Whole-grain foods and chronic disease: evidence from epidemiological and intervention studies

Cereal-based foods are key components of the diet and they dominate most food-based dietary recommendations in order to achieve targets for intake of carbohydrate, protein and dietary fibre. Processing (milling) of grains to produce refined grain products removes key nutrients and phytochemicals from the flour and although in some countries nutrients may be replaced with mandatory fortification, overall this refinement reduces their potential nutritional quality. There is increasing evidence from both observational and intervention studies that increased intake of less-refined, whole-grain (WG) foods has positive health benefits. The highest WG consumers are consistently shown to have lower risk of developing CVD, type 2 diabetes and some cancers. WG consumers may also have better digestive health and are likely to have lower BMI and gain less weight over time. The bulk of the evidence for the benefits of WG comes from observational studies, but evidence of benefit in intervention studies and potential mechanisms of action is increasing. Overall this evidence supports the promotion of WG foods over refined grain foods in the diet, but this would require adoption of standard definitions of 'whole grain' and 'whole-grain foods' which will enable innovation by food manufacturers, provide clarity for the consumer and encourage the implementation of food-based dietary recommendations and public health strategies

The impact of dietary fibre intake on the physiology and health of the stomach and upper gastrointestinal tract

This review is the first in a series of three articles considering how different types of dietary fibre may affect how the gut functions and gut health. This first review will focus on the impact of dietary fibre intake on the upper gastrointestinal tract (i.e. the mouth, oesophagus and stomach). While a larger body of evidence links fibre intake to bowel health and disease, it is apparent that the presence of fibre, whether as an added ingredient in foods, or as an integral part of the structure of plant foods, also plays key roles on oral and gastric secretions and upper gut motility. These actions are possibly modulated through fibre’s effects on the physicochemical properties of luminal contents in the gut. The major physiological functions of the mouth, oesophagus and stomach are discussed and recent evidence relating dietary fibre intake to these actions is introduced. A summary of evidence linking habitual dietary fibre consumption to major mucosal diseases of the upper gastrointestinal tract is also provided

Dietary seaweed and human health

Seaweed as an ingredient is growing in popularity largely due to its perceived health-giving properties supported by findings from epidemiological studies. Increased seaweed consumption has been linked to reduced risk of various diseases however there is a paucity of evidence for health benefits derived from robust randomised controlled trials (RCT). Emerging data from short-term RCT involving seaweed isolates are promising. Further investigation of seaweed as a wholefood ingredient is warranted. This review aims to highlight the food uses and potential health benefits of seaweeds

The potential health benefits of seaweed and seaweed extract

Edible seaweeds have historically been consumed by coastal populations across the globe. Today, seaweed is still part of the habitual diet in many Asian countries. Seaweed consumption also appears to be growing in popularity in Western cultures, due both to the influx of Asian cuisine as well as notional health benefits associated with consumption. Isolates of seaweeds (particularly viscous polysaccharides) are used in an increasing number of food applications in order to improve product acceptability and extend shelf-life. Epidemiological evidence suggests regular seaweed consumption may protect against a range of diseases of modernity. The addition of seaweed and seaweed isolates to foods has already shown potential to enhance satiety and reduce the postprandial absorption rates of glucose and lipids in acute human feeding studies, highlighting their potential use in the development of anti-obesity foods. As seaweeds and seaweed isolates have the potential to both benefit health and improve food acceptability, seaweeds and seaweed isolates offer exciting potential as ingredients in the development of new food products. This review will outline the evidence from human and experimental studies that suggests consumption of seaweeds and seaweed isolates may impact on health (both positively and negatively). Finally, this review will highlight current gaps in knowledge in this area and what future strategies should be adopted for maximising seaweed's potential food uses

Assessment of the Acute Effects of Carbonated Beverage Consumption on Symptoms and Objective Markers of Gastric Reflux

Previous studies have suggested that carbonated beverages may cause gastro-oesophageal reflux. Pepsin (the major enzyme secreted by the stomach) has been suggested to be an objective, acute marker of a reflux event. This pilot study aimed to investigate whether intake of carbonated beverages could affect pepsin concentration in saliva or reflux symptoms. This was assessed by a randomised, crossover trial where participants consumed 330 mL of beverage (carbonated cola, degassed cola or water) at separate visits. Saliva samples and symptom questionnaires were collected at baseline and over the 30 min postprandial period. Pepsin was detected in all saliva samples. No difference was found in the salivary pepsin concentrations between treatments at all time points. There were significantly higher scores (p > 0.05) for feelings of fullness, heartburn, urge to belch and frequency of belches after ingestion of carbonated cola than degassed cola and water. The ingestion of carbonated beverages did not appear to increase postprandial pepsin concentration in saliva compared to other beverages but did evoke higher levels of reflux-related symptoms such as fullness, heartburn and belching. This suggests carbonated beverages may cause symptoms associated with reflux but do not drive detectable levels of gastric juice to reach the oral cavity

Wholegrain Food Acceptance in Young Singaporean Adults

Previous epidemiological evidence suggests that habitual consumption of whole grains is associated with reduction of disease risk. While wholegrain food consumption appears to be increasing in Singapore, it is still low, with more infrequent consumption noted in younger Singaporeans. Therefore, the primary objective of this study is to determine the knowledge of whole grains and barriers to consumption of wholegrain foods. Thirty participants (age range 21–26 year, 19 females) took part in two focus groups separated by a 2-week period in which participants trialled a range of wholegrain foods. Barriers towards whole grain consumption and experiences of products during this familiarization period were discussed during the focus groups and knowledge of whole grains was assessed by questionnaire. Potential barriers such as personal factors, product-specific factors and external factors were identified with sensory and habitual being stronger barriers. The whole grain familiarization period did not alter the taste expectations of the consumers but it did manage to increase acceptance for four of the wholegrain products tested (muesli, cookies, granola bars and wholewheat pasta). These findings suggest existing barriers to wholegrain food consumption should be considered by public health agencies and manufacturing companies

Energy Expenditure, Availability, and Dietary Intake Assessment in Competitive Female Dragon Boat Athletes

Dragon boat racing requires high physical activity levels during competition and training. The female athletic triad refers to a number of negative health consequences (e.g., amenorrhoea, low bone mineral density, and low energy availability) that may result from high physical activity in female athletes in parallel with inadequate dietary intake. This study aimed to estimate energy expenditure and dietary adequacy in female competitive dragon boat athletes. Following ethical approval, energy expenditure was assessed by use of SensewearTM armbands (which measure movement as well as galvanic heat loss) on nine dragon boat athletes preparing for the Southeast Asian Games 2013. The mean estimated energy expenditure for the athletes was 2226 ± 711 kJ/day. Mean total energy, recorded using three-day food diaries (6715 ± 2518 kJ/day) and energy availability (99 ± 56 kJ/kg/day), were low. Estimated micronutrient intake (calcium 699.3 ± 328.7 mg/day and iron 10.6 ± 4.7 mg/day) did not meet recommended daily allowances of 800 mg/day and 19 mg/day, respectively. The low intake of energy, calcium, and iron noted within this study could have negative effects on performance and short- and long-term health in female dragon boat athletes

The Interaction of Large Bowel Microflora with the Colonic Mucus Barrier

The colonic mucus barrier is the first line of defence that the underlying mucosa has against the wide range of potentially damaging agents of microbial, endogenous, and dietary origin that occur within the colonic lumen. The functional component of mucus is the secreted, polymeric glycoprotein mucin. The mucus barrier can either act as an energy source or a support medium for growth to the intestinal microflora. The mucus barrier appears to effectively partition the vast number of microbial cells from the underlying epithelium. The normal functionality and biochemistry of this mucus barrier appears to be lost in diseases of the colorectal mucosa. Germ-free animal studies have highlighted the necessity of the presence of the colonic microflora to drive the maturation of the colonic mucosa and normal mucus production. A number of by-products of the microflora have been suggested to be key luminal drivers of colonic mucus secretion

The effect of dietary intake, physical activity and posture on pepsin concentrations detected in the saliva of free-living, healthy individuals

Introduction: Diet and lifestyle are believed to be major causes of gastric reflux. The occurrence of reflux is associated with a number of respiratory, oesophageal and airways conditions. Previous studies have used oesophageal monitoring to assess the occurrence of reflux events. Such measurements may only measure "bulk" rather than "microreflux" events. Such technology is also likely to impact on both habitual dietary intake and physical activity due to the nature of the assessment. Aim: To assess the impact of meal intake and physical activity on pepsin concentrations in saliva collected from free-living individuals throughout the day. Methods: Fifty-one participants (aged 18+, non-smokers with no current chronic or acute respiratory conditions, bloodborne diseases, or diagnosis of reflux disease) provided saliva samples before (< 30 min) and after (< 1 h) meals and physical activity bouts or before and after sleep. Dietary intake and physical activity were monitored by diary over this time. Dietary intake was analyzed using Windiets® software, while physical activity output was calculated from pre-existing tables of energy expenditure. Saliva samples were analyzed for pepsin content using a previously described ELISA methodology. Wilcoxon matched pairs rank sign tests were performed on before- and after-meal/physical activity/sleep samples. Results: Fifty-seven paired pre-and post-meal,48 paired pre- and post-physical activity samples and 168 pre- and post-sleep samples were analyzed. Mean(standard deviation) pepsin concentrations in saliva were significantly higher (P=0.037) in the pre-meal samples (44.2(42.2)) than the post-meal samples (32.8(29.6)). Post-sleep pepsin concentrations (196.4(323.4)) were significantly higher (P< 0.001) than pre-sleep (102.3(152.8)). There was no significant difference (P=0.491) between pre-(45.2(56.8)) and post-(40.8(38.6)) physical activity saliva samples. Conclusions: Analysis of pepsin in saliva is a useful method to assess the impact of lifestyle on reflux event occurrence. Increased preprandial salivary pepsin concentrations may be due to microreflux events driven by the cephalic phase of digestion

Alginate as a protease inhibitor in vitro and in a model gut system; selective inhibition of pepsin but not trypsin

Alginates are widely used in the food and medical industries, including as a Gastro-Oesophagul Reflux treatment. This work investigates the inhibitory effects of alginate on the reflux aggressors trypsin and pepsin and the role of alginate-substrate binding, pH and alginate structure on inhibition. Alginates were shown to reduce pepsin activity by up to 53.9% (±9.5SD) in vitro. Strong positive correlation between alginate mannuronate residue frequency and levels of pepsin inhibition was observed. Limited inhibition of trypsin was shown. Viscometric observations of pH dependent interactions between alginate and protein suggest a mechanism whereby pH dependent ionic interactions reduce substrate availability to enzyme at acidic pH. To understand how dietary protein digestion is affected by alginate, proteolytic digestion was investigated in an in vitro model of the upper digestive tract. Significant inhibition of proteolysis was shown in the gastric phase of digestion, but not the small intestinal phase