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1.
Am J Clin Nutr ; 110(2): 473-484, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31190057

RESUMO

BACKGROUND: Little is known about the contribution of genetic variation to food timing, and breakfast has been determined to exhibit the most heritable meal timing. As breakfast timing and skipping are not routinely measured in large cohort studies, alternative approaches include analyses of correlated traits. OBJECTIVES: The aim of this study was to elucidate breakfast skipping genetic variants through a proxy-phenotype genome-wide association study (GWAS) for breakfast cereal skipping, a commonly assessed correlated trait. METHODS: We leveraged the statistical power of the UK Biobank (n = 193,860) to identify genetic variants related to breakfast cereal skipping as a proxy-phenotype for breakfast skipping and applied several in silico approaches to investigate mechanistic functions and links to traits/diseases. Next, we attempted validation of our approach in smaller breakfast skipping GWAS from the TwinUK (n = 2,006) and the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium (n = 11,963). RESULTS: In the UK Biobank, we identified 6 independent GWAS variants, including those implicated for caffeine (ARID3B/CYP1A1), carbohydrate metabolism (FGF21), schizophrenia (ZNF804A), and encoding enzymes important for N6-methyladenosine RNA transmethylation (METTL4, YWHAB, and YTHDF3), which regulates the pace of the circadian clock. Expression of identified genes was enriched in the cerebellum. Genome-wide correlation analyses indicated positive correlations with anthropometric traits. Through Mendelian randomization (MR), we observed causal links between genetically determined breakfast skipping and higher body mass index, more depressive symptoms, and smoking. In bidirectional MR, we demonstrated a causal link between being an evening person and skipping breakfast, but not vice versa. We observed association of our signals in an independent breakfast skipping GWAS in another British cohort (P = 0.032), TwinUK, but not in a meta-analysis of non-British cohorts from the CHARGE consortium (P = 0.095). CONCLUSIONS: Our proxy-phenotype GWAS identified 6 genetic variants for breakfast skipping, linking clock regulation with food timing and suggesting a possible beneficial role of regular breakfast intake as part of a healthy lifestyle.

2.
Nutrients ; 11(6)2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31159235

RESUMO

Results from some observational studies suggest that higher whole grain (WG) intake is associated with lower risk of weight gain. Ovid Medline was used to conduct a literature search for observational studies and randomized controlled trials (RCTs) assessing WG food intake and weight status in adults. A meta-regression analysis of cross-sectional data from 12 observational studies (136,834 subjects) and a meta-analysis of nine RCTs (973 subjects) was conducted; six prospective cohort publications were qualitatively reviewed. Cross-sectional data meta-regression results indicate a significant, inverse correlation between WG intake and body mass index (BMI): weighted slope, -0.0141 kg/m2 per g/day of WG intake (95% confidence interval (CI): -0.0207, -0.0077; r = -0.526, p = 0.0001). Prospective cohort results generally showed inverse associations between WG intake and weight change with typical follow-up periods of five to 20 years. RCT meta-analysis results show a nonsignificant pooled standardized effect size of -0.049 kg (95% CI -0.297, 0.199, p = 0.698) for mean difference in weight change (WG versus control interventions). Higher WG intake is significantly inversely associated with BMI in observational studies but not RCTs up to 16 weeks in length; RCTs with longer intervention periods are warranted.

3.
Nutr Rev ; 77(7): 487-497, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31086952

RESUMO

Whole-grain (WG) consumption is known to have beneficial effects on human health. However, the influence of WGs on the microbiota is not well understood. To evaluate how WG intake modulates the gut microbiota composition, a literature review of human intervention studies was conducted. Whole grain, whether a mixed WG food or diet (n = 5) or specific WG intervention (WG wheat [n = 5], barley [n = 2], rye [n = 2] or rice, corn, or oats [n = 1 for each]), generally modified microbiota composition but did so inconsistently across measurements of microbial diversity and taxa. Interventions used both parallel and crossover designs and varied from single product substitutions to fully controlled diets with WG exposures of 3-12 weeks. The effect of amount of WG was difficult to capture due to variable reporting of WG. Methods used to measure microbiota varied in ability to resolve changes at different taxonomic levels, and comparisons of interventions using similar methods was lacking. Because many dietary components besides WGs alter gut microbiota, further research is needed, particularly in linking microbiota changes to health outcomes, and study design recommendations for future research on WGs and microbiota are warranted.

4.
Obesity (Silver Spring) ; 27(4): 670-677, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30825267

RESUMO

OBJECTIVE: This study examined the longitudinal associations between genetic risk, change in diet quality, and change in visceral adipose tissue (ΔVAT), abdominal subcutaneous adipose tissue (ΔSAT), and pericardial adipose tissue (ΔPAT). METHODS: A total of 1,677 Framingham Heart Study participants who had ectopic fat depots measured using computed tomography were analyzed. Diet quality was quantified using a Mediterranean-style diet score (MDS) and genetic risk by depot-specific genetic risk scores (GRSs). RESULTS: Per SD improvement in MDS, there was 50 cm3 (95% CI: 14-86; P = 0.007) less fat accumulation in VAT, 52 cm3 (95% CI: 12-92; P = 0.01) less fat accumulation in SAT, and 1.3 cm3 (95% CI: 0.1-2.4; P = 0.04) less fat accumulation in PAT. No association was observed between GRSs and ΔVAT or ΔSAT. Each 1-SD increase in the PAT GRS was associated with a 1.2-cm3 (95% CI: 0.1-2.3; P = 0.03) increase in ΔPAT. In participants with higher PAT GRS, those with ΔMDS ≥ 0 had a favorable change in PAT compared with the counterparts with ΔMDS < 0 (P = 0.008). CONCLUSIONS: Longitudinal improvements in diet quality are associated with less ectopic fat accumulation. This study suggests that diet quality may play a critical role in improving ectopic adiposity profiles.

5.
Nutrients ; 11(3)2019 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-30875784

RESUMO

Public interest in popular diets is increasing, in particular whole-food plant-based (WFPB) and vegan diets. Whether these diets, as theoretically implemented, meet current food-based and nutrient-based recommendations has not been evaluated in detail. Self-identified WFPB and vegan diet followers in the Adhering to Dietary Approaches for Personal Taste (ADAPT) Feasibility Survey reported their most frequently used sources of information on nutrition and cooking. Thirty representative days of meal plans were created for each diet. Weighted mean food group and nutrient levels were calculated using the Nutrition Data System for Research (NDSR) and data were compared to DRIs and/or USDA Dietary Guidelines/MyPlate meal plan recommendations. The calculated HEI-2015 scores were 88 out of 100 for both WFPB and vegan meal plans. Because of similar nutrient composition, only WFPB results are presented. In comparison to MyPlate, WFPB meal plans provide more total vegetables (180%), green leafy vegetables (238%), legumes (460%), whole fruit (100%), whole grains (132%), and less refined grains (-74%). Fiber level exceeds the adequate intakes (AI) across all age groups. WFPB meal plans failed to meet the Recommended Dietary Allowances (RDA)s for vitamin B12 and D without supplementation, as well as the RDA for calcium for women aged 51⁻70. Individuals who adhere to WFBP meal plans would have higher overall dietary quality as defined by the HEI-2015 score as compared to typical US intakes with the exceptions of calcium for older women and vitamins B12 and D without supplementation. Future research should compare actual self-reported dietary intakes to theoretical targets.


Assuntos
Dieta Vegana/estatística & dados numéricos , Ingestão de Energia , Valor Nutritivo , Recomendações Nutricionais , Idoso , Estudos Transversais , Dieta Saudável , Humanos , Internet , Pessoa de Meia-Idade , Inquéritos e Questionários
6.
Nutrients ; 11(2)2019 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-30678099

RESUMO

Military researchers utilize a five-item healthy eating score (HES-5) in the Global Assessment Tool (GAT) questionnaire to quickly assess the overall diet quality of military personnel. This study aimed to modify the HES-5 to improve its validity relative to the 2015 Healthy Eating Index (HEI-2015) in active duty military personnel (n = 333). A food frequency questionnaire was used to calculate HEI-2015 scores and to assess sugar-sweetened beverage (SSB) intake in 8-oz (SSB-8) and 12-oz servings. GAT nutrition questions were used to calculate HES-5 scores and capture breakfast and post-exercise recovery fueling snack (RFsnack) frequencies. Two scoring options were considered for the highest RFsnack category: "4" vs. "5" (RFsnack-5). Potential candidates were added alone and in combination to the HES-5 and compared to the HEI-2015 with a Pearson correlation coefficient. Scores with the highest correlations were compared via a z-score equation to identify the simplest modification to the HES-5. Correlations between HES-5 and HEI-2015 scores in total participants, males, and females were 0.41, 0.45 and 0.32, respectively. Correlations were most significantly improved in total participants by adding RFsnack-5, SSB-8, RFsnack-5 + SSB-8, and RFsnack-5 + SSB-8 + breakfast, though the addition of SSB-8 + RFsnack-5 performed best (r = 0.53). Future work should consider scoring mechanisms, serving sizes, and question wording.


Assuntos
Inquéritos sobre Dietas/métodos , Inquéritos sobre Dietas/normas , Militares , Valor Nutritivo , Adulto , Comportamento Alimentar , Feminino , Dieta Saudável , Humanos , Masculino , Reprodutibilidade dos Testes
7.
Nutrients ; 10(8)2018 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-30096913

RESUMO

Consumption of whole grains have been associated with reduced risk of chronic diseases in many observational studies; yet, results of intervention studies are mixed. We aimed to use evidence mapping to capture the methodological and reporting variability in whole grain intervention studies that may contribute to this inconsistency. We conducted a reproducible search in OVID Medline for whole grain human intervention studies (published 1946 to February 2018). After screening based on a priori criteria, we identified 202 publications describing a total of 213 unique trials. Over half (55%) were acute trials, lasting ≤1 day, 30% were moderate duration studies (up to 6 weeks) and 15% were of longer duration (more than 6 weeks). The majority of acute trials (75%) examined measures of glycaemia and/or insulinemia, while most of the longer trials included measures of cardiometabolic health (71%), appetite/satiety (57%) and weight/adiposity (56%). Among the moderate and long duration trials, there was a wide range of how whole grains were described but only 10 publications referenced an established definition. Only 55% of trials reported the actual amount of whole grains (in grams or servings), while 36% reported the amount of food/product and 9% did not report a dose at all. Of the interventions that provided a mixture of whole grains, less than half (46%) reported the distribution of the different grain types. Reporting of subject compliance also varied and only 22% used independent biomarkers of whole grain intake. This evidence map highlights the need to standardize both study protocols and reporting practices to support effective synthesis of study results and provide a stronger foundation to better inform nutrition scientists and public health policy.


Assuntos
Ensaios Clínicos como Assunto/métodos , Dietoterapia/métodos , Prática Clínica Baseada em Evidências/métodos , Dieta Saudável , Tamanho da Porção , Projetos de Pesquisa , Grãos Integrais , Determinação de Ponto Final , Humanos , Valor Nutritivo , Cooperação do Paciente , Recomendações Nutricionais , Fatores de Tempo , Resultado do Tratamento
8.
Mol Psychiatry ; 2018 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-29988085

RESUMO

Macronutrient intake, the proportion of calories consumed from carbohydrate, fat, and protein, is an important risk factor for metabolic diseases with significant familial aggregation. Previous studies have identified two genetic loci for macronutrient intake, but incomplete coverage of genetic variation and modest sample sizes have hindered the discovery of additional loci. Here, we expanded the genetic landscape of macronutrient intake, identifying 12 suggestively significant loci (P < 1 × 10-6) associated with intake of any macronutrient in 91,114 European ancestry participants. Four loci replicated and reached genome-wide significance in a combined meta-analysis including 123,659 European descent participants, unraveling two novel loci; a common variant in RARB locus for carbohydrate intake and a rare variant in DRAM1 locus for protein intake, and corroborating earlier FGF21 and FTO findings. In additional analysis of 144,770 participants from the UK Biobank, all identified associations from the two-stage analysis were confirmed except for DRAM1. Identified loci might have implications in brain and adipose tissue biology and have clinical impact in obesity-related phenotypes. Our findings provide new insight into biological functions related to macronutrient intake.

9.
Curr Dev Nutr ; 2(5): nzy012, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29955724

RESUMO

Background: Although there is interest in popular diets such as vegan and vegetarian, Paleo, and other "whole food" diets, existing cohort studies lack data for these subgroups. The use of electronic data capture and Web-based surveys in nutrition research may be valuable for future studies by allowing targeting of specific dietary subgroups. Objective: The aim was to perform a Feasibility Survey (FS) to assess the practicality of Web-based research methods to gather data and to maximize response rates among followers of popular diets. Methods: The FS was an open, voluntary, 15-min survey conducted over 8 wk in the summer of 2015. Recruitment targeted self-identified followers of popular diets from a convenience sample, offering no incentives, via social media and e-newsletters shared by recruitment partners. Feasibility was assessed by number of responses, survey completion rate, distribution of diets, geographic location, and willingness to participate in future research. Results: A total of 14,003 surveys were initiated; 13,787 individuals consented, and 9726 completed the survey (71% of consented). The numbers of unique visitors to the questionnaire site, view rate, and participation rate were not captured. Among respondents with complete demographic data, 83% were female and 93% were white. Diet designations were collapsed into the following groups: whole-food, plant-based (25%); vegan and raw vegan (19%); Paleo (14%); try to eat healthy (11%); vegetarian and pescatarian (9%); whole food (8%); Weston A Price (5%); and low-carbohydrate (low-carb) (4%). Forced-response, multiple-choice questions produced the highest response rates (0-2% selected "prefer not to answer"). The percentage who were willing to complete future online questionnaires was 86%, diet recall was 93%, and food diary was 75%; the percentages willing to provide a finger-stick blood sample, venipuncture blood sample, urine sample, and stool sample were 60%, 44%, 58%, and 42%, respectively. Conclusions: This survey suggests that recruiting followers of popular diets is feasible with the use of Web-based methods. The unbalanced sample with respect to sex and race/ethnicity could be corrected with specific recruitment strategies using targeted online marketing techniques.

10.
Nutr Cancer ; 70(5): 776-786, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29781707

RESUMO

Case-control studies suggest that higher whole grain and lower refined grain intakes are associated with reduced cancer risk, but longitudinal evidence is limited. The objective of this prospective cohort study is to evaluate associations between whole and refined grains and their food sources in relation to adiposity-related cancer risk. Participants were adults from the Framingham Offspring cohort (N = 3,184; ≥18 yr). Diet, measured using a food frequency questionnaire, medical and lifestyle data were collected at exam 5 (1991-95). Between 1991 and 2013, 565 adiposity-related cancers were ascertained using pathology reports. Cox proportional hazards models were used to estimate adjusted hazard ratios and 95% confidence intervals for associations of whole and refined grains with risk of adiposity-related cancers combined and with risk of breast and prostate cancers in exploratory site-specific analyses. Null associations between whole and refined grains and combined incidence of adiposity-related cancers were observed in multivariable-adjusted models (HR: 0.94; 95% CI: 0.71-1.23 and HR: 0.98; 95% CI: 0.70-1.38, respectively). In exploratory analyses, higher intakes of whole grains (oz eq/day) and whole grain food sources (servings/day) were associated with 39% and 47% lower breast cancer risk (HR: 0.61; 95% CI: 0.38-0.98 and HR: 0.53; 95% CI: 0.33-0.86, respectively). In conclusion, whole and refined grains were not associated with adiposity-related cancer risk. Whole grains may protect against breast cancer, but findings require confirmation within a larger sample and in other ethnic groups.

11.
J Clin Invest ; 128(2): 545-555, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29388924

RESUMO

Increased sugar consumption is increasingly considered to be a contributor to the worldwide epidemics of obesity and diabetes and their associated cardiometabolic risks. As a result of its unique metabolic properties, the fructose component of sugar may be particularly harmful. Diets high in fructose can rapidly produce all of the key features of the metabolic syndrome. Here we review the biology of fructose metabolism as well as potential mechanisms by which excessive fructose consumption may contribute to cardiometabolic disease.

12.
Diabetologia ; 61(2): 317-330, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29098321

RESUMO

AIMS/HYPOTHESIS: Sugar-sweetened beverages (SSBs) are a major dietary contributor to fructose intake. A molecular pathway involving the carbohydrate responsive element-binding protein (ChREBP) and the metabolic hormone fibroblast growth factor 21 (FGF21) may influence sugar metabolism and, thereby, contribute to fructose-induced metabolic disease. We hypothesise that common variants in 11 genes involved in fructose metabolism and the ChREBP-FGF21 pathway may interact with SSB intake to exacerbate positive associations between higher SSB intake and glycaemic traits. METHODS: Data from 11 cohorts (six discovery and five replication) in the CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) Consortium provided association and interaction results from 34,748 adults of European descent. SSB intake (soft drinks, fruit punches, lemonades or other fruit drinks) was derived from food-frequency questionnaires and food diaries. In fixed-effects meta-analyses, we quantified: (1) the associations between SSBs and glycaemic traits (fasting glucose and fasting insulin); and (2) the interactions between SSBs and 18 independent SNPs related to the ChREBP-FGF21 pathway. RESULTS: In our combined meta-analyses of discovery and replication cohorts, after adjustment for age, sex, energy intake, BMI and other dietary covariates, each additional serving of SSB intake was associated with higher fasting glucose (ß ± SE 0.014 ± 0.004 [mmol/l], p = 1.5 × 10-3) and higher fasting insulin (0.030 ± 0.005 [log e pmol/l], p = 2.0 × 10-10). No significant interactions on glycaemic traits were observed between SSB intake and selected SNPs. While a suggestive interaction was observed in the discovery cohorts with a SNP (rs1542423) in the ß-Klotho (KLB) locus on fasting insulin (0.030 ± 0.011 log e pmol/l, uncorrected p = 0.006), results in the replication cohorts and combined meta-analyses were non-significant. CONCLUSIONS/INTERPRETATION: In this large meta-analysis, we observed that SSB intake was associated with higher fasting glucose and insulin. Although a suggestive interaction with a genetic variant in the ChREBP-FGF21 pathway was observed in the discovery cohorts, this observation was not confirmed in the replication analysis. TRIAL REGISTRATION: Trials related to this study were registered at clinicaltrials.gov as NCT00005131 (Atherosclerosis Risk in Communities), NCT00005133 (Cardiovascular Health Study), NCT00005121 (Framingham Offspring Study), NCT00005487 (Multi-Ethnic Study of Atherosclerosis) and NCT00005152 (Nurses' Health Study).


Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Bebidas , Glicemia/metabolismo , Jejum/sangue , Fatores de Crescimento de Fibroblastos/genética , Insulina/sangue , Edulcorantes , Feminino , Humanos , Masculino
13.
Diabetes Care ; 40(12): 1695-1702, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28978672

RESUMO

OBJECTIVE: Magnesium intake is inversely associated with risk of type 2 diabetes in many observational studies, but few have assessed this association in the context of the carbohydrate quality of the diet. We hypothesized that higher magnesium intake is associated with lower risk of type 2 diabetes, especially in the context of a poor carbohydrate-quality diet characterized by low cereal fiber or high glycemic index (GI) or glycemic load (GL). RESEARCH DESIGN AND METHODS: In the Nurses' Health Study (NHS; 1984-2012, n = 69,176), NHS2 (1991-2013, n = 91,471), and the Health Professionals' Follow-Up Study (1986-2012, n = 42,096), dietary intake was assessed from food frequency questionnaires every 4 years. Type 2 diabetes was ascertained by biennial and supplementary questionnaires. We calculated multivariate hazard ratios (HRs) of magnesium intake and incident diabetes, adjusted for age, BMI, family history of diabetes, physical activity, smoking, hypertension, hypercholesterolemia, GL, energy intake, alcohol, cereal fiber, polyunsaturated fats, trans fatty acids, and processed meat, and we considered the joint associations of magnesium and carbohydrate quality on diabetes risk. RESULTS: We documented 17,130 incident cases of type 2 diabetes over 28 years of follow-up. In pooled analyses across the three cohorts, those with the highest magnesium intake had 15% lower risk of type 2 diabetes compared with those with the lowest intake (pooled multivariate HR in quintile 5 vs. 1: 0.85 [95% CI 0.80-0.91], P < 0.0001). Higher magnesium intake was more strongly associated with lower risk of type 2 diabetes among participants with high GI or low cereal fiber than among those with low GI or high cereal fiber (both P interaction <0.001). CONCLUSIONS: Higher magnesium intake is associated with lower risk of type 2 diabetes, especially in the context of lower carbohydrate-quality diets.


Assuntos
Diabetes Mellitus Tipo 2/prevenção & controle , Carboidratos da Dieta/normas , Magnésio/administração & dosagem , Adulto , Glicemia , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/epidemiologia , Dieta , Carboidratos da Dieta/administração & dosagem , Fibras na Dieta/administração & dosagem , Suplementos Nutricionais , Ingestão de Energia , Feminino , Seguimentos , Qualidade dos Alimentos , Índice Glicêmico , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Enfermeiras e Enfermeiros , Modelos de Riscos Proporcionais , Fatores de Risco , Estados Unidos
14.
BMC Public Health ; 17(1): 310, 2017 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-28399838

RESUMO

BACKGROUND: Nutrition clubs (NC) operate in community settings and provide members with nutrition education and meal replacements for weight management. NC are owned and operated by distributors of Herbalife products. There are over 6200 NC in the US, but there has been no independent assessment of the association of these NC with biomarkers of health. METHODS: We conducted a cross-sectional pilot study to compare the health status of 100 NC members to 100 community-matched controls (CC) in the greater Boston area. Each CC was matched to a NC member for community of residence (zip code), age category, gender, BMI category, race/ethnicity, education level (category), and readiness to make health changes. Measures obtained included cardio-metabolic risk factors, body composition, markers of nutritional status, reported health status, dietary intake, physical activity, sleep and depression. RESULTS: Participants were predominantly female (64%) and Hispanic (73%). NC members had significantly lower fasting insulin (P < 0.001) and lower HbA1c (P = 0.008), higher levels of 25 hydroxy-vitamin D (P = 0.001), and vitamin E:cholesterol ratio (P < 0.001), and lower prevalence of metabolic syndrome (P = 0.02) compared to CC. In addition, most of the NC members (99%) were satisfied with Herbalife NC membership for themselves and their families. A higher percentage of NC members (86%) compared to CC (32%) reported being in much better or somewhat better health compared to a year ago (P < 0.001); and they reported significantly better physical health (P = 0.03), and fewer sleep problems (P = 0.03). CONCLUSION: Herbalife NC membership was positively associated with perceived health and measured cardiometabolic benefits. However, causality cannot be inferred from these findings.


Assuntos
Dieta , Nível de Saúde , Apoio Social , Adolescente , Adulto , Fatores Etários , Biomarcadores , Composição Corporal , Índice de Massa Corporal , Boston , Estudos Transversais , Exercício , Jejum , Feminino , Hemoglobina A Glicada/análise , Humanos , Insulina/sangue , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Estado Nutricional , Projetos Piloto , Fatores Sexuais , Sono , Fatores Socioeconômicos , Adulto Jovem
15.
J Acad Nutr Diet ; 117(5): 681-682, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28449790
16.
Nutrients ; 9(2)2017 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-28208609

RESUMO

Interest is rapidly growing around the role of the human gut microbiota in facilitating beneficial health effects associated with consumption of dietary fiber. An evidence map of current research activity in this area was created using a newly developed database of dietary fiber intervention studies in humans to identify studies with the following broad outcomes: (1) modulation of colonic microflora; and/or (2) colonic fermentation/short-chain fatty acid concentration. Study design characteristics, fiber exposures, and outcome categories were summarized. A sub-analysis described oligosaccharides and bacterial composition in greater detail. One hundred eighty-eight relevant studies were identified. The fiber categories represented by the most studies were oligosaccharides (20%), resistant starch (16%), and chemically synthesized fibers (15%). Short-chain fatty acid concentration (47%) and bacterial composition (88%) were the most frequently studied outcomes. Whole-diet interventions, measures of bacterial activity, and studies in metabolically at-risk subjects were identified as potential gaps in the evidence. This evidence map efficiently captured the variability in characteristics of expanding research on dietary fiber, gut microbiota, and physiological health benefits, and identified areas that may benefit from further research. We hope that this evidence map will provide a resource for researchers to direct new intervention studies and meta-analyses.


Assuntos
Fibras na Dieta/administração & dosagem , Microbioma Gastrointestinal , Trato Gastrointestinal/microbiologia , Ácidos Graxos Voláteis/metabolismo , Fermentação , Humanos , Estudos Observacionais como Assunto , Oligossacarídeos/administração & dosagem , Ensaios Clínicos Controlados Aleatórios como Assunto
17.
Artigo em Inglês | MEDLINE | ID: mdl-29375475

RESUMO

The consumption of sugar-sweetened beverages (SSB), which includes soft drinks, fruit drinks, and other energy drinks, is associated with excess energy intake and increased risk for chronic metabolic disease among children and adults. Thus, reducing SSB consumption is an important strategy to prevent the onset of chronic diseases, and achieve and maintain a healthy body weight. The mechanisms by which excessive SSB consumption may contribute to complex chronic diseases may partially depend on an individual's genetic predisposition. Gene-SSB interaction investigations, either limited to single genetic loci or including multiple genetic variants, aim to use genomic information to define mechanistic pathways linking added sugar consumption from SSBs to those complex diseases. The purpose of this review is to summarize the available gene-SSB interaction studies investigating the relationships between genetics, SSB consumption, and various health outcomes. Current evidence suggests there are genetic predispositions for an association between SSB intake and adiposity; evidence for a genetic predisposition between SSB and type 2 diabetes or cardiovascular disease is limited.

18.
J Acad Nutr Diet ; 117(2): 251-264, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27863994

RESUMO

Enduring misconceptions about the physical effects of fiber in the gut have led to misunderstandings about the health benefits attributable to insoluble and soluble fiber. This review will focus on isolated functional fibers (eg, fiber supplements) whose effects on clinical outcomes have been readily assessed in well-controlled clinical studies. This review will also focus on three health benefits (cholesterol lowering, improved glycemic control, and normalizing stool form [constipation and diarrhea]) for which reproducible evidence of clinical efficacy has been published. In the small bowel, clinically meaningful health benefits (eg, cholesterol lowering and improved glycemic control) are highly correlated with the viscosity of soluble fibers: high viscosity fibers (eg, gel-forming fibers such as b-glucan, psyllium, and raw guar gum) exhibit a significant effect on cholesterol lowering and improved glycemic control, whereas nonviscous soluble fibers (eg, inulin, fructooligosaccharides, and wheat dextrin) and insoluble fibers (eg, wheat bran) do not provide these viscosity-dependent health benefits. In the large bowel, there are only two mechanisms that drive a laxative effect: large/coarse insoluble fiber particles (eg, wheat bran) mechanically irritate the gut mucosa stimulating water and mucous secretion, and the high water-holding capacity of gel-forming soluble fiber (eg, psyllium) resists dehydration. Both mechanisms require that the fiber resist fermentation and remain relatively intact throughout the large bowel (ie, the fiber must be present in stool), and both mechanisms lead to increased stool water content, resulting in bulky/soft/easy-to-pass stools. Soluble fermentable fibers (eg, inulin, fructooligosaccharide, and wheat dextrin) do not provide a laxative effect, and some fibers can be constipating (eg, wheat dextrin and fine/smooth insoluble wheat bran particles). When making recommendations for a fiber supplement, it is essential to recognize which fibers possess the physical characteristics required to provide a beneficial health effect, and which fiber supplements are supported by reproducible, rigorous evidence of one or more clinically meaningful health benefits.


Assuntos
Fibras na Dieta/administração & dosagem , Medicina Baseada em Evidências , Trato Gastrointestinal/metabolismo , Glicemia/metabolismo , Colesterol/sangue , Fezes/química , Galactanos/administração & dosagem , Humanos , Inulina/administração & dosagem , Laxantes/administração & dosagem , Mananas/administração & dosagem , Gomas Vegetais/administração & dosagem , Psyllium/administração & dosagem , Ensaios Clínicos Controlados Aleatórios como Assunto , Viscosidade , beta-Glucanas/administração & dosagem
19.
J Nutr ; 146(12): 2544-2550, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27934644

RESUMO

BACKGROUND: Previous studies have shown an inconsistent relation between habitual beverage consumption and insulin resistance and prediabetes. OBJECTIVE: The objective of the present study was to test the hypothesis that the consumption of sugar-sweetened beverages (SSBs), rather than diet soda, is associated with long-term progression of insulin resistance and the development of prediabetes. METHODS: We analyzed the prospective association between cumulative mean consumption of SSBs or diet soda and incident prediabetes (n = 1685) identified across a median of 14 y of follow-up in participants [mean ± SD age: 51.9 ± 9.2 y; 59.6% women; mean ± SD body mass index (BMI; kg/m2): 26.3 ± 4.4] of the Framingham Offspring cohort. The prospective association between beverage consumption and change in homeostasis model assessment of insulin resistance (HOMA-IR; n = 2076) over ∼7 y was also analyzed. The cumulative mean consumption of SSBs and diet soda was estimated by using food-frequency questionnaires. Multivariable Cox proportional hazards models and linear regression models were implemented to estimate the HRs of incident prediabetes and change in HOMA-IR, respectively. RESULTS: After adjustment for multiple potential confounders, including baseline BMI, we observed that SSB intake was positively associated with incident prediabetes (P-trend < 0.001); the highest SSB consumers (>3 servings/wk; median: 6 servings/wk) had a 46% higher risk of developing prediabetes than did the SSB nonconsumers (HR: 1.46; 95% CI: 1.16, 1.83). Higher SSB intake was also associated with a greater increase in HOMA-IR (P-trend = 0.006). No prospective associations were observed between diet soda intake and risk of prediabetes (P-trend = 0.24) or changes in HOMA-IR (P-trend = 0.25). These associations were similar after additional adjustment for change in BMI. CONCLUSION: Regular SSB intake, but not diet soda intake, is associated with a greater increase in insulin resistance and a higher risk of developing prediabetes in a group of middle-aged adults.


Assuntos
Carboidratos/efeitos adversos , Bebidas Gaseificadas/análise , Resistência à Insulina , Estado Pré-Diabético , Edulcorantes/efeitos adversos , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
20.
Nutrients ; 8(12)2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27983687

RESUMO

While dietary fiber plays an important role in the health benefits associated with whole grain consumption, other ingredients concentrated in the outer bran layer, including alkylresorcinols, lignans, phenolic acids, phytosterols, and tocols, may also contribute to these outcomes. To determine the acute bioavailability and pharmacokinetics of the major phytochemicals found in barley and oats, we conducted a randomized, three-way crossover trial in 13 healthy subjects, aged 40-70 years with a body mass index (BMI) of 27-35.9 kg/m². After a two-day run-in period following a diet low in phytochemicals, subjects were randomized to receive muffins made with either 48 g whole oat flour, whole barley flour, or refined wheat flour plus cellulose (control), with a one-week washout period between each intervention. At the same time, an oral glucose tolerance test was administered. In addition to plasma phytochemical concentrations, glucose and insulin responses, biomarkers of antioxidant activity, lipid peroxidation, inflammation, and vascular remodeling were determined over a 24-h period. There was no significant effect on acute bioavailability or pharmacokinetics of major phytochemicals. Administered concurrently with a glucose bolus, the source of whole grains did not attenuate the post-prandial response of markers of glucoregulation and insulin sensitivity, inflammation, nor vascular remodeling compared to the refined grain control. No significant differences were observed in the bioavailability or postprandial effects between whole-oat and whole-barley compared to a refined wheat control when administered with a glucose challenge. These null results may be due, in part, to the inclusion criteria for the subjects, dose of the whole grains, and concurrent acute administration of the whole grains with the glucose bolus.


Assuntos
Avena/química , Farinha , Hordeum/química , Compostos Fitoquímicos/farmacocinética , Período Pós-Prandial/efeitos dos fármacos , Adulto , Idoso , Análise de Variância , Área Sob a Curva , Disponibilidade Biológica , Glicemia/análise , Estudos Cross-Over , Método Duplo-Cego , Feminino , Glucose/administração & dosagem , Teste de Tolerância a Glucose , Voluntários Saudáveis , Humanos , Insulina/sangue , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Edulcorantes/administração & dosagem , Triticum/química
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