Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health.

Research into the analysis, physical properties and health effects of dietary fibre has continued steadily over the last 40-50 years. From the knowledge gained, countries have developed guidelines for their populations on the optimal amount of fibre to be consumed each day. Food composition tables from many countries now contain values for the dietary fibre content of foods, and, from these, combined with dietary surveys, population intakes have been determined. The present review assessed the uniformity of the analytical methods used, health claims permitted, recommendations and intakes, particularly from national surveys across Europe and around the world. It also assessed current knowledge on health effects of dietary fibre and related the impact of different fibre types on health. The overall intent was to be able to provide more detailed guidance on the types of fibre which should be consumed for good health, rather than simply a total intake figure, the current situation. Analysis of data indicated a fair degree of uniformity in the definition of dietary fibre, the method used for analysis, the recommended amount to be consumed and a growing literature on effects on digestive health and disease risk. However, national dietary survey data showed that intakes do not reach recommendations and very few countries provide guidance on the types of fibre that are preferable to achieve recommended intakes. Research gaps were identified and ideas suggested to provide information for more detailed advice to the public about specific food sources that should be consumed to achieve health benefits.

The influence of socio-demographic, psychological and knowledge-related variables alongside perceived cooking and food skills abilities in the prediction of diet quality in adults: a nationally representative cross-sectional study.

BACKGROUND: Interventions to increase cooking skills (CS) and food skills (FS) as a route to improving overall diet are popular within public health. This study tested a comprehensive model of diet quality by assessing the influence of socio-demographic, knowledge- and psychological-related variables alongside perceived CS and FS abilities. The correspondence of two measures of diet quality further validated the Eating Choices Index (ECI) for use in quantitative research. METHODS: A cross-sectional survey was conducted in a quota-controlled nationally representative sample of 1049 adults aged 20-60 years drawn from the Island of Ireland. Surveys were administered in participants' homes via computer-assisted personal interviewing (CAPI) assessing a range of socio-demographic, knowledge- and psychological-related variables alongside perceived CS and FS abilities. Regression models were used to model factors influencing diet quality. Correspondence between 2 measures of diet quality was assessed using chi-square and Pearson correlations. RESULTS: ECI score was significantly negatively correlated with DINE Fat intake (r = -0.24, p < 0.001), and ECI score was significantly positively correlated with DINE Fibre intake (r = 0.38, p < 0.001), demonstrating a high agreement. Findings indicated that males, younger respondents and those with no/few educational qualifications scored significantly lower on both CS and FS abilities. The relative influence of socio-demographic, knowledge, psychological variables and CS and FS abilities on dietary outcomes varied, with regression models explaining 10-20 % of diet quality variance. CS ability exerted the strongest relationship with saturated fat intake (ß = -0.296, p < 0.001) and was a significant predictor of fibre intake (ß = -0.113, p < 0.05), although not for healthy food choices (ECI) (ß = 0.04, p > 0.05). CONCLUSION: Greater CS and FS abilities may not lead directly to healthier dietary choices given the myriad of other factors implicated; however, CS appear to have differential influences on aspects of the diet, most notably in relation to lowering saturated fat intake. Findings suggest that CS and FS should not be singular targets of interventions designed to improve diet; but targeting specific sub-groups of the population e.g. males, younger adults, those with limited education might be more fruitful. A greater understanding of the interaction of factors influencing cooking and food practices within the home is needed.

Irregularity of energy intake at meals: prospective associations with the metabolic syndrome in adults of the 1946 British birth cohort.

Irregularity in eating patterns could be a potential cardiometabolic risk factor. We aimed to study the associations of irregular intake of energy at meals in relation to cardiometabolic risk factors 10 and 17 years later. Variability of energy intake data - derived from 5-d estimated diet diaries of cohort members of the National Survey for Health and Development collected at ages 36 (n 1416), 43 (n 1505) and 53 years (n 1381) - was used as a measure for irregularity. Associations between meal irregularity scores with cardiometabolic risk factors measured 10 and 17 years later were investigated using linear mixed models and logistic regression models. The results showed that irregularity scores changed significantly over the years (P<0·05). At age 36 years, subjects with a more irregular intake of energy at lunch (OR 1·42; 95 % CI 1·05, 1·91) and between meals (OR 1·35; 95 % CI 1·01, 1·82) had an increased risk for the metabolic syndrome 17 years later; at lunch was also associated with an increased waist circumference (OR 1·58; 95 % 1·27, 1·96) and TAG levels (OR 1·33; 95 % CI 1·02, 1·72). At age 43 years, subjects with a more irregular intake at breakfast had an increased risk of the metabolic syndrome 10 years later (OR 1·53; 95 % CI 1·15, 2·04), as well as an increased BMI (OR 1·66; 95 % CI 1·31, 2·10), waist circumference (OR 1·53; 95 % CI 1·23, 1·90) and diastolic blood pressure (OR 1·42; 95 % CI 1·13, 1·78). In conclusion, subjects with a more irregular intake of energy, mostly at breakfast and lunch, appeared to have an increased cardiometabolic risk 10 and 17 years later.

DINO (Diet In Nutrients Out) - an integrated dietary assessment system.

OBJECTIVE: The current paper describes Diet In Nutrients Out (DINO), an integrated dietary assessment system incorporating dietary data entry and nutritional analysis within one platform for use in dietary assessment in small-scale intervention studies to national surveys. DESIGN: DINO contains >6000 food items, mostly aggregated composites of branded foods, across thirty-one main food groups divided into 151 subsidiary groups for detailed reporting requirements, with fifty-three core nutrient fields. SETTING: MRC Human Nutrition Research (HNR), Cambridge, UK and MRC Keneba, Gambia. SUBJECTS: DINO is used across dietary assessment projects at HNR and MRC Keneba. RESULTS: DINO contains macro- and micronutrients as well as additional variables of current research and policy interest, such as caffeine, whole grains, vitamin K and added sugars. Disaggregated data are available for fruit, vegetables, meat, fish and cheese in composite foods, enabling greater accuracy when reporting food consumption or assessing adherence to dietary recommendations. Portion sizes are categorised in metric and imperial weights, with standardised portion sizes for each age group. Regular reviews are undertaken for portion sizes and food composition to ensure contemporary relevance. A training programme and a checking schedule are adhered to for quality assurance purposes, covering users and data. Eating context questions are integrated to record where and with whom the respondent is eating, allowing examination between these factors and the foods consumed. CONCLUSIONS: An up-to-date quality-assured system for dietary assessment is crucial for nutritional surveillance and research, but needs to have the flexibility to be tailored to address specific research questions.

Regular breakfast consumption and type 2 diabetes risk markers in 9- to 10-year-old children in the child heart and health study in England (CHASE): a cross-sectional analysis.

BACKGROUND: Regular breakfast consumption may protect against type 2 diabetes risk in adults but little is known about its influence on type 2 diabetes risk markers in children. We investigated the associations between breakfast consumption (frequency and content) and risk markers for type 2 diabetes (particularly insulin resistance and glycaemia) and cardiovascular disease in children. METHODS AND FINDINGS: We conducted a cross-sectional study of 4,116 UK primary school children aged 9-10 years. Participants provided information on breakfast frequency, had measurements of body composition, and gave fasting blood samples for measurements of blood lipids, insulin, glucose, and glycated haemoglobin (HbA1c). A subgroup of 2,004 children also completed a 24-hour dietary recall. Among 4,116 children studied, 3,056 (74%) ate breakfast daily, 450 (11%) most days, 372 (9%) some days, and 238 (6%) not usually. Graded associations between breakfast frequency and risk markers were observed; children who reported not usually having breakfast had higher fasting insulin (percent difference 26.4%, 95% CI 16.6%-37.0%), insulin resistance (percent difference 26.7%, 95% CI 17.0%-37.2%), HbA1c (percent difference 1.2%, 95% CI 0.4%-2.0%), glucose (percent difference 1.0%, 95% CI 0.0%-2.0%), and urate (percent difference 6%, 95% CI 3%-10%) than those who reported having breakfast daily; these differences were little affected by adjustment for adiposity, socioeconomic status, and physical activity levels. When the higher levels of triglyceride, systolic blood pressure, and C-reactive protein for those who usually did not eat breakfast relative to those who ate breakfast daily were adjusted for adiposity, the differences were no longer significant. Children eating a high fibre cereal breakfast had lower insulin resistance than those eating other breakfast types (p for heterogeneity <0.01). Differences in nutrient intakes between breakfast frequency groups did not account for the differences in type 2 diabetes markers. CONCLUSIONS: Children who ate breakfast daily, particularly a high fibre cereal breakfast, had a more favourable type 2 diabetes risk profile. Trials are needed to quantify the protective effect of breakfast on emerging type 2 diabetes risk. Please see later in the article for the Editors' Summary.

Development of the Eating Choices Index (ECI): a four-item index to measure healthiness of diet.

OBJECTIVE: Current indices of diet quality generally include intakes of specific foods or nutrients. We sought to develop an index that discriminates healthy and unhealthy eating choices for use in large surveys as a short questionnaire and as a measure in existing studies with adequate dietary data. DESIGN: The Eating Choices Index (ECI) score included four components: (i) consumption of breakfast, (ii) consumption of two portions of fruit per day, (iii) type of milk consumed and (iv) type of bread consumed, each providing a score from 1 to 5. In analysis of 5 d food records, the ECI score was examined in relation to macronutrients, fibre, vitamin C, Fe, Ca and folate using Pearson correlations. Variation with sex, BMI, socio-economic status, marital status, smoking status and physical activity were also investigated. SETTING: Medical Research Council National Survey of Health and Development. SUBJECTS: Individuals (n 2256) aged 43 years. RESULTS: The ECI score (mean 12·3 (sd 3·5)) was significantly positively associated with protein, carbohydrate, fibre, vitamin C, Fe, Ca and folate (r = 0·2-0·5; P < 0·001) and significantly negatively associated with fat intake (r = -0·2; P < 0·001); ECI scores were not correlated with total energy intake. Individuals with a lower ECI score were more likely to be men (P < 0·001), overweight or obese (P < 0·001), have lower socio-economic status (P < 0·001), smoke more (P < 0·001) and be less physically active (P < 0·001). CONCLUSIONS: ECI scores correlated with nutrient profiles consistent with a healthy diet. It provides a simple method to rank diet healthiness in large observational studies.

Adult macronutrient intake and physical capability in the MRC National Survey of Health and Development.

BACKGROUND: poor physical capability is associated with higher subsequent risk of disability and mortality in older people. Energy and macronutrient intakes may play a role in the maintenance of physical capability. This analysis aimed to examine the role of intakes of energy and the macronutrients, protein, carbohydrate and fat in early and mid-adulthood on objective measures of physical capability in later adulthood in the MRC National Survey of Health and Development (1946 British birth cohort). METHODS: adult diet assessed by a 5-day diary at 36 years (1982) and 43 years (1989). Physical capability was assessed at 53 years. Objective measures were height, weight and three measures of physical capability: grip strength, standing balance time and chair rises. RESULTS: using multiple linear regression analysis, modest positive associations were found between energy intake at 36 and 43 years and grip strength at 53 years. Results for macronutrients were mixed although there was some indication of relationships of protein intake with grip strength and standing balance time. CONCLUSIONS: higher energy intake in midlife may play a role in the prevention of muscle weakness in later life. Higher protein intakes may also be related to physical capability but further research is needed.

The quality of midday meals eaten at school by adolescents; school lunches compared with packed lunches and their contribution to total energy and nutrient intakes.

OBJECTIVE: To compare food and nutrient intakes from midday meals provided by schools with those from packed lunches and to estimate the contribution from food eaten at midday to the total daily energy and nutrient intakes of teenagers. DESIGN: Dietary data were recorded in 4 d estimated diaries of which 2 d were school days. The school day data were analysed for total and midday energy and nutrient intakes. The latter were compared with the recommendations of the Caroline Walker Trust (CWT). SETTING: Cambridgeshire, UK, 2006. SUBJECTS: Teenagers (n 757) aged 14-15 years, from eighteen secondary schools, who reported food eaten at school. RESULTS: The contribution to total daily energy intake from all lunches eaten at school was 29 % (boys) and 28 % (girls). School meals provided greater quantities of protein, starch, carotene and folate but also more saturated fats and Na than packed lunches. Intakes of energy and several nutrients fell below the CWT recommendations for both types of lunch. School meals and packed lunches provided different types of foods; greater quantities of rice, pasta and vegetables in school meals; more yoghurt, cheese, fruit and juices but also more confectionery and soft drinks in packed lunches. CONCLUSIONS: There has been concern that schoolchildren who are not opting for lunch provided by schools are compromising the overall quality of their diet, but the present study showed small differences in nutrient content between packed and school lunches. These data were collected in 2005­2007 before the government programme of improvements reached secondary schools.

Patterns of sociodemographic and food practice characteristics in relation to fruit and vegetable consumption in children: results from the U.K. National Diet and Nutrition Survey Rolling Programme (2008-2010).

OBJECTIVE: Few studies have considered the combined effects of home-related determinants on children's diet. The present study investigated independent associations between sociodemographic and food practice (SFP) characteristics and fruit and vegetable consumption in U.K. children and the combined effects of SFP on consumption using pattern analysis. DESIGN: Diet was assessed using 4 d food diaries, SFP were collected using computer-assisted personal interview. Linear regressions were used to test associations; principal component analysis was used to identify patterns of SFP characteristics. Regression of fruit (g/d) and vegetables (g/d) v. component scores of each pattern were performed. SETTING: U.K. National Diet and Nutrition Survey Rolling Programme (2008­2010). SUBJECTS: Children aged 1.5­10 years (n 642). RESULTS: Significant associations were found between fruit and vegetable consumption and household socio-economic status. Pattern 1, which was positively correlated with household structure characteristics, was associated with increased fruit consumption (P < 0.001). Pattern 2, characterised by positive correlations for socio-economic status, fruit availability and organic food purchase, and negatively correlated with household size and the number of children per household, was associated with higher fruit and vegetable consumption (both P < 0.001). Pattern 3, characterised by high frequency of eating out and eating takeaway, was associated with a lower consumption of both fruit (P < 0.012) and vegetables (P < 0.023). CONCLUSIONS: Patterns of SFP determinants may be more informative than individual characteristics in relation to dietary outcomes. Results have public health implications on the healthfulness of meals eaten out of home and in takeaways, as well as the need to reduce diet inequality in larger households with lower socio-economic status.

Vitamins, minerals, essential fatty acids and colorectal cancer risk in the United Kingdom Dietary Cohort Consortium.

The risk for colorectal cancer may be influenced by the dietary intake of various vitamins, minerals and essential fatty acids. We conducted a pooled analysis of dietary data collected using food diaries in seven prospective studies in the United Kingdom Dietary Cohort Consortium. Five hundred sixty-five cases of colorectal cancer were matched with 1,951 controls on study centre, age, sex and recruitment date. Dietary intakes of retinol, vitamin A, thiamin, riboflavin, vitamin B6, folate, vitamin B12, vitamin D, calcium, iron, magnesium, potassium, n - 6 fatty acids, n - 3 fatty acids and the ratio of n - 6 to n - 3 fatty acids were estimated and their associations with colorectal cancer examined using conditional logistic regression models, adjusting for exact age, height, weight, energy intake, alcohol intake, fiber intake, smoking, education, social class and physical activity. There were no statistically significant associations between colorectal cancer risk and dietary intake of any of the vitamins, minerals or essential fatty acids examined.

Assessing eating context and fruit and vegetable consumption in children: new methods using food diaries in the UK National Diet and Nutrition Survey Rolling Programme.

BACKGROUND: Eating context is the immediate environment of each eating occasion (EO). There is limited knowledge on the effects of the eating context on food consumption in children, due to the difficulty in measuring the multiple eating contexts children experience throughout the day. This study applied ecological momentary assessment using food diaries to explore the relationships between eating context and fruit and vegetable consumption in UK children. METHODS: Using 4 d unweighed food diaries, data were collected for 642 children aged 1.5-10y in two years of the UK National Diet and Nutrition Survey (2008-2010). Participants recorded all foods and drinks consumed at each EO, where and with whom the food was consumed, whether the TV was on and if eaten at a table. Mixed logistic regression and mixed multinomial logistic regression were used to calculate associations between eating contexts and fruit and vegetables (FV) consumed by quartiles. RESULTS: Of 16,840 EOs, 73% took place at home and 31% with parents only. Frequency of eating alone and with friends increased with age. Compared to eating at home, children aged 1.5-3y were more likely to consume fruit at care outside home (>10-50g OR:2.39; >50-100g OR:2.12); children aged 4-6y were more likely to consume fruit (>50-100g OR:3.53; >100g OR:1.88) and vegetables at school (>30-60g OR:3.56). Compared to eating with parents only, children aged 1.5-3y were more likely to consume fruit with friends (>10-50g OR:2.69; >50-100g OR:3.49), and with carer and other children/others (>10-50g OR:2.25); children aged 4-6y were more likely to consume fruit (>50-100g OR:1.96) and vegetables with friends (>30-60g OR:3.56). Children of all ages were more likely to eat vegetables when the TV was off than on and at a table than not at table. CONCLUSIONS: The use of food diaries to capture multiple eating contexts and detailed fruit and vegetable consumption data was demonstrated at a population level. Higher odds of FV consumption were seen from structured settings such as school and care outside home than at home, as well as when eating at a table and the TV off. This study highlights eating contexts where provision of fruit and vegetables could be improved, especially at home. Future research should take eating context into consideration when planning interventions to target children's food consumption and eating behaviour.

National Diet and Nutrition Survey: fat and fatty acid intake from the first year of the rolling programme and comparison with previous surveys.

High saturated fat intake is an established risk factor for several chronic diseases. The objective of the present study is to report dietary intakes and main food sources of fat and fatty acids (FA) from the first year of the National Diet and Nutrition Survey (NDNS) rolling programme in the UK. Dietary data were collected using 4 d estimated food diaries (n 896) and compared with dietary reference values (DRV) and previous NDNS results. Total fat provided 34-36 % food energy (FE) across all age groups, which was similar to previous surveys for adults. Men (19-64 years) and older girls (11-18 years) had mean intakes just above the DRV, while all other groups had mean total fat intakes of < 35 % FE. SFA intakes were lower compared with previous surveys, ranging from 13 to 15 % FE, but still above the DRV. Mean MUFA intakes were 12·5 % FE for adults and children aged 4-18 years and all were below the DRV. Mean n-3 PUFA intake represented 0·7-1·1 % FE. Compared with previous survey data, the direction of change for n-3 PUFA was upwards for all age groups, although the differences in absolute terms were very small. Trans-FA intakes were lower than in previous NDNS and were less than 2 g/d for all age groups, representing 0·8 % FE and lower than the DRV in all age groups. In conclusion, dietary intake of fat and FA is moving towards recommended levels for the UK population. However, there remains room for considerable further improvement.

Estimating the alcohol-breast cancer association: a comparison of diet diaries, FFQs and combined measurements.

The alcohol-breast cancer association has been established using alcohol intake measurements from Food Frequency Questionnaires (FFQ). For some nutrients diet diary measurements are more highly correlated with true intake compared with FFQ measurements, but it is unknown whether this is true for alcohol. A case-control study (656 breast cancer cases, 1905 matched controls) was sampled from four cohorts in the UK Dietary Cohort Consortium. Alcohol intake was measured prospectively using FFQs and 4- or 7-day diet diaries. Both relied on fixed portion sizes allocated to given beverage types, but those used to obtain FFQ measurements were lower. FFQ measurements were therefore on average lower and to enable fair comparison the FFQ was "calibrated" using diet diary portion sizes. Diet diaries gave more zero measurements, demonstrating the challenge of distinguishing never-from episodic-consumers using short term instruments. To use all information, two combined measurements were calculated. The first is an average of the two measurements with special treatment of zeros. The second is the expected true intake given both measurements, calculated using a measurement error model. After confounder adjustment the odds ratio (OR) per 10 g/day of alcohol intake was 1.05 (95 % CI 0.98, 1.13) using diet diaries, and 1.13 (1.02, 1.24) using FFQs. The calibrated FFQ measurement and combined measurements 1 and 2 gave ORs 1.10 (1.03, 1.18), 1.09 (1.01, 1.18), 1.09 (0.99,1.20), respectively. The association was modified by HRT use, being stronger among users versus non-users. In summary, using an alcohol measurement from a diet diary at one time point gave attenuated associations compared with FFQ.

Benefits of dietary fibre for children in health and disease.

Fibre is an essential nutrient in the human diet that is crucial for human health. It provides a range of functional benefits, including stool bulking, and physiological benefits through fermentation of diverse fibre types by the gut microbiome including cholesterol lowering, glycaemic control and weight control. The by-products of the fermentation of fibre in the gut confer health benefits that extend beyond the gut to the immune system and organs such as the liver, kidneys and the brain. A lack of fibre in the diet has been associated with several disorders in children including constipation, irritable bowel syndrome, allergies and immune-related disorders. In paediatric practice, concerns exist over tolerance of dietary fibre which may lead to unnecessary restrictions, especially for children receiving nutritional support. One reason for this may be the terminology which has historically been used. Fibre is often described in terms of its physico-chemical properties (solubility, viscosity), rather than its physiological effects/functionality (fermentability, bulking effects). To describe fibre in these latter terms represents more clearly the important role it plays. Most international guidelines recommend a daily quantity of fibre, failing to mention the quality aspect of the fibre required for health. Here we consider the evidence base for the current recommendations for daily fibre intakes for healthy children, those requiring nutritional support and those with functional gastrointestinal disorders. We also consider the importance of the gut microbiome and the role of fibre in maintaining gut microbial health and its role in health beyond the gut.

National Diet and Nutrition Survey: UK food consumption and nutrient intakes from the first year of the rolling programme and comparisons with previous surveys.

The National Diet and Nutrition Survey (NDNS) is a cross-sectional survey designed to gather data representative of the UK population on food consumption, nutrient intakes and nutritional status. The objectives of the present paper were to identify and describe food consumption and nutrient intakes in the UK from the first year of the NDNS rolling programme (2008-09) and compare these with the 2000-01 NDNS of adults aged 19-64 years and the 1997 NDNS of young people aged 4-18 years. Differences in median daily food consumption and nutrient intakes between the surveys were compared by sex and age group (4-10 years, 11-18 years and 19-64 years). There were no changes in energy, total fat or carbohydrate intakes between the surveys. Children aged 4-10 years had significantly lower consumption of soft drinks (not low calorie), crisps and savoury snacks and chocolate confectionery in 2008-09 than in 1997 (all P < 0·0001). The percentage contribution of non-milk extrinsic sugars to food energy was also significantly lower than in 1997 in children aged 4-10 years (P < 0·0001), contributing 13·7-14·6 % in 2008-09 compared with 16·8 % in 1997. These changes were not as marked in older children and there were no changes in these foods and nutrients in adults. There was still a substantial proportion (46 %) of girls aged 11-18 years and women aged 19-64 years (21 %) with mean daily Fe intakes below the lower reference nutrient intake. Since previous surveys there have been some positive changes in intakes especially in younger children. However, further attention is required in other groups, in particular adolescent girls.

Meat, poultry and fish and risk of colorectal cancer: pooled analysis of data from the UK dietary cohort consortium.

OBJECTIVE: Some but not all epidemiological studies have reported that high intakes of red and processed meat are associated with an increased risk of colorectal cancer. In the UK Dietary Cohort Consortium, we examined associations of meat, poultry and fish intakes with colorectal cancer risk using standardised individual dietary data pooled from seven UK prospective studies. METHODS: Four- to seven-day food diaries were analysed, disaggregating the weights of meat, poultry and fish from composite foods to investigate dose-response relationships. We identified 579 cases of colorectal cancer and matched with 1,996 controls on age, sex and recruitment date. Conditional logistic regression models were used to estimate odds ratios for colorectal cancer associated with meat, poultry and fish intakes, adjusting for relevant covariables. RESULTS: Disaggregated intakes were moderately low, e.g. mean red meat intakes were 38.2 g/day among male and 28.7 g/day among female controls. There was little evidence of association between the food groups examined and risk for colorectal cancer: Odds ratios (95% confidence intervals) for a 50 g/day increase were 1.01 (0.84-1.22) for red meat, 0.88 (0.68-1.15) for processed meat, 0.97 (0.84-1.12) for red and processed meat combined, 0.80 (0.65-1.00) for poultry, 0.92 (0.70-1.21) for white fish and 0.89 (0.70-1.13) for fatty fish. CONCLUSIONS: This study using pooled data from prospective food diaries, among cohorts with low to moderate meat intakes, shows little evidence of association between consumption of red and processed meat and colorectal cancer risk.

Dietary fibre and phytate--a balancing act: results from three time points in a British birth cohort.

An investigation was carried out to determine whether there were significant changes in the intake of dietary fibre (NSP) and phytate of adult men and women in the UK from 1982 (aged 36 years) to 1999 (aged 53 years). The 1253 subjects studied were members of the Medical Research Council National Survey of Health and Development; a longitudinal study of a nationally representative cohort of births in 1946. Food intake was recorded in a 5 d diary at age 36 years in 1982, 43 years in 1989 and 53 years in 1999. The food composition database was amended with revised values for phytate. Outcome measures were mean intakes of total NSP and phytate by year, sex and food source. There were significant changes in total NSP and phytate intake over the three time points. Intakes of NSP rose significantly between 1982 and 1999 for men and women but phytate intakes rose significantly only between 1989 and 1999. Cereal foods were the most important source of both NSP and phytate. Between 1989 and 1999 there was a significant increase in the contribution from pasta, rice and other grains. The present study shows that an increase in dietary fibre that is in accordance with dietary guidelines would almost inevitably be accompanied by a rise in phytate. The increased dietary phytate is discussed in relation to its recognised inhibition of mineral absorption and its merits with regard to protection against some cancers and other diseases of an ageing population.

An algorithm to assess intestinal iron availability for use in dietary surveys.

In nutritional epidemiology, it is often assumed that nutrient absorption is proportional to nutrient intake. For several nutrients, including non-haem Fe, this assumption may not hold. Depending on the nutrients ingested with non-haem Fe, its availability for absorption varies greatly. Therefore, using Fe intake to examine associations between Fe and health can impact upon the validity of findings. Previous algorithms that adjust Fe intakes for dietary factors known to affect absorption have been found to underestimate Fe absorption and, in the present study, perform poorly on independent dietary data. We have designed a new algorithm to adjust Fe intakes for the effects of ascorbic acid, meat, fish and poultry, phytate, polyphenols and Ca, incorporating not only absorption data from test meals but also current understanding of Fe absorption. In so doing, we have created a robust and universal Fe algorithm with potential for use in large cohorts. The algorithm described aims not to predict Fe absorption but available Fe in the gut, a measure we believe to be of greater use in epidemiological research. Available Fe is Fe available for absorption from the gastrointestinal tract, taking into account enhancing or inhibiting effects of dietary modifiers. Our algorithm successfully estimated average Fe availability in test meal data used to construct the algorithm and, unlike other algorithms tested, also provided plausible predictions when applied to independent dietary data. Future research is needed to evaluate the extent to which this algorithm is useful in epidemiological research to relate Fe to health outcomes.

The effect of different meals on the absorption of stable isotope-labelled phylloquinone.

Few studies have investigated the absorption of phylloquinone (vitamin K1). We recruited twelve healthy, non-obese adults. On each study day, fasted subjects took a capsule containing 20 microg of 13C-labelled phylloquinone with one of three meals, defined as convenience, cosmopolitan and animal-oriented, in a three-way crossover design. The meals were formulated from the characteristics of clusters identified in dietary pattern analysis of data from the National Diet and Nutrition Survey conducted in 2000-1. Plasma phylloquinone concentration and isotopic enrichment were measured over 8 h. Significantly more phylloquinone tracer was absorbed when consumed with the cosmopolitan and animal-oriented meals than with the convenience meal (P = 0.001 and 0.035, respectively). Estimates of the relative availability of phylloquinone from the meals were: convenience meal = 1.00; cosmopolitan meal = 0.31; animal-oriented meal = 0.23. Combining the tracer data with availability estimates for phylloquinone from the meals provides overall relative bioavailability values of convenience = 1.00, cosmopolitan = 0.46 and animal-oriented = 0.29. Stable isotopes provide a useful tool to investigate further the bioavailability of low doses of phylloquinone. Different meals can affect the absorption of free phylloquinone. The meal-based study design used in the present work provides an approach that reflects more closely the way foods are eaten in a free-living population.

Feasibility of an estimated method using graduated utensils to estimate food portion size in infants aged 4 to 18 months.

The Diet and Nutrition Survey of Infants and Young Children (DNSIYC) was carried out in 2011 to assess the nutrient intakes of 4 to 18 month old infants in the UK. Prior to the main stage of DNSIYC, pilot work was undertaken to determine the impact of using graduated utensils to estimate portion sizes. The aims were to assess whether the provision of graduated utensils altered either the foods given to infants or the amount consumed by comparing estimated intakes to weighed intakes. Parents completed two 4-day food diaries over a two week period; an estimated diary using graduated utensils and a weighed diary. Two estimated diary formats were tested; half the participants completed estimated diaries in which they recorded the amount of food/drink served and the amount left over, and the other half recorded the amount of food/drink consumed only. Median daily food intake for the estimated and the weighed method were similar; 980g and 928g respectively. There was a small (6.6%) but statistically significant difference in energy intake reported by the estimated and the weighed method; 3189kJ and 2978kJ respectively. There were no statistically significant differences between estimated intakes from the served and left over diaries and weighed intakes (p>0.05). Estimated intakes from the amount consumed diaries were significantly different to weighed intakes (food weight (g) p = 0.02; energy (kJ) p = 0.01). There were no differences in intakes of amorphous (foods which take the shape of the container, e.g. pureed foods, porridge) and discrete food items (individual pieces of food e.g. biscuits, rice cakes) between the two methods. The results suggest that the household measures approach to reporting portion size, with the combined use of the graduated utensils, and recording the amount served and the amount left over in the food diaries, may provide a feasible alternative to weighed intakes.