This review covers current knowledge of selenium in the environment, dietary intakes, metabolism and status, functions in the body, thyroid hormone metabolism, antioxidant defense systems and oxidative metabolism, and the immune system. Selenium toxicity and links between deficiency and Keshan disease and Kashin-Beck disease are described. The relationships between selenium intake/status and various health outcomes, in particular gastrointestinal and prostate cancer, cardiovascular disease, diabetes, and male fertility, are reviewed, and recent developments in genetics of selenoproteins are outlined. The rationale behind current dietary reference intakes of selenium is explained, and examples of differences between countries and/or expert bodies are given. Throughout the review, gaps in knowledge and research requirements are identified. More research is needed to improve our understanding of selenium metabolism and requirements for optimal health. Functions of the majority of the selenoproteins await characterization, the mechanism of absorption has yet to be identified, measures of status need to be developed, and effects of genotype on metabolism require further investigation. The relationships between selenium intake/status and health, or risk of disease, are complex but require elucidation to inform clinical practice, to refine dietary recommendations, and to develop effective public health policies.

Selenium in human health and disease.

The intent of this chapter is to enhance understanding of various dietary assessment methods so that the most appropriate method for a particular need is chosen. This review focuses only on individual level food intake assessment. It is intended to serve as a resource for those who wish to assess diet in a research study using individual measurements for group level analysis. The chapter reviews major dietary assessment methods, their advantages and disadvantages, and validity; describes which dietary assessment methods are appropriate for different types of studies and populations; and discusses specific issues that relate to all methods.

Dietary Assessment Methodology

Objectives: To estimate global, regional (21 regions) and national (187 countries) sodium intakes in adults in 1990 and 2010. Design: Bayesian hierarchical modelling using all identifiable primary sources. Data sources and eligibility: We searched and obtained published and unpublished data from 142 surveys of 24 h urinary sodium and 103 of dietary sodium conducted between 1980 and 2010 across 66 countries. Dietary estimates were converted to urine equivalents based on 79 pairs of dual measurements. Modelling methods: Bayesian hierarchical modelling used survey data and their characteristics to estimate mean sodium intake, by sex, 5 years age group and associated uncertainty for persons aged 20+ in 187 countries in 1990 and 2010. Country-level covariates were national income/person and composition of food supplies. Main outcome measures: Mean sodium intake (g/day) as estimable by 24 h urine collections, without adjustment for non-urinary losses. Results: In 2010, global mean sodium intake was 3.95 g/day (95% uncertainty interval: 3.89 to 4.01). This was nearly twice the WHO recommended limit of 2 g/day and equivalent to 10.06 (9.88–10.21) g/day of salt. Intake in men was ∼10% higher than in women; differences by age were small. Intakes were highest in East Asia, Central Asia and Eastern Europe (mean >4.2 g/day) and in Central Europe and Middle East/

https://bmjopen.bmj.com/content/bmjopen/3/12/e003733.full.pdf

Global, regional and national sodium intakes in 1990 and 2010: a systematic analysis of 24 h urinary sodium excretion and dietary surveys worldwide

The EFSA Comprehensive European Food Consumption Database (Comprehensive Database) has been built from existing national information on food consumption at a detailed level. Competent organisations in the European Union's Member States provided EFSA with data from those most recent national dietary survey in their country, at the level of consumption by the individual consumer. This included food consumption data concerning infants (2 surveys from 2 Member States), toddlers (8 surveys from 8 Member States), children (16 surveys from 14 Member States), adolescents (14 surveys from 12 Member States), adults (21 surveys from 20 Member States), elderly (9 surveys from 9 Member States) and very elderly (8 surveys from 8 Member States) for a total of 32 different dietary surveys carried out in 22 different Member States. Surveys on children were mainly obtained through the Article 36 project. Individual food consumption data and exposure assessment studies for children (acronym EXPOCHI). The aim of the present document is to give an overview of the Comprehensive Database and to provide guidance on its use for dietary exposure assessments. Summary statistics of this database are available on the EFSA website.

Guidance of EFSA: Use of the EFSA Comprehensive European Food Consumption Database in exposure assessment

https://www.drtsoukalas.com/uploads/file/SODIUM%20INTAKE%20HYPERTENSION%20FINLAND.pdf

Sodium intake and hypertension.

In diet surveys, quantitative underestimation of food consumption may be due to intentional misreporting or false portion-size reporting. Perception of food photographs used as aids for assessing the actual amounts may have an effect. This study was carried out to assess the validity of food photographs. A real-time test protocol where 52 presented food servings were compared against photographed portions with similar food items. Volunteers from the Rehabilitation Company Petrea (in Turku) were recruited, 161 adults participated, and for 146 subjects, complete data were collected. The proportions of correct estimations and reporting errors, in weights and percentages, are presented by gender and food group. Food descriptors, portion-size options and subject characteristics were studied as potential determinants of accuracy in portion-size estimation. The total proportion of exactly correct estimations was 51% in men and 49% in women. The overall reporting error was −10 g in men and +1 g in women for the 52 food servings. Underreporting was typical for bread, spread and cold cuts and dishes in both genders. Over-reporting was typical for cereals in both genders and for snacks, vegetables and fruit in women. The estimation error was associated with the portion-size options but not associated with the energy density of food items, education or body mass index. Food portions in photographs seem to be a useful aid for the quantification of most food items. However, validation studies are needed to test the applicability of photographs for estimating current portions and for searching better tools in dietary surveys.

Accuracy in the estimation of food servings against the portions in food photographs.

Objective To estimate cross-sectional and long-term dietary sodium intakes and sources in Finland, and to evaluate the validity of 48-h recall to assess sodium intake. Design Cross-sectional dietary surveys and food availability data (Food Balance Sheets). Setting Dietary surveys were carried out in Finland in 1992, 1997 and 2002. Food availability data were collected from 1980 to 1999. Subjects A stratified random sample was drawn from the population register. The total number of participants in the three dietary surveys was 6730. In the subsample for urine collection, the number of participants was 879. Interventions Nutrient intakes were estimated on the basis of a 3-day food diary in 1992, a 24-h recall in 1997 and a 48-h recall in 2002. The 24-h urinary excretion of sodium was used to validate sodium intake. In addition, salt intake was estimated based on Food Balance Sheets. Results Sodium intake has slowly decreased since the early 1980s. Reported daily sodium intake correlated significantly with sodium excretion. Conclusions Sodium intake has decreased during the last two decades, but is still higher than the recommended daily intake. Sodium intake estimation based on dietary surveys and food availability data is a valid method provided that the food composition database is up to date and of good quality. Sponsorship All surveys were funded by the National Public Health Institute in Finland and the Ministry of Social Affairs and Health.

Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium.

Background High dietary intake of nitrate and nitrite might increase the risk of type 1 diabetes. To our knowledge, no earlier prospective study has explored whether maternal dietary intake of nitrate and nitrite during pregnancy is associated with the risk of type 1 diabetes in the offspring. Objective Our aim was to study association between maternal intake of nitrate and nitrite during pregnancy and the risk of islet autoimmunity and type 1 diabetes in the offspring. Design Children born between 1997 and 2004 at Oulu and Tampere University Hospitals in Finland and carrying increased human leukocyte antigen (HLA)-conferred risk for type 1 diabetes were followed in the Type 1 Diabetes Prediction and Prevention (DIPP) study from 3 mo of age. Islet autoantibodies were screened at 3- to 12-mo intervals from serum samples. Of 4879 children, 312 developed islet autoimmunity and 178 developed type 1 diabetes during a 15-y follow-up. Maternal intake of nitrate and nitrite during the eighth month of pregnancy was assessed after birth using a validated self-administered FFQ. Cox proportional hazards regression was used for the statistical analyses. Results Maternal intake of nitrate and nitrite during pregnancy was not associated with the child's risk of islet autoimmunity [nitrate: HR 0.99 (95% CI: 0.88, 1.11); nitrite: HR 1.03 (95% CI: 0.92, 1.15)] or type 1 diabetes [nitrate: HR 1.02 (95% CI: 0.88, 1.17); nitrite: HR 0.97 (95% CI: 0.83, 1.12)] when adjusted for energy (residual method), sex, HLA risk group, and family history of diabetes. Further adjustment for dietary antioxidants (vitamin C, vitamin E, and selenium) did not change the results. Conclusion Maternal dietary intake of nitrate or nitrite during pregnancy is not associated with the risk of islet autoimmunity or type 1 diabetes in the offspring genetically at risk for type 1 diabetes.

H Reinivuo

Papers

Accuracy in the estimation of food servings against the portions in food photographs.

Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium.

Maternal Nitrate and Nitrite Intakes during Pregnancy and Risk of Islet Autoimmunity and Type 1 Diabetes: The DIPP Cohort Study.