Relative validity and reproducibility of a food frequency questionnaire to assess dietary fiber intake in Danish adults

Background: Differences in habitual dietary fiber intake may modify effects of dietary fiber interventions, thus measurement of habitual dietary fiber intake is relevant to apply in intervention studies on fiber-rich foods, and food frequency questionnaire (FFQ) is a commonly used method. Rye bread is the major contributor of dietary fiber in the Danish population, and a nation-specific FFQ is therefore needed. Objective: The aim of this study was to assess the relative validity and reproducibility of a self-administered quantitative FFQ designed to assess total dietary fiber intake among Danish adults. Design: In order to assess the relative validity of the FFQ, a total of 125 participants completed both a 7-day weighed dietary recording (DR) and an FFQ consisting of 60 questions. To evaluate the reproducibility of the FFQ, a sub-group of 12 participants subsequently completed an FFQ approximately 6 months later. Results: Estimates of mean dietary fiber intake were 24.9±9.8 and 28.1±9.4 g/day when applying the FFQ and DR, respectively, where FFQ estimates were ~12% lower (p<0.001). Pearson's correlation coefficient between the estimated dietary fiber intake of the two methods was r=0.63 (p<0.001), and 62% of the participants were grouped into the same tertile of intake according to the two methods. The estimates of mean dietary intake of first and second FFQ were very similar (22.2±4.0 and 23.3±4.1 g/day, respectively, p=0.42) and showed a correlation of r=0.95 (95% CI 0.83–0.99). Conclusion: The developed FFQ showed moderate underestimation of dietary fiber intake (g/day), adequate ranking of subjects according to their dietary fiber intake, and good reproducibility. The FFQ is therefore believed to be a valuable tool for epidemiology and screening in human interventions, where intake of dietary fibers is of specific interest

Supplementation with dairy calcium and/or flaxseed fibers in conjunction with orlistat augments fecal fat excretion without altering ratings of gastrointestinal comfort

BACKGROUND: Orlistat is a lipase inhibitor which reduced absorption of dietary fat by ~30% thereby inducing a weight loss; however, side effects occur as a consequence of increased colonic fat content. To test the hypothesis that most gastrointestinal side events induced by treatment with orlistat could be prevented/ameliorated by concomitant use of natural dietary components, flaxseed fiber (FF) and/or dairy calcium (Ca), binding liquid fats to more solid complexes. METHODS: A randomized controlled dietary intervention study. Thirty-eight obese adults completed a 1-week run-in period, where all participants were treated with orlistat (60 mg t.i.d) and were hereafter randomized to 12 weeks dietary supplementation with/without 5 g FF (FF+/FF-) and/or 1200 mg dairy calcium (Ca+/Ca-) in conjunction with orlistat. All feces were collected for 3 days, and diet was recorded for 5 days, during run-in and week 4. The primary end-point, gastrointestinal symptoms, was assessed biweekly. At baseline and after 12 weeks, cardiometabolic risk markers and anthropometrics were evaluated as secondary end-points. RESULTS: Both FF and Ca increased fecal fat excretion (P = 0.02 and P = 0.04, respectively). Although fecal fat excretion increased by ~100% in the FF+/Ca + group, and only by ~12% in the FF-/Ca + group, no interaction between FF and Ca was present, suggesting an additive effect. The fecal fat excretion was ~10 g/d higher with FF and Ca (~25 g/d) compared to fecal fat excretion with orlistat alone (~15 g/d). Mean ratings of severity of diarrhea tended to increase with Ca (P = 0.03) but not with FF. No other gastrointestinal symptoms, or a composite score of symptoms, were affected by the dietary supplements. Body weight was reduced in all groups but did not differ between groups, whereas waist circumference was most reduced in the FF+/Ca + group. No effects of dietary supplements on cardiometabolic risk factors were observed, except a slight increase in diastolic blood pressure (P = 0.03) with FF, but not Ca. CONCLUSIONS: Our results do not support an improvement in orlistat-induced gastrointestinal side effects by concomitant use of FF and Ca. However, fecal fat excretion was increased with both FF and Ca in the absence of a worsening of symptoms, warranting further studies powered to detect potential additive weight loss effects. TRIAL REGISTRATION: Ethical Committee of the Capital Region of Denmark reg. no. H-1-2010-110, 02-11-2010 database no. NCT01320228, 21-03-2011. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12986-017-0164-8) contains supplementary material, which is available to authorized users

Identification of weak and gender specific effects in a short 3 weeks intervention study using barley and oat mixed linkage β-glucan dietary supplements:a human fecal metabolome study by GC-MS

Introduction: Mixed-linkage (1\ue2\u86\u923),(1\ue2\u86\u924)-\uce\ub2-d-glucans (BG) reduce cholesterol level and insulin response in humans. Despite this, their role in human metabolism and a mode of action remains largely unknown. Objectives: To investigate the effects of three structurally different BG on human fecal metabolome in a full cross-over intervention using GC-MS metabolomics. Methods: Over three weeks of intervention, young healthy adults received food supplemented with BG from oat, two different BG from barley or a non-fiber control in a full cross-over design. Untargeted metabolomics and short chain fatty acid analysis was performed on day three fecal samples. ANOVA-simultaneous component analysis was applied to partition the data variation according to the study design, and PLS-DA was used to select most discriminative metabolite markers. Results: Univariate and multivariate data analysis revealed a dominating effect of inter-individual variances followed by a gender effect. Weak effects of BG intake were identified including an increased level of gamma-amino-butyrate and palmitoleic acid in males and a decreased level of enterolactone in females. Barley and oat derived BG were found to influence the human fecal metabolome differently. Barley BG increased the relative level of formate in males and isobutyrate, isovalerate, 2-methylbutyrate in females. In total 15, 3 and 11 human fecal metabolites were significantly different between control vs. BG, control vs. oat BG, and barley BG vs. oat BG, respectively. Conclusions: The study show that human fecal metabolome largely reflects individual (\ue2\u88\ubc28% variation) and gender (\ue2\u88\ubc15% variation) differences, whereas the treatment\uc2\ua0effect of the BG (\ue2\u88\ubc8% variation) only manifests in a few key metabolites (primarily by the metabolites: d-2-aminobutyric acid, palmitoleic acid, linoleic acid and 11-eicosenoic acid)