In vitro estimation of iron availability from a range of plant foods: influence of phytate, ascorbate and citrate

Plant foods were digested in vitro and the proportion of iron which diffused across a semi-permeable membrane was used as an index of Fe availability. The mean (with SEM) Fe diffusibility from a group of eighteen cereals, legumes and nuts was very low, 2.1 (0.25)%, whereas from a group of sixteen fruits and vegetables it was high, 31.7 (1.09)%. The difference between the two food groups was highly significant (P less than 0.001). The results for Fe diffusibility correlated well with literature values for the in vivo absorption of Fe from similar foods (r0.84, P less than 0.01). When phytate, citrate and ascorbate were added to selected foods in amounts corresponding to endogenous levels, only phytate and citrate gave the expected effects on Fe diffusibility. Ascorbate only enhanced Fe diffusibility to the expected extent when it was added in much larger amounts, not normally found in foods. When added to cereal foods, orange juice was found to enhance greatly Fe diffusibility even when its content of ascorbate was completely destroyed by boiling followed by prolonged storage. When citrate and ascorbate were added to cereal foods in amounts equivalent to those found in fresh orange juice, both enhanced Fe diffusibility but citrate was far more effective. It is concluded that phytate is a major inhibitor of Fe diffusibility in cereals, legumes and nuts. However, citrate rather than ascorbate would appear to be the major enhancer of Fe diffusibility from many fruits and vegetables. The implications of the present results are discussed in relation to the relative influence of phytate, citrate and ascorbate on dietary Fe availability.     

Key foods in Sweden: Identifying high priority foods for future food composition analysis

High quality food composition data are essential in cutting-edge research, for example on diet and health, so regular updates and improvements of food composition data are necessary. However, food analyses are expensive, and for optimal use of resources, tools to aid prioritisation are required. This study sought to identify key foods in the Swedish diet, in order to set priorities for future nutrient analyses of foods. A slightly modified version of the key foods approach developed by the Nutrient Data Laboratory in the United States was used. Existing nutrient values were combined with food consumption data from the national dietary survey Riksmaten Adults 2010–11. Key foods were identified group-wise using key nutrients for each food group. Of the 1894 foods included in the survey, 320 (17%) were identified as key foods contributing 75% of intake of the key nutrients in each food group. These key foods will be prioritised in future food composition analyses.     

Importance of food composition data to nutrition and public health

INTRODUCTION: Adequate nutrition is one of the pillars of public health. Before developing and implementing effective intervention programmes to improve nutrition at the population level, it is important to know the nutritional situation of the target group. ASSESSMENT OF ENERGY AND NUTRIENT INTAKE: The estimation of nutrient intake from food consumption requires reliable data on food composition. These data are also the fundamentals of food-based dietary guidelines for healthy nutrition, containing the necessary information on food sources for different nutrients. Furthermore, food composition tables can provide information on chemical forms of nutrients and the presence and amounts of interacting components, and thus provide information on their bioavailability. For some nutrients such as vitamin A, vitamin E and niacin, the concept of equivalence has been introduced to account for differences in the availability and biological activity of different chemical forms. NON-NUTRITIVE FOOD COMPONENTS: Although most food composition tables focus on energy, macro- and micronutrients, interest in non-nutritive components is increasing. Considering the beneficial effects of biologically active secondary plant cell compounds such as polyphenols and carotenoids, more data on these are needed. On the other hand, there are a number of naturally occurring or 'man-made' non-nutritive substances with negative effects, and to control exposure, the main dietary sources must be known. Another aspect is contaminants, which could have detrimental effects on consumers' health. Among these are agrochemicals, industrial pollutants reaching the food chain and substances formed during food preparation. A valid risk assessment requires data on exposure, and thus on the contents of contaminants in foods. However, these data are highly variable and may significantly differ even within narrowly confined regions. CURRENT FOOD COMPOSITION DATABASES ARE FAR FROM COMPLETE: The fact that composition tables generally do not provide information about the origin of substances found in food can also influence their usability. For example, the German Nutrient Data base does not discriminate between naturally occurring and added sucrose impeding the estimation of added sucrose intake that should be limited. Points of focus: Considering the increasing number of persons relying on community nutrition and catering, healthy menu lines can improve the consumers' diets and contribute to nutrient supply. The development and implementation of appropriate guidelines also need food composition databases (FCBs) to compose meals. The ever-increasing number of new food preparations and manufactured products has resulted in a need for procedures for regularly updated data. Moreover, there is a lack of data particularly for essential trace elements such as copper, chromium or molybdenum and also vitamin K, as well as the already mentioned non-nutritive components. Limited comparability between countries is another issue. Regional differences arise especially from the use of local varieties, different soil quality or meteorological aspects. This variability is further increased with composite meals because of variation in recipes. CONCLUSION: Information about food composition is necessary for the assessment of diet quality and the development and application of food-based dietary guidelines, providing a useful tool for the field of public health nutrition. In this regard, more attention should be paid to the preparation, extension and maintenance of FCBs.     

Reduction in estimated vitamin A intake induced by new food composition tables in Japan, where vitamin A is taken mostly from plant foods

A revised edition of the standard tables of food composition was implemented in Japan in 2005; one of the major revision points is the change of retinol activity equivalents for pro-vitamin A carotenoids. This preliminary analysis was conducted to examine whether the revision affects the estimation of vitamin A intake; and if so, to what extent. Accordingly, a field survey was conducted to collect 24-h duplicates of daily foods of citizens, and 26 adult women volunteered. Application of the procedures in the new and previous standard tables of food composition gave 537 microg retinol activity equivalent and 704 microg retinol equivalence, respectively, for daily vitamin A intake. Thus, the changes in retinol activity equivalents induced substantial reduction (by 24%) in estimation of vitamin A intake among the Japanese population, for whom pro-vitamin A carotenoids in plant foods are the major sources (76%) for vitamin A, and retinol accounts for only 35% (on the retinol activity equivalent basis).     

Reduction in estimated vitamin A intake induced by new food composition tables in Japan,where vitamin A is taken mostly from plant foods

A revised edition of the standard tables of food composition was implemented in Japan in 2005; one of the major revision points is the change of retinol activity equivalents for pro-vitamin A carotenoids. This preliminary analysis was conducted to examine whether the revision affects the estimation of vitamin A intake; and if so, to what extent. Accordingly, a field survey was conducted to collect 24-h duplicates of daily foods of citizens, and 26 adult women volunteered. Application of the procedures in the new and previous standard tables of food composition gave 537 µg retinol activity equivalent and 704 µg retinol equivalence, respectively, for daily vitamin A intake. Thus, the changes in retinol activity equivalents induced substantial reduction (by 24%) in estimation of vitamin A intake among the Japanese population, for whom pro-vitamin A carotenoids in plant foods are the major sources (76%) for vitamin A, and retinol accounts for only 35% (on the retinol activity equivalent basis).     

Comparison of national food supply,household food availability and individual food consumption data in Portugal

The present study aimed to compare Portuguese food and nutrient data retrieved from three distinct sources of dietary data: national food supply, household food availability and individual food consumption. In particular it was intended to validate the use of the dietary data derived from the Portuguese household budget surveys (HBS). The data sources used were food balance sheets (FBS) (1990, 1995 and 2000) generated by the Food and Agriculture Organization (FAO), HBS (1990, 1995 and 2000) collected by the National Statistics Institute (INE) and individual consumption obtained through a food frequency questionnaire (FFQ) applied in the context of the EpiPorto study circa 2000. Thirteen comparable food groups were established for analysis. Total energy, macronutrients and other selected dietary components were considered. The average daily values of different dietary sources were compared in absolute amounts (g/person per day) and in relative energy contribution (%E). To evaluate association and agreement between sources, Spearman’s correlation coefficients and distance matrices based on Euclidian distances were computed. The obtained average daily per capita amounts reflect the different points of data collection in the food chain; HBS fall in the expected position, below FBS and closer to FFQ. Agreement between FBS, HBS and FFQ was higher when data were expressed in relative energy contribution than when absolute amounts were considered. In general, the observed discrepancies between the three data sources could be attributed to known differences in the methodological approaches. This study supports the finding that despite their constraints the HBS-derived data are a valid option to evaluate dietary habits in Portugal.     

An animal model to study iron availability from human diets.

1. The retention of ferric- and ferrous-iron was determined in guinea-pigs and monkeys using 55Fe and 59Fe. 2. The bioavailability of Fe from two typical Indian diets based on rice and wheat was determined in humans and monkeys using a 59Fe tracer and whole-body counting. 3. The retention ratio, ferric-Fe; ferrous-Fe was 0-90 in guinea-pigs and 0-33 in monkeys, indicating that monkeys absorb ferrous-Fe preferentially. 4. In monkeys retention of Fe from the test diets, as from ferrous ascorbate was lower than that in humans. 5. When food-Fe retention was expressed in relation to inorganic-Fe retention the value for retention ratio, food Fe: inorganic Fe in monkeys was similar to that in human subjects. 6. The results indicate that the monkey can be used as a model to study Fe absorption from human diets.     

Optimising food composition data flow within the UK food supply chain and to external stakeholders

The UK national food composition tables provide reasonable coverage of primary produce and basic raw and cooked foods, but it is difficult for them to keep abreast of the fast moving processed and convenience food market. The food industry has an inherent need to generate and share food composition data on food products and therefore many of these data exist within the food industry, embedded in their core Enterprise and Resource Planning (ERP) software. A survey was conducted to explore the current uses and flow of food composition data within the UK food supply chain, and identify potential barriers to effective data transfer. Results indicate that providing food composition data is perceived as a frustrating, time-consuming task, and limitations lie in the lack of commonly agreed systems, processes and standards for the transfer of these data from those who generate it to those who need it. Within logistics and finance functions, industry is moving closer to a completely collaborative model via implementation of the Global Data Synchronisation Network (GDSN) infrastructure and methodology. This approach, if implemented for food composition data, has the potential to enable high quality food composition data to be accessible ‘at the push of a button’.     

Measuring availability of healthy foods: agreement between directly measured and self-reported data

A major challenge in studies of the impact of the local food environment is the accuracy of measures of healthy food access. The authors assessed agreement between self-reported and directly measured availability of healthful choices within neighborhood food stores and examined the validity of reported availability using directly measured availability as a "gold standard." Reported availability was measured via a phone survey of 1,170 adults in Baltimore, Maryland, in 2004. Directly measured availability was assessed in 226 food stores in 2006 using a modified Nutrition Environment Measures Survey in Stores (NEMS-S). Whites, college-educated individuals, and higher income households (≥$50,000) had significantly higher reported and directly measured availability than did blacks, those with less education, and lower income households. Persons in areas with above average directly measured availability reported above average availability 70%-80% of the time (sensitivity = 79.6% for all stores within 1 mile (1.6 km) of participants' homes and 69.6% for the store with the highest availability within 1 mile). Those with below average directly measured availability reported low availability only half the time. With revisions to improve specificity, self-reported measures can be reasonable indicators of healthy food availability and provide feasible proxy measures of directly assessed availability.     

Protein and starch digestibility and iron availability in developed weaning foods as affected by roasting

Locally available cereals and pulses such as rice ( Oryza sativa ), kangini ( Setaria italica ), sanwak ( Echinochloa frumentacea ), green gram [Vigna radiata) and jaggery (unrefined brown sugar) were used to formulate three weaning foods. Cereal, pulse and jaggery were mixed in the ratio of 70:30:25. Roasting was the main processing technique used in the formulation of these weaning foods. The developed weaning foods were found to be economical and acceptable. The chemical composition of developed weaning foods was within the range prescribed by Indian Standard Institute (ISI). On roasting, in vitro protein and starch digestibility of weaning foods increased by 15–21% and 16–19%, respectively. Roasting also improved in vitro iron availability by 12–19%. These observations indicated that the weaning foods prepared from locally available food ingredients resulted in significant improvement in protein and starch digestibility and iron availability and could be used as supplements for meeting the nutritional requirements of infants.     

Vitamin E content of foods: comparison of results obtained from food composition tables and HPLC analysis

BACKGROUND & AIMS: Data on vitamin E content of foods are essential for nutrition research and its application. The aim of this study was to investigate the precision of calculated vitamin E content of prepared meals. METHODS: The vitamin E content of 69 dishes of a menu cycle sampled at two occasions were calculated using 4 different food composition tables (FCT) and measured by HPLC. RESULTS: Data were complete for 50-69 dishes. The proportion of dishes with differences between FCTs < or = 20% were 17-100%. Differences between HPLC and the Souci-Fachmann-Kraut table were < or = 20% in 8/46 dishes for alpha- and in 14/46 dishes for gamma-tocopherol. Differences fell in the order of baked > raw > fried/roasted > boiled > mixed prepared foods. The 2 samplings taken 6 months apart showed considerable differences. CONCLUSIONS: There are substantial differences in calculated/measured vitamin E content of prepared foods: (i) between different FCTs; (ii) between FCTs and HPLC, and (iii) between different seasons. This can be explained by intrinsic variability (breeding, season, country of origin, ripeness, freshness) and food processing, as well as selection of FCTs and should be taken into account when interpreting data of dietary intervention studies.     

Generating fatty acid and vitamin D composition data of Indonesian foods

The Indonesian food composition table lacks data on individual fatty acids; data on vitamin D is incomplete. The primary aim of this study was to generate data on individual fatty acid content of Indonesian foods. Secondary objective was to analyze vitamin D content. Based on intake data of 4–12 year old children from a nationally representative Indonesian survey, 120 foods contributing 95% to children’s total polyunsaturated fatty acid intake were selected for chemical analysis of fat and fatty acid content. Vitamin D3 was analyzed in a subset of 60 foods. Food samples were collected throughout Indonesia; per food one representative composite sample was chemically analyzed. Of the analyzed foods, sardines (0.97 g/100 g), tempeh (0.62 g/100 g) and tofu (0.56 g/100 g) had the highest n-3 fatty acids content, peanuts (15.9 g/100 g) and palm oil (11.4 g/100 g) were richest in n-6 fatty acids. Vitamin D3 content in foods was limited. This paper significantly contributes to the current knowledge on the fatty acid and vitamin D content of a broad range of commonly consumed Indonesian foods, which can be used in future research to monitor dietary intake and guide policy makers and the food industry to steer nutrient intake in the Indonesian population.     

Quality control materials development for proximate composition determination in baby foods to enhance the Portuguese food composition database: Packaging conditions

Food matrix reference materials play an important role in the quality of data used in food composition databanks concerning the precision, trueness and accuracy of analytical values. In this work the feasibility studies according to ISO 34 (ISO, 2000) of two commercial baby foods (ready-to-eat baby soup and milk-based powdered infant formula) were evaluated to check for their suitability as quality control materials for the analysis of moisture, protein, fat, ash and acidity. The suitability of plastic packaging materials to guarantee the reference materials’ characteristics is discussed. Official methods of analysis were used to evaluate the homogeneity and to monitor short-term and long-term stability studies. ANOVA was carried out to confirm homogeneity within and between samples. ISO 34 method was applied to monitor stability at different temperatures. The coefficients of variation obtained between sachets for milk-based powdered infant formula were less than 4.4% for moisture and 0.5% for fat. The stability data over 8.5 months storage period at 20 °C, 5 °C and ?20 °C and ?70 °C indicate that both materials are stable depending on the parameter studied and temperature. According to results, quality control materials (QCMs) prepared in agreement with ISO 34 requirements are a valuable tool in food composition analysis.