Impact of Pasta Intake on Body Weight and Body Composition: A Technical Review.

Pasta is a staple carbohydrate across many cultures but has been implicated in overweight and obesity due to its position as a refined carbohydrate. Yet, the unique structure of pasta and its low glycemic response suggest it may contribute to a healthy body weight. The purpose of this review is to summarize the literature on the effects of pasta and dietary patterns high in pasta on body weight and body composition outcomes, and evaluate potential mechanisms by which pasta may influence body weight. A search of PubMed and CENTRAL identified 38 relevant studies examining pasta intake and body weight outcomes or potential mechanisms. Observational studies generally report no association or an inverse association of pasta intake with body weight/body composition outcomes. One clinical trial reported no difference in weight loss between a hypocaloric diet with high intake vs. low intake of pasta. Pasta may influence body weight via its low glycemic response, but evidence of effects on appetite, appetite-related hormones, and gastric emptying is limited and inconclusive. In conclusion, observational and limited clinical data suggest pasta is either inversely or not associated with overweight or obesity in healthy children and adults, and does not contribute to weight gain within the context of a healthy diet.

The Relationship of Ready-to-Eat Cereal Intake and Body Weight in Adults: A Systematic Review of Observational Studies and Controlled Trials.

Results from observational studies indicate that consumption of ready-to-eat cereal (RTEC) is associated with higher diet quality and lower incidence of overweight and obesity in adults compared with other breakfasts or skipping breakfast. However, randomized controlled trials (RCTs) have had inconsistent results regarding effects of RTEC consumption on body weight and composition. This systematic review aimed to evaluate the effect of RTEC intake on body weight outcomes in observational studies and RCTs in adults. A search of PubMed and Cochrane Central Register of Controlled Trials (CENTRAL) databases yielded 28 relevant studies, including 14 observational studies and 14 RCTs. Results from observational studies demonstrate that frequent RTEC consumers (usually ≥4 servings/wk) have lower BMI, lower prevalence of overweight/obesity, less weight gain over time, and less anthropometric evidence of abdominal adiposity compared with nonconsumers, or less frequent consumers. RCT results suggest that RTEC may be used as a meal or snack replacement as part of a hypocaloric diet, but this approach is not superior to other options for those attempting to achieve an energy deficit. In addition, RTEC consumption was not associated with significantly less loss of body weight, or with weight gain, in any of the RCTs. RTEC intake is associated with favorable body weight outcomes in adults in observational studies. RTEC does not hinder weight loss when used as a meal or snack replacement within a hypocaloric diet. Additional long-term RCTs (≥6 mo) in both hypocaloric and ad libitum conditions are recommended to evaluate further the potential effects of RTEC consumption on body weight outcomes. PROSPERO (CRD42022311805).

The Impact of Ready-to-Eat Cereal Intake on Body Weight and Body Composition in Children and Adolescents: A Systematic Review of Observational Studies and Controlled Trials.

Results from observational studies suggest that children and adolescents consuming ready-to-eat cereals (RTECs) have a healthier BMI and lower odds of overweight and obesity than consumers of other breakfasts or breakfast skippers. However, randomized controlled trials in children and adolescents are few and have been inconsistent in demonstrating a causal relationship between RTEC intake and body weight or body composition. The objective of this study was to evaluate the effect of RTEC intake on body weight and body composition outcomes in children and adolescents. Prospective cohort, cross-sectional and controlled trials in children or adolescents were included. Retrospective studies and studies in subjects with disease, other than obesity, type-2 diabetes (T2D), metabolic syndrome, or prediabetes, were excluded. A search in PubMed and CENTRAL databases yielded 25 relevant studies, which were qualitatively analyzed. Fourteen of the 20 observational studies demonstrated that children and adolescents consuming RTEC have a lower BMI, lower prevalence and odds of overweight/obesity and more favorable indicators of abdominal obesity than nonconsumers or less frequent consumers. Controlled trials were few and only one reported a loss of 0.9 kg in overweight/obese children with RTEC consumption when accompanied by nutrition education. The risk of bias was low for most studies, but six had some concerns or high risk. The results were similar with presweetened and nonpresweetened RTEC. No studies reported a positive association of RTEC intake with body weight or body composition. Although controlled trials do not show a direct effect of RTEC consumption on body weight or body composition, the preponderance of observational data supports the inclusion of RTEC as part of a healthy dietary pattern for children and adolescents. Evidence also suggests similar benefits on body weight and body composition regardless of the sugar content. Additional trials are needed to determine the causality between RTEC intake and body weight and body composition outcomes. PROSPERO REGISTRATION: CRD42022311805.

Whole grain intake, compared to refined grain, improves postprandial glycemia and insulinemia: a systematic review and meta-analysis of randomized controlled trials.

Whole grain (WG) intake has been associated with reduced risk of type 2 diabetes (T2D) and may protect against T2D by lowering postprandial glycemia and insulinemia and improving insulin sensitivity. The objective of this systematic review and meta-analysis was to evaluate the effect of WG intake, compared to refined grain (RG) intake, on postprandial glycemia and insulinemia and markers of glycemic control and insulin resistance in randomized controlled trials (RCTs) in adults. A search of PubMed and Scopus yielded 80 relevant RCTs. Compared to RG, WG intake significantly reduced postprandial glycemia (SMD: -0.30; 95% CI: -0.43, -0.18; P < 0.001), insulinemia (SMD: -0.23; 95% CI: -0.35, -0.10; P < 0.001) and glycated hemoglobin (HbA1c) (SMD: -0.21; 95% CI: -0.37, -0.06; P = 0.007). There was no effect of WG on fasting glucose, fasting insulin, or homeostatic model assessment of insulin resistance (HOMA-IR). These results suggest WG foods improve short-term glycemia and insulinemia, which may improve HbA1c, a marker of long-term glycemic control. This may partially explain the inverse association between WG intake and risk of T2D, but further investigations are needed to understand if short-term reductions in glycemia translate to longer term benefits in reducing the risk of T2D.Systematic Review Registration: PROSPERO Registration CRD42020180069.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.2017838.

Red meat consumption and risk factors for type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND OBJECTIVES: Results from observational studies suggest an association of red meat intake with risk of type 2 diabetes mellitus (T2D). However, results from randomized controlled trials (RCTs) have not clearly supported a mechanistic link between red meat intake and T2D risk factors. Therefore, a systematic review and meta-analysis were conducted on RCTs evaluating the effects of diets containing red meat (beef, pork, lamb, etc.), compared to diets with lower or no red meat, on markers of glucose homeostasis in adults. METHODS: A search of PubMed and CENTRAL yielded 21 relevant RCTs. Pooled estimates were expressed as standardized mean differences (SMDs) between the red meat intervention and the comparator intervention with less or no red meat. RESULTS: Compared to diets with reduced or no red meat intake, there was no significant impact of red meat intake on insulin sensitivity (SMD: -0.11; 95% CI: -0.39, 0.16), insulin resistance (SMD: 0.11; 95% CI: -0.24, 0.45), fasting glucose (SMD: 0.13; 95% CI: -0.04, 0.29), fasting insulin (SMD: 0.08; 95% CI: -0.16, 0.32), glycated hemoglobin (HbA1c; SMD: 0.10; 95% CI: -0.37, 0.58), pancreatic beta-cell function (SMD: -0.13; 95% CI: -0.37, 0.10), or glucagon-like peptide-1 (GLP-1; SMD: 0.10; 95% CI: -0.37, 0.58). Red meat intake modestly reduced postprandial glucose (SMD: -0.44; 95% CI: -0.67, -0.22; P < 0.001) compared to meals with reduced or no red meat intake. The quality of evidence was low to moderate for all outcomes. CONCLUSIONS: The results of this meta-analysis suggest red meat intake does not impact most glycemic and insulinemic risk factors for T2D. Further investigations are needed on other markers of glucose homeostasis to better understand whether a causal relationship exists between red meat intake and risk of T2D. PROSPERO REGISTRATION: CRD42020176059.

Ready-to-eat cereal consumption is associated with improved nutrient intakes and diet quality in Canadian adults and children across income levels.

Background: Results from observational studies suggest ready-to-eat cereal (RTEC) consumption is associated with higher diet quality. In the United States, studies have shown that RTEC is an important contributor to nutrient intakes across income levels. However, it is unknown if this association varies by income level in the Canadian population. Given its affordability, RTEC may represent an important source of nutrients for lower-income individuals. Objective: This study evaluated the association of RTEC consumption with nutrient intakes and diet quality across household income levels in Canadian adults and children. Methods: Income and dietary data from 24 h dietary recalls were obtained from the 2015 Canadian Community Health Survey (CCHS)-Nutrition in 6,181 children (2-18 years) and 13,908 adults (19+ years). Diet quality was assessed with a modified Nutrient Rich Food Index (NRF) 9.3. Income levels were stratified into low, middle, and high based on family size, and data were analyzed by RTEC consumption and income level using multivariate linear regression adjusted for energy, age, and sex. Results: Diet quality was greater in adult and child RTEC consumers across all household income levels. Children and adults consuming RTEC also had higher nutrient intakes, including shortfall nutrients such as calcium, dietary fiber, iron, magnesium, and vitamin D. RTEC provided <10% of energy intake, <4% of saturated fat intake, and <9% of total sugar intake across all ages and income levels, while also providing one-third of daily iron intake and at least 10% of daily intake of dietary fiber, thiamin, folate, and vitamin B6. Conclusion: RTEC consumption was associated with improved nutrient intakes and diet quality in adults and children across household income levels. Nutrient dense and affordable food choices, such as RTEC, may be a helpful strategy to improve the diet quality of Canadians, particularly those with a lower household income.

Ready-to-eat cereal is an affordable breakfast option associated with better nutrient intake and diet quality in the US population.

Background: Results from observational studies have reported ready-to-eat cereal (RTEC) consumers have higher dietary quality and nutrient intake compared to consumers of non-RTEC breakfasts or those who do not eat breakfast. Yet, there have been few investigations on the relationship of RTEC to meal costs at breakfast and across the day, which may be one reason some consumers choose to not consume breakfast. Objective: The objective of this study is to evaluate the contribution of RTEC consumed at breakfast to nutrient intake and adequacy, diet quality and meal costs in a nationally representative sample of children and adults in the US. Methods: Dietary data from 2,259 children (2-18 years) and 4,776 adults (≥19 years) in the National Health and Nutrition Examination Survey (NHANES) 2017-2018 were evaluated to compare nutrient intake, adequacy, dietary quality, and food costs in RTEC breakfast consumers, non-RTEC breakfast consumers and those who did not consume breakfast. Results: RTEC breakfast consumers made up 28% of children and 12% of adults. Children and adults consuming RTEC for breakfast had higher intakes of carbohydrate, dietary fiber, calcium, magnesium, iron, zinc, phosphorus, potassium, B vitamins, vitamins A and D, whole grains, and total dairy compared to consumers of non-RTEC breakfast or no breakfast. There were no differences by breakfast status for sodium, saturated fat, or added sugar, except adults consuming RTEC had lower added sugar intake compared to those who did not consume breakfast. RTEC breakfast consumers were also more likely to meet estimated average requirements (EAR) for intake of several nutrients and had overall higher dietary quality. For children, breakfast meal costs were less for RTEC breakfast compared to non-RTEC breakfast, but total daily meal costs were similar for consumers of RTEC and non-RTEC breakfasts. Conclusion: RTEC breakfasts may contribute to greater nutrient intake and diet quality in children and adults in the US without increasing total daily meal costs.

Implementing the 2020-2025 Dietary Guidelines for Americans: Recommendations for a Path Forward.

The Dietary Guidelines for Americans (DGA) provide science-based recommendations for healthy dietary patterns to promote health and reduce risk of chronic diseases. Yet, since their inception in 1980 and updates every 5 y, Americans fall short of meeting dietary recommendations and diet-related chronic diseases continue to be a public health concern. In May of 2021, the Institute of Food Technologists and the Department of Food Science at the University of Massachusetts, Amherst, convened a diverse group of thought leaders in health, nutrition, and food science to identify opportunities and approaches to improve consumer adoption of the DGA recommendations. The invited leaders collaborated in roundtable discussions to develop recommendations and strategies to promote adoption of the DGA recommendations after hearing sessions on the latest consumer trends, advances in food science and technology, and effective communications approaches. Participants agreed that changes in consumer behaviors and heightened interest in health due to the novel coronavirus pandemic have created an opportune time to engage consumers about healthy eating. Communications must be simple, tailored to the consumer, and delivered by influencer(s)/spokesperson(s) who are credible sources and share personal values. Innovations in food science and technology have enabled improvements in the safety, health, acceptability, affordability, and availability of foods, but opportunities to provide more options to enhance consumption of desired food groups, such as fruits, vegetables, and whole grains, remain. Moving Americans toward healthier dietary patterns aligned with DGA recommendations will require collaborations within the food sector and beyond to achieve broad-scale amplification and investment.

Implementing the 2020-2025 Dietary Guidelines for Americans: Recommendations for a path forward.

The Dietary Guidelines for Americans (DGA) provide science-based recommendations for healthy dietary patterns to promote health and reduce risk of chronic diseases. Yet, since their inception in 1980 and updates every 5 years, Americans fall short of meeting dietary recommendations and diet-related chronic diseases continue to be a public health concern. In May of 2021, the Institute of Food Technologists and the Department of Food Science at the University of Massachusetts, Amherst, convened a diverse group of thought leaders in health, nutrition, and food science to identify opportunities and approaches to improve consumer adoption of the DGA recommendations. The invited leaders collaborated in roundtable discussions to develop recommendations and strategies to promote adoption of the DGA recommendations after hearing sessions on the latest consumer trends, advances in food science and technology, and effective communications approaches. Participants agreed that changes in consumer behaviors and heightened interest in health due to the novel coronavirus pandemic have created an opportune time to engage consumers about healthy eating. Communications must be simple, tailored to the consumer, and delivered by influencer(s)/spokesperson(s) who are credible sources and share personal values. Innovations in food science and technology have enabled improvements in the safety, health, acceptability, affordability, and availability of foods but opportunities to provide more options to enhance consumption of desired food groups, such as fruits, vegetables, and whole grains, remain. Moving Americans toward healthier dietary patterns aligned with DGA recommendations will require collaborations within the food sector and beyond to achieve broad scale amplification and investment.

Effects of Whole Grain Intake, Compared with Refined Grain, on Appetite and Energy Intake: A Systematic Review and Meta-Analysis.

Results from observational studies indicate that whole grain (WG) intake is inversely associated with BMI and risk of weight gain. WG intake may influence energy balance and body composition through effects on appetite and energy intake. To evaluate the impact of WG food consumption on appetite and energy intake, a systematic review and meta-analysis was performed of results from randomized controlled trials (RCTs) assessing WG food consumption, appetite, and energy intake in adults. A search of PubMed, Scopus, and Food Science and Technology Abstracts yielded 36 RCTs measuring subjective appetite ratings after consuming WG foods compared with refined grain (RG) controls. Thirty-two of these studies reported AUCs for subjective appetite (hunger, fullness, satiety, desire to eat, or prospective consumption) and/or energy intake and were included in the meta-analysis. Pooled estimates from meta-analyses are expressed as standardized mean differences (SMDs). Compared with RG foods, intake of WG foods resulted in significant differences in AUCs for subjective hunger (SMD: -0.34; 95% CI: -0.46, -0.22; P < 0.001), fullness (SMD: 0.49; 95% CI: 0.31, 0.66; P < 0.001), satiety (SMD: 0.33; 95% CI: 0.18, 0.47; P < 0.001), and desire to eat (SMD: -0.33; 95% CI: -0.46, -0.20; P < 0.001). There were small, nonsignificant reductions in prospective consumption ratings (P = 0.08) and energy intake (P = 0.07) with WG intake compared with RG. These results support the view that consumption of WG foods, compared with RG foods, significantly impacts subjective appetite, and might partly explain the inverse associations between WG food intake and risk of overweight, obesity, and weight gain over time. PROSPERO registration: CRD42020148217.

Cost savings of reduced constipation rates attributed to increased dietary fiber intakes: a decision-analytic model.

BACKGROUND: Nearly five percent of Americans suffer from functional constipation, many of whom may benefit from increasing dietary fiber consumption. The annual constipation-related healthcare cost savings associated with increasing intakes may be considerable but have not been examined previously. The objective of the present study was to estimate the economic impact of increased dietary fiber consumption on direct medical costs associated with constipation. METHODS: Literature searches were conducted to identify nationally representative input parameters for the U.S. population, which included prevalence of functional constipation; current dietary fiber intakes; proportion of the population meeting recommended intakes; and the percentage that would be expected to respond, in terms of alleviation of constipation, to a change in dietary fiber consumption. A dose-response analysis of published data was conducted to estimate the percent reduction in constipation prevalence per 1 g/day increase in dietary fiber intake. Annual direct medical costs for constipation were derived from the literature and updated to U.S. $ 2012. Sensitivity analyses explored the impact on adult vs. pediatric populations and the robustness of the model to each input parameter. RESULTS: The base case direct medical cost-savings was $12.7 billion annually among adults. The base case assumed that 3% of men and 6% of women currently met recommended dietary fiber intakes; each 1 g/day increase in dietary fiber intake would lead to a reduction of 1.9% in constipation prevalence; and all adults would increase their dietary fiber intake to recommended levels (mean increase of 9 g/day). Sensitivity analyses, which explored numerous alternatives, found that even if only 50% of the adult population increased dietary fiber intake by 3 g/day, annual medical costs savings exceeded $2 billion. All plausible scenarios resulted in cost savings of at least $1 billion. CONCLUSIONS: Increasing dietary fiber consumption is associated with considerable cost savings, potentially exceeding $12 billion, which is a conservative estimate given the exclusion of lost productivity costs in the model. The finding that $12.7 billion in direct medical costs of constipation could be averted through simple, realistic changes in dietary practices is promising and highlights the need for strategies to increase dietary fiber intakes.

Docosahexaenoic acid in plasma phosphatidylcholine may be a potential marker for in vivo phosphatidylethanolamine N-methyltransferase activity in humans.

BACKGROUND: Choline is an essential nutrient for humans, and part of this requirement is met by endogenous synthesis catalyzed by hepatic phosphatidylethanolamine N-methyltransferase (PEMT). PEMT activity is difficult to estimate in humans because it requires a liver biopsy. Previously, we showed that mice that lack functional PEMT have dramatically reduced concentrations of docosahexaenoic acid (DHA; 22:6n-3) in plasma and of liver phosphatidylcholine (PtdCho)-a phospholipid formed by PEMT. OBJECTIVE: The objective was to evaluate plasma PtdCho-DHA concentrations as a noninvasive marker of liver PEMT activity in humans. DESIGN: Plasma PtdCho-DHA concentrations were measured in 72 humans before and after they consumed a low-choline diet, and correlations were analyzed in relation to estrogen status, PEMT polymorphism rs12325817, the ratio of plasma S-adenosylmethionine (AdoMet) to S-adenosylhomocysteine (AdoHcy), and dietary choline intake; all of these factors are associated with changes in liver PEMT activity. PtdCho-DHA and PEMT activity were also measured in human liver specimens. RESULTS: At baseline, the portion of PtdCho species containing DHA (pmol PtdCho-DHA/nmol PtdCho) was higher in premenopausal women than in men and postmenopausal women (P < 0.01). This ratio was lower in premenopausal women with the rs12325817 polymorphism in the PEMT gene (P < 0.05), and PtdCho-DHA concentration and PEMT activity were lower in human liver samples from women who were homozygous for PEMT rs12325817 (P < 0.05). The ratio of DHA-PtdCho to PtdCho in plasma was directly correlated with the ratio of AdoMet to AdoHcy (P = 0.0001). The portion of PtdCho species containing DHA in plasma was altered in subjects who consumed a low-choline diet. CONCLUSION: PtdCho-DHA may be useful as a surrogate marker for in vivo hepatic PEMT activity in humans. This trial was registered at clinicaltrials.gov as NCT00065546.

Dietary docosahexaenoic acid supplementation modulates hippocampal development in the Pemt-/- mouse.

The development of fetal brain is influenced by nutrients such as docosahexaenoic acid (DHA, 22:6) and choline. Phosphatidylethanolamine-N-methyltransferase (PEMT) catalyzes the biosynthesis of phosphatidylcholine from phosphatidylethanolamine enriched in DHA and many humans have functional genetic polymorphisms in the PEMT gene. Previously, it was reported that Pemt(-/-) mice have altered hippocampal development. The present study explores whether abnormal phosphatidylcholine biosynthesis causes altered incorporation of DHA into membranes, thereby influencing brain development, and determines whether supplemental dietary DHA can reverse some of these changes. Pregnant C57BL/6 wild type (WT) and Pemt(-/-) mice were fed a control diet, or a diet supplemented with 3 g/kg of DHA, from gestational day 11 to 17. Brains from embryonic day 17 fetuses derived from Pemt(-/-) dams fed the control diet had 25-50% less phospholipid-DHA as compared with WT (p < 0.05). Also, they had 60% more neural progenitor cell proliferation (p < 0.05), 60% more neuronal apoptosis (p < 0.01), and 30% less calretinin expression (p < 0.05; a marker of neuronal differentiation) in the hippocampus compared with WT. The DHA-supplemented diet increased fetal brain Pemt(-/-) phospholipid-DHA to WT levels, and abrogated the neural progenitor cell proliferation and apoptosis differences. Although this diet did not change proliferation in the WT group, it halved the rate of apoptosis (p < 0.05). In both genotypes, the DHA-supplemented diet increased calretinin expression 2-fold (p < 0.05). These results suggest that the changes in hippocampal development in the Pemt(-/-) mouse could be mediated by altered DHA incorporation into membrane phospholipids, and that maternal dietary DHA can influence fetal brain development.

Beneficial effects of resistant starch on laxation in healthy adults.

OBJECTIVE: This randomized, double-blind crossover trial evaluated the effects of a type 3 novel resistant starch (RS) versus wheat bran (WB) on faecal weight, frequency, and consistency in healthy adults. METHODS: Following a 14-day baseline period during which subjects (n=14) consumed low-fibre (<2 g) test products, participants were assigned to receive 25 g RS or WB fibre daily for 14 days, then crossed over to the opposite treatment after a 7-day washout. RESULTS: Daily faecal output increased from 128.8+/-68.7 g at baseline to 164.2+/-88.4 g with RS and 194.5+/-92.0 g with WB (both P<0.02 versus baseline). No significant differences among the three conditions were observed for bowel movement frequency. Faecal consistency ratings were increased with WB (P=0.001), but unchanged with RS. CONCLUSIONS: Dietary RS and WB increase faecal output in healthy adults.

Upregulation of p21Waf1/Cip1 expression in vivo by butyrate administration can be chemoprotective or chemopromotive depending on the lipid component of the diet.

The overall goal of this research was to separate out the effects of butyrate from its fiber source and determine in vivo if it upregulates colonic histone acetylation, p21(Waf1/Cip1) expression (p21) and apoptosis and if this sequela of events is protective against aberrant crypt foci (ACF) formation. Eighty Sprague-Dawley rats were provided defined diets with either corn oil or fish oil as the lipid source, +/- butyrate-containing capsules targeted for release in the colon and +/- azoxymethane (AOM) (10 rats per group). Diets were provided for 11 weeks and at termination colonocyte nuclear histone H4 and p21 expression were determined by immunohistochemistry, apoptosis was measured by the terminal deoxynucleotide transferase biotin-dUTP nick end labeling assay and aberrant crypt numbers and multiplicity were enumerated. Luminal butyrate levels were also quantified. AOM injection repressed p21 expression, which was reversed by butyrate supplementation. Although butyrate enhanced p21 expression with both dietary lipid sources, the increase in p21 resulted in an increase in apoptosis and decrease in ACF with fish oil, but had no effect on apoptosis and increased ACF with corn oil. This significant interaction between fat, butyrate (fiber) and p21 expression with one combination being protective and the other promotive of colon carcinogenesis reinforces the importance of considering diet as a key factor in chemoprevention.

Effect of novel maize-based dietary fibers on postprandial glycemia and insulinemia.

BACKGROUND: Postprandial hyperglycemia has been associated with increased oxidative stress and the development of diabetes, heart disease and all-cause mortality. OBJECTIVE: To assess the effect of novel maize-based dietary fibers on postprandial glycemia and to assess the correlation between a rapid in vitro digestibility system and the blood glucose response. METHODS: In a clinical study, 12 healthy volunteers were fed seven test beverages containing maize-based fiber ingredients (25g total carbohydrate) along with 2 control meals on separate occasions in random order. Capillary blood samples were obtained and the relative glycemic and insulinemic responses were assessed by calculating the incremental area under the 2 h blood response curves. In vitro digestibility studies of the test fibers and control were also undertaken to determine if these correlated with the clinical findings. RESULTS: All test fibers resulted in significantly lower glycemic and insulinemic responses for the incremental area under the curve (iAUC) and at all time points compared with the control (P < 0.05). The in vitro digestibility curves were comparable to the cumulative in vivo iAUCs. In vitro data expressed as percent digestion correlated significantly with the in vivo iAUC for the first 30min of the test meal (P < 0.05). CONCLUSION: These novel maize-based dietary fibers all produce lower postprandial glycemic and insulinemic responses than the control. While further assessment is necessary in beverage and foods containing these fibers, they may be effective in applications for dietary strategies to control diabetes and other chronic diseases. In addition, the in vitro digestibility assay correlated well with in vivo data and may be useful in guiding product development.

Choline: Dietary Requirements and Role in Brain Development.

Choline is needed for the maintenance of the structural integrity and signaling functions of cell membranes, for neurotransmission, and for transport of lipids and as a source of methyl groups. Choline can be made de novo in the body, but some individuals must also obtain choline in the diet to prevent deficiency symptoms. A number of environmental and genetic factors influence dietary requirements for choline, and average intakes in the population vary widely. Therefore, certain individuals may be at greater risk of choline deficiency. Choline is critical during fetal development, particularly during the development of the brain, where it can influence neural tube closure and lifelong memory and learning functions.

An increase in reactive oxygen species by dietary fish oil coupled with the attenuation of antioxidant defenses by dietary pectin enhances rat colonocyte apoptosis.

We showed previously that the dietary combination of fish oil, rich in (n-3) fatty acids, and the fermentable fiber pectin enhances colonocyte apoptosis in a rat model of experimentally induced colon cancer. In this study, we propose that the mechanism by which this dietary combination heightens apoptosis is via modulation of the colonocyte redox environment. Male Sprague-Dawley rats (n = 60) were fed 1 of 2 fats (corn oil or fish oil) and 1 of 2 fibers (cellulose or pectin) for 2 wk before determination of reactive oxygen species (ROS), oxidative DNA damage, antioxidant enzyme activity [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx)] and apoptosis in isolated colonocytes. Fish oil enhanced ROS, whereas the combination of fish oil and pectin suppressed SOD and CAT and enhanced the SOD/CAT ratio compared with a corn oil and cellulose diet. Despite this modulation to a seemingly prooxidant environment, oxidative DNA damage was inversely related to ROS in the fish oil and pectin diet, and apoptosis was enhanced relative to other diets. Furthermore, apoptosis increased exponentially as ROS increased. These results suggest that the enhancement of apoptosis associated with fish oil and pectin feeding may be due to a modulation of the redox environment that promotes ROS-mediated apoptosis.

Pro-oxidant environment of the colon compared to the small intestine may contribute to greater cancer susceptibility.

The colon and small intestine have inherent differences (e.g. redox status) that may explain the variation in cancer occurrence at these two sites. This study examined basal and induced (oxidative challenge) reactive oxygen species (ROS) generation, antioxidant enzyme activity and oxidative DNA damage. Basal ROS and antioxidant enzyme activities in the colon were greater than in the small intestine. During oxidative stress, 8-oxo-deoxyguanosine (8-oxodG) DNA adducts in the colon exceeded levels in the small intestine concomitant with increased ROS. Thus the colon responds to oxidative stress less effectively than the small intestine, possibly contributing to increased cancer incidence at this site.

Fish oil increases mitochondrial phospholipid unsaturation, upregulating reactive oxygen species and apoptosis in rat colonocytes.

We have shown that a combination of fish oil (high in n-3 fatty acids) with the butyrate-producing fiber pectin, upregulates apoptosis in colon cells exposed to the carcinogen azoxymethane, protecting against colon tumor development. We now hypothesize that n-3 fatty acids prime the colonocytes such that butyrate can initiate apoptosis. To test this, 30 Sprague-Dawley rats were provided with diets differing in the fatty acid composition (corn oil, fish oil or a purified fatty acid ethyl ester diet). Intact colon crypts were exposed ex vivo to butyrate, and analyzed for reactive oxygen species (ROS), mitochondrial membrane potential (MMP), translocation of cytochrome C to the cytosol, and caspase-3 activity (early events in apoptosis). The fatty acid composition of the three major mitochondrial phospholipids was also determined, and an unsaturation index calculated. The unsaturation index in cardiolipin was correlated with ROS levels (R = 0.99; P = 0.02). When colon crypts from fish oil and FAEE-fed rats were exposed to butyrate, MMP decreased (P = 0.041); and translocation of cytochrome C to the cytosol (P = 0.037) and caspase-3 activation increased (P = 0.032). The data suggest that fish oil may prime the colonocytes for butyrate-induced apoptosis by enhancing the unsaturation of mitochondrial phospholipids, especially cardiolipin, resulting in an increase in ROS and initiating apoptotic cascade.