activation. The concentrations of fecal secondary bile acids (deoxycholic acid, lithocholic acid, and 12-ketolithocholic acid) and of fecal mutagenic activity in TA98 and TA100 with and without S9 activation were significantly lower during the wheat bran and cellulose supplementation periods. Oat fiber supplementation had no such effect on these fecal constituents. Thus, the increased fiber intake in the form of wheat bran or cellulose may reduce the production and/or excretion of mutagens in the stools and decrease the concentration of fecal secondary bile acids in humans.

https://cancerres.aacrjournals.org/content/canres/49/16/4629.full.pdf

Biochemical epidemiology of colon cancer: effect of types of dietary fiber on fecal mutagens, acid, and neutral sterols in healthy subjects.

Because of potential significance of fecal mutagens and secondary bile acids in the pathogenesis of colonie cancer and of inverse association between dietary fiber and colonie cancer risk, the effect of dietary wheat and rye fiber on fecal mutagenic activity and bile acid levels was studied in 15 healthy men and women who were consuming high fat/moderately low fiber diets and excreting high levels of fecal mutagens and bile acids. Each participant provided two 24-h stool specimens and a 3-day diet record while consuming their normal diet (control). All subjects were then asked to consume their normal diet plus 11 g of supplemental fiber per day in the form of whole grain bread for 4 weeks. During the last week of diet intervention, each subject provided two 24-h stool specimens and a 3-day dietary record. Fecal samples collected from both periods were analyzed for bile acids and for mutagens using Salmonella typhimurium strains TA98 and TA 100 with and without nticrosomal activa tion. The concentration of fecal secondary bile acids was significantly lower during the fiber supplemental period in all subjects. Fiber supple mentation also inhibited the fecal mutagenic activity in IA100 and TA98 with and without microsomal activation. Thus, the increased fiber intake in the form of whole wheat and rye bread may reduce the production and/ or excretion of fecal mutagens and decrease the concentration of fecal secondary bile acids in humans.

Metabolic epidemiology of colon cancer - effect of dietary fiber on fecal mutagens and bile-acids in healthy-subjects

A feasibility study was instituted to determine if women with postmenopausal breast cancer would follow a low‐fat diet (20% of kcal) for at least four months. Nineteen women, whose baseline food intake was 1,504 ± 420 kcal with 56 ± 16 g of fat, reported a decrease in fat intake to 21 ± 6 g after two months of dietary intervention. Serum concentrations of cholesterol, HDL cholesterol, and estradiol were significantly reduced by the fifth month on the diet. We conclude that self‐selected patients can adhere to a low‐fat diet, and that serum cholesterol may serve as an indicator of dietary compliance.

Response to a diet low in total fat in women with postmenopausal breast cancer: a pilot study.

In a hospital‐based case‐control study, consumption of lactose‐containing (dairy) foods and foods containing β‐carotene by 71 women with epithelial cancer of the ovary and 141 matched controls was investigated. No significant differences were found between cases and controls in the frequency of consumption of dairy foods or in the amount of lactose consumed. Consumption of carrots was found to decrease risk. Logistic regression analyses indicated a protective effect of high β‐carotene intake (odds ratio = 0.3, 95% confidence interval = 0.1–0.8), after adjusting for body mass, smoking, and lactose consumption.

Althea Engle

Papers

Effect of dietary fiber on colonic bacterial enzymes and bile acids in relation to colon cancer

Biochemical epidemiology of colon cancer: effect of types of dietary fiber on fecal mutagens, acid, and neutral sterols in healthy subjects.

Metabolic epidemiology of colon cancer - effect of dietary fiber on fecal mutagens and bile-acids in healthy-subjects

Response to a diet low in total fat in women with postmenopausal breast cancer: a pilot study.

Nutritional risk factors and ovarian cancer.