Filling America's fiber intake gap: summary of a roundtable to probe realistic solutions with a focus on grain-based foods

Perspective: Closing the Dietary Fiber Gap: An Ancient Solution for a 21st Century Problem

An important gap exists between the daily amounts of fiber recommended in the human diet (28-42 g/d) and that which is actually consumed (median intake, 12-14 g/d). In fact, <5% of Americans meet the recommended intake for dietary fiber, and the magnitude of the gap is large, approximately a 50-70% shortfall. Because considerable evidence indicates that dietary fiber affects normal physiologic function and the onset of chronic diseases and their progression, the fiber gap represents an opportune target at which dietary interventions can be directed. This perspective considers whether a scientific basis exists for the current lack of emphasis on pulse crops, that is, grain legumes (common bean, chickpea, lentils, and garden pea) as a concentrated, inexpensive, and widely available source of dietary fiber. Attention is directed to this topic because the fiber gap has existed for decades with little improvement despite nutrition labeling, consumer education about the value of whole-grain cereal crop-based products, and the introduction of many fiber-enriched foods. The time is long overdue to identify additional approaches that have the potential to close the dietary fiber gap. To this end, the potential role of pulse crops in remediating this gap is examined.

Plant-Based Diets: A Physician's Guide

Because of the ever-increasing body of evidence in support of the health advantages of plant-based nutrition, there is a need for guidance on implementing its practice. This article provides physicians and other health care practitioners an overview of the myriad benefits of a plant-based diet as well as details on how best to achieve a well-balanced, nutrient-dense meal plan. It also defines notable nutrient sources, describes how to get started, and offers suggestions on how health care practitioners can encourage their patients to achieve goals, adhere to the plan, and experience success.

Effects of high-sugar and high-fiber meals on physical activity behaviors in Latino and African American adolescents

OBJECTIVE

This crossover experimental study examined the acute effects of high-sugar/low-fiber (HSLF) vs. low-sugar/high-fiber (LSHF) meals on sedentary behavior (SB) and light-plus activity (L+) in minority adolescents with overweight and obesity.

METHODS

87 Latino and African American adolescents (mean age = 16.3 ± 1.2 years, mean BMI z-score = 2.02 ± 0.52, 56.8% Latino, 51.1% male) underwent two experimental meal conditions during which they consumed HSLF or LSHF meals. Physical activity and SB were measured using accelerometers, and blood glucose and insulin were collected every 30 minutes over 5 hours. Mixed models were used to examine the temporal trends of SB and L+, whether the temporal trends of SB and L+ differed by meal condition, and the influence of blood glucose and insulin on the activity behaviors.

RESULTS

SB and L+ fluctuated over time during the HSLF condition but were stable during the LSHF condition. SB and L+ were influenced by the blood glucose response to the HSLF meals. Insulin did not influence SB or L+ in either meal condition.

CONCLUSIONS

Sugar and fiber content of meals can have differing acute impacts on activity behaviors in minority adolescents with overweight and obesity, possibly due to differing metabolic responses.

Low demanding parental feeding style is associated with low consumption of whole grains among children of recent immigrants

We explored the influence of immigrant mothers feeding style on their children's fruit, vegetable and whole grain intake and how this relationship differed by mother's time in the U.S. Baseline data were collected on mother-child (3-12 yrs) dyads enrolled in Live Well (n = 313), a community-based, participatory, randomized controlled lifestyle intervention (2008-2013). Socio-demographics, years of residence in the U.S., behavioral data, and responses to the Caregiver's Feeding Styles Questionnaire (CFSQ) were obtained from the mother. Measured heights and weights were obtained for both mother and child. Child dietary intake was assessed using the Block Food Screener. Separate multiple linear regression models were run, adjusting for child and mother covariates. Interactions between feeding styles and years in the U.S. (<5 and ≥ 5 years), ethnicity, and child age were tested. Sixty-nine percent of mothers were overweight or obese, 46% of the children were overweight or obese. For mothers in the U.S. for<5 years, having a low demanding/high responsive style was associated with lower child intake of whole grains in adjusted models vs. a high demanding/high responsive style (p < 0.05). This was not seen for mothers in the U.S. for≥5 years. Thus, the influence of feeding style on dietary intake may change with length of time in the U.S. These hypotheses-generating findings call for future research to understand how broader socio-cultural factors influence the feeding dynamic among immigrants.

Ten-year trends in fiber and whole grain intakes and food sources for the United States population: National Health and Nutrition Examination Survey 2001-2010

Current U.S. dietary guidance includes recommendations to increase intakes of both dietary fiber and whole grain (WG). This study examines fiber and WG intakes, food sources and trends from 2001 to 2010 based on National Health and Nutrition Examination Survey (NHANES) data for children/adolescents (n = 14,973) and adults (n = 24,809). Mean fiber intake for children/adolescents was 13.2 (±0.1) g/day. Mean fiber intake for adults 19–50 years (y) was 16.1 (±0.2) g/day and for adults 51+ was 16.1 (±0.2) g/day. There were significant increases in fiber intake from 2001–2010 for children/adolescents and for adults 51+ y. Mean WG intake for children/adolescents was 0.52 (±0.01) oz eq/day. Mean WG intake for adults 19–50 y was 0.61 (±0.02) oz eq/day and for adults 51+ 0.86 (±0.02) oz eq/day. There were no significant changes in WG intake for any age group from 2001–2010. The main food groups contributing to dietary fiber intake for children/adolescents were vegetables (16.6%), grain mixtures (16.3%), other foods (15.8%) and fruits (11.3%). For adults 19+ y, the main sources of dietary fiber were vegetables (22.6%), other foods (14.3%), grain mixtures (12.0%) and fruits (11.1%). Major WG sources for children/adolescents included ready-to-eat cereals (RTEC) (31%), yeast breads/rolls (21%) and crackers and salty grain snacks (21%). The main sources of WG for adults 19+ were yeast breads/rolls (27%), RTEC (23%) and pastas/cooked cereals/rice (21%). Recommending cereals, breads and grain mixtures with higher contents of both dietary fiber and WG, along with consumer education, could increase intakes among the United States (U.S.) population.

Identifying practical solutions to meet America's fiber needs: proceedings from the Food & Fiber Summit

Fiber continues to be singled out as a nutrient of public health concern. Adequate intakes of fiber are associated with reduced risk for cardiovascular disease, cancer, diabetes, certain gastrointestinal disorders and obesity. Despite ongoing efforts to promote adequate fiber through increased vegetable, fruit and whole-grain intakes, average fiber consumption has remained flat at approximately half of the recommended daily amounts. Research indicates that consumers report increasingly attempting to add fiber-containing foods, but there is confusion around fiber in whole grains. The persistent and alarmingly low intakes of fiber prompted the “Food & Fiber Summit,” which assembled nutrition researchers, educators and communicators to explore fiber’s role in public health, current fiber consumption trends and consumer awareness data with the objective of generating opportunities and solutions to help close the fiber gap. The summit outcomes highlight the need to address consumer confusion and improve the understanding of sources of fiber, to recognize the benefits of various types of fibers and to influence future dietary guidance to provide prominence and clarity around meeting daily fiber recommendations through a variety of foods and fiber types. Potential opportunities to increase fiber intake were identified, with emphasis on meal occasions and food categories that offer practical solutions for closing the fiber gap.

Bran fibers and satiety in women who do not exhibit restrained eating

BACKGROUND

Foods that are high in dietary fiber can promote satiety, but previous studies report conflicting results.

OBJECTIVE

The objective was to determine differences in satiety response to three conditions (10 g oat bran, 10 g barley bran and a low fiber condition) consumed at dinner and breakfast. In addition, we compared energy intake at an ad libitum lunch after consumption of the breakfast bars.

DESIGN

Randomized, double-blind crossover study.

PARTICIPANTS/SETTING

42 normal weight women.

INTERVENTION

Women consumed a dinner food bar from one of the three conditions the evening before testing. On test mornings, fasted women consumed the corresponding breakfast food bar with their choice of coffee, tea or water. An ad libitum pizza lunch was served 4 hours after breakfast.

PRIMARY OUTCOMES

Visual analogue scales (VAS) were used to assess satiety at baseline, 15, 30, 45, 60, 90, 120, 180 and 240 minutes. Energy intake was assessed by an ad libitum pizza lunch (4 hours after breakfast) and 24-hour energy intake was measured by a food diary.

STATISTICAL ANALYSES

Treatments were compared using the mixed-effects linear models. Outcomes are reported as mean ± SEM.

RESULTS

There were no significant differences among conditions on any of the satiety scales and no significant differences among conditions in energy consumed at lunch or over 24 hours. The fiber bars were well tolerated and no significant differences were found for gastrointestinal tolerance.

CONCLUSIONS

Our results do not support an effect of bran fibers on satiety above a low fiber control. We acknowledge results of this study may be intricately tied to the choice of a single pizza lunch, as other ad libitum meal options could have resulted in different outcomes.

Use of sodium butyrate as an alternative to dietary fiber: effects on the embryonic development and anti-oxidative capacity of rats

In this study, we evaluated the effect of replacing dietary fiber with sodium butyrate on reproductive performance and antioxidant defense in a high fat diet during pregnancy by using a rat model. Eighty virgin female Sprague Dawley rats were fed one of four diets—(1) control diet (C group), (2) high fat + high fiber diet (HF group), (3) high-fat +5% sodium butyrate diet (SB group), and (4) HF diet + α-cyano-4-hydroxy cinnamic acid (CHC group)—intraperitoneally on days 8, 10, 12, 14, and 16 of gestation. SB and dietary fiber had similar effects on improving fetal number and reducing the abortion rate; however, the anti-oxidant capacity of maternal serum, placenta, and fetus was superior in the HF group than in the SB group. In comparison, CHC injection decreased reproductive performance and antioxidant defense. Both dietary fiber (DF) and SB supplementation had a major but different effect on the expression of anti-oxidant related genes and nutrient transporters genes. In summary, our data indicate that SB and DF showed similar effect on reproductive performance, but SB cannot completely replace the DF towards with respect to redox regulation in high-fat diet; and SB might influence offspring metabolism and health differently to DF.

Evaluation of yellow pea fibre supplementation on weight loss and the gut microbiota: a randomized controlled trial

BACKGROUND

Fibre intake among North Americans is currently less than half the recommended amount. Consumers are interested in food products that could promote weight loss and improve health. Consequently, evaluation of unique fibre sources with potential gut-mediated benefits for metabolic health warrants investigation. Our objective is to assess the effects of yellow pea fibre supplementation on weight loss and gut microbiota in an overweight and obese adult population.

METHODS/DESIGN

In a double blind, placebo controlled, parallel group study, overweight and obese (BMI = 25-38) adults will be randomized to either a 15 g/d yellow pea fibre supplemented group or isocaloric placebo group for 12 weeks (n = 30/group). The primary outcome measure is a change in body fat from baseline to 12 weeks. Secondary outcomes include glucose tolerance, appetite regulation, serum lipids and inflammatory markers. Anthropometric data (height, weight, BMI, and waist circumference) and food intake (by 3-day weighed food records) will be measured at baseline and every 4 weeks thereafter. Subjective ratings of appetite will be recorded by participants at home on a weekly basis using validated visual analogue scales. At week 0 and at the end of the study (week 12), an ad libitum lunch buffet protocol for objective food intake measures and dual-energy X-ray absorptiometry (DXA) scan for body composition will be completed. Participants will be instructed not to change their exercise habits during the 12 week study. Glucose and insulin will be measured during an oral glucose tolerance test at weeks 0 and 12. Levels of lipids and CRP will be measured and inflammatory markers (adiponectin, leptin, TNF-α, IL-6 and IL-8) in the serum will be quantified using Milliplex kits. Mechanisms related to changes in gut microbiota, serum and fecal water metabolomics will be assessed.

DISCUSSION

Globally the development of functional foods and functional food ingredients are critically needed to curb the rise in metabolic disease. This project will assess the potential of yellow pea fibre to improve weight control via gut-mediated changes in metabolic health in overweight and obese adults.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01719900) Registered October 23, 2012.

Diabetes in North America and the Caribbean: an update

The North America and Caribbean (NAC) Region faces a high burden of diabetes. In 2013, the number of children (aged 0-14 years) with type 1 diabetes was 108,600, with 16.7 new cases diagnosed per 100,000 children. Furthermore, there were 36,755,500 individuals with diabetes (mostly type 2 diabetes) in adults (20-79 years), and an additional 44,277,700 individuals had impaired glucose tolerance. The age-adjusted prevalence of diabetes in adults was 9.6%; the second highest among the seven Regions of the International Diabetes Federation. This estimate is expected to grow to 9.9% by 2035. There was some heterogeneity in the estimates within the Region with the age-adjusted prevalence for the USA estimated at 9.2%, 7.9% for Canada, 12.6% for Mexico, and 9.6% for the Caribbean islands. Mortality due to diabetes in the NAC Region is not limited to older age groups, with 37.6% of deaths occurring in people under the age of 60. The economic impact was also enormous, with healthcare expenditure due to diabetes estimated at 263.2 billion USD for 2013 - the highest of all IDF Regions. Diabetes threatens the public health and economies of countries in the NAC Region, and efforts in prevention and management must be intensified in order to surmount this growing problem.

Total dietary fiber intakes in the US population are related to whole grain consumption: results from the National Health and Nutrition Examination Survey 2009 to 2010

Whole grain (WG) foods have been shown to reduce chronic disease risk and overweight. Total dietary fiber is associated with WG and its health benefits. The purpose was to determine whether associations exist between WG intake (no-WG intake, 0 ounce equivalent [oz eq]; low, >0-<3 oz eq; high, ≥3 oz eq) and total dietary fiber intake among Americans 2 years and older. One-day food intake data from the US National Health and Nutrition Examination Survey 2009 to 2010 (n = 9042) showed that only 2.9% and 7.7% of children/adolescents (2-18 years) and adults (≥19 years) consumed at least 3 WG oz eq/d, respectively. For children/adolescents and adults, individuals in the high WG intake group were 59 and 76 times more likely to fall in the third fiber tertile, respectively, compared with those with no-WG intake. Total dietary fiber intake from food sources varied by WG intake group for children/adolescents and adults with more total dietary fiber consumed from ready-to-eat (RTE) and hot cereals and yeast breads/rolls in the high WG intake group compared with the no-WG intake group. Major WG sources for children/adolescents and adults included yeast bread/rolls (24% and 27%, respectively), RTE cereals (25% and 20%, respectively), and oatmeal (12% and 21%, respectively). Among those with the highest WG intake, WG RTE cereal with no added bran was the greatest contributor to total dietary fiber compared with other RTE cereal types. Whole grain foods make a substantial contribution to total dietary fiber intake and should be promoted to meet recommendations.

Developing a standard definition of whole-grain foods for dietary recommendations: summary report of a multidisciplinary expert roundtable discussion

Although the term "whole grain" is well defined, there has been no universal standard of what constitutes a "whole-grain food," creating challenges for researchers, the food industry, regulatory authorities, and consumers around the world. As part of the 2010 Dietary Guidelines for Americans, the U.S. Dietary Guidelines Technical Advisory Committee issued a call to action to develop definitions for whole-grain foods that could be universally accepted and applied to dietary recommendations and planning. The Committee's call to action, and the lack of a global whole-grain food definition, was the impetus for the Whole Grain Roundtable held 3-5 December 2012 in Chicago, Illinois. The objective was to develop a whole-grain food definition that is consistent with the quartet of needs of science, food product formulation, consumer behavior, and label education. The roundtable's expert panel represented a broad range of expertise from the United States and Europe, including epidemiology and dietary intervention researchers, consumer educators, government policy makers, and food and nutrition scientists from academia and the grain food industry. Taking into account the totality, quality, and consistency of available scientific evidence, the expert panel recommended that 8 g of whole grain/30 g serving (27 g/100 g), without a fiber requirement, be considered a minimum content of whole grains that is nutritionally meaningful and that a food providing at least 8 g of whole grains/30-g serving be defined as a whole-grain food. Having an established whole-grain food definition will encourage manufacturers to produce foods with meaningful amounts of whole grain, allow consistent product labeling and messaging, and empower consumers to readily identify whole-grain foods and achieve whole-grain dietary recommendations.

The future of recommendations on grain foods in dietary guidance

Grain foods serve as an important source of energy, essential nutrients, and sometimes fiber. Recognizing that fiber continues to be identified as a nutrient of public health priority, there is an urgent need to address the ongoing fiber intake deficit. The focus in dietary guidance on whole grains as a source of fiber from the grains food group has not improved levels of fiber consumption. Consumer confusion around whole grains and fiber, combined with the wide range of fiber amounts found in whole-grain-labeled products, suggests that the current recommendation to "make half your grains whole" may be oversimplified in its intent to support increased fiber intakes. Nutrition educators and policy makers need to bring the conversation back to balancing all grain food choices, including enriched grains, whole grains, bran-based grain foods, and other grain-based foods with fiber, with greater emphasis on differentiating grain foods by the fiber they deliver. Changes in labeling, policy recommendations, and consumer messages are needed to help make this happen.

Major cereal grain fibers and psyllium in relation to cardiovascular health

Numerous studies reveal the cardiovascular benefits of consuming dietary fiber and, especially, cereal fiber. Cereal fiber is associated with cardiovascular risk reduction through multiple mechanisms and consuming a variety of cereal fiber sources offers health benefits specific to the source. Certain cereal fibers have been studied more extensively than others and provide greater support for their incorporation into a healthful diet. β-glucan from oats or barley, or a combination of whole oats and barley, and soluble fiber from psyllium reduces the risk of coronary heart disease; inulin-type fructans added to foods and beverages may modestly decrease serum triacylglycerols; arabinoxylan and resistant starch may improve glycemic control. Individuals with low cereal fiber intake should increase their intake of whole grains in order to receive the benefits of whole grains in addition to fiber. For those adjusting to the texture and palatability of whole grains, turning to added-fiber products rich in β-glucan and psyllium may allow them to reach their fiber goals without increasing caloric intake.

Analysis of Average Daily Fiber Intake Among Ready-to-Eat Cereal Consumers

There is no minimum fiber requirement for on-pack whole-grain claims, yet consumers perceive products made with whole grains to provide at least a good source of fiber. To understand how this misperception may be fueling Americans’ fiber intake shortfall, this study investigated the impact on fiber intakes of ready-to-eat (RTE) cereal products with whole-grain claims. A 14-day eating frequency diary was collected from US free-living households over 3 years in the NPD Group’s National Eating Trends (NET) panel (n=10,708). Average daily fiber intake and sources were calculated from the types and frequency of food and beverages consumed at meals. T-tests were conducted on mean fiber intake at breakfast and daily to identify significant differences between all adults, adults consuming whole-grain RTE cereals with <3 g of fiber per serving, and adults consuming whole-grain RTE cereals with ≥3 g of fiber per serving. Adults eating whole-grain RTE cereals with ≥3 g of fiber per serving consumed 42% more fiber at breakfast and 14% more daily fiber than typical adults. Individuals choosing whole-grain RTE cereal with ≥3 g of fiber per serving consume significantly more fiber at breakfast and throughout the day relative to all adults and to adults eating whole-grain RTE cereals with <3 g of fiber per serving.

The interplay between fiber and the intestinal microbiome in the inflammatory response

Fiber intake is critical for optimal health. This review covers the anti-inflammatory roles of fibers using results from human epidemiological observations, clinical trials, and animal studies. Fiber has body weight-related anti-inflammatory activity. With its lower energy density, a diet high in fiber has been linked to lower body weight, alleviating obesity-induced chronic inflammation evidenced by reduced amounts of inflammatory markers in human and animal studies. Body weight-unrelated anti-inflammatory activity of fiber has also been extensively studied in animal models in which the type and amount of fiber intake can be closely monitored. Fermentable fructose-, glucose-, and galactose-based fibers as well as mixed fibers have shown systemic and local intestinal anti-inflammatory activities when plasma inflammatory markers and tissue inflammation were examined. Similar anti-inflammatory activities have also been demonstrated in some human studies that controlled total fiber intake. The anti-inflammatory activities of synbiotics (probiotics plus fiber) were reviewed as well, but there was no convincing evidence indicating higher efficacy of synbiotics compared with that of fiber alone. Adverse effects have not been observed with the amount of fiber intake or supplementation used in studies, although patients with Crohn's disease may be more sensitive to inulin intake. Several possible mechanisms that may mediate the body weight-unrelated anti-inflammatory activity of fibers are discussed based on the in vitro and in vivo evidence. Fermentable fibers are known to affect the intestinal microbiome. The immunomodulatory role of the intestinal microbiome and/or microbial metabolites could contribute to the systemic and local anti-inflammatory activities of fibers.

Dietary fiber future directions: integrating new definitions and findings to inform nutrition research and communication

The CODEX Alimentarius definition of dietary fiber includes all nondigestible carbohydrate polymers with a degree of polymerization of 3 or more as dietary fiber with the proviso that they show health benefits. The global definition, if accepted by all authoritative bodies, offers a chance for international harmonization in research, food composition tables, and food labeling. Its nonacceptance highlights problems that may develop when definitions vary by region. The definition requires that the research community agrees upon physiological effects for which there is substantial scientific agreement, e.g., fibers' effects on laxation and gut health, on attenuating blood lipids and blood glucose and insulin, and in promoting fermentation in the large bowel. The definition also necessitates the delineation of research protocols to prove the benefits of various isolated and synthesized fibers. These should emanate from evidence-based reviews that fairly weigh epidemiological data while considering that added fibers are not reflected in many food composition databases. They then should include well-controlled, randomized, control trials and utilize animal studies to determine mechanisms. Agreement on many study variables such as the type of subject and the type of baseline diet that best fits the question under investigation will also be needed. Finally, the definition establishes that all types of fiber can address the severe fiber consumption gap that exists throughout the world by recognizing that the combination of fiber-rich and -fortified foods increases fiber intake while allowing consumers to stay within allowed energy levels.