Dietary assessment methods for intakes of iron, calcium, selenium, zinc and iodine

Development and validation of a food frequency questionnaire to assess habitual iodine intake among women of childbearing age

BACKGROUND

Adequate iodine status is critical for thyroid hormone synthesis, which is essential for foetal brain development. Suboptimal iodine status has been reported in young women across Europe. Although urinary iodine concentration (UIC) is a good indicator of recent exposure, it does not reflect habitual iodine intake. This study aimed to develop and validate an iodine-specific food frequency questionnaire (I-FFQ) to assess habitual intake in Irish women aged 18-50 years.

METHODS

A 47-item interviewer-administered I-FFQ, informed by national food consumption data on Irish women aged 18-35 years, was developed and validated in a study of 100 nonpregnant women using a 4-day weighed food diary (FD) and UIC as the reference methods. Correlation, cross-classification and Bland-Altman analyses were used to assess agreement and bias between the I-FFQ and FD. Validity coefficients were calculated using the method of triads.

RESULTS

Median (interquartile range [IQR]) UIC was 82 (49, 139) µg/L. Median (IQR) intakes were 161 (106, 217) and 133 (98, 182) µg/day for the I-FFQ and FD, respectively (p = 0.001). Estimates were moderately correlated (r = 0.434), and the I-FFQ classified 89% of participants into the same or adjacent tertile of intake as the FD. Validity coefficients for the I-FFQ, FD and UIC were 0.542, 0.800 and 0.228, respectively. Though repeatability analyses 10 weeks later (n = 69) showed slight differences in estimates of intake (I-FFQ1: 164 (104, 210) µg/day; I-FFQ2: 132 (67, 237) µg/day), intakes were highly correlated between administrations (r = 0.627, p = 0.001).

CONCLUSIONS

The I-FFQ provides a reasonable estimate of habitual iodine intake in young women.

Association between the Carbohydrate Quality Index (CQI) and Nutritional Adequacy in a Pediatric Cohort: The SENDO Project

Suboptimal micronutrient intake in children remains a public health concern around the world. This study examined the relationship between a previously defined dietary carbohydrate quality index (CQI) and the risk of micronutrient intake inadequacy in a pediatric cohort of Spanish preschoolers. Children aged 4-5 years old were recruited at their medical center or at school, and information on sociodemographic, dietary, and lifestyle variables were collected through a self-administered online questionnaire. Dietary information was obtained from a validated 147-item semi-quantitative food frequency questionnaire. We calculated the CQI and categorized participants into quartiles according to their scores. We assessed the intakes of 20 micronutrients and evaluated the probability of intake inadequacy by using the estimated average requirement cut-off point. Generalized estimating equations were used to adjust for potential confounders and account for the intra-cluster correlations between siblings. The adjusted proportions of children with an inadequate intake of ≥three micronutrients were 23%, 12%, 11%, and 9% in the first, second, third, and fourth quartiles of the CQI, respectively. Children in the highest quartile of the CQI had 0.22-fold lower odds (95% CI 0.10-0.48) of having ≥three inadequate micronutrient intakes than their peers in the lowest quartile. These findings reinforce the relevance of carbohydrate quality in children's diets.

Association of egg consumption with colorectal polyp prevalence: findings from the Lanxi Pre-Colorectal Cancer Cohort (LP3C) in China

Eggs contain high-quality protein, lavish vitamins and other bioactive nutrients but are rich in cholesterol. Our study is designed to assess the association of egg intake with polyp prevalence. A total of 7068 participants at a high risk of CRC from the Lanxi Pre-Colorectal Cancer Cohort Study (LP3C) were recruited. A food frequency questionnaire (FFQ) was utilized to obtain dietary data through a face-to-face interview. Cases of colorectal polyps were identified by electronic colonoscopy. The logistic regression model was exploited to achieve odds ratios (ORs) and 95% confidence intervals (CIs). Overall 2064 cases of colorectal polyps were identified in the 2018-2019 survey of LP3C. A positive association of egg consumption with colorectal polyp prevalence was found after the multivariable adjustment [OR_{Q4 vs. Q1} (95% CI): 1.23 (1.05-1.44); P_trend = 0.01]. However, a positive relationship disappeared after further adjustment for dietary cholesterol (P_trend = 0.37), which explained that the harmful role of eggs could be ascribed to the high content of dietary cholesterol. Besides, a positive trend was found between dietary cholesterol and polyp prevalence [OR (95% CI): 1.21 (0.99-1.47); P_trend = 0.04]. Furthermore, replacing 1 egg (50 g d^-1) with an equal amount of total dairy products was related to 11% lower colorectal polyp prevalence [OR (95% CI): 0.89 (0.80-0.99); P = 0.03]. In summary, higher egg consumption was correlated with a higher polyp prevalence among the Chinese population at a high risk of CRC, which was ascribed to the high content of dietary cholesterol in eggs. Besides, individuals with the highest dietary cholesterol tended to have a higher polyp prevalence. Reducing the consumption of eggs and replacing eggs with total dairy products as alternative protein sources may prevent the occurrence of polyps in China.

Healthful and unhealthful provegetarian food patterns and micronutrient intake adequacy in the SUN cohort

OBJECTIVE

To investigate the association between different versions of a provegetarian food pattern (FP) and micronutrient inadequacy.

DESIGN

Cross-sectional analysis. Dietary intake was assessed at baseline through a validated 136-item FFQ. Participants were classified according to groups of different versions of a provegetarian FP: overall, healthful and unhealthful. The prevalence of inadequate intake of vitamins B1, B2, B3, B6, B12, C, A, D, E, folic acid, Zn, I, Se, Fe, Ca, K, P, Mg and Cr was evaluated using the estimated average requirement (EAR) cut-point method and the probabilistic approach. Logistic regression analyses were conducted to estimate the probability of failing to meet EAR for either ≥ 3 or ≥ 6 micronutrients.

SETTING

Seguimiento Universidad de Navarra (SUN) cohort.

PARTICIPANTS

17 825 Spanish adults.

RESULTS

Overall, subjects in the highest group of the unhealthful provegetarian FP had the highest prevalence of inadequate dietary intake for every vitamin and mineral, compared to those in the lowest group. The adjusted OR of failing to meet ≥ 3 EAR (highest v. lowest group) was 0·65 (0·54, 0·69) for the overall, 0·27 (0·24, 0·31) for the healthful and 9·04 (7·57, 10·4) for the unhealthful provegetarian FP.

CONCLUSION

A higher adherence to an overall and healthful provegetarian FP was inversely associated with the risk of failing to meet EAR values, whereas the unhealthful version was directly associated with micronutrient inadequacy. Provegetarian FP should be well planned, prioritising nutrient-dense plant foods and minimising ultra-processed and unhealthy ones.

Dietary calcium intake and change in bone mineral density in older adults: a systematic review of longitudinal cohort studies

Many older adults do not achieve recommended intakes of calcium and there is some concern over the potential impact of this on bone health. The objective of this review was to examine evidence from cohort studies on the relationship between calcium intake and change in bone mineral density (BMD) in older adults, something not undertaken in the last two decades. Data sources included Ovid Medline, Embase, and PubMed and references from retrieved reviews and articles. The final search was performed in February 2021. We included cohort studies of calcium intake in participants aged >50 years with change in BMD over ≥1 year as an outcome. We identified 23 studies of women and 7 of men. Most studies found no association between calcium intake and change in BMD in women (71%) or men (71%). Among women, five studies reported high rates (>30% of participants) of hormone treatment or osteoporosis therapy (HT/OT) use; 80% of these studies reported a positive association between calcium intake and change in BMD, compared with 10% of studies in which HT/OT use was low. No study in women in which the mean age was >60 years reported a positive association between calcium intake and change in BMD. We conclude that calcium intake across the ranges consumed in these studies (mean intake in all but one study >500 mg/day) is not an important determinant of bone loss, particularly among women >60 years. The positive findings in studies with high rates of HT/OT use are likely to arise from confounding as a result of co-administration of calcium supplements with these medications.

The relationship of different levels of high iodine and goiter in school children: a meta-analysis

Background

Over the past decade, the phenomenon of high urine iodine (HUI) and high water iodine (HWI) has become more common. But the risk of goiter caused by different levels of HUI and HWI remains unclear.

Objectives

To explore the risk of goiter development caused by HUI and HWI, and compare the risk of goiter development from different levels of high iodine.

Methods

The Medline, Cochrane library, Embase, China National Knowledge Infrastructure and Wan fang databases were searched for relevant population-based studies investigating the link between high iodine levels and goiter development in mainland China. Three reviewers extracted data from the included studies independently, assessing the prevalence of goiter development due to high iodine.

Results

Taking 100 μg/L ≤ UIC < 300 μg/L (UIC = urinary iodine concentration) as the reference group, the odds ratio (OR) regarding high iodine levels and goiter formation was 1.74 (95% CI 1.50, 2.01, P < 0.001), if the water iodine concentration (WIC) was greater than 100 μg/L, the OR between goiter development and WIC was 4.74 (95% CI 1.15, 19.46, P = 0.001). The Linear trend analysis of HUI and goiter showed that the prevalence of goiter increased with the increase of UIC (χ² = 734.605, P < 0.001).

Conclusions

When the UIC ≥ 300 μg/L or the WIC ≥ 100 μg/L, the risk of goiter will increase. The higher the UIC, the greater the risk of goiter development. In order to improve the public thyroid health, we should adhere to the monitoring of urinary iodine and water iodine, and keep them at an appropriate level.

Trial registration

PROSPEROCR, CRD42020197620. Registered 8 August 2020, https://www.crd.york.ac.uk/PROSPERO/.

Zinc Nutritional Status in a Series of Children with Chronic Diseases: A Cross-Sectional Study

BACKGROUND

Zinc is an essential trace element for the normal growth and development of human beings. The main objective was to evaluate the nutritional status of zinc and its association with nutritional indicators in a series of children with chronic diseases.

METHODS

The prevalence of patients with dietary zinc deficiency or deficit zinc intake (<80% DRI: dietary reference intake) was analyzed through prospective 72 h dietary surveys, and serum zinc deficiency or hypozincemia (≤70 µg/dL in children under 10 years of age in both sexes and in females older than 10 years and <74 μg/dL in males older than 10 years) was measured through atomic absorption spectrophotometry. The participants were classified according to their nutritional status by body mass index (BMI).

RESULTS

Mean serum zinc level in obese (87 µg/dL), undernourished (85 µg/dL), and eutrophic children (88 µg/dL) were normal, but in the undernutrition (60% DRI) and eutrophic (67% DRI) groups the mean dietary zinc intake was low compared to that in the obesity group (81% DRI). There were different associations between nutritional parameters, dietary zinc intake, and serum zinc. All patients with hypozincemia had dietary zinc deficiency.

CONCLUSIONS

In the whole series, 69% of participants showed a zinc intake lower than recommended and might be at high risk of zinc deficiency.

Se Status Prediction by Food Intake as Compared to Circulating Biomarkers in a West Algerian Population

Algeria is the largest country in Africa, located close to the Mediterranean coastal area, where nutrients consumption varies widely. Local data on selenium composition of foods are not available. We postulated a close correlation between selenium status predictions from food consumption analysis with a quantitative analysis of circulating biomarkers of selenium status. Population characteristics were recorded from 158 participants and dietary selenium intake was calculated by 24-h recall. The average total plasma selenium was 92.4 ± 18.5 µg/L and the mean of selenium intake was 62.7 µg/day. The selenoprotein P concentration was 5.5 ± 2.0 mg/L and glutathione peroxidase 3 activity was 247.3 ± 41.5 U/L. A direct comparison of the dietary-derived selenium status to the circulating selenium biomarkers showed no significant interrelation. Based on absolute intakes of meat, potato and eggs, a model was deduced that outperforms the intake composition-based prediction from all food components significantly (DeLong’s test, p = 0.029), yielding an area under the curve of 82%. Selenium status prediction from food intake remains a challenge. Imprecision of survey method or information on nutrient composition makes extrapolating selenium intake from food data providing incorrect insights into the nutritional status of a given population, and laboratory analyses are needed for reliable information.

Vegans, Vegetarians, and Omnivores: How Does Dietary Choice Influence Iodine Intake? A Systematic Review

Vegan and vegetarian diets are becoming increasingly popular. Dietary restrictions may increase the risk of iodine deficiency. This systematic review aims to assess iodine intake and status in adults following a vegan or vegetarian diet in industrialised countries. A systematic review and quality assessment were conducted in the period May 2019–April 2020 according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were identified in Ovid MEDLINE, Embase, Web of Science, PubMed, Scopus, and secondary sources. Fifteen articles met inclusion criteria. Participants included 127,094 adults (aged ≥ 18 years). Vegan groups presented the lowest median urinary iodine concentrations, followed by vegetarians, and did not achieve optimal status. The highest iodine intakes were recorded in female vegans (1448.0 ± 3879.0 µg day⁻¹) and the lowest in vegetarians (15.6 ± 21.0 µg day⁻¹). Omnivores recorded the greatest intake in 83% of studies. Seaweed contributed largely to diets of vegans with excessive iodine intake. Vegans appear to have increased risk of low iodine status, deficiency and inadequate intake compared with adults following less restrictive diets. Adults following vegan and vegetarian diets living in countries with a high prevalence of deficiency may be more vulnerable. Therefore, further monitoring of iodine status in industrialised countries and research into improving the iodine intake and status of adults following vegan and vegetarian diets is required.

Nutrient intake in aging infants and toddlers: 3-year follow-up of the Nutrintake study

We performed a 3-year follow-up of the children enrolled into the Nutrintake Study to evaluate the changes of anthropometry and nutrient intake in aging infants and toddlers. Nutrient intake was assessed using a 7-day weighted food-diary. Of the 390 Nutrintake children, 164 (42%) participated in the present study. Their median (IQR) age was 54 (48; 66) months and their anthropometrical status, expressed as standard deviation scores, remained stable during the follow-up. During the same period, there was no biologically relevant change in the intake of macronutrients expressed as percentage of energy while median increases of 757 mg/day, 0.7 mg/day and 3.1 g/1000 kcal per day were detected for sodium, iron and fibre, respectively. As compared to the Italian reference standards, the Nutrintake children continued to show at the 3-year follow-up an excessive intake of simple carbohydrates, proteins, sodium, and a low intake of iron and fibre.

Reproducibility and Validity of a Short Food Frequency Questionnaire for Dietary Assessment in Children Aged 7⁻9 Years in Spain

The purpose of this study was to examine if the short semi-quantitative food frequency questionnaire (FFQ) is a reliable and valid tool to assess the diet of Spanish children aged 7-9 years. We collected data from 156 children of the birth cohort INMA (Infancia y Medio Ambiente (Environment and Childhood)). Children's parents or care-givers completed a 46-item FFQ on two occasions over a 9-12-month period about the children's diet. To explore the reproducibility of the FFQ, the nutrient and food group intake collected from the both FFQs were compared, while validity was examined by contrasting the nutrient values from the FFQs and the average of three 24-hour dietary recalls (24hDRs) taken in this period, and also with the concentration of several vitamins in the blood (carotenoids, vitamin D and α-tocopherol). Pearson and de-attenuated correlation coefficients were calculated. The average correlation coefficients for nutrient intake's reproducibility was 0.41, ranging from 0.25 (calcium) to 0.65 (β-carotene), and for food group intake was 0.45, ranging from 0.18 (cereals) to 0.68 (sweetened beverages). Correlation coefficients slightly improved when we compared energy-adjusted intakes. The average correlation coefficients for validity against 24hDRs was 0.34 for energy-adjusted intakes, and 0.39 when de-attenuation coefficients were used. The validity coefficients against the blood concentrations of vitamins were 0.38 for β-cryptoxanthin, 0.26 for lycopene, 0,23 for α-carotene and 0.15 for β-carotene, all of them statistically significant (p < 0.05). This study suggests that our brief FFQ is a suitable tool for the dietary assessment of a wide range of nutrients and food groups in children 7-9 years, despite the low to moderate reproducibility and validity observed for some nutrients.

A systematic review of reviews identifying UK validated dietary assessment tools for inclusion on an interactive guided website for researchers: www.nutritools.org

Background: Health researchers may struggle to choose suitable validated dietary assessment tools (DATs) for their target population. The aim of this review was to identify and collate information on validated UK DATs and validation studies for inclusion on a website to support researchers to choose appropriate DATs.Design: A systematic review of reviews of DATs was undertaken. DATs validated in UK populations were extracted from the studies identified. A searchable website was designed to display these data. Additionally, mean differences and limits of agreement between test and comparison methods were summarized by a method, weighting by sample size.Results: Over 900 validation results covering 5 life stages, 18 nutrients, 6 dietary assessment methods, and 9 validation method types were extracted from 63 validated DATs which were identified from 68 reviews. These were incorporated into www.nutritools.org. Limits of agreement were determined for about half of validations. Thirty four DATs were FFQs. Only 17 DATs were validated against biomarkers, and only 19 DATs were validated in infant/children/adolescents.Conclusions: The interactive www.nutritools.org website holds extensive validation data identified from this review and can be used to guide researchers to critically compare and choose a suitable DAT for their research question, leading to improvement of nutritional epidemiology research.

Dietary Zinc and Risk of Prostate Cancer in Spain: MCC-Spain Study

Zinc is a key trace element in normal prostate cell metabolism, and is decreased in neoplastic cells. However, the association between dietary zinc and prostate cancer (PC) in epidemiologic studies is a conflicting one. Our aim was to explore this association in an MCC-Spain case-control study, considering tumor aggressiveness and extension, as well as genetic susceptibility to PC. 733 incident cases and 1228 population-based controls were included for this study. Dietary zinc was assessed using a food frequency questionnaire, and genetic susceptibility was assessed with a single nucleotide polymorphisms (SNP)-based polygenic risk score (PRS). The association between zinc intake and PC was evaluated with mixed logistic and multinomial regression models. They showed an increased risk of PC in those with higher intake of zinc (Odds Ratio (OR) tertile 3vs1: 1.39; 95% Confidence interval (CI):1.00–1.95). This association was mainly observed in low grade PC (Gleason = 6 RRR tertile 3vs1: 1.76; 95% CI:1.18–2.63) as well as in localized tumors (cT1-cT2a RRR tertile 3vs1: 1.40; 95% CI:1.00–1.95) and among those with higher PRS (OR tertile 3vs1: 1.50; 95% CI:0.89–2.53). In conclusion, a higher dietary zinc intake could increase the risk of low grade and localized tumors. Men with higher genetic susceptibility might also have a higher risk of PC associated with this nutrient intake.

Micronutrient intake adequacy and depression risk in the SUN cohort study

PURPOSE

The aim of the study was to prospectively assess the association between micronutrient intake adequacy and risk of depression.

METHODS

This dynamic cohort study involves Spanish university graduates (SUN Project). Dietary intake was assessed at baseline and after 10 years of follow-up with a semi-quantitative food frequency questionnaire. Micronutrient intake adequacy for vitamins B1, B2, B3, B6, B12, C, A, D, E, folic acid, zinc, iodine, selenium, iron, calcium, potassium, phosphorus, magnesium and chrome was estimated. Inadequate intake for each nutrient was defined when the intake of the nutrient was below the estimated average requirements (EAR) if available or the adequate intake levels, if EARs were not available. We compared participants with inadequate intake for ≥4 nutrients vs. those with one nutrient. Participants were classified as having incident depression if they had no previous history of depression or antidepressants use at baseline, but they reported during follow-up a new clinical diagnosis of depression by a physician, use of antidepressant drugs, or both. Time-dependent multivariable Cox regression models were fitted.

RESULTS

After a median follow-up of 8.5 years, 953 new cases of depression were observed among 13,983 participants. Participants with inadequate intake for ≥4 nutrients showed a significantly higher risk of depression [multivariable hazard ratio (HR) = 1.37; 95% confidence interval (CI) 1.01-1.85]. When the analyses were updated with repeated assessments of intakes, the association was attenuated and it was no longer statistically significant (Multivariable HR = 1.11; 95% CI 0.82-1.51).

CONCLUSIONS

Micronutrient inadequacy in four or more micronutrients could exert a moderate role in the development of depression.

The Possibility of Applying the Vitamin D Brief Food Frequency Questionnaire as a Tool for a Country with No Vitamin D Data in Food Composition Tables

Although the role of vitamin D is well known, the possibility of assessing its intake may be constricted in countries with no vitamin D data in food composition tables, as in the case of Croatia. The aim of the presented study was to adjust the VIDEO-FFQ (Vitamin D Estimation Only-Food Frequency Questionnaire), previously validated in Poland, to the Croatian population and to assess the validity and reproducibility of the adjusted Cro-VIDEO-FFQ (Croatian-VIDEO-FFQ). The study involved a group of Croatian women aged 20⁻30 and the Polish questionnaire was adjusted for a population due to similarities of the nutritional habits between countries. 106 individuals were recruited and 63 completed all the stages of the study. Participants conducted a 3-day dietary record and filled out the Cro-VIDEO-FFQ1 (first stage), as well as the same questionnaire (Cro-VIDEO-FFQ2) 6 weeks after (second stage). The following vitamin D intakes were observed in the studied group: 1.9 µg (0.2⁻8.0 µg) for 3-day dietary record, 3.3 µg (1.1⁻10.6 µg) for Cro-VIDEO-FFQ1, 3.6 µg (1.4⁻7.8 µg) for Cro-VIDEO-FFQ2. The Bland-Altman indexes in assessment of validity and reproducibility were 4.8% and 6.3%, respectively, with mean differences of 0.55 µg and 0.12 µg, as well as limits of agreement -0.91⁻2.01 µg and -0.44⁻0.69 µg. The kappa coefficient indicated a fair agreement for validity (0.21) and substantial for reproducibility (0.62), while correlations were significant (p = 0.0027, r = 0.37 for validity; p < 0.0001, r = 0.80 for reproducibility). It was observed that VIDEO-FFQ may be adjusted as a simple tool to assess vitamin D intake in a population with no vitamin D data in food composition tables, while Cro-VIDEO-FFQ may be a valid tool for nutritional assessment in Croatia.

Selenium intake and metabolic syndrome: A systematic review

BACKGROUND & AIMS

Metabolic syndrome is a multi-causal disease. Its treatment includes lifestyle changes with a focus on weight loss. This systematic review assessed the association between Selenium intake and metabolic syndrome.

METHODS

Data were collected mainly from four databases: PubMed, CENTRAL (Cochrane), Scopus and Web of Knowledge. Keywords related to metabolic syndrome, selenium, as well as metabolic syndrome features were searched. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. A systematic review protocol was registered at PROSPERO (n. 42016046321). Two reviewers independently screened 2957 abstracts. Six studies were included to perform data extraction with standardized spreadsheets. The risk of bias was assessed by using specific tools according to the design of the relevant studies. An assessment was carried out based on the appropriateness of the study reports accordingly to STROBE and the CONSORT-based checklist for each study design.

RESULTS

Three studies found no association between Selenium intake and metabolic syndrome; two of them found an inverse association; and one study found a direct association between Selenium intake and metabolic syndrome. One study also showed an inverse association between Selenium intake and the prevalence of high waist circumference, high diastolic blood pressure, and hyperglycaemia in women.

CONCLUSIONS

Overall, based on the argumentation and results of this study, it is possible to conclude that Selenium intake and metabolic syndrome are not clearly associated in adults and elderly.

Assessment of Validity and Reproducibility of the Zinc-Specific Dietary Intake Questionnaire Conducted for Young Polish Female Respondents

One of the brief methods enabling the assessment of the zinc intake and identification of individuals characterized by insufficient zinc intake, is zinc-specific food frequency questionnaire. The aim of the study was to assess the validity and reproducibility of the elaborated zinc-specific food frequency questionnaire ZINC-FFQ (Zinc INtake Calculation—Food Frequency Questionnaire) in a group of young Polish female respondents. The validity was assessed in comparison with 3-day dietary records, while reproducibility was assessed for the ZINC-FFQ filled in twice (FFQ1 and FFQ2—six weeks apart). Bland–Altman indexes in the assessment of validity were 5.5% (FFQ1) and 6.7% (FFQ2), while in assessment of reproducibility it was 3.3%. In the assessment of reproducibility, 83% of respondents were classified into the same category of zinc intake adequacy and 72% of respondents were classified into the same tertile, that contributed to weighted κ statistic of 0.65 (substantial agreement). It may be concluded, that ZINC-FFQ is characterized by a validity on a satisfactory and reproducibility on a very good level, in a group of young Polish female respondents, and may be applied to indicate individuals characterized by the risk of insufficient intake.

Relative validity of a web-based food frequency questionnaire for Danish adolescents

Background

With increased focus on dietary intake among youth and risk of diseases later in life, it is of importance, prior to assessing diet-disease relationships, to examine the validity of the dietary assessment tool. This study’s objective was to evaluate the relative validity of a self-administered web-based FFQ among Danish children aged 12 to 15 years.

Methods

From a nested sub-cohort within the Danish National Birth Cohort, 124 adolescents participated. Four weeks after completion of the FFQ, adolescents were invited to complete three telephone-based 24HRs; administered 4 weeks apart. Mean or median intakes of nutrients and food groups estimated from the FFQ were compared with the mean of 3x24HRs. To assess the level of ranking we calculated the proportion of correctly classified into the same quartile, and the proportion of misclassified (into the opposite quartile). Spearman’s correlation coefficients and de-attenuated coefficients were calculated to assess agreement between the FFQ and 24HRs.

Results

The mean percentage of all food groups, for adolescents classified into the same and opposite quartile was 35 and 7.5%, respectively. Mean Spearman’s correlation was 0.28 for food groups and 0.35 for nutrients, respectively. Adjustment for energy and within-person variation in the 24HRs had little effect on the magnitude of the correlations for food groups and nutrients. We found overestimation by the FFQ compared with the 24HRs for fish, fruits, vegetables, oils and dressing and underestimation by the FFQ for meat/poultry and sweets. Median intake of beverages, dairy, bread, cereals, the mean total energy and carbohydrate intake did not differ significantly between the two methods.

Conclusion

The relative validity of the FFQ compared with the 3x24HRs showed that the ranking ability differed across food groups and nutrients with best ranking for estimated intake of dairy, fruits, and oils and dressing. Larger variation was observed for fish, sweets and vegetables. For nutrients, the ranking ability was acceptable for fatty acids and iron. When evaluating estimates from the FFQ among Danish adolescents these findings should be considered.

Electronic supplementary material

The online version of this article (10.1186/s12937-018-0312-7) contains supplementary material, which is available to authorized users.

Validity and Reproducibility of the Iodine Dietary Intake Questionnaire Assessment Conducted for Young Polish Women

The aim of this study was to analyse a designed brief iodine dietary intake questionnaire based on a food frequency assessment (IOdine Dietary INtake Evaluation-Food Frequency Questionnaire—IODINE-FFQ), including the assessment of validity and reproducibility in a group of 90 Polish women aged 20–35 years. Participants collected 3-day dietary records and filled in the IODINE-FFQ twice (FFQ1—directly after the dietary record and FFQ2—6 weeks later). The analysis included an assessment of validity (comparison with the results of the 3-day dietary record) and of reproducibility (comparison of the results obtained twice—FFQ1 and FFQ2). In the analysis of validity, a Bland-Altman index of 5.5% and 4.4% was recorded, respectively for FFQ1 and FFQ2. In the analysis of reproducibility it was 6.7%, but the share of individuals correctly classified into tertiles was over 70% (weighted κ of 0.675). It was stated, that assessment of IODINE-FFQ revealed a satisfactory level of validity and reproducibility in the analysis of Bland-Alman plot. The IODINE-FFQ may be indicated as a tool for the assessment of iodine intake in the young women in Poland, however further studies should be considered in order to obtain the practical tool for public health specialists. Due to the lack of validated iodine-specific food frequency questionnaires for countries of Eastern Europe, the IODINE-FFQ may be adjusted for courtiers other than Poland including iodine-fortified products.

Zinc Status and Risk of Cardiovascular Diseases and Type 2 Diabetes Mellitus-A Systematic Review of Prospective Cohort Studies

Zinc is an essential trace element with proposed therapeutic effects in Type 2 diabetes mellitus (DM), however, the associations between zinc status and the prospective risks of cardiovascular diseases (CVD) and Type 2 DM have not been evaluated. The current systematic review aims to determine the relationships between zinc intake or plasma/serum zinc levels and prospective incidence of CVD and Type 2 DM. Fourteen papers describing prospective cohort studies were included, reporting either CVD (n = 91,708) and/or Type 2 DM (n = 334,387) outcomes. Primary analyses from four out of five studies reported no association between zinc intake and CVD events, when adjusted for multiple variables. Higher serum zinc level was associated with lower risk of CVD in three out of five studies; pronounced effects were observed in vulnerable populations, specifically those with Type 2 DM and patients referred to coronary angiography. The limited evidence available suggests no association between zinc status and Type 2 DM risk. Further investigations into the mechanisms of zinc's action on the pathogenesis of chronic diseases and additional evidence from observational studies are required to establish a recommendation for dietary zinc in relation to the prevention of CVD and Type 2 DM.

Significant Beneficial Association of High Dietary Selenium Intake with Reduced Body Fat in the CODING Study

Selenium (Se) is a trace element which plays an important role in adipocyte hypertrophy and adipogenesis. Some studies suggest that variations in serum Se may be associated with obesity. However, there are few studies examining the relationship between dietary Se and obesity, and findings are inconsistent. We aimed to investigate the association between dietary Se intake and a panel of obesity measurements with systematic control of major confounding factors. A total of 3214 subjects participated in the study. Dietary Se intake was determined from the Willett food frequency questionnaire. Body composition was measured using dual-energy X-ray absorptiometry. Obese men and women had the lowest dietary Se intake, being 24% to 31% lower than corresponding normal weight men and women, classified by both BMI and body fat percentage. Moreover, subjects with the highest dietary Se intake had the lowest BMI, waist circumference, and trunk, android, gynoid and total body fat percentages, with a clear dose-dependent inverse relationship observed in both gender groups. Furthermore, significant negative associations discovered between dietary Se intake and obesity measurements were independent of age, total dietary calorie intake, physical activity, smoking, alcohol, medication, and menopausal status. Dietary Se intake alone may account for 9%–27% of the observed variations in body fat percentage. The findings from this study strongly suggest that high dietary Se intake is associated with a beneficial body composition profile.

Vitamin D-rich marine Inuit diet and markers of inflammation - a population-based survey in Greenland

The traditional Inuit diet in Greenland consists mainly of fish and marine mammals, rich in vitamin D. Vitamin D has anti-inflammatory capacity but markers of inflammation have been found to be high in Inuit living on a marine diet. Yet, the effect of vitamin D on inflammation in Inuit remains unsettled. This led us to investigate the association between vitamin D and markers of inflammation in a population with a high intake of a marine diet. We studied 535 Inuit and non-Inuit living in West and East Greenland. Information concerning dietary habits was obtained by interview-based FFQ. Blood samples were drawn for analysis of 25-hydroxyvitamin D, high-sensitivity C-reactive protein (hsCRP) and chitinase-3-like protein 1(YKL-40). Participants were divided into three groups based on degree of intake of the traditional Inuit diet. The diet groups (Inuit diet/mixed diet/imported foods) were associated with vitamin D levels in serum (74·2, 69·8 and 52·9 nm; P < 0·001), hsCRP (1·6, 1·4 and 1·3 mg/l; P = 0·002) and YKL-40 (130, 95 and 61 ng/ml; P < 0·001), respectively. YKL-40 level decreased with rising vitamin D level in Inuit (Inuit diet P = 0·002; mixed diet P = 0·011). YKL-40 was lower in groups with higher vitamin D levels after adjusting for other factors known to influence inflammation (P < 0·001). This was not seen for hsCRP. In conclusion, vitamin D and markers of inflammation vary in parallel with the intake of the marine Inuit diet. Vitamin D levels were inversely associated with YKL-40 levels, but no association with hsCRP was found. The hypothesised anti-inflammatory effect of vitamin D was not supported. Other factors in the marine diet may be speculated to influence inflammation.

Relative Validity of Three Food Frequency Questionnaires for Assessing Dietary Intakes of Guatemalan Schoolchildren

Objective

To determine the relative validity of three food frequency questionnaires (FFQs) compared with results from 24-hour dietary recalls for measuring dietary intakes in Guatemalan schoolchildren.

Design

A cross-sectional study of primary caregivers (mothers or grandmothers) of 6–11 year-old children. Caregivers completed one of three constructed FFQs to measure the child’s dietary consumption in the last week: FFQ1 did not incorporate portion sizes; FFQ2 provided portion sizes; and FFQ3 incorporated pictures of median portion sizes. During the same week, each caregiver also completed three 24-hour dietary recalls. Results from the FFQ were compared with corresponding results from the 24-hour dietary recalls.

Setting

Santa Catarina Pinula, peri-urban Guatemala City.

Subjects

Caregivers (n = 145) of 6–11 year-old children: 46 completed FFQ1, 49 completed FFQ2, and 50 completed FFQ3.

Results

The mean values for all nutrients obtained from the 24-hour dietary recall were lower than for those obtained from the FFQs, excluding folic acid in FFQ3, cholesterol and zinc in FFQ2, and cholesterol, folic acid, magnesium, potassium, sodium, and zinc in FFQ1. Energy-adjusted Pearson correlation coefficients ranged from 0.07 (protein) to 0.54 (cholesterol) for FFQ1 and from 0.05 to 0.74 for FFQ2 and FFQ3. Agreement by both methods (FFQ and 24-hour dietary recalls) of classifying children into the same or adjacent quartiles of energy-adjusted nutrient consumption ranged from 62.0% for cholesterol to 95.9% for vitamin B12 across all three FFQs.

Conclusions

Our FFQs had moderate to good relative validity in measuring energy and nutrient intakes for 6–11 year-old Guatemalan children. More evidence is needed to evaluate their reproducibility and applicability in similar populations.

Estimation of dietary iron bioavailability from food iron intake and iron status

Currently there are no satisfactory methods for estimating dietary iron absorption (bioavailability) at a population level, but this is essential for deriving dietary reference values using the factorial approach. The aim of this work was to develop a novel approach for estimating dietary iron absorption using a population sample from a sub-section of the UK National Diet and Nutrition Survey (NDNS). Data were analyzed in 873 subjects from the 2000–2001 adult cohort of the NDNS, for whom both dietary intake data and hematological measures (hemoglobin and serum ferritin (SF) concentrations) were available. There were 495 men aged 19–64 y (mean age 42.7±12.1 y) and 378 pre-menopausal women (mean age 35.7±8.2 y). Individual dietary iron requirements were estimated using the Institute of Medicine calculations. A full probability approach was then applied to estimate the prevalence of dietary intakes that were insufficient to meet the needs of the men and women separately, based on their estimated daily iron intake and a series of absorption values ranging from 1–40%. The prevalence of SF concentrations below selected cut-off values (indicating that absorption was not high enough to maintain iron stores) was derived from individual SF concentrations. An estimate of dietary iron absorption required to maintain specified SF values was then calculated by matching the observed prevalence of insufficiency with the prevalence predicted for the series of absorption estimates. Mean daily dietary iron intakes were 13.5 mg for men and 9.8 mg for women. Mean calculated dietary absorption was 8% in men (50^th percentile for SF 85 µg/L) and 17% in women (50^th percentile for SF 38 µg/L). At a ferritin level of 45 µg/L estimated absorption was similar in men (14%) and women (13%). This new method can be used to calculate dietary iron absorption at a population level using data describing total iron intake and SF concentration.

Adherence to dietary and lifestyle recommendations and prostate cancer risk in the prostate testing for cancer and treatment (ProtecT) trial

BACKGROUND

The World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR) published eight recommendations for cancer prevention, but they are not targeted at prostate cancer prevention. We investigated whether adherence to the WCRF/AICR recommendations and a prostate cancer dietary index is associated with prostate cancer risk.

METHODS

We conducted a nested case-control study of 1,806 prostate-specific antigen (PSA)-detected prostate cancer cases and 12,005 controls in the ProtecT trial. We developed a prostate cancer dietary index by incorporating three dietary factors most strongly associated with prostate cancer. Scores were computed to quantify adherence to the WCRF/AICR recommendations and the prostate cancer dietary index separately.

RESULTS

The prostate cancer dietary index score was associated with decreased risk of prostate cancer [OR per 1 score increment: 0.91; 95% confidence interval (CI): 0.84-0.99; Ptrend = 0.04] but the WCRF/AICR index score was not (OR: 0.99; 95% CI: 0.94-1.05; Ptrend = 0.71). There was no heterogeneity in association by prostate cancer stage (P = 0.81) or grade (P = 0.61). Greater adherence to recommendations to increase plant foods (OR per 0.25 index score increment: 0.94; 95% CI: 0.89-0.99; Ptrend = 0.02) and tomato products (OR adherence vs. nonadherence: 0.82; 95% CI: 0.70-0.97; P = 0.02) was inversely associated with overall prostate cancer risk.

CONCLUSIONS

Adherence to the prostate cancer-specific dietary recommendations was associated with decreased risk of prostate cancer. High intake of plant foods and tomato products in particular may help protect against prostate cancer.

IMPACT

Meeting the WCRF/AICR recommendations alone is insufficient for prostate cancer prevention. Additional dietary recommendations should be developed.

Study of selenium intake and disposition in various matrices based on mathematical algorithms derived from pooled biomonitoring data

Biomonitoring is increasingly used to assess exposure to selenium (Se) in the population. However, there is little harmonization among protocols used in the different studies (varying biological matrices, differences in expression of results (concentrations versus amounts, units)). This makes inter-comparison of biomonitoring results across studies difficult. From a public health risk perspective, it also becomes challenging to estimate baseline levels in biological matrices for populations exposed by various sources. The aim of this study was thus to perform a systematic analysis of the relationship between Se intakes and biological concentrations based on published data. Inclusion and exclusion criteria were used and led to select 75 published biomonitoring data in humans from an extended review of Se biomonitoring studies. This represents 8 628 individuals who provided biological samples aiming at documenting Se exposure and/or Se concentrations in two or more biological matrices. Mathematical algorithms that relate Se intakes to biological concentrations and establish matrix-to-matrix associations were derived from these pooled biomonitoring data. Logarithmic regressions showed good correlations between Se intakes and whole blood concentrations (R(2)=0.884), plasma concentrations (R(2)=0.863) and urinary excretion rates (R(2)=0.958). Blood and plasma concentrations were also strongly related (R(2)=0.874), as were whole blood concentrations and urinary excretion rates (R(2)=0.953). The interpretation of the log-regression coefficients allowed illustrating Se physiology. Se concentrations in plasma tend to plateau when daily intake exceed 150 μg/d, whereas Se in urine increases rapidly above this threshold. The application of the algorithms to other independent data sets in order to reconstruct past Se intakes confirmed that interpretation of results on the basis of Se in integuments may be misleading if external contamination is not avoided. This approach based on pooled data covered a wide range of exposure and the large number of data integrated increased the level of confidence of results.

Association between dietary carbohydrate intake quality and micronutrient intake adequacy in a Mediterranean cohort: the SUN (Seguimiento Universidad de Navarra) Project

Epidemiological research confirms that the prevalence of suboptimal micronutrient intakes across Europe is an emerging concern in terms of public health. The aim of the present study was to investigate the association between a new index of carbohydrate (CHO) quality and micronutrient intake adequacy in the ‘Seguimiento Universidad de Navarra (SUN)’ cohort. The baseline assessment extended from 1999 to March 2012. We assessed 16 841 participants who completed a validated 136-item semi-quantitative FFQ at baseline. We created a new index to evaluate CHO quality for the following four criteria: dietary fibre intake; glycaemic index; whole grains:total grains ratio; solid CHO:total CHO ratio. The subjects were classified into quintiles according to this index. We evaluated the intakes of Zn, I, Se, Fe, Ca, K, P, Mg, Cr and vitamins B1, B2, B3, B6, B12, C, A, D, E and folic acid. The probability of intake adequacy was evaluated using the estimated average requirement cut-point approach and the probabilistic approach. Logistic regression analysis was used to assess the nutritional adequacy according to the CHO quality index (CQI). Participants in the highest quintile of CQI were found to have the lowest prevalence of inadequacy. A higher quality of CHO intake was found to be associated with a lower risk of nutritional inadequacy in comparison with the lowest quintile of CQI (adjusted OR 0·06, 95 % CI 0·02, 0·16;Pfor trend < 0·001). A higher CQI was found to be strongly associated with better micronutrient intake adequacy in the young Mediterranean cohort, stressing the importance of focusing nutritional education not only on CHO quantity, but also on quality.

EURRECA-Estimating selenium requirements for deriving dietary reference values

Current reference values for selenium, an essential micronutrient, are based on the intake of selenium that is required to achieve maximal glutathione peroxidase activity in plasma or erythrocytes. In order to assess the evidence of relevance to setting dietary reference values for selenium, the EURRECA Network of Excellence focused on systematic searches, review, and evaluation of (i) selenium status biomarkers and evidence for relationships between intake and status biomarkers, (ii) selenium and health (including the effect of intake and/or status biomarkers on cancer risk, immune function, HIV, cognition, and fertility), (iii) bioavailability of selenium from the diet, and (iv) impact of genotype/single nucleotide polymorphisms on status or health outcomes associated with selenium. The main research outputs for selenium and future research priorities are discussed further in this review.

EURRECA-Evidence-based methodology for deriving micronutrient recommendations

The EURopean micronutrient RECommendations Aligned (EURRECA) Network of Excellence explored the process of setting micronutrient recommendations to address the variance in recommendations across Europe. Work centered upon the transparent assessment of nutritional requirements via a series of systematic literature reviews and meta-analyses. In addition, the necessity of assessing nutritional requirements and the policy context of setting micronutrient recommendations was investigated. Findings have been presented in a framework that covers nine activities clustered into four stages: stage one "Defining the problem" describes Activities 1 and 2: "Identifying the nutrition-related health problem" and "Defining the process"; stage two "Monitoring and evaluating" describes Activities 3 and 7: "Establishing appropriate methods," and "Nutrient intake and status of population groups"; stage three "Deriving dietary reference values" describes Activities 4, 5, and 6: "Collating sources of evidence," "Appraisal of the evidence," and "Integrating the evidence"; stage four "Using dietary reference values in policy making" describes Activities 8 and 9: "Identifying policy options," and "Evaluating policy implementation." These activities provide guidance on how to resolve various issues when deriving micronutrient requirements and address the methodological and policy decisions, which may explain the current variation in recommendations across Europe. [Supplementary materials are available for this article. Go to the publisher's online edition of Critical Reviews in Food Science and Nutrition for the following free supplemental files: Additional text, tables, and figures.].

Relative validity of micronutrient and fiber intake assessed with two new interactive meal- and Web-based food frequency questionnaires

BACKGROUND

The meal- and Web-based food frequency questionnaires, Meal-Q and MiniMeal-Q, were developed for cost-efficient assessment of dietary intake in epidemiological studies.

OBJECTIVE

The objective of this study was to evaluate the relative validity of micronutrient and fiber intake assessed with Meal-Q and MiniMeal-Q. The reproducibility of Meal-Q was also evaluated.

METHODS

A total of 163 volunteer men and women aged between 20 and 63 years were recruited from Stockholm County, Sweden. Assessment of micronutrient and fiber intake with the 174-item Meal-Q was compared to a Web-based 7-day weighed food record (WFR). Two administered Meal-Q questionnaires were compared for reproducibility. The 126-item MiniMeal-Q, developed after the validation study, was evaluated in a simulated validation by using truncated Meal-Q data.

RESULTS

The study population consisted of approximately 80% women (129/163) with a mean age of 33 years (SD 12) who were highly educated (130/163, 80% with >12 years of education) on average. Cross-classification of quartiles with the WFR placed 69% to 90% in the same/adjacent quartile for Meal-Q and 67% to 89% for MiniMeal-Q. Bland-Altman plots with the WFR and the questionnaires showed large variances and a trend of increasing underestimation with increasing intakes. Deattenuated and energy-adjusted Spearman rank correlations between the questionnaires and the WFR were in the range ρ=.25-.69, excluding sodium that was not statistically significant. Cross-classifications of quartiles of the 2 Meal-Q administrations placed 86% to 97% in the same/adjacent quartile. Intraclass correlation coefficients for energy-adjusted intakes were in the range of .50-.76.

CONCLUSIONS

With the exception of sodium, this validation study demonstrates Meal-Q and MiniMeal-Q to be useful methods for ranking micronutrient and fiber intake in epidemiological studies with Web-based data collection.

Micronutrient intakes among women of reproductive age in Vietnam

BACKGROUND

Micronutrient deficiencies are a public health concern worldwide negatively affecting maternal and child health outcomes. The primary underlying causes of micronutrient deficiencies are insufficient intake and poor bioavailability of micronutrients. However, reliable data on micronutrient intakes are sparse. The objectives of this study were to identify the key local food sources providing the majority of micronutrients and assess the adequacy and determinants of micronutrient intakes.

METHODS

The study used data from a survey of 4,983 rural women of reproductive age (WRA) participating in a preconception micronutrient supplementation trial in Vietnam. Micronutrient intakes were assessed using a validated 107-item semi-quantitative food-frequency questionnaire. Multivariate linear and logistic regression analyses were used to examine the association between socioeconomic status and micronutrient intakes.

RESULTS

Starchy staples were the main source of iron and zinc (37% and 54%, respectively) with only a small proportion from meat (10% and 18%, respectively). The primary source of folate and vitamin A were vegetables; vitamin B12 came from meat and eggs. The proportion of the population with intakes below the estimated average requirement was 25% for iron, 16% for zinc, 54% for folate, 64% for vitamin B12 and 27% for vitamin A. Socioeconomic status was the main determinant of micronutrient intakes. WRA in the highest quintile consumed 26% more iron, 19% more zinc, 36% more folate, 82% more vitamin B12 and 47% more vitamin A compared to those in the lowest quintile. Women in the upper quintiles of SES were more likely to obtain nutrients from more nutritious and higher bioavailable foods than those in the lowest quintile.

CONCLUSIONS

Underprivileged women were at increased risk for insufficient micronutrient intakes due to poor diet quality. Targeted efforts to promote the consumption of local nutrient rich foods along with educational programs and social development are needed.

Validity and reproducibility of a Spanish dietary history

Objective

To assess the validity and reproducibility of food and nutrient intake estimated with the electronic diet history of ENRICA (DH-E), which collects information on numerous aspects of the Spanish diet.

Methods

The validity of food and nutrient intake was estimated using Pearson correlation coefficients between the DH-E and the mean of seven 24-hour recalls collected every 2 months over the previous year. The reproducibility was estimated using intraclass correlation coefficients between two DH-E made one year apart.

Results

The correlations coefficients between the DH-E and the mean of seven 24-hour recalls for the main food groups were cereals (r = 0.66), meat (r = 0.66), fish (r = 0.42), vegetables (r = 0.62) and fruits (r = 0.44). The mean correlation coefficient for all 15 food groups considered was 0.53. The correlations for macronutrients were: energy (r = 0.76), proteins (r = 0.58), lipids (r = 0.73), saturated fat (r = 0.73), monounsaturated fat (r = 0.59), polyunsaturated fat (r = 0.57), and carbohydrates (r = 0.66). The mean correlation coefficient for all 41 nutrients studied was 0.55. The intraclass correlation coefficient between the two DH-E was greater than 0.40 for most foods and nutrients.

Conclusions

The DH-E shows good validity and reproducibility for estimating usual intake of foods and nutrients.

Association between polymorphisms in glutathione peroxidase and selenoprotein P genes, glutathione peroxidase activity, HRT use and breast cancer risk

Breast cancer (BC) is one of the most common cancers in women. Evidence suggests that genetic variation in antioxidant enzymes could influence BC risk, but to date the relationship between selenoproteins and BC risk remains unclear. In this report, a study population including 975 Danish cases and 975 controls matched for age and hormone replacement therapy (HRT) use was genotyped for five functional single nucleotide polymorphisms (SNPs) in SEPP1, GPX1, GPX4 and the antioxidant enzyme SOD2 genes. The influence of genetic polymorphisms on breast cancer risk was assessed using conditional logistic regression. Additionally pre-diagnosis erythrocyte GPx (eGPx) activity was measured in a sub-group of the population. A 60% reduction in risk of developing overall BC and ductal BC was observed in women who were homozygous Thr carriers for SEPP1 rs3877899. Additionally, Leu carriers for GPX1 Pro198Leu polymorphism (rs1050450) were at ∼2 fold increased risk of developing a non-ductal BC. Pre-diagnosis eGPx activity was found to depend on genotype for rs713041 (GPX4), rs3877899 (SEPP1), and rs1050450 (GPX1) and on HRT use. Moreover, depending on genotype and HRT use, eGPx activity was significantly lower in women who developed BC later in life compared with controls. Furthermore, GPx1 protein levels increased in human breast adenocarcinoma MCF7 cells exposed to β-estradiol and sodium selenite.In conclusion, our data provide evidence that SNPs in SEPP1 and GPX1 modulate risk of BC and that eGPx activity is modified by SNPs in SEPP1, GPX4 and GPX1 and by estrogens. Our data thus suggest a role of selenoproteins in BC development.

Markers for nutrition studies: review of criteria for the evaluation of markers

INTRODUCTION

Markers are important tools to assess the nutrition status and effects of nutrition interventions. There is currently insufficient consensus in nutrition sciences on how to evaluate markers, despite the need for properly evaluating them.

OBJECTIVES

To identify the criteria for the evaluation of markers related to nutrition, health and disease and to propose generic criteria for evaluation.

METHOD

The report on "Evaluation of Biomarker and Surrogate Endpoints in Chronic Disease" from the Institute of Medicine was the starting point for the literature search. Additionally, specific search strategies were developed for Pubmed.

RESULTS

In nutrition, no set of criteria or systematic approach to evaluate markers is currently available. There is a reliance on the medical area where statistical methods have been developed to quantify the evaluation of markers. Even here, a systematic approach is lacking-markers are still evaluated on a case-by-case basis. The review of publications from the literature search resulted in a database with definitions, criteria for validity and the rationale behind the criteria. It was recognized that, in nutrition, a number of methodological aspects differ from medical research.

CONCLUSIONS

The following criteria were identified as essential elements in the evaluation of markers: (1) the marker has a causal biological link with the endpoint, (2) there is a significant association between marker and endpoint in the target population, (3) marker changes consistently with the endpoint, e.g., in response to an intervention, and (4) change in the marker explains a substantial proportion of the change in the endpoint in response to the intervention.

Relative validity of the food frequency questionnaire used to assess dietary intake in the Leiden Longevity Study

Background

Invalid information on dietary intake may lead to false diet-disease associations. This study was conducted to examine the relative validity of the food frequency questionnaire (FFQ) used to assess dietary intake in the Leiden Longevity Study.

Methods

A total of 128 men and women participating in the Leiden Longevity Study were included in the present validation study. The performance of the FFQ was evaluated using the mean of three 24-hour recalls as the reference method. Evaluation in estimating dietary intake at the group level was done by paired t-tests. The relative validity of the individual energy adjusted level of intake was assessed with correlation analyses (Pearson’s), with correction for measurement error.

Results

On group level, the FFQ overestimated as well as underestimated absolute intake of various nutrients and foods. The Bland and Altman plot for total energy intake showed that the agreement between the FFQ and the 24-hour recalls was dependent of intake level. Pearson correlation coefficients ranged from 0.21 (alpha linolenic acid) to 0.78 (ethanol) for nutrients and from -0.02 (legumes, non-significant) to 0.78 (alcoholic beverages) for foods. Adjustment for energy intake slightly lowered the correlation coefficients for nutrients (mean coefficient: 0.48 versus 0.50), while adjustment for within-subject variation in the 24-h recalls resulted in higher correlation coefficients for both nutrients and foods (mean coefficient: 0.69 for nutrients and 0.65 for foods).

Conclusions

For most nutrients and foods, the ability of the FFQ to rank subjects was acceptable to good.

Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study

OBJECTIVE

To investigate the association between long term intake of dietary and supplemental calcium and death from all causes and cardiovascular disease.

DESIGN

Prospective longitudinal cohort study.

SETTING

Swedish mammography cohort, a population based cohort established in 1987-90.

PARTICIPANTS

61 433 women (born between 1914 and 1948) followed-up for a median of 19 years.

MAIN OUTCOME MEASURES

Primary outcome measures, identified from registry data, were time to death from all causes (n=11 944) and cause specific cardiovascular disease (n=3862), ischaemic heart disease (n=1932), and stroke (n=1100). Diet was assessed by food frequency questionnaires at baseline and in 1997 for 38 984 women, and intakes of calcium were estimated. Total calcium intake was the sum of dietary and supplemental calcium.

RESULTS

The risk patterns with dietary calcium intake were non-linear, with higher rates concentrated around the highest intakes (≥1400 mg/day). Compared with intakes between 600 and 1000 mg/day, intakes above 1400 mg/day were associated with higher death rates from all causes (hazard ratio 1.40, 95% confidence interval 1.17 to 1.67), cardiovascular disease (1 49, 1.09 to 2.02), and ischaemic heart disease (2.14, 1.48 to 3.09) but not from stroke (0.73, 0.33 to 1.65). After sensitivity analysis including marginal structural models, the higher death rate with low dietary calcium intake (<600 mg/day) or with low and high total calcium intake was no longer apparent. Use of calcium tablets (6% users; 500 mg calcium per tablet) was not on average associated with all cause or cause specific mortality but among calcium tablet users with a dietary calcium intake above 1400 mg/day the hazard ratio for all cause mortality was 2.57 (95% confidence interval 1.19 to 5.55).

CONCLUSION

High intakes of calcium in women are associated with higher death rates from all causes and cardiovascular disease but not from stroke.

Evaluating the quality of dietary intake validation studies

Within the EURopean micronutrient RECommendations Aligned Network of Excellence (EURRECA), a scoring system was developed to assess the quality of dietary intake validation studies. The scoring system included three steps. The first step was to give each study a quality score, which included five components: sample size, statistics used, data collection procedure, consideration of seasonality and supplement use. Scores ranged from 0 to 7, and validation studies classified as very good ( > or = 5), good (5-3.5), acceptable/reasonable (3.5-2.5) and poor ( < 2.5). The second and third steps included an adjustment/weighting of the correlation coefficient according to the quality score and moreover a rating of the adjusted/weighted correlation. The scoring system was tested in 124 validation studies that included at least one vitamin. Only 5.6 % of the 124 studies were judged to be of very good quality according to the quality score, 41.9 % of good quality and 16.9 % had a poor rating. When adjusting for the study quality scores, crude and adjusted mean correlations of vitamins A, C, D and E intakes were similar, but the percentage of correlation values classified as poor or very good was higher after adjustment. These results show the importance of considering the quality of studies validating dietary assessment methods and the correlations obtained for the micronutrient of interest when interpreting effects observed in epidemiological studies using dietary assessment methods. Without a doubt, this subject constitutes a key topic for research in nutritional epidemiology.

Blood selenium levels and contribution of food groups to selenium intake in adolescent girls in Iceland

BACKGROUND/OBJECTIVES

Significant changes have been reported in dietary habits and food availability in Iceland that would be expected to compromise selenium intake and status, especially among young people. These include substantial decreases in the consumption of fish and milk, as well as the selenium content of imported wheat. The aim of this study was to assess selenium in the diet and whole blood of adolescent girls, as well as define the most important foods contributing to intake and blood concentrations of selenium.

DESIGN

The subjects were 96 randomly selected girls, aged 16-20, who answered a validated food frequency questionnaire (FFQ) for dietary assessment. Selenium intake from each food group was calculated in µg/day. Blood samples were collected for measurement of whole blood selenium.

RESULTS

Mean dietary selenium was 51±25 µg/day. Milk/dairy products, including cheese, contributed 36±14% of total dietary selenium; fish 18±12%; and bread/cereal products 13±6%. Mean whole blood selenium was 117±12 µg/l (range 90-208); nearly 90% of subjects were above the optimal level of 100 µg/l. Fish and bread/cereal products were the only foods significantly correlated with selenium in blood (r=0.32; P=0.002 and r=0.22; P=0.04, respectively) while no correlation was found with milk and dairy products in spite of their greater contribution to total selenium intake.

CONCLUSION

In this population of Icelandic adolescent girls, selenium intake and status seem acceptable. Judging from associations between intake and blood levels, fish and cereals may be the most important contributors to blood selenium.

Explaining the variability in recommended intakes of folate, vitamin B12, iron and zinc for adults and elderly people

Objective

To signal key issues for harmonising approaches for establishing micronutrient recommendations by explaining observed variation in recommended intakes of folate, vitamin B12, Fe and Zn for adults and elderly people.

Design

We explored differences in recommended intakes of folate, vitamin B12, Fe and Zn for adults between nine reports on micronutrient recommendations. Approaches used for setting recommendations were compared as well as eminence-based decisions regarding the selection of health indicators indicating adequacy of intakes and the consulted evidence base.

Results

In nearly all reports, recommendations were based on the average nutrient requirement. Variation in recommended folate intakes (200–400 μg/d) was related to differences in the consulted evidence base, whereas variation in vitamin B12recommendations (1·4–3·0 μg/d) was due to the selection of different CV (10–20 %) and health indicators (maintenance of haematological status or basal losses). Variation in recommended Fe intakes (men 8–10 mg/d, premenopausal women 14·8–19·6 mg/d, postmenopausal women 7·5–10·0 mg/d) was explained by different assumed reference weights and bioavailability factors (10–18 %). Variation in Zn recommendations (men 7–14 mg/d, women 4·9–9·0 mg/d) was also explained by different bioavailability factors (24–48 %) as well as differences in the consulted evidence base.

Conclusions

For the harmonisation of approaches for setting recommended intakes of folate, vitamin B12, Fe and Zn across European countries, standardised methods are needed to (i) select health indicators and define adequate biomarker concentrations, (ii) make assumptions about inter-individual variation in requirements, (iii) derive bioavailability factors and (iv) collate, select, interpret and integrate evidence on requirements.

Total zinc intake may modify the glucose-raising effect of a zinc transporter (SLC30A8) variant: a 14-cohort meta-analysis

OBJECTIVE

Many genetic variants have been associated with glucose homeostasis and type 2 diabetes in genome-wide association studies. Zinc is an essential micronutrient that is important for β-cell function and glucose homeostasis. We tested the hypothesis that zinc intake could influence the glucose-raising effect of specific variants.

RESEARCH DESIGN AND METHODS

We conducted a 14-cohort meta-analysis to assess the interaction of 20 genetic variants known to be related to glycemic traits and zinc metabolism with dietary zinc intake (food sources) and a 5-cohort meta-analysis to assess the interaction with total zinc intake (food sources and supplements) on fasting glucose levels among individuals of European ancestry without diabetes.

RESULTS

We observed a significant association of total zinc intake with lower fasting glucose levels (β-coefficient ± SE per 1 mg/day of zinc intake: -0.0012 ± 0.0003 mmol/L, summary P value = 0.0003), while the association of dietary zinc intake was not significant. We identified a nominally significant interaction between total zinc intake and the SLC30A8 rs11558471 variant on fasting glucose levels (β-coefficient ± SE per A allele for 1 mg/day of greater total zinc intake: -0.0017 ± 0.0006 mmol/L, summary interaction P value = 0.005); this result suggests a stronger inverse association between total zinc intake and fasting glucose in individuals carrying the glucose-raising A allele compared with individuals who do not carry it. None of the other interaction tests were statistically significant.

CONCLUSIONS

Our results suggest that higher total zinc intake may attenuate the glucose-raising effect of the rs11558471 SLC30A8 (zinc transporter) variant. Our findings also support evidence for the association of higher total zinc intake with lower fasting glucose levels.

Assessing the validity of a food frequency questionnaire among low-income women in São Paulo, southeastern Brazil

This study describes the validity of a food frequency questionnaire (FFQ) in 93 low-income women (20-65 years), participating in a case-control study in São Paulo, Brazil. Two FFQ (FFQ1 and FFQ2, 12 months apart) and three 24-hour dietary recalls (24hR) were conducted between 2003 and 2004 to estimate dietary intake during the past year. The Pearson correlation coefficients (crude, energy-adjusted and de-attenuated) were used for comparisons between FFQ and 24hR. The agreement between the methods was further examined by the Bland-Altman analysis. For the assessment of long-term reliability, the energy-adjusted intra-class correlation coefficients were mostly around 0.40, but higher for vitamin A and folate (0.50-0.56). Energy-adjusted, attenuation-corrected Pearson validity correlations between FFQ and DR ranged from 0.30-0.54 for macronutrients to 0.20-0.48 for micronutrients, with higher value for calcium (0.75). There were small proportions of grossly misclassified nutrient intakes, while Bland-Altman plots indicated that the FFQ is accurate in assessing nutrient intake at a group level.

Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study

OBJECTIVE

To investigate associations between long term dietary intake of calcium and risk of fracture of any type, hip fractures, and osteoporosis.

DESIGN

A longitudinal and prospective cohort study, based on the Swedish Mammography Cohort, including a subcohort, the Swedish Mammography Cohort Clinical.

SETTING

A population based cohort in Sweden established in 1987.

PARTICIPANTS

61,433 women (born between 1914 and 1948) were followed up for 19 years. 5022 of these women participated in the subcohort.

MAIN OUTCOME MEASURES

Primary outcome measures were incident fractures of any type and hip fractures, which were identified from registry data. Secondary outcome was osteoporosis diagnosed by dual energy x ray absorptiometry in the subcohort. Diet was assessed by repeated food frequency questionnaires.

RESULTS

During follow-up, 14,738 women (24%) experienced a first fracture of any type and among them 3871 (6%) a first hip fracture. Of the 5022 women in the subcohort, 1012 (20%) were measured as osteoporotic. The risk patterns with dietary calcium were non-linear. The crude rate of a first fracture of any type was 17.2/1000 person years at risk in the lowest quintile of calcium intake, and 14.0/1000 person years at risk in the third quintile, corresponding to a multivariable adjusted hazard ratio of 1.18 (95% confidence interval 1.12 to 1.25). The hazard ratio for a first hip fracture was 1.29 (1.17 to 1.43) and the odds ratio for osteoporosis was 1.47 (1.09 to 2.00). With a low vitamin D intake, the rate of fracture in the first calcium quintile was more pronounced. The highest quintile of calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture, hazard ratio 1.19 (1.06 to 1.32).

CONCLUSION

Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis.