J.H.M. de Vries

Validation of the assessment of folate and vitamin B12 intake in women of reproductive age: The method of triads

Objective:To validate the folate and vitamin B12 intakes estimated by a food-frequency questionnaire (FFQ) designed to be used in a case-control study on the association between maternal dietary intake and the risk of having a child with a congenital heart defect.Design and subjects:The FFQ was filled out by 53 women of reproductive age. Immediately thereafter, blood samples were taken to determine serum folate, red blood cell (RBC) folate and serum vitamin B12 concentrations. Subsequently, three dietary 24-h recalls (24HR) were completed during a period of three successive weeks and used as a reference method. The recalls comprised two weekdays and one weekend day. Using the method of triads, validity coefficients were calculated by comparing nutrient intakes derived from the FFQ and 24HR with the corresponding nutritional biomarkers in blood. The validity coefficient is the correlation between the dietary intake reported by the FFQ and the unknown ‘true’ dietary intake.Results:The comparison of B-vitamin intakes reported by the FFQ and the mean of the 24HR revealed deattenuated correlation coefficients of 0.98 for folate and 0.66 for vitamin B12. The correlation coefficients between the B-vitamin intakes estimated by the FFQ and concentrations of serum folate, RBC folate and serum vitamin B12 were 0.20, 0.28 and 0.21, respectively. The validity coefficients for serum folate, RBC folate and serum vitamin B12 were 0.94, 0.75 and 1.00, respectively. The estimated folate and vitamin B12 intakes were comparable with the results of the most recent Dutch food consumption survey.Conclusions:The adapted FFQ is a reliable tool to estimate the dietary intake of energy, macronutrients, folate and vitamin B12 in women of reproductive age. Therefore, this FFQ is suitable for the investigation of nutrient-disease associations in future.Sponsorship:Funding was provided by the Netherlands Heart Foundation (Grant 2002.B027).

Comparing four methods to estimate usual intake distributions

Background/Objectives:The aim of this paper was to compare methods to estimate usual intake distributions of nutrients and foods. As ‘true’ usual intake distributions are not known in practice, the comparison was carried out through a simulation study, as well as empirically, by application to data from the European Food Consumption Validation (EFCOVAL) Study in which two 24-h dietary recalls (24-HDRs) and food frequency data were collected. The methods being compared were the Iowa State University Method (ISU), National Cancer Institute Method (NCI), Multiple Source Method (MSM) and Statistical Program for Age-adjusted Dietary Assessment (SPADE).Subjects/Methods:Simulation data were constructed with varying numbers of subjects (n), different values for the Box–Cox transformation parameter (λBC) and different values for the ratio of the within- and between-person variance (rvar). All data were analyzed with the four different methods and the estimated usual mean intake and selected percentiles were obtained. Moreover, the 2-day within-person mean was estimated as an additional ‘method’. These five methods were compared in terms of the mean bias, which was calculated as the mean of the differences between the estimated value and the known true value. The application of data from the EFCOVAL Project included calculations of nutrients (that is, protein, potassium, protein density) and foods (that is, vegetables, fruit and fish).Results:Overall, the mean bias of the ISU, NCI, MSM and SPADE Methods was small. However, for all methods, the mean bias and the variation of the bias increased with smaller sample size, higher variance ratios and with more pronounced departures from normality. Serious mean bias (especially in the 95th percentile) was seen using the NCI Method when rvar=9, λBC=0 and n=1000. The ISU Method and MSM showed a somewhat higher s.d. of the bias compared with NCI and SPADE Methods, indicating a larger method uncertainty. Furthermore, whereas the ISU, NCI and SPADE Methods produced unimodal density functions by definition, MSM produced distributions with ‘peaks’, when sample size was small, because of the fact that the populations usual intake distribution was based on estimated individual usual intakes. The application to the EFCOVAL data showed that all estimates of the percentiles and mean were within 5% of each other for the three nutrients analyzed. For vegetables, fruit and fish, the differences were larger than that for nutrients, but overall the sample mean was estimated reasonably.Conclusions:The four methods that were compared seem to provide good estimates of the usual intake distribution of nutrients. Nevertheless, care needs to be taken when a nutrient has a high within-person variation or has a highly skewed distribution, and when the sample size is small. As the methods offer different features, practical reasons may exist to prefer one method over the other.

Effect of a high monounsaturated fatty acids diet and a Mediterranean diet on serum lipids and insulin sensitivity in adults with mild abdominal obesity

BACKGROUND AND AIMS Diets high in monounsaturated fatty acids (MUFA) such as a Mediterranean diet may reduce the risk of cardiovascular diseases by improving insulin sensitivity and serum lipids. Besides being high in MUFA, a Mediterranean diet also contains abundant plant foods, moderate wine and low amounts of meat and dairy products, which may also play a role. We compared the effects of a high MUFA-diet with a diet high in saturated fatty acids (SFA) and the additional effect of a Mediterranean diet on insulin sensitivity and serum lipids. METHODS AND RESULTS A randomized parallel controlled-feeding trial was performed, in 60 non-diabetics (40-65 y) with mild abdominal obesity. After a two week run-in diet high in SFA (19 energy-%), subjects were allocated to a high MUFA-diet (20 energy-%), a Mediterranean diet (MUFA 21 energy-%), or the high SFA-diet, for eight weeks. The high MUFA and the Mediterranean diet did not affect fasting insulin concentrations. The high MUFA-diet reduced total cholesterol (-0.41 mmol/L, 95% CI -0.74, -0.09) and LDL-cholesterol (-0.38 mmol/L, 95% CI -0.65, -0.11) compared with the high SFA-diet, but not triglyceride concentrations. The Mediterranean diet increased HDL-cholesterol concentrations (+0.09 mmol/L, 95% CI 0.0, 0.18) and reduced the ratio of total cholesterol/HDL-cholesterol (-0.39, 95% CI -0.62, -0.16) compared with the high MUFA-diet. CONCLUSION Replacing a high SFA-diet with a high MUFA or a Mediterranean diet did not affect insulin sensitivity, but improved serum lipids. The Mediterranean diet was most effective, it reduced total and LDL-cholesterol, and also increased HDL-cholesterol and reduced total cholesterol/HDL-cholesterol ratio.

Self-reported energy intake by FFQ compared with actual energy intake to maintain body weight in 516 adults

It is generally assumed that a FFQ is not suitable to estimate the absolute levels of individual energy intake. However, in epidemiological studies, reported nutrients by FFQ are often corrected for this intake. The objective of the present study was to assess how accurately participants report their energy intakes by FFQ. We compared reported energy intake with actual energy intake needed to maintain stable body weights during eleven controlled dietary trials. FFQ were developed to capture at least 90 % of energy intake. Participants, 342 women and 174 men, with a mean BMI of 22.8 (SD 3.1) kg/m2 filled out the FFQ just before the trials. Energy intakes during the trials were calculated from provided foods and reported free-food items, representing 90 and 10 % of energy intake, respectively. Mean reported energy intake was 97.5 (SD 12.7) % of actual energy intake during the trials; it was 98.9 (SD 15.2) % for women and 94.7 (SD 16.3) % for men (P = 0.004 for difference between sexes). Correlation coefficients between reported and actual energy intakes were 0.82 for all participants, 0.74 for women and 0.80 for men. Individual reported energy intake as a percentage of actual intake ranged from 56.3 to 159.6 % in women and from 43.8 to 151.0 % in men. In conclusion, the FFQ appeared to be accurate for estimating the mean level of energy intakes of these participants and for ranking them according to their intake. However, the large differences found on the individual level may affect the results of epidemiological studies in an unknown direction if nutrients are corrected for energy intakes reported by FFQ.

Dietary intake and status of folate and vitamin B12 and their association with homocysteine and cardiovascular disease in European populations

Background/Objectives:Folate and vitamin B12 have been suggested to play a role in chronic diseases like cardiovascular diseases. The objectives are to give an overview of the actual intake and status of folate and vitamin B12 in general populations in Europe, and to evaluate these in view of the current vitamin recommendations and the homocysteine concentration.Methods:Searches in Medline with ‘folic acid’, ‘folate’ and ‘vitamin B12’, ‘B12’ or ‘cobalamin’ as key words were combined with the names of the European countries. Populations between 18 and 65 years were included.Results:Sixty-three articles reporting on studies from 15 European countries were selected. Low folate intakes were observed in Norway, Sweden, Denmark and the Netherlands. Low intakes of vitamin B12 were not common and only seen in one small Greek study. In the countries with a low intake of folate, the recommended levels were generally not achieved, which was also reflected in the folate status. Vitamin B12 intake was not strongly associated with the vitamin B12 status, which can explain why in the Netherlands and Germany the vitamin B12 status was inadequate, despite sufficient intake levels. In countries with a low folate intake in particular, the Hcy concentration was higher than ideal.Conclusions:Populations from the Nordic countries, the Netherlands, Germany and Greece may need to improve their intakes of folic acid, B12 or both to either meet the recommendations or to optimize their statuses. This could be achieved via a food-based approach, food fortification or supplements.

The standardized computerized 24-h dietary recall method EPIC-Soft adapted for pan-European dietary monitoring

Background/Objectives:The EPIC-Soft program (the software initially developed to conduct 24-h dietary recalls (24-HDRs) in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) was recommended as the best way to standardize 24-HDRs for future pan-European dietary monitoring. Within European Food Consumption Validation (EFCOVAL), EPIC-Soft was adapted and further developed on various aspects that were required to optimize its use. In this paper, we present the structure and main interview steps of the EPIC-Soft program, after implementation of a series of new specifications deemed to satisfy specific requirements of pan-European monitoring surveys and other international studies.Subjects/Methods:Updates to optimize the EPIC-Soft program were ascertained according to the following stepwise approach: (1) identification of requested specifications to be potentially implemented through an ad hoc ‘EPIC-Soft specifications questionnaire’ sent to past, current and possible future users of the software; (2) evaluation of the specifications in collaboration with two ad hoc task force groups and through a workshop; (3) development of a technical solution for each retained specification; (4) implementation of the specifications by software developers; (5) testing and amendment of bugs.Results:A number of new specifications and facilities were implemented to EPIC-Soft program. In addition, the software underwent a full reprogramming and migration to a modern Windows environment, including changes in its internal architecture and user interface. Although the overall concept and structure of the initial software were not changed substantially, these improvements ease the current and future use of EPIC-Soft and increase further its adaptation to other countries and study contexts.Conclusions:EPIC-Soft is enriched with further functions and facilities expected to fulfil specific needs of pan-European dietary monitoring and risk assessment purposes. The validity, feasibility and relevance of this software for different national and international study designs, and the logistical aspects related to its implementation are reported elsewhere.

The European Food Consumption Validation Project: conclusions and recommendations

Background/Objectives:To outline and discuss the main results and conclusions of the European Food Consumption Validation (EFCOVAL) Project.Subjects/Methods:The EFCOVAL Project was carried out within the EU Sixth Framework Program by researchers in 11 EU countries. The activities focused on (1) the further development of the EPIC-Soft software (the software developed to conduct 24-h dietary recalls (24-HDRs) in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) and the validation of the 2-day non-consecutive 24-HDR method using EPIC-Soft, (2) defining and investigating the applicability of the most appropriate dietary assessment method to younger age groups and expanding the applicability of the software for use in exposure assessment of some potentially hazardous chemicals and (3) to improve the methodology and statistical methods that estimate usual intake distributions from short-term dietary intake information and develop a methodology to quantify uncertainty in usual intake distributions.Results:The preexisting EPIC-Soft application was reprogrammed into a Windows environment and more than 60 new specifications were implemented in the software. A validation study showed that two non-consecutive EPIC-Soft 24-HDRs are suitable to estimate the usual intake distributions of protein and potassium of European adult populations. The 2-day non-consecutive 24-HDRs in combination with a food propensity questionnaire also appeared to be appropriate to rank individuals according to their fish and fruit and vegetable intake in a comparable way in five European centers. Dietary intake of (young) children can be assessed by the combination of EPIC-Soft 24-HDRs and food recording booklets. The EPIC-Soft-standardized method of describing foods is useful to estimate dietary exposure to potentially hazardous chemicals such as specific flavoring substances. With the developed Multiple Source Method, repeated non-consecutive 24-HDR data in combination with food propensity data can be used to estimate the population distribution of the usual intake by estimating the individual usual intakes.Conclusions:The findings provide sufficient evidence to conclude that the repeated 24-HDR using EPIC-Soft for standardization in combination with a food propensity questionnaire and modeling of usual intake is a suitable method for pan-European surveillance of nutritional adequacy and food safety among healthy adults and maybe in children aged 7 years and older. To facilitate this methodology in other European countries, the next step is to provide and standardize an implementation plan that accounts for maintenance and updates, sampling designs, national surveillance programs, tailored capacity building and training, and linkage to food composition and occurrence databases.

Consumption of a High Monounsaturated Fat Diet Reduces Oxidative Phosphorylation Gene Expression in Peripheral Blood Mononuclear Cells of Abdominally Overweight Men and Women

The Mediterranean (MED) diet is often considered health-promoting due to its high content of MUFA and polyphenols. These bioactive compounds can affect gene expression and accordingly may regulate pathways and proteins related to cardiovascular disease prevention. This study aimed to identify the effects of a MED-type diet, and the replacement of SFA with MUFA in a Western-type diet, on peripheral blood mononuclear cell (PBMC) gene expression and plasma proteins. Abdominally overweight men and women (waist: women ≥80 cm, men ≥94 cm) were allocated to an 8-wk, completely controlled SFA diet (19% daily energy as SFA), a MUFA diet (20% daily energy MUFA), or a MED diet (21% daily energy MUFA). Concentrations of 124 plasma proteins and PBMC whole-genome transcriptional profiles were assessed. Consumption of the MUFA and MED diets, compared with the SFA diet, decreased the expression of oxidative phosphorylation (OXPHOS) genes, plasma connective tissue growth factor, and apoB concentrations. Compared with the MED and SFA diets, the MUFA diet changed the expression of genes involved in B-cell receptor signaling and endocytosis signaling. Participants who consumed the MED diet had lower concentrations of proinflammatory proteins at 8 wk compared with baseline. We hypothesize that replacement of SFA with MUFA may improve health, thereby reducing metabolic stress and OXPHOS activity in PBMC. The MED diet may have additional antiatherogenic effects by lowering proinflammatory plasma proteins.

Biomarker-based evaluation of two 24-h recalls for comparing usual fish, fruit and vegetable intakes across European centers in the EFCOVAL Study

Background/Objectives:A standardized methodology is important to enable consistent monitoring of dietary intake across European countries. For this reason, we evaluated the comparability of the assessment of usual food intake collected with two non-consecutive computerized 24-h dietary recalls (24-HDRs) and a food propensity questionnaire (FPQ) among five European centers.Subjects/Methods:Two 24-HDRs using EPIC-Soft (the software developed to conduct 24-HDRs in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) were performed to determine fish, fruit and vegetable (FV) consumed by 600 adults in Belgium (BE), the Czech Republic (CZ), France (FR), the Netherlands (NL) and Norway (NO) in a validation study. An FPQ was used to identify non-consumers. Information from the 24-HDRs and FPQ were used to estimate individual usual food intake by the Multiple Source Method (MSM). Blood samples were drawn to determine fatty acids in phospholipids and serum carotenoids as biomarkers of fish, and FV intake, respectively.Results:The pooled correlation between usual fish intake and eicosapentaenoic acid plus docosahexaenoic acid in phospholipids was 0.19 in men and 0.31 in women (P for heterogeneity >0.50) and center-specific correlations ranged between 0.08 (CZ) and 0.28 (BE and NO) in men, and between 0.19 (BE) and 0.55 (FR) in women. For usual FV intake, the pooled correlation with serum carotenoids was 0.31 in men and 0.40 in women (P for heterogeneity >0.10); the center-specific correlations varied between 0.07 (NO) and 0.52 (FR) in men, and between 0.25 (NL) and 0.45 (NO) in women.Conclusion:Two standardized 24-HDRs using EPIC-Soft and an FPQ appeared to be appropriate to rank individuals according to their fish and FV intake in a comparable way among five European centers.

Dietary assessment in elderly people: experiences gained from studies in the Netherlands.

Background/Objectives:In selecting a dietary assessment method, several aspects such as the aim of the study and the characteristics of the target population should be taken into account. In elderly people, diminished functionality and cognitive decline may hamper dietary assessment and require tailored approaches to assess dietary intake. The objective of this paper is to summarize our experience in dietary assessment in a number of different studies in population groups over 65 years of age in the Netherlands, and to discuss this experience in the perspective of other nutrition surveys in the elderly.Methods:In longitudinal studies, we applied a modified dietary history; in clinical nursing home studies, trained staff observed and recorded food consumption; and in a controlled trial in healthy elderly men, we used a food frequency questionnaire (FFQ).Results:For all methods applied in the community-dwelling elderly people, validation studies showed a similar underestimation of intake of 10–15% compared with the reference value. In the care-depending elderly, the underestimation was less: 5% according to an observational method. The methods varied widely in the resources required, including burden to the participants, field staff and finances.Conclusions:For effective dietary assessment in older adults, the major challenge will be to distinguish between those elderly who are able to respond correctly to the less intensive methods, such as 24-h recalls or FFQ, and those who are not able to respond to these methods and require adapted techniques, for example, observational records.BACKGROUND/OBJECTIVES In selecting a dietary assessment method, several aspects such as the aim of the study and the characteristics of the target population should be taken into account. In elderly people, diminished functionality and cognitive decline may hamper dietary assessment and require tailored approaches to assess dietary intake. The objective of this paper is to summarize our experience in dietary assessment in a number of different studies in population groups over 65 years of age in the Netherlands, and to discuss this experience in the perspective of other nutrition surveys in the elderly. METHODS In longitudinal studies, we applied a modified dietary history; in clinical nursing home studies, trained staff observed and recorded food consumption; and in a controlled trial in healthy elderly men, we used a food frequency questionnaire (FFQ). RESULTS For all methods applied in the community-dwelling elderly people, validation studies showed a similar underestimation of intake of 10-15% compared with the reference value. In the care-depending elderly, the underestimation was less: 5% according to an observational method. The methods varied widely in the resources required, including burden to the participants, field staff and finances. CONCLUSIONS For effective dietary assessment in older adults, the major challenge will be to distinguish between those elderly who are able to respond correctly to the less intensive methods, such as 24-h recalls or FFQ, and those who are not able to respond to these methods and require adapted techniques, for example, observational records.