SACN Carbohydrates and Health Report

Carbohydrates are a major source of energy in the diet. Classified according to their chemistry, carbohydrates can be divided into sugars (monosaccharides and disaccharides), polyols, oligosaccharides (malto-oligosaccharides and non-digestible oligosaccharides) and polysaccharides (starch and non-starch polysaccharides). However, this classification does not allow a simple translation into nutritional effects since each class of carbohydrates has overlapping physiological properties and effects on health. Carbohydrates can also be classified according to their digestion and absorption in the human small intestine. Digestible carbohydrates are absorbed and digested in the small intestine; non-digestible carbohydrates are resistant to hydrolysis in the small intestine and reach the large intestine where they are at least partially fermented by the commensal bacteria present in the colon. There is no universal definition of the term ‘dietary fibre’; broadly speaking, it refers to some or all of the constituents of non-digestible carbohydrates and may also include other quantitatively minor components (e.g.lignin) that are associated with non-digestible carbohydrates in plant cell walls.  

An investigation into the properties of non-digestible carbohydrates that selectively promote colonic propionate production

Short chain fatty acids (SCFA), including propionate, are produced by the bacterial fermentation of carbohydrates in the colon. Propionate has many potential roles in health, including inhibiting cholesterol synthesis, de novo lipogenesis and increasing satiety. The profile of SCFA produced is determined by both the substrate available and the bacteria present and may be influenced by environmental conditions within the lumen of the colon. Whilst it may be beneficial to increase colonic propionate production, dietary strategies to achieve this are unproven. Adding propionate to food leads to poorer organoleptic properties, and oral propionate is absorbed in the small intestine. The optimum way to selectively increase colonic propionate would be to select fermentable carbohydrates that selectively promote propionate production. To date, few studies have undertaken a systematic assessment of the factors leading to increased colonic propionate production making the selection of propiogenic carbohydrates challenging. The aim of this thesis was to identify the best carbohydrates for selectively increasing propionate production, and to explore the factors which control propionate production. This work started with a systematic review of the literature for evidence of candidate carbohydrates, which led to a screen of ‘propiogenic’ substrates using in vitro batch fermentations and mechanistic analysis of the impact of pH, bond linkage and orientation using a range of sugars, polysaccharides and fibre sources. A new unit for SCFA production was developed to allow comparison of results from in vitro studies encompassing a range different methodologies found in the literature. The systematic review found that rhamnose yielded the highest rate and proportion of propionate production whereas, for polysaccharides, β-glucan ranked highest for rate and guar gum ranked highest for molar production, but this was not replicated across all studies. Thus, no single NDC was established as highly propiogenic. Some substrates appeared more propiogenic than others and when these were screened in vitro. Laminarin, and other β-glucans ranked highest for propionate production. Legume fibre and mycoprotein fibre were also propiogenic. A full complement of glucose disaccharides were tested to examine the role glycosidic bond orientation and position on propionate production. Of the glucose disaccharides tested, β(1-4) bonding was associated with increased proportion of propionate and α(1-1) and β(1-4) increased the rate and proportion of butyrate production. In conclusion, it appears that for fibre to affect satiety, high intakes of fibre are needed, and which a major mechanism is thought to occur via propionate. Within this thesis it was identified that rather than selecting specific fibres, increasing overall intakes of highly fermentable carbohydrates is as effective at increasing propionate production. Selecting carbohydrates with beta-bonding, particularly laminarin and other β(1-4) fermentable carbohydrates leads to marginal increases in propionate production. Compared with targeted delivery of propionate to the colon, fermentable carbohydrates examined in this thesis have lesser and variable effects on propionate production. A more complete understanding of the impact of bond configurations in polysaccharides, rather than disaccharides, may help selection or design of dietary carbohydrates which selectively promote colonic propionate production substrates for inclusion in functional foods. Overall this study has concluded that few substrates are selectively propiogenic and the evidence suggests that similar changes in propionate production may be achieved by modest changes in dietary fibre intake

Chemical composition of cultivated seaweed ulva clathrata (Roth) C. Agardh

Samples of cultivated Ulva clathrata were collected from a medium scale system (MSS, 1.5 1.5 m tank), or from a large scale system (LSS, 0.8 ha earthen pond). MSS samples were dried directly while the LSS sample was washed in freshwater and pressed before drying. Crude protein content ranged 20–26%, essential amino acids accounting for 32–36% of crude protein. The main analysed monosaccharides were rhamnose (36–40%), uronic acids (27–29%), xylose (10–13%) and glucose (10–16%). Some notable variations between MSS and LSS samples were observed for total dietary fibre (26% vs 41%), saturated fatty acids (31% vs 51%), PUFAS (33% vs 13%), carotenoids (358 vs 169 mg kg1 dw) and for Ca (9 vs 19 g kg1 ), Fe (0.6 vs 4.2 g kg1 ), Cu (44 vs 14 mg kg1 ), Zn (93 vs 17 mg kg1 ) and As (2 vs 9 mg kg1 ). The chemical composition of U. clathrata indicates that it has a good potential for its use in human and animal food.

Fiber, a component for health gastrointestinal endocrine system

Dietary fiber was classified according to its solubility in an attempt to relate physiological effects to chemical types of fiber. Soluble fibers (B-glucans, gums, wheat dextrin, psyllium, pectin, inulin) were considered to have benefits on serum lipids, while insoluble fibers (cellulose, lignin, pectins, hemicelluloses) were linked with laxation benefits. More important characteristics of fiber in terms of physiological benefits are viscosity and fermentability. Viscous fibers (pectins, B-glucans, gums, psyllium) are those that have gel-forming properties in the intestinal tract, and fermentable fibers (wheat dextrin, pectins, B-glucans, gum, inulin) are those that can be metabolized by colonic bacteria. Objective: To summarize the beneficial effects of dietary fiber, as nutraceuticals, in order to maintain a healthy gastrointestinal system. Methods: Our study is a systematic review. Electronic databases, including PubMed, Medline, with supplement of relevant websites, were searched. We included randomized and non-randomized clinical trials, epidemiological studies (cohort and case-control). We excluded case series, case reports, in vitro and animal studies. Results: The WHO, the U.S. Food and Drug Administration (FDA), the Heart Foundation and the Romanian Dietary Guidelines recommends that adults should aim to consume approximately 25–30 g fiber daily. Dietary fiber is found in the indigestible parts of cereals, fruits and vegetables. There are countries where people don’t eat enough food fibers, these people need to take some kind of fiber supplement. Evidence has been found that dietary fiber from whole foods or supplements may (1) reduce the risk of cardiovascular disease by improving serum lipids and reducing serum total and low-density lipoprotein (LDL) cholesterol concentrations, (2) decreases the glycaemic index of foods, which leads to an improvement in glycemic response, positive impact on diabetes, (3) protect against development of obesity by increasing satiety hormone leptin concentrations, (4) reduced risk of developing colorectal cancer by normalizes bowel movements, improve the integrity of the epithelial layer of the intestines, increase the resistance against pathogenic colonization, have favorable effects on the gut microbiome, wich is the second genomes of the microorganisms, (5) have a positive impact on the endocrine system by gastrointestinal polypeptide hormonal regulation of digestion, (6) have prebiotic effect by short-chain fatty acids (SCFA) production; butyrate acid is the preferred energy source for colonic epithelial cells, promotes normal cell differentiation and proliferation, and also help regulate sodium and water absorption, and can enhance absorption of calcium and other minerals. Although all prebiotics are fiber, not all fiber is prebiotic. This generally refers to the ability of a fiber to increase the growth of bifidobacteria and lactobacilli, which are beneficial to human health, and (7) play a role in improving immune function via production of SCFAs by increases T helper cells, macrophages, neutrophils, and increased cytotoxic activity of natural killer cells. Conclusion: Fiber consumption is associated with high nutritional value and antioxidant status of the diet, enhancing the effects on human health. Fibers with prebiotic properties can also be recommended as part of fiber intake. Due to the variability of fiber’s effects in the body, it is important to consume fiber from a variety of sources. Increasing fiber consumption for health promotion and disease prevention is a critical public health goal.

Atitudes da população portuguesa em relação à fibra alimentar

Introdução: A fibra dietética (FD) tem feito parte da dieta humana desde há milénios, embora os seus benefícios tenham sido reconhecidos, principalmente, nas últimas décadas. Objetivos: Porque a FD é um componente importante de uma dieta saudável, o objetivo deste trabalho foi avaliar os hábitos de consumo dos Portugueses, bem como o seu conhecimento sobre os alimentos ricos em fibras e as suas atitudes em relação à rotulagem dos alimentos. Métodos: Foi realizado um estudo descritivo transversal usando uma amostra não-probabilística de 382 participantes. Resultados: Os resultados mostraram que a ingestão de alimentos ricos em fibras, como frutas, vegetais e cereais, foi muito menor do que a ingestão recomendada. Os resultados também indicaram que a maioria das pessoas não presta a atenção desejada à rotulagem de alimentos ou à informação nutricional. Conclusões: O nível geral de conhecimento sobre FD foi considerado insatisfatório, e, portanto, é necessário mais educação nutricional e desenvolver esforços para informar as pessoas acerca da importância da FD como parte da sua dieta diária.

Diverticulosis y relación con el consumo de fibra en pacientes del Hospital Universitario de la Samaritana

Introducción: La diverticulosis es la condición más frecuentemente encontrada en la colonoscopia, condición asintomática, con un alto costo para el sistema de salud. Diversos factores han demostrado estar en relación con la aparición de la enfermedad. En nuestra población, esta información se desconoce; el objetivo del estudio es la caracterización de la población con diverticulosis y su relación con la frecuencia de la ingesta de fibra. Materiales y Métodos: Estudio observacional prospectivo de corte transversal con componente analítico. Realizado a todas las personas que asistieron al HUS a realización de colonoscopia entre Noviembre de 2015 y Abril de 2016. Se recolectaron datos de la frecuencia de fibra ingerida a través de entrevistas basadas. Resultados: Se estudiaron 278 personas, 55.7% mujeres. La prevalencia de diverticulosis fue de 21.58%, siendo más frecuente en mujeres ( 66,7%), 31% entre los 71-80 años, 2,16% tenían antecedente familiar de diverticulosis; principal sitio de afectación fue colon sigmoide en las mujeres y el colon descendente en los hombres. En las personas con diverticulosis el consumo de harina de trigo fue mayor (91,67% vs 86,7%), mientras el consumo de frutas fue mayor en las personas que no presentaron diverticulosis (83,49% vs 78,33%). Conclusiones: La prevalencia de diverticulosis es similar a lo reportado en la literatura. Así mismo se encontró un mayor consumo de fibra en la población sin divertículos lo que hace pensar que a pesar de que esta condición es multifactorial , el consumo de mayores cantidades de fibra puede prevenir la aparición de la misma

The effects of level of dietary protein on the milk production and rumen physiology of dairy cows fed a diet based on a tropical grass hay

zFour rumen-fistulated, multiparous Holstein-Friesian cows in early lactation were offered mixed diets based on rhodes grass hay (Chloris gayana) cv. Callide containing 13, 14, 15 or 16% crude protein (CP) on a dry matter basis, in a 4 x 4 latin square design. The estimated undegradable protein concentration in these diets was similar with rumen degradable protein concentration varying. Cows fed a diet containing 13% CP had lower (P = 0.07) milk yields than cows in other treatments (20.4 vs 21.9, 22.0 and 22.2 L/d for 13, 14, 15 and 16% CP, respectively). A positive linear relationship was found (P = 0.06) between organic matter intake and dietary CP%. There were negative linear relationships between dietary CP% and digestibilities of dry matter (P = 0.09), organic matter (P = 0.06) and neutral detergent fibre (P = 0.02). Feeding a diet containing 13% CP resulted in significantly lower (P = 0.001) molar proportions (%) of rumen valerate in comparison with other treatments. The molar proportions of isovalerate differed (P = 0.001) between treatments (0.66, 0.78, 0.89 and 1.04%) for 13, 14, 15 and 16% CP, respectively). Dietary protein level had no effect on rates of passage, in situ digestion of rhodes grass hay or ratios of allantoin: creatinine in urine. These data showed that increasing the dietary CP concentration of lactating cows fed diets based on rhodes grass hay increased intakes and not significantly improved at dietary CP concentrations above 14% DM.

Compliance with dietary recommendations in the population of Geneva, Switzerland: a ten-year trend study (1999-2009)

Introduction: There is little information regarding compliance with dietary recommendations in Switzerland. Objectives: To assess the trends in compliance with dietary recommendations in the Geneva population for period 1999 - 2009. Methods: Ten cross-sectional, population-based surveys (Bus Santé study). Dietary intake was assessed using a self-administered, validated semi quantitative Food Frequency Questionnaire. Compliance with the Swiss Society for Nutrition recommendations for nutrient intake was assessed. In all 9320 participants aged 35 to 75 years (50% women) were included. Trends were assessed by logistic regression adjusting for age, smoking stats, education and nationality, using survey year as the independent variable. Results: After excluding participants with extreme intakes, the percentage of participants with a cholesterol consumption< 300 mg/day increased from 40.8% in 1999 to 43.6% in 2009 for men (multivariate-adjusted p for trend = 0.04) and from 57.8% to 61.4% in women (multivariate-adjusted p for trend = 0.06). Calcium intake > 1 g/day decreased from 53.3% to 46.0% in men and from 47.6% to 40.7% in women (multivariate-adjusted p for trend< 0.001). Adequate iron intake decreased from 68.3%to 65.3% in men and from 13.3% to 8.4% in women (multivariate-adjusted p for trend< 0.001). Conversely, no significant changes were observed for carbohydrates, protein, total fat (including saturated, monounsaturated and polyunsaturated fatty acids), fibre, vitamins D and A. Conclusion: Fewimprovements were noted in adherence to dietary recommendations in the Geneva population between 1999 and 2009. The low and decreasing prevalence of adequate calcium and iron intake are of concern.

Trends in dietary intake in Switzerland, 1999 to 2009.

OBJECTIVE: To assess nutrition trends of the Geneva population for the period 1999-2009. DESIGN: Bus Santé Geneva study, which conducts annual health surveys in random samples of the Geneva population. Dietary intake was assessed using a validated FFQ and trends were assessed by linear regression. SETTING: Population-based survey. SUBJECTS: Data from 9283 participants (50% women, mean age 51·5 (sd 10·8) years) were analysed. RESULTS: In both genders total energy intake decreased from 1999 to 2009, by 2·9% in men and by 6·3% in women (both trends P < 0·005). Vegetable protein and total carbohydrate intakes, expressed as a percentage of total energy intake, increased in women. MUFA intake increased while SFA, PUFA and alcohol intakes decreased in both genders. Intakes of Ca, Fe and carotene decreased in both genders. No changes in fibre, vitamin D and vitamin A intakes were found. Similar findings were obtained after excluding participants with extreme dietary intakes, except that the decreases in SFA, vegetable protein and carbohydrate were no longer significant in women. CONCLUSIONS: Between 1999 and 2009, a small decrease in total energy intake was noted in the Geneva population. Although the decrease in alcohol and SFA intakes is of interest, the decrease in Ca and Fe intakes may have adverse health effects in the future.

Dietary patterns associated with diet quality among First Nations women living on reserves in British Columbia

Les Indigènes canadiens vivent une rapide transition nutritionnelle marquée par une consommation accrue des produits commercialisés au dépit des aliments traditionnels. Ce mémoire cherche à identifier les patrons alimentaires associés à une meilleure alimentation des femmes autochtones vivant dans les réserves en Colombie Britannique. L’échantillon (n=493) a été sélectionné de l’étude ‘First Nations Food, Nutrition, and Environment Study’. L’étude a utilisé des rappels alimentaires de 24 heures. Pour identifier les patrons alimentaires, un indice de qualité alimentaire (QA) basé sur 10 éléments nutritionnels (fibre alimentaire, gras totaux/saturés, folate, magnésium, calcium, fer, vitamines A, C, D) a permis de classifier les sujets en trois groupes (tertiles). Ces groupes ont été comparés sur leur consommation de 25 groupes alimentaires (GAs) en employant des tests statistiques non-paramétriques (Kruskal-Wallis et ANCOVA). Une analyse discriminante (AD) a confirmé les GAs associés à la QA. La QA des sujets était globalement faible car aucun rappel n’a rencontré les consommations recommandées pour tous les 10 éléments nutritionnels. L'AD a confirmé que les GAs associés de façon significative à la QA étaient ‘légumes et produits végétaux’, ‘fruits’, ‘aliments traditionnels’, ‘produits laitiers faibles en gras’, ‘soupes et bouillons’, et ‘autres viandes commercialisées’ (coefficients standardisés= 0,324; 0,295; 0,292; 0,282; 0,157; -0.189 respectivement). Le pourcentage de classifications correctes était 83.8%. Nos résultats appuient la promotion des choix alimentaires recommandés par le « Guide Alimentaire Canadien- Premières Nations, Inuits, et Métis ». Une consommation accrue de légumes, fruits, produits laitiers faibles en gras, et aliments traditionnels caractérise les meilleurs patrons alimentaires.

Effects of Different Feeding Regimes on the Digestibility and Faecal Excretion of Nitrogen, Soluble Carbohydrates and Fibre Fractions in Water Buffaloes kept under Subtropical Conditions

In the course of the ‘Livestock Revolution’, extension and intensification of, among others, ruminant livestock production systems are current phenomena, with all their positive and negative side effects. Manure, one of the inevitable secondary products of livestock rearing, is a valuable source of plant nutrients and its skillful recycling to the soil-plant interface is essential for soil fertility, nutrient - and especially phosphorus - uses efficiency and the preservation or re-establishment of environmentally sustainable farming systems, for which organic farming systems are exemplarily. Against this background, the PhD research project presented here, which was embedded in the DFG-funded Research Training Group 1397 ‘Regulation of soil organic matter and nutrient turnover in organic agriculture ’ investigated possibilities to manipulate the diets of water buffalo (Bubalus bubalis L.) so as to produce manure of desired quality for organic vegetable production, without affecting the productivity of the animals used. Consisting of two major parts, the first study (chapter 2) tested the effects of diets differing in their ratios of carbon (C) to nitrogen (N) and of structural to non-structural carbohydrates on the quality of buffalo manure under subtropical conditions in Sohar, Sultanate of Oman. To this end, two trials were conducted with twelve water buffalo heifers each, using a full Latin Square design. One control and four tests diets were examined during three subsequent 7 day experimental periods preceded each by 21 days adaptation. Diets consisted of varying proportions of Rhodes grass hay, soybean meal, wheat bran, maize, dates, and a commercial concentrate to achieve a (1) high C/N and high NDF (neutral detergent fibre)/SC (soluble carbohydrate) ratio (HH), (2) low C/N and low NDF/SC ratio (LL); (3) high C/N and low NDF/SC ratio (HL) and (4) low C/N and high NDF/SC (LH) ratio. Effects of these diets, which were offered at 1.45 times maintenance requirements of metabolizable energy, and of individual diet characteristics, respectively, on the amount and quality of faeces excreted were determined and statistically analysed. The faeces produced from diets HH and LL were further tested in a companion PhD study (Mr. K. Siegfried) concerning their nutrient release in field experiments with radish and cabbage. The second study (chapter 3) focused on the effects of the above-described experimental diets on the rate of passage of feed particles through the gastrointestinal tract of four randomly chosen animals per treatment. To this end, an oral pulse dose of 683 mg fibre particles per kg live weight marked with Ytterbium (Yb; 14.5 mg Yb g-1 organic matter) was dosed at the start of the 7 day experimental period which followed 21 days of adaptation. During the first two days a sample for Yb determination was kept from each faecal excretion, during days 3 – 7 faecal samples were kept from the first morning and the first evening defecation only. Particle passage was modelled using a one-compartment age-dependent Gamma-2 model. In both studies individual feed intake and faecal excretion were quantified throughout the experimental periods and representative samples of feeds and faeces were subjected to proximate analysis following standard protocols. In the first study the organic matter (OM) intake and excretion of LL and LH buffaloes were significantly lower than of HH and HL animals, respectively. Digestibility of N was highest in LH (88%) and lowest in HH (74%). While NDF digestibility was also highest in LH (85%) it was lowest in LL (78%). Faecal N concentration was positively correlated (P≤0.001) with N intake, and was significantly higher in faeces excreted by LL than by HH animals. Concentrations of fibre and starch in faecal OM were positively affected by the respective dietary concentrations, with NDF being highest in HH (77%) and lowest in LL (63%). The faecal C/N ratio was positively related (P≤0.001) to NDF intake; C/N ratios were 12 and 7 for HH and LL (P≤0.001), while values for HL and LH were 11.5 and 10.6 (P>0.05). The results from the second study showed that dietary N concentration was positively affecting faecal N concentration (P≤0.001), while there was a negative correlation with the faecal concentration of NDF (P≤0.05) and the faecal ratios of NDF/N and C/N (P≤0.001). Particle passage through the mixing compartment was lower (P≤0.05) for HL (0.033 h-1) than for LL (0.043 h-1) animals, while values of 0.034 h-1 and 0.038 h-1 were obtained for groups LH and HH. At 55.4 h, total tract mean retention time was significantly (P≤0.05) lower in group LL that in all other groups where these values varied between 71 h (HH) and 79 h (HL); this was probably due to the high dietary N concentration of diet LL which was negatively correlated with time of first marker appearance in faeces (r= 0.84, P≤0.001), while the dietary C concentration was negatively correlated with particle passage through the mixing compartment (r= 0.57, P≤0.05). The results suggest that manure quality of river buffalo heifers can be considerably influenced by diet composition. Despite the reportedly high fibre digestion capacity of buffalo, digestive processes did not suppress the expression of diet characteristics in the faeces. This is important when aiming at producing a specific manure quality for fertilization purposes in (organic) crop cultivation. Although there was a strong correlation between the ingestion and the faecal excretion of nitrogen, the correlation between diet and faecal C/N ratio was weak. To impact on manure mineralization, the dietary NDF and N concentrations seem to be the key control points, but modulating effects are achieved by the inclusion of starch into the diet. Within the boundaries defined by the animals’ metabolic and (re)productive requirements for energy and nutrients, diet formulation may thus take into account the abiotically and biotically determined manure turnover processes in the soil and the nutrient requirements of the crops to which the manure is applied, so as to increase nutrient use efficiency along the continuum of the feed, the animal, the soil and the crop in (organic) farming systems.

Varying the dietary supply of C and N to manipulate the manure composition of water buffalo heifers in Oman

Optimizing the composition of manure has the potential to reduce nutrient losses to the environment and to increase crop yields. In this study the effect of dietary ratios of carbon (C) to nitrogen (N) and neutral detergent fibre (NDF) to soluble carbohydrates (SC) on faeces composition of water buffalo heifers was assessed. Two digestibility trials were conducted with 12 animals each, fed one control and four test diets composed to achieve (1) high C/N and high NDF/SC ratios (HH), (2) low C/N and low NDF/SC ratios (LL), (3) high C/N and low NDF/SC ratios (HL) and (4) low C/N and high NDF/SC (LH) ratios. Faecal C/N ratios were generally lower than dietary C/N ratios, but the reduction was especially large for high C/N ratio diets (HH=55 %, HL=51 %). Faecal N concentration was positively correlated (r^2 = 0.6; P < 0.001) with N intake, but the increase in faecal N was more pronounced for diets that supplied low amounts of N. Faecal NDF concentration was positively related to NDF intake (r^2 = 0.42; P < 0.001), as well as the faecal C/N ratio (r^2 = 0.3; P < 0.001). Results demonstrate that C/N ratio and NDF concentration of buffalo manure were affected by diet composition. Diets with high C/N ratio and low NDF/SC ratio are preferable with regard to manure quality, but may not satisfy the nutritional requirements of producing animals, since N concentration in these diets was low and fibre concentration simultaneously high.

Dietary, physiological, genetic and pathological influences on postprandial lipid metabolism

Most of diurnal time is spent in a postprandial state due to successive meal intakes during the day. As long as the meals contain enough fat, a transient increase in triacylglycerolaemia and a change in lipoprotein pattern occurs. The extent and kinetics of such postprandial changes are highly variable and are modulated by numerous factors. This review focuses on factors affecting postprandial lipoprotein metabolism and genes, their variability and their relationship with intermediate phenotypes and risk of CHD. Postprandial lipoprotein metabolism is modulated by background dietary pattern as well as meal composition (fat amount and type, carbohydrate, protein, fibre, alcohol) and several lifestyle conditions (physical activity, tobacco use), physiological factors (age, gender, menopausal status) and pathological conditions (obesity, insulin resistance, diabetes mellitus). The roles of many genes have been explored in order to establish the possible implications of their variability in lipid metabolism and CHD risk. The postprandial lipid response has been shown to be modified by polymorphisms within the genes for apo A-I, A-IV, AN, E, B, C-I and C-III, lipoprotein lipase, hepatic lipase, fatty acid binding and transport proteins, microsomal trigyceride transfer protein and scavenger receptor class B type I. Overall, the variability in postprandial response is important and complex, and the interactions between nutrients or dietary or meal compositions and gene variants need further investigation. The extent of present knowledge and needs for future studies are discussed in light of ongoing developments in nutrigenetics.

Fibre and effects on probiotics (the prebiotic concept)

The burden (economic and medicinal) of acute and chronic gut disorders continues to increase. As efficient therapies are few, attention has turned towards the use of so-called functional foods to mediate against gut disorder. These target particular genera of gut bacteria seen as beneficial, e.g. bifidobacteria, lactobacilli. The use of products containing live microbial species (probiotics) has a long history of use in humans and many trials have been reported as 'positive'. Taking the view that positive components of the gut flora already exist in the intestinal tract, the prebiotic concept has been developed. Here, dietary carbohydrates have a selective metabolism within the gut flora thereby shifting the community towards a more advantageous structure. Conventional fibres like pectins, cellulose, etc. are not selectively metabolised by gut bacteria. However, certain oligosaccharides do have this capability. Most research has been conducted with fructooligosaccharides, like inulin, which have a powerful bifidogenic effect. Trials are ongoing to determine the clinical benefits of prebiotic use. Intestinal disorders like ulcerative colitis, gastroenteritis and irritable bowel syndrome are particular targets. (c) 2004 Elsevier Ltd. All rights reserved.

Estimated intake of dietary phytoestrogens in Australian women and evaluation of correlates of phytoestrogen intake

The role of dietary phytoestrogens in health has been of continued interest and debate, but available data on the distribution of intake in the Australian diet is scarce. Therefore, we aimed to estimate phytoestrogen consumption in Australian women, describe the pattern of intake and identify correlates of high phytoestrogen intake. Study participants were 2078 control women (18-79 y) from two population-based case-control studies on gyneacological cancers (2002-2007). Dietary information was obtained using a 135-item semiquantitative FFQ and intakes of isoflavones, lignans, enterolignans and coumestans, including their individual components, were estimated using a database of phytoestrogen content in food developed in the UK. Median total intake (energy-adjusted) of phytoestrogens was 1.29 mg/d, of isoflavones 611 μg/d, of lignans 639 μg/d, of enterolignans 21μg/d and of coumestrol 8 μg/d. Both isoflavone and lignan intake were strongly skewed towards higher values and positively correlated with age. Women consumed on average 2 serves of soy foods/week. Compared to low phytoestrogen consumers (≤1.29 mg/d, median split), high phytoestrogen consumers (>1.29 mg/d) were slightly older, less likely to be smokers, had a higher educational and physical activity level, lower BMI, lower intake of dietary fat, and higher intake of fibre, selected micronutrient and soy food (all p<0.03). The daily intake of phytoestrogens in Australian women with predominantly Caucasian ethnicity is approximately 1 mg, similar to other Western populations, but considerably lower than among Asian women. However, those with a relatively high phytoestrogen diet seem to have healthier lifestyle and more favourable dietary profile compared to others.