Cereal Fiber Intake Research Articles

Dietary fibre intake and risks of cancers of the colon and rectum in the European prospective investigation into cancer and nutrition (EPIC).

BackgroundEarlier analyses within the EPIC study showed that dietary fibre intake was inversely associated with colorectal cancer risk, but results from some large cohort studies do not support this finding. We explored whether the association remained after longer follow-up with a near threefold increase in colorectal cancer cases, and if the association varied by gender and tumour location.Methodology/Principal FindingsAfter a mean follow-up of 11.0 years, 4,517 incident cases of colorectal cancer were documented. Total, cereal, fruit, and vegetable fibre intakes were estimated from dietary questionnaires at baseline. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models stratified by age, sex, and centre, and adjusted for total energy intake, body mass index, physical activity, smoking, education, menopausal status, hormone replacement therapy, oral contraceptive use, and intakes of alcohol, folate, red and processed meats, and calcium. After multivariable adjustments, total dietary fibre was inversely associated with colorectal cancer (HR per 10 g/day increase in fibre 0.87, 95% CI: 0.79–0.96). Similar linear associations were observed for colon and rectal cancers. The association between total dietary fibre and risk of colorectal cancer risk did not differ by age, sex, or anthropometric, lifestyle, and dietary variables. Fibre from cereals and fibre from fruit and vegetables were similarly associated with colon cancer; but for rectal cancer, the inverse association was only evident for fibre from cereals.Conclusions/SignificanceOur results strengthen the evidence for the role of high dietary fibre intake in colorectal cancer prevention.

Dietary fibre intake and ischaemic heart disease mortality: the European Prospective Investigation into Cancer and Nutrition-Heart study

Evidence from prospective studies is consistent in showing an inverse association between dietary fibre intake and risk of ischaemic heart disease (IHD), but whether dietary fibre from various food sources differ in their effect on IHD risk is less clear. The objective of this study was to assess the associations of total and food sources of dietary fibre with IHD mortality in the European Prospective Investigation into Cancer and Nutrition-Heart study. Participants were 306,331 men and women from eight European countries. Dietary fibre intake was assessed using centre or country-specific diet questionnaires and calibrated using a 24-h diet recall. After an average follow-up of 11.5 years, there were 2381 IHD deaths among participants without cardiovascular disease at baseline. The calibrated intake of dietary fibre was inversely related with IHD mortality; each 10 g/day was associated with a 15% lower risk (relative risk (RR) 0.85; 95% confidence interval (CI): 0.73-0.99, P=0.031). There was no difference in the associations of the individual food sources of dietary fibre with the risk of IHD mortality; RR for each 5 g/day higher cereal fibre intake was 0.91 (CI: 0.82-1.01), RR for each 2.5 g/day fruit fibre intake was 0.94 (CI: 0.88-1.01) and RR for each 2.5 g/day vegetable fibre intake was 0.90 (95% CI: 0.76-1.07). A higher consumption of dietary fibre is associated with a lower risk of fatal IHD with no clear difference in the association with IHD for fibre from cereals, fruits or vegetables.

Alkylresorcinol Metabolite Concentrations in Spot Urine Samples Correlated with Whole Grain and Cereal Fiber Intake but Showed Low to Modest Reproducibility over One to Three Years in U.S. Women1–3

AbstractTwo alkylresorcinol (AR) metabolites, 3, 5-dihydroxybenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA), in urine have been suggested as biomarkers of whole grain (WG) and cereal fiber intake but the long-term reproducibility and correlation with habitual intake has not been determined. Therefore, we evaluated the long-term reproducibility of AR metabolites in spot urine samples and investigated their correlation with habitual WG and cereal fiber intake in U.S. women. AR metabolites were analyzed in 104 women participating in the Nurses' Health Study II and WG and fiber intakes were assessed using a FFQ. Long-term reproducibility was assessed by calculating the intra-class correlation coefficients (ICC) using samples taken 1–3 y (mean 1.8 y) apart. The observed Spearman correlation coefficients (rs) and rs adjusted for within-participant variation in the biomarker were calculated between WG and fiber intake and biomarkers. The long-term reproducibility was poor for DHBA [ICC = 0.17 (95% CI: 0.05, 0.43)] and modest for DHPPA [ICC = 0.31 (95% CI: 0.17, 0.51)]. The correlation between WG intake in 1995 and DHPPA measured 2 y later was 0.37 (P < 0.0001); the adjusted correlation was 0.60 (95% CI: 0.37, 0.76). Cereal fiber and WG intake were similarly correlated to the biomarkers. DHPPA in spot urine samples reflected WG intake despite relatively low intake of food sources of AR. The poor to modest reproducibility may limit the use of single measurements of these biomarkers in cohort studies in the US, where WG intake is relatively low and has changed over time. But DHPPA in repeated samples may be useful for validating WG intake and assessing compliance in WG intervention studies.

Alkylresorcinol metabolites in urine correlate with the intake of whole grains and cereal fibre in free-living Swedish adults

Alkylresorcinols (AR) have been established as short/medium-term biomarkers for whole grain (WG) wheat and rye intake; and AR metabolites, 3,5-dihydroxybenzoic acid and 3-(3,5-dihydroxyphenyl)-propanoic acid, have been suggested as complementary biomarkers to AR. The present study examined the medium-term reproducibility and relative validity of urinary AR metabolites as biomarkers for WG and cereal fibre intake. A total of sixty-six free-living Swedes completed 3 d weighed food records and provided single 24 h urine collections and morning urine spot samples on two occasions, 2-3 months apart. The medium-term reproducibility of urinary AR metabolites was moderate when assessed in 24 h collections and lower in creatinine (CR)-adjusted morning urine. Mean AR metabolite 24 h excretions correlated well with total WG (r(s) 0·31-0·52, P < 0·05) and cereal fibre (r(s) 0·46-0·58, P < 0·001) intake on both occasions. As expected, correlations with WG (r(s) 0·28-0·38, P < 0·05) and cereal fibre (r(s) 0·35-0·42, P < 0·01) were weaker for mean CR-adjusted AR metabolite concentrations in spot samples of morning urine, although the adjusted concentrations correlated well with 24 h urinary excretion (r(s) 0·69-0·73, P < 0·001). Adjustment for intra-individual variations substantially improved the correlations between intake and excretion. These findings suggest that urinary AR metabolites can successfully reflect the medium-term intake of WG and cereal fibre when adjusted for intra-individual variation in this population, where rye was the major contributor to high WG intake. The performance of urinary AR metabolites as medium-term biomarkers appears to be comparable to that of fasting plasma AR concentration in this population.

Whole Grains, Legumes, and Health

The consumption of whole grains and legumes is recommended by public health agencies around the world. The recommendation to consume legumes is based on them being a good source of protein, fiber, and several micronutrients including iron and zinc. However, legumes tend to be consumed infrequently by many people in industrialized countries. Dietary interventions with legumes have yielded mixed results on health outcomes, and there may be reluctance by some people to increase the amount of legumes in their diets due to unfamiliarity with the food. The recommendations for whole grains are based on purported health benefits of consuming whole grain over refined grain products. In comparison with their refined counterparts, whole grain foods tend to be higher in phytochemicals and fiber, and in several micronutrients including some of the B vitamins, magnesium, and selenium. Based on subjective dietary intake data, observational studies are reasonably consistent in their findings that higher cereal fiber and magnesium intakes are associated with lower risk of type 2 diabetes and cardiovascular disease. An objective marker of whole-grain intake would be useful, and in this regard, alkylresorcinols, compounds present in the bran particularly of wheat and rye, can be measured in biological fluids as potential biomarkers of wheat and rye intake. Despite the recommendations, interventions with whole-grain foods have produced mixed results on health markers. One factor contributing to the variability in outcomes may be grain structure. Intact grain structure distinguishes “whole grain” from “whole meal,” a process in which the whole grains have been ground. The starch contained in an entirely or partially intact grain is surrounded by the fibrous seed coat. Chewing helps to release the starch from within the seed coat; however, not all of the starch will be released, and access by digestive enzymes will be hindered. This hindrance is often regarded as a good quality as it slows starch digestion and glucose absorption, aiding blood glucose control. Another factor in starch digestion is the type of fiber. Some grain fibers are water soluble and highly fermentable, and form viscous gels. The formation of the gels also slows down starch digestion and glucose absorption. A third factor associated with improved blood glucose control is the “subsequent meal effect,” a phenomenon in which the benefit of slowly absorbed carbohydrate on blood glucose at one meal is extended to the meal following. Thus, the recommendations to consume whole grain foods are supported by mechanistic plausibility, whilst the variability in outcomes of whole-grain and legume intervention studies may be related to differences in study design and compliance. This special issue of the Journal of Nutrition and Metabolism explores some of the issues regarding the consumption of whole grains and legumes on health outcomes. It comprises three review and two research articles. Included is a comprehensive review of studies describing the “subsequent meal effect” in which mechanisms for the effect are discussed and research challenges suggested. The status of alkylresorcinols as biomarkers of whole-grain intake is presented that includes suggestions for further validation work and recommendations on how this might be achieved. The health benefits of beta-glucan, a fiber found in oat and barley bran, are reviewed including discussion of its effect when consumed as a component of the whole grain or as an extracted product. Mechanisms of action and challenges in the use of beta-glucans are discussed. The effect on postprandial blood glucose of incorporating whole grains into bread is reported with comparisons made among sprouted-grain, sourdough, and mixed grain breads in a group of overweight and obese men. At the other end of the nutritional spectrum, the effects of using locally grown grains and legumes as a porridge base with which to feed undernourished children are presented. General recommendations to consume whole-grain and legume foods appear to be well founded although there is much work to be done to identify grain/legume types, components, and intakes consistent with well-being among people of varying demographics and states of health. We hope that topics raised in this special issue lead to further research aimed at advancing our knowledge pertaining to whole-grain and legume consumption leading to strong evidence-based intake recommendations. Bernard Venn Frank Thies Carol O'Niel

Acculturation and Sociocultural Influences on Dietary Intake and Health Status among Puerto Rican Adults in Massachusetts

Background Previous studies have shown the negative consequences of acculturation on lifestyle factors, health status, and dietary intake of Hispanic immigrants in the United States. Despite prevalent type 2 diabetes and low socioeconomic status among Puerto Rican adults living on the US mainland, little is known about acculturation in this group. Objective We investigated associations among acculturation, lifestyle characteristics, health status, and carbohydrate nutrition in Puerto Rican adults. A secondary objective was to investigate possible confounding and/or effect modification on these associations by socioeconomic status. Design Cross-sectional data from the Boston Puerto Rican Health Study, which included 1,219 Puerto Ricans in the Boston area, aged 45 to 75 years. Statistical analyses Characteristics were compared using analysis of covariance, linear trend, and Pearson's χ 2 tests across quartiles of acculturation. Tests for interaction by poverty status were conducted. Proportional contributions of foods to intake of total carbohydrate and fiber were assessed using SAS RANK (version 9.1.3, 2002-2003, SAS Institute, Cary, NC). Results Levels of acculturation were low, despite young age at first arrival to the US mainland (25.4±12.3 years) and long length of stay (34.2±12.2 years). Greater English language use was associated with higher socioeconomic status, alcohol consumption, physical activity, better perceived health, and less central obesity. Acculturation was associated with lower legume fiber and greater cereal fiber intake. Among those above the poverty threshold, acculturation was associated with lower dietary glycemic index and starch intake, and greater fruit and nonstarchy vegetable intake. Conclusions In contrast to studies with Mexican Americans, the association of acculturation with dietary quality in these Puerto Rican adults was mixed, but tended toward better carbohydrate quality. Dietary recommendations should include maintenance of traditional, healthful dietary practices, including consumption of legumes, but also reduction in refined grains, and greater inclusion of fruit, nonstarchy vegetables, and whole grains. Interventions to improve access to better quality carbohydrate sources are necessary for this group disproportionately affected by diabetes.

Cereal fiber and coronary heart disease: a comparison of modeling approaches for repeated dietary measurements, intermediate outcomes, and long follow-up

The appropriate manner of incorporating incident angina, coronary artery bypass surgery (CABG), percutaneous coronary intervention (PCI), diabetes, hypertension, and hypercholesterolemia, which may be both intermediate events and time-dependent confounders, into analyses of diet and coronary heart disease (CHD) is not clear. Using data from 72,266 women in the Nurses' Health Study between 1984 and 2006, the authors examined the relation between report of intermediate events and change in cereal fiber intake and used different proportional hazards models to evaluate the association between cereal fiber and CHD. Cereal fiber intake increased significantly among participants who reported hypercholesterolemia (0.42g/day; 95% CI: 0.34, 0.51g/day) and diabetes (0.07g/day with each additional 2-year increment; 95% CI: 0.01, 0.13g/day). However, angina, CABG/PCI, and hypertension were not associated with a change in cereal fiber intake and thus were not important time-dependent confounders. Cereal fiber intake was inversely associated with risk of CHD in all proportional hazards models, but results varied modestly depending on the approach used to incorporate multiple measures of diet. Because stopping the updating of dietary variables when an intermediate event is diagnosed may lead to misclassification, future analyses should consider updating diet even after these diagnoses to best represent long-term intake. To best evaluate associations with incidence of disease, considerations should include the temporal trends in diet, changes in intake following intermediate events, and latency patterns. Sensitivity analyses can also be useful.

Intake of dietary fiber, especially from cereal foods, is associated with lower incidence of colon cancer in the HELGA cohort

The role of dietary fiber on the risk of colon and rectal cancer has been investigated in numerous studies, but findings have been inconsistent. The purpose of this study was to examine associations between intake of dietary fiber and risk of incident colon (including distal and proximal colon) and rectal cancer in the prospective Scandinavian HELGA cohort and to determine if fiber source (vegetables, fruits, potatoes, cereals) impacted the association. We included 1,168 incident cases (691 colon, 477 rectal cancer), diagnosed during a median of 11.3 years, among 108,081 cohort members. Sex-specific incidence rate ratios (IRRs) of colon and rectal cancer were related to intake of total or specific fiber source using Cox proportional hazards models. For men, an inverse association was observed between intake of total fiber and the risk of colon cancer per an incremental increase of 10 g day(-1) , IRR (95% CI): 0.74 (0.64-0.86). Intake of cereal fiber per 2 g day(-1) was associated with an IRR of 0.94 (0.91-0.98), which was also seen for intake of cereal fiber from foods with high fiber content (≥ 5 g per 100 g product), where the IRR per 2 g day(-1) was 0.94 (0.90-0.98). In women, intake of cereal fiber per 2 g day(-1) was also associated with lower risk of colon cancer, 0.97 (0.93-1.00). No clear associations were seen for rectal cancer. Our data indicate a protective role of total and cereal fiber intake, particularly from cereal foods with high fiber content, in the prevention of colon cancer.

Plasma Alkylresorcinol Concentrations Correlate with Whole Grain Wheat and Rye Intake and Show Moderate Reproducibility over a 2- to 3-Month Period in Free-Living Swedish Adults

AbstractPlasma alkylresorcinols (AR) are useful as dietary biomarkers of wheat and rye whole grain (WG) during interventions but need to be validated in free-living populations. This study estimated the medium-term reproducibility and relative validity of plasma AR as biomarkers of WG and cereal fiber intake. Seventy-two Swedish adults kept 3-d weighed food records on 2 occasions 23 mo apart. Of these men and women, 51 provided a fasting blood sample at the end of each occasion. In addition, 18 participants provided 3 fasting and 3 nonfasting samples for 3 consecutive days on the first and second occasions, respectively. Dietary and blood variables did not differ between the 2 occasions. Nonfasting plasma total AR concentration [210 nmol/L (95% CI: 140, 314)] was higher than fasting [99 nmol/L (95% CI: 72, 137)] (P < 0.0001). Mean WG intake was 70 61 g/d (41% from rye) and the intra-class correlation coefficient was 0.44 (95% CI: 0.26, 0.63) for total WG intake and 0.47 (95% CI: 0.27, 0.67) for the fasting plasma total AR concentration, suggesting moderate reproducibility. Fasting plasma total AR moderately correlated with WG rye + wheat (rs = 0.53; P < 0.001) and cereal fiber intake (rs = 0.32; P < 0.05) when using mean values from both occasions. This suggests that plasma AR concentration in fasting samples can be used as a biomarker of rye + wheat WG intake in free-living populations with a high and consistent WG intake.

Magnesium Intake and Risk of Type 2 Diabetes

OBJECTIVEEmerging epidemiological evidence suggests that higher magnesium intake may reduce diabetes incidence. We aimed to examine the association between magnesium intake and risk of type 2 diabetes by conducting a meta-analysis of prospective cohort studies.RESEARCH DESIGN AND METHODSWe conducted a PubMed database search through January 2011 to identify prospective cohort studies of magnesium intake and risk of type 2 diabetes. Reference lists of retrieved articles were also reviewed. A random-effects model was used to compute the summary risk estimates.RESULTSMeta-analysis of 13 prospective cohort studies involving 536,318 participants and 24,516 cases detected a significant inverse association between magnesium intake and risk of type 2 diabetes (relative risk [RR] 0.78 [95% CI 0.73–0.84]). This association was not substantially modified by geographic region, follow-up length, sex, or family history of type 2 diabetes. A significant inverse association was observed in overweight (BMI ≥25 kg/m2) but not in normal-weight individuals (BMI <25 kg/m2), although test for interaction was not statistically significant (Pinteraction = 0.13). In the dose-response analysis, the summary RR of type 2 diabetes for every 100 mg/day increment in magnesium intake was 0.86 (95% CI 0.82–0.89). Sensitivity analyses restricted to studies with adjustment for cereal fiber intake yielded similar results. Little evidence of publication bias was observed.CONCLUSIONSThis meta-analysis provides further evidence supporting that magnesium intake is significantly inversely associated with risk of type 2 diabetes in a dose-response manner.

Effect of dietary fiber intake on breast cancer risk according to estrogen and progesterone receptor status

There is few data on the association between dietary fiber intake and estrogen receptor (ER)/progesterone receptor (PR)-defined breast cancer risk. The present study aimed to investigate the associations between total dietary fiber and dietary fiber fractions intake and breast cancer risk by ER and PR status in a hospital-based case-control study among Chinese women. Four hundred and thirty-eight cases with primary breast cancer were consecutively recruited from June 2007 to August 2008 and frequency matched to 438 controls by age (5-year interval) and residence (rural/urban). A validated food frequency questionnaire was used to assess the dietary intake through a face-to-face interview. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence interval (CI) after adjusting for various potential confounders. A statistically significant inverse association was found between total dietary fiber and fiber fractions intake and breast cancer risk. The adjusted ORs (95% CIs) for the highest versus the lowest quartile of intake were 0.31 (0.20-0.47) for total dietary fiber, 0.73 (0.48-1.11) for soy fiber, 0.48 (0.22-0.97) for vegetable fiber and 0.54 (0.31-0.92) for fruit fiber. No association was observed for cereal fiber intake and risk. An inverse association between dietary fiber intake and breast cancer risk was observed in ER+, ER-, PR+, ER+PR+ and ER-PR+ tumors. Our results suggest that consumption of total dietary fiber and fiber from vegetable and fruit was inversely associated with breast cancer risk. These inverse associations were more prominent in some subtypes of ER and PR breast cancers.

Diets and Hormonal Levels in Postmenopausal Women With or Without Breast Cancer

The role of diet in breast cancer (BC) risk is unclear. Fiber could reduce BC risk, through the enterohepatic circulation of estrogens. We examined the relationship between diet and sex hormones in postmenopausal women with or without BC. Thirty-one postmenopausal women (10 omnivores, 11 vegetarians, and 10 BC omnivores) were recruited. Dietary records (5 days) and hormone levels (3 days) were evaluated on 4 occasions over 1 yr. Vegetarians showed a lower fat/fiber ratio, a higher intake of total and cereal fiber (g/d)/body weight (kg), a significantly lower level of plasma estrone-sulfate, estradiol, free-estradiol, free-testosterone, and ring D oxygenated estrogens, and a significantly higher level of sex-hormone-binding-globulin than BC subjects. Fiber was consumed in slightly larger amounts by omnivores than by BC subjects. Omnivores had significantly lower plasma testosterone and estrone-sulfate but higher sex-hormone-binding-globulin than BC subjects. No difference was found for the urinary 16-oxygenated estrogens. However, the 2-MeO-E1/2-OH-E1 ratio was significantly lower in omnivores than in BC group. This ratio is positively associated with the fat/fiber ratio. In conclusion, testosterone may contribute to causing alterations in the levels of catechol estrogens and 16-oxygenated estrogens. The fat/fiber ratio appears to be useful in evaluating dietary effects on estrogen metabolism.

A comparison of the literature on the association between intakes of bran, cereal fiber, and whole grains and risk and biomarkers of heart disease

A literature review was conducted on the association between intakes of cereal fiber, bran, and whole grains, and risk reduction of heart disease. The purpose of this review was to compare health‐related benefits from bran/cereal fiber and whole grains from observational studies. MEDLINE was used to search the scientific literature for relevant studies. Other studies were identified by bibliographic searches for relevant articles. Intakes of cereal fiber, bran, mixtures of whole grains and bran, and whole grains are inversely associated with risk of heart disease and/or heart disease biomarkers. A majority of prospective studies comparing bran/cereal fiber and whole grains for risk of heart disease showed that bran or cereal fiber intake was more protective than whole grain intake. Most studies included cereals containing at least 25% of whole grain or bran content by weight in the whole grain food category. In the scientific literature, whole grain effects have been confounded with those from bran. Limited studies investigated the association between whole grain as defined by FDA (excludes ≥25% bran and bran cereals) and heart disease risk and/or biomarkers of heart disease. The data indicate that bran and cereal fiber play a role in the health benefits gained from whole grains. Implications of these findings will be discussed.Funded by a grant from the Kellogg company.

Carbohydrate intake, blood lipids, and diabetes in the Boston Puerto Rican Health Study

Puerto Rican adults have prevalent type 2 diabetes (T2D) and dyslipidemia, possibly contributed to by high carbohydrate intake, but this remains understudied. We examined cross-sectional relationships among carbohydrate intake, glycemic index (GI), glycemic load (GL) and fiber with blood lipids in Puerto Ricans aged 45–75 y, with (n=480) and without (n=733) T2D. Dietary intake was compared by T2D status using Pearson's chi-square test, ANCOVA, and tests for linear trend. Consistent with recommendations, individuals with T2D had lower intake of total carbohydrate, GL, and total sugars (all P<0.0001), and greater intake of cereal fiber (P<0.001), relative to those without T2D, which was reflected in lower consumption of sugar (P<0.0001), soft drinks (P<0.0001), and fruit juice (P=0.02), and greater consumption of oatmeal (P<0.001). Low HDL-C was prevalent in both groups (65 vs. 56%, P=0.004, respectively). Higher intakes of carbohydrate and GL were inversely associated with HDL-C (P-trend<0.0001), but not with triacylglycerols, in those without T2D. An inverse association between dietary fiber and HDL-C appeared to be confounded by carbohydrate intake, likely from frequent consumption of legumes with white rice, a refined carbohydrate food. Puerto Rican adults with T2D showed likely dietary modification. Improvement in carbohydrate quality should be emphasized to improve HDL-C status in this population.

Letter by Thornton Regarding Article, “Whole-Grain, Cereal Fiber, Bran, and Germ Intake and the Risks of All-Cause and Cardiovascular Disease-Specific Mortality Among Women With Type 2 Diabetes Mellitus”

To the Editor: I was very interested to read the recent article by He and colleagues1 published in Circulation showing the beneficial effects of diets containing increased fiber (whole grain and bran) on cardiovascular disease-specific mortality among women with type 2 diabetes mellitus. At first glance, this is rather logical, and follows previous studies of the same group as well as by others.2 However, there appears to be one aspect overlooked slightly in this report …

Response to Letter Regarding Article, “Whole-Grain, Cereal Fiber, Bran, and Germ Intake and the Risks of All-Cause and Cardiovascular Disease-Specific Mortality Among Women With Type 2 Diabetes Mellitus”

We appreciate the interest of Dr Thornton in our analyses on the intakes of whole grain and its components in relation to all-cause and cardiovascular disease (CVD)-specific mortality among women with type 2 diabetes.1 In his letter, Dr Thornton noted that high fluid intake might decrease insulin resistance, improve cardiovascular regulation, and lead to decreased cardiovascular mortality. One potential mechanism is that increasing fluid intake increases blood volume, which in turn lowers plasma levels of …

Carbohydrate Nutrition Is Associated with the 5-Year Incidence of Chronic Kidney Disease1–3

It has been shown that dietary glycemic index (GI) and fiber could have a role in the development of chronic diseases; however, the link between carbohydrate nutrition and development of chronic kidney disease (CKD) is unclear. We aimed to determine whether cross-sectional and longitudinal associations exist between carbohydrate nutrition (mean dietary GI, dietary intakes of carbohydrate, sugar, starch, and fiber) and CKD. Data included 2600 Blue Mountains Eye Study (1997–1999) participants aged ≥50 y. Baseline biochemistry including serum creatinine was measured. Moderate CKD was defined as estimated glomerular filtration rate (eGFR) < 60 mL·min-1·1.73 m-2. Dietary data were collected in a semiquantitative FFQ. Cross-sectionally, participants in the 4th quartile of mean dietary GI intake compared with those in the first quartile (reference) had a 55% increased likelihood of having eGFR < 60 mL·min-1·1.73 m-2 [multivariable-adjusted OR = 1.55 (95% CI = 1.07–2.26); P-trend = 0.01]. After multivariable adjustment, participants in the 4th quartile of dietary cereal fiber intake compared with those in the first quartile (reference) had a 50% reduced risk of incident moderate CKD (P-trend = 0.03). Higher baseline consumption of energy-dense, nutrient-poor sources of carbohydrate (e.g. cookies) yielded a 3-fold higher risk of incident CKD (P-trend = 0.01). In summary, we observed a novel link between high cereal fiber intake and reduced incidence of moderate CKD and this was supported by the cross-sectional association with dietary GI. Conversely, our data suggest that higher intake of energy-dense, nutrient-poor sources of carbohydrate, potentially through acute hyperglycemia, could impair renal function.

Health benefits of cereal fibre: a review of clinical trials.

Cereal fibre and whole-grain intakes have been consistently associated in the epidemiological literature with reduced mortality and risk of chronic disease including obesity, CVD and type 2 diabetes. The present review focuses on intervention trials with three primary aims: (1) understanding the mechanisms through which fibre consumption improves health (for example, examination of intermediate endpoints reflecting improved lipid, glucose and energy metabolism); (2) close evaluation of qualitative factors which modify fibre's effectiveness including physiochemical properties (for example, solubility, fermentability and viscosity), fibre extract molecular weight, fibre particle size and botanical structure of the fibre source grain; and (3) identification of areas in which additional research is needed. The first two aims typify the goals of nutrition research, in that improved understanding of the specific factors which determine fibre's health benefits has critical implications for dietary recommendations as well as improving understanding of physiological mechanisms. The third aim acknowledges the substantial gap between recommended and actual fibre intakes in many developed countries including the USA and the UK. In recognition of this deficit in total fibre intake, food manufacturing processes increasingly utilise fibre extracts and concentrates as food additives. However, whether fibre extracts provide similar health benefits to the fibre supplied in the constituents of whole grain is largely unexplored. The relative benefits of fibre extracts compared with whole-grain fibre sources therefore represent a critical area in which additional research is needed.

Risk Factors for Mortality in the Nurses’ Health Study: A Competing Risks Analysis

Few studies have examined multiple risk factors for mortality or formally compared their associations across specific causes of death. The authors used competing risks survival analysis to evaluate associations of lifestyle and dietary factors with all-cause and cause-specific mortality among 50,112 participants in the Nurses' Health Study. There were 4,893 deaths between 1986 and 2004: 1,026 from cardiovascular disease, 931 from smoking-related cancers, 1,430 from cancers not related to smoking, and 1,506 from all other causes. Age, body mass index at age 18 years, weight change, height, current smoking and pack-years of smoking, glycemic load, cholesterol intake, systolic blood pressure and use of blood pressure medications, diabetes, parental myocardial infarction before age 60 years, and time since menopause were directly related to all-cause mortality, whereas there were inverse associations for physical activity and intakes of nuts, polyunsaturated fat, and cereal fiber. Moderate alcohol consumption was associated with decreased mortality. A model that incorporated differences in the associations of some risk factors with specific causes of death had a significantly better fit compared with a model in which all risk factors had common associations across all causes. In the future, this new model may be used to identify individuals at increased risk of mortality.

Plasma and Urinary Alkylresorcinol Metabolites as Potential Biomarkers of Breast Cancer Risk in Finnish Women: A Pilot Study

Alkylresorcinols (ARs) are shown to be good biomarkers of consumption of rye and whole-grain wheat products in man. The aim of this pilot study was to investigate AR metabolites as potential biomarkers of breast cancer (BC) risk in Finnish women since intake of cereal fiber and its components has been proposed to reduce this risk through an effect on the enterohepatic circulation of estrogens. This was a cross-sectional and observational pilot study. A total of 20 omnivores, 20 vegetarians, and 16 BC women (6–12 mo after operation) were investigated on 2 occasions 6 mo apart. Dietary intake (5-days record), plasma/urinary AR metabolites [3,5-dihydroxybenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA)] and plasma/urinary enterolactone were measured. The groups were compared using nonparametric tests. We observed that plasma DHBA (P = 0.007; P = 0.03), plasma DHPPA (P = 0.02; P = 0.01), urinary DHBA (P = 0.001; P = 0.003), urinary DHPPA (P = 0.001; P = 0.001), and cereal fiber intake (P = 0.007; P = 0.003) were significantly lower in the BC group compared to the vegetarian and omnivore groups, respectively. Based on measurements of AR metabolites in urine and in plasma, whole-grain rye and wheat cereal fiber intake is low in BC subjects. Thus, urinary and plasma AR metabolites may be used as potential biomarkers of BC risk in women. This novel approach will likely also facilitate studies of associations between rye and whole-grain wheat cereal fiber intake and other diseases. Our findings should, however, be confirmed with larger subject populations.