Measuring vitamins and minerals in dietary supplements for nutrition studies in the USA

Overview of dietary assessment methods for measuring intakes of foods, beverages, and dietary supplements in research studies

Measuring the dietary intakes of individuals for research and monitoring purposes is notoriously challenging and is subject to both random and systematic measurement error. In this review, the strengths and limitations of current methods to assess dietary and supplemental exposures are described. Traditional methods of dietary assessment include food records, food frequency questionnaires, 24-hour recalls, and screening tools; digital and mobile methods that leverage technology are available for these traditional methods. Ultimately, the choice of assessment method is dependent upon the research question, the study design, sample characteristics, and the size of the sample, to name just a few. Despite their challenges, dietary assessment tools are an important dimension of nutrition research and monitoring.

Dietary approaches to managing nonalcoholic fatty liver disease

ABSTRACT

Nonalcoholic fatty liver disease (NAFLD), a multisystem, prevalent liver disease, can be managed with lifestyle interventions, including diet, given the lack of well-established pharmacologic therapies. This review explores the different dietary approaches that have been found effective in the management of NAFLD, offering a unique resource to healthcare professionals.

Determination of Vitamins K1, K2 MK-4, MK-7, MK-9 and D3 in Pharmaceutical Products and Dietary Supplements by TLC-Densitometry

Vitamin K is a group of lipophilic molecules. Forms of vitamin K play an essential role in the activation of specific proteins involved in blood clotting cascade or bone metabolism. Another molecule belonging to the fat-soluble vitamins group that also plays an important role in calcium metabolism is vitamin D3. The dietary supplements containing vitamins K and D3 are one of the most frequently consumed by patients. The objective of this work was to develop a simple, fast and sensitive thin-layer chromatography (TLC)-densitometric procedure for the simultaneous quantitative analysis of vitamins K and D3 in pharmaceutical products and dietary supplements. The analysis of vitamins was performed on the silica gel RP-18 F₂₅₄s plates with methanol-ethanol-isopropanol in a volume ratio of 15:1:4 as a mobile phase. The densitometric measurements were made at 254 nm. The method was validated by checking the specificity, linearity, precision, recovery, limit of detection, limit of quantification and robustness in accordance with International Conference on Harmonization (ICH) guidelines. The method was shown to be specific, accurate (recoveries were from 95.78 to 104.96%), linear over the tested range (correlation coefficient, exceeding 0.99), and precise (precision and intermediate precision RSD below 2.70% for all analytes). The satisfactory results of the validation of the method indicate that it can be used in the quality control of dietary supplements and pharmaceutical products containing vitamins K and D3.

The efficiency of ultrasonic-assisted extraction of cyanocobalamin is greater than heat extraction

Cyanocobalamin, like other water-soluble vitamins, is susceptible to degradation due to exposure to heat, UV, oxygen and pH. Built on our previous finding, this study aimed to assess the extraction efficiency of cyanocobalamin from dietary supplements. Particularly, cyanocobalamin extraction in a 100 °C water bath was compared with ultrasonic-assisted extraction, with and without the addition of 1 mg/L sorbitol, xylitol and erythritol. Ground defatted samples of supplement tablets were initially treated for 15 min, centrifuged and filtered before quantitative HPLC analysis. Addition of sorbitol and xylitol significantly minimised the thermal degradation during extraction in a 100 °C water bath, as shown in measured cyanocobalamin (~145 μg/tablet) that was higher than the control (100 μg/tablet, p < 0.05). Despite the addition of sugar alcohols, mean cyanocobalamin in ultrasonic extracted samples (~170 μg/tablet) was not significantly different from those without (p > 0.05). Overall, mean cyanocobalamin in sonicated samples was higher than heat-extracted counterparts, suggesting that extraction in a 100 °C water bath was likely to cause thermal degradation. It was possible that ultrasonic-assisted extraction had no effect on cyanocobalamin stability and would lead to a higher extraction efficiency. Therefore, 15 min extraction in an ultrasonic bath can be suggested to be adequate to release cyanocobalamin before its quantitative determination.

Best Practices for Dietary Supplement Assessment and Estimation of Total Usual Nutrient Intakes in Population-Level Research and Monitoring

The use of dietary supplements (DS) is pervasive and can provide substantial amounts of micronutrients to those who use them. Therefore when characterizing dietary intakes, describing the prevalence of inadequacy or excess, or assessing relations between nutrients and health outcomes, it is critical to incorporate DS intakes to improve exposure estimates. Unfortunately, little is known about the best methods to assess DS, and the structure of measurement error in DS reporting. Several characteristics of nutrients from DS are salient to understand when comparing to those in foods. First, DS can be consumed daily or episodically, in bolus form and can deliver discrete and often very high doses of nutrients that are not limited by energy intakes. These characteristics contribute to bimodal distributions and distributions severely skewed to the right. Labels on DS often provide nutrient forms that differ from those found in conventional foods, and underestimate analytically derived values. Finally, the bioavailability of many nutrient-containing DS is not known and it may not be the same as the nutrients in a food matrix. Current methods to estimate usual intakes are not designed specifically to handle DS. Two temporal procedures are described to refer to the order that nutrient intakes are combined relative to usual intake procedures, referred to as a "shrinking" the distribution to remove random error. The "shrink then add" approach is preferable to the "add then shrink" approach when users and nonusers are combined for most research questions. Stratifying by DS before usual intake methods is another defensible option. This review describes how to incorporate nutrient intakes from DS to usual intakes from foods, and describes the available methods and fit-for-purpose of different analytical strategies to address research questions where total usual intakes are of interest at the group level for use in nutrition research and to inform policy decisions. Clinical Trial Registry: NCT03400436.

Evaluation of Mineral Contents of Multi-Vitamin and Minerals Currently Sold in South Korea

Dietary supplements are popular worldwide and their use has been increasing. The purpose of this study was to evaluate the mineral contents of multi-vitamins and minerals (MVMs) in most commonly sold among dietary supplements. Ninety popular MVM supplements sold in South Korea were surveyed regarding their characteristics and ingredients including minerals listed on the labels through off-line and on-line search. Daily mineral contents of the MVM supplements were compared with Korean Dietary Reference Intakes (DRIs) by target populations. The average price of 90 MVM supplements was $41.3 per bottle, with a price of $0.9 per day and the average number of minerals contained per supplement was 4.7. A total 14 minerals were found in the MVM supplements including calcium, phosphorus, sodium, potassium, and magnesium. Nine minerals (e.g. calcium, magnesium, and iron) were included in more than 30% of the MVM supplements examined. When daily mineral dose of MVMs was compared to DRIs, calcium was the lowest (34.0% of recommended intake [RI]) and chromium was the highest (218.7% of adequate intake [AI]), and zinc, copper, selenium, and chromium were also higher than their RI or AI levels. The daily mineral contents of the 90 MVM supplements were below the tolerable upper-intake level, but some minerals were higher than RI or AI with high variance among products. Therefore, there is a great need to educate the public for the adequate selection and use of MVM supplements based on the contents of MVM supplements and individual's mineral intake derived from the diet.

Dietary Supplement Ingredient Database (DSID) and the Application of Analytically Based Estimates of Ingredient Amount to Intake Calculations

OBJECTIVE

We describe the purpose of the Dietary Supplement Ingredient Database (DSID), the statistical methodology underlying online calculators of analytically verified supplement content estimates, and the application and significance of DSID label adjustments in nutritional epidemiology.

BACKGROUND AND HISTORY

During dietary supplement (DS) manufacturing, many ingredients are added at higher than declared label amounts, but overages are not standardized among manufacturers. As a result, researchers may underestimate nutrient intakes from DSs. The DSID provides statistical tools on the basis of the results of chemical analysis to convert label claims into analytically predicted ingredient amounts. These adjustments to labels are linked to DS products reported in NHANES.

RATIONALE

Tables summarizing the numbers of NHANES DS products with ingredient overages and below label content show the importance of DSID adjustments to labels for accurate intake calculations.

RECENT DEVELOPMENTS

We show the differences between analytically based estimates and labeled content for vitamin D, calcium, iodine, caffeine, and omega-3 (n-3) fatty acids and their potential impact on the accuracy of intake assessments in large surveys. Analytical overages >20% of label levels are predicted for several nutrients in 50-99% of multivitamin-mineral products (MVMs) reported in NHANES: for iodine and selenium in adult MVMs, for iodine and vitamins D and E in children's MVMs, and for iodine, chromium, and potassium in nonprescription prenatal MVMs. Predicted overages of 10-20% for calcium can be applied to most MVMs and overages >10% for folic acid in the vast majority of adult and children's MVMs.

FUTURE DIRECTIONS

DSID studies are currently evaluating ingredient levels in prescription prenatal MVMs and levels of constituents in botanical DSs.

CONCLUSIONS

We estimate that the majority of MVM products reported in NHANES have significant overages for several ingredients. It is important to account for nonlabeled additional nutrient exposure from DSs to better evaluate nutritional status in the United States.

Dietary Supplements: Regulatory Challenges and Research Resources

Many of the scientific and regulatory challenges that exist in research on the safety, quality and efficacy of dietary supplements are common to all countries as the marketplace for them becomes increasingly global. This article summarizes some of the challenges in supplement science and provides a case study of research at the Office of Dietary Supplements at the National Institutes of Health, USA, along with some resources it has developed that are available to all scientists. It includes examples of some of the regulatory challenges faced and some resources for those who wish to learn more about them.

The Best of Times

I came of age as a nutrition scientist during the best of times-years that spanned a rapidly changing world of food and nutrition science, politics, and policy that greatly broadened the specialty and its influence on public affairs. I followed the conventional route in academe, working my way up the academic ladder in Boston from a base first in a school of public health and later in a teaching hospital and medical school, interspersed with stints in Washington, DC. Thus I tell a tale of two cities. Those were the best of times because nutrition science and policy converged and led to important policies and programs that shaped the field for the next 50 years.

Is Nutrient Content and Other Label Information for Prescription Prenatal Supplements Different from Nonprescription Products?

BACKGROUND

Prenatal supplements are often recommended to pregnant women to help meet their nutrient needs. Many products are available, making it difficult to choose a suitable supplement because little is known about their labeling and contents to evaluate their appropriateness.

OBJECTIVE

To determine differences between prescription and nonprescription prenatal supplements available in the United States regarding declared nutrient and nonnutrient ingredients and the presence of dosing and safety-related information.

DESIGN

Using two publicly available databases with information about prenatal supplement products, information from prescription and nonprescription product labels were extracted and evaluated. For the 82 prescription and 132 nonprescription products, declared label amounts of seven vitamins and minerals, docosahexaenoic acid (DHA), the presence of other nonnutrient components, and the presence of key safety and informational elements as identified in two Department of Health and Human Services Office of Inspector General (OIG)'s 2003 reports were compiled and compared.

RESULTS

Compared with nonprescription products, prescription products contained significantly fewer vitamins (9±0.2 vs 11±0.3; P≤0.05) and minerals (4±0.1 vs 8±0.3; P≤0.05). Declared amounts of folic acid were higher in prescription products, whereas vitamin A, vitamin D, iodine, and calcium were higher in the nonprescription products. Amounts of iron, zinc, and DHA were similar. Virtually all products contained levels of one or more nutrients that exceeded the Recommended Dietary Allowances for pregnant and/or lactating women. Product type also influenced ingredients added. Fewer prescription products contained botanical ingredients (6% prescription vs 33% nonprescription) and probiotics (2% prescription vs 8% nonprescription). Only prescription products contained the stool softener docusate sodium.

CONCLUSIONS

Our analysis of prenatal supplements indicates that prescription and nonprescription supplements differ in terms of declared composition and nutrient strength, but have labels that are similarly sparse regarding aspects of use such as dosing information.

Analytical ingredient content and variability of adult multivitamin/mineral products: national estimates for the Dietary Supplement Ingredient Database

BACKGROUND

Multivitamin/mineral products (MVMs) are the dietary supplements most commonly used by US adults. During manufacturing, some ingredients are added in amounts exceeding the label claims to compensate for expected losses during the shelf life. Establishing the health benefits and harms of MVMs requires accurate estimates of nutrient intake from MVMs based on measures of actual rather than labeled ingredient amounts.

OBJECTIVES

Our goals were to determine relations between analytically measured and labeled ingredient content and to compare adult MVM composition with Recommended Dietary Allowances (RDAs) and Tolerable Upper Intake Levels.

DESIGN

Adult MVMs were purchased while following a national sampling plan and chemically analyzed for vitamin and mineral content with certified reference materials in qualified laboratories. For each ingredient, predicted mean percentage differences between analytically obtained and labeled amounts were calculated with the use of regression equations.

RESULTS

For 12 of 18 nutrients, most products had labeled amounts at or above RDAs. The mean measured content of all ingredients (except thiamin) exceeded labeled amounts (overages). Predicted mean percentage differences exceeded labeled amounts by 1.5-13% for copper, manganese, magnesium, niacin, phosphorus, potassium, folic acid, riboflavin, and vitamins B-12, C, and E, and by ∼25% for selenium and iodine, regardless of labeled amount. In contrast, thiamin, vitamin B-6, calcium, iron, and zinc had linear or quadratic relations between the labeled and percentage differences, with ranges from -6.5% to 8.6%, -3.5% to 21%, 7.1% to 29.3%, -0.5% to 16.4%, and -1.9% to 8.1%, respectively. Analytically adjusted ingredient amounts are linked to adult MVMs reported in the NHANES 2003-2008 via the Dietary Supplement Ingredient Database (http://dsid.usda.nih.gov) to facilitate more accurate intake quantification.

CONCLUSIONS

Vitamin and mineral overages were measured in adult MVMs, most of which already meet RDAs. Therefore, nutrient overexposures from supplements combined with typical food intake may have unintended health consequences, although this would require further examination.

Feasibility of including green tea products for an analytically verified dietary supplement database

The Dietary Supplement Ingredient Database (DSID) is a federally funded, publicly accessible dietary supplement database that currently contains analytically derived information on micronutrients in selected adult and children's multivitamin and mineral (MVM) supplements. Other constituents in dietary supplement products such as botanicals are also of interest and thus are being considered for inclusion in the DSID. Thirty-eight constituents, mainly botanicals were identified and prioritized by a federal interagency committee. Green tea was selected from this list as the botanical for expansion of the DSID. This article describes the process for prioritizing dietary ingredients in the DSID. It also discusses the criteria for inclusion of these ingredients, and the approach for selecting and testing products for the green tea pilot study.

Recent developments in multivitamin/mineral research

The 2010 Dietary Guidelines Advisory Committee was charged with the task of investigating the effects of multivitamin/mineral supplements on healthy populations and also on those with chronic disease. The evidence from which the committee prepared its conclusions was graded on 5 fundamental criteria: quality, consistency, quantity, clinical impact, and generalizability. The committee concluded that for the general healthy population, evidence was insufficient to make a multivitamin/mineral recommendation. On the other hand, the committee noted the value of some supplemental nutrients for at-risk populations such as iron, folic acid, and vitamin B-12. However, most of the studies referenced for the research used the conventional, all-encompassing, and oversimplified definition of a multivitamin/mineral as being a supplement containing 3 or more vitamins with or without minerals. In the few years since the committee released its 2010 report, several randomized clinical trials showing the benefits of daily multivitamin/mineral supplementation have been completed using supplements containing at least 10 or more vitamins and/or minerals, but there also continues to be some reports that do not find benefit from such supplements. Furthermore, several steps have been taken to advance the science behind these supplements so that consumers, physicians, and government agencies can all have more confidence in understanding the role of supplemental nutrition in the American diet. This review provides new evidence from 2010 onward addressing the committee's primary concerns about multivitamin/mineral research in regard to improving public health. It also includes several recent studies that may be of interest to future committees indicating the potential benefits of these supplements on improving the cognitive performance and mental well-being of healthy populations.

Do dietary supplements improve micronutrient sufficiency in children and adolescents?

OBJECTIVE

To examine if children use supplements to fill gaps in nutritionally inadequate diets or whether supplements contribute to already adequate or excessive micronutrient intakes from foods.

STUDY DESIGN

Data were analyzed for children (2-18 years) from the National Health and Nutrition Examination Survey 2003-2006, a nationally representative, cross-sectional survey (n = 7250). Diet was assessed using two 24-hour recalls, and dietary supplement use was assessed with a 30-day questionnaire.

RESULTS

Prevalence of supplements use was 21% (<2 years) and 42% (2-8 years). Supplement users had higher micronutrient intakes than nonusers. Calcium and vitamin D intakes were low for all children. Inadequate intakes of phosphorus, copper, selenium, folate, and vitamins B-6 and B-12 were minimal from foods alone among 2-8 year olds. However, among 9-18 year olds, a higher prevalence of inadequate intakes of magnesium, phosphorus, and vitamins A, C, and E were observed. Supplement use increased the likelihood of intakes above the upper tolerable intake level for iron, zinc, copper, selenium, folic acid, and vitamins A and C.

CONCLUSIONS

Even with the use of supplements, more than a one-third of children failed to meet calcium and vitamin D recommendations. Children 2-8 years old had nutritionally adequate diets regardless of supplement use. However, in children older than 8 years, dietary supplements added micronutrients to diets that would have otherwise been inadequate for magnesium, phosphorus, vitamins A, C, and E. Supplement use contributed to the potential for excess intakes of some nutrients. These findings may have implications for reformulating dietary supplements for children.

Summary of an NIH workshop to identify research needs to improve the monitoring of iodine status in the United States and to inform the DRI

The Office of Dietary Supplements (ODS) at the NIH sponsored a workshop on May 12-13, 2011, to bring together representatives from various NIH institutes and centers as a first step in developing an NIH iodine research initiative. The workshop also provided an opportunity to identify research needs that would inform the dietary reference intakes for iodine, which were last revised in 2001. Iodine is required throughout the life cycle, but pregnant women and infants are the populations most at risk of deficiency, because iodine is required for normal brain development and growth. The CDC monitors iodine status of the population on a regular basis, but the status of the most vulnerable populations remains uncertain. The NIH funds very little investigator-initiated research relevant to iodine and human nutrition, but the ODS has worked for several years with a number of other U.S. government agencies to develop many of the resources needed to conduct iodine research of high quality (e.g., validated analytical methods and reference materials for multiple types of samples). Iodine experts, scientists from several U.S. government agencies, and NIH representatives met for 2 d to identify iodine research needs appropriate to the NIH mission.

Examination of vitamin intakes among US adults by dietary supplement use

BACKGROUND

More than half of US adults use dietary supplements. Some reports suggest that supplement users have higher vitamin intakes from foods than nonusers, but this observation has not been examined using nationally representative survey data.

OBJECTIVE

The purpose of this analysis was to examine vitamin intakes from foods by supplement use and how dietary supplements contribute to meeting or exceeding the Dietary Reference Intakes for selected vitamins using data from the National Health and Nutrition Examination Survey among adults (aged ≥19 years) in 2003-2006 (n=8,860).

RESULTS

Among male users, mean intakes of folate and vitamins A, E, and K from food sources were significantly higher than among nonusers. Among women, mean intakes of folate and vitamins A, C, D, and E from foods were higher among users than nonusers. Total intakes (food and supplements) were higher for every vitamin we examined among users than the dietary vitamin intakes of nonusers. Supplement use helped lower the prevalence of intakes below the Estimated Average Requirement for every vitamin we examined, but for folic acid and vitamins A, B-6, and C, supplement use increased the likelihood of intakes above the Tolerable Upper Intake Level.

CONCLUSIONS

Supplement use was associated with higher mean intakes of some vitamins from foods among users than nonusers, but it was not associated with the prevalence of intakes less than the Estimated Average Requirement from foods. Those who do not use vitamin supplements had significantly higher prevalence of inadequate vitamin intakes; however, the use of supplements can contribute to excess intake for some vitamins.

Sources and determinants of vitamin D intake in Danish pregnant women

Vitamin D deficiency during pregnancy has been associated with the development of several adverse health outcomes, e.g., pre-eclampsia, gestational diabetes mellitus, preterm delivery, low birth weight, birth length, and bone mineral content. The aims of the present study were to estimate the intake and sources of vitamin D in Danish pregnant women and to examine potential determinants of vitamin D intake of the recommended level (10 µg per day). In 68,447 Danish pregnant women the mean ± SD for vitamin D intake was 9.23 ± 5.60 µg per day (diet: 3.56 ± 2.05 µg per day, supplements: 5.67 ± 5.20 µg per day). 67.6% of the women reported use of vitamin D supplements but only 36.9% reported use of vitamin D supplements of at least 10 µg. Supplements were the primary source of vitamin D for the two higher quartiles of total vitamin D intake, with diet being the primary source for the two lower quartiles. Determinants of sufficient total vitamin D intake were: high maternal age, nulliparity, non-smoking, and filling out of the Food Frequency Questionnaire (FFQ) during summer or fall. We propose that clinicians encourage vitamin D supplementation among pregnant women, with special focus on vulnerable groups such as the young, smokers and multiparous women, in order to improve maternal and fetal health both during and after pregnancy.

Vitamin food fortification today

Historically, food fortification has served as a tool to address population-wide nutrient deficiencies such as rickets by vitamin D fortified milk. This article discusses the different policy strategies to be used today. Mandatory or voluntary fortification and fortified foods, which the consumer needs, also have to comply with nutritional, regulatory, food safety and technical issues. The ‘worldwide map of vitamin fortification’ is analysed, including differences between develop and developing countries. The vitamins, folate and vitamin D, are taken as practical examples in the review of the beneficial effect of different strategies on public health. The importance of the risk–benefit aspect, as well as how to identify the risk groups, and the food vehicles for fortification is discussed.

A three-part, mixed-effects model to estimate the habitual total vitamin D intake distribution from food and dietary supplements in Dutch young children

Statistical modeling of habitual micronutrient intake from food and dietary supplements using short-term measurements is hampered by heterogeneous variances and multimodality. Summing short-term intakes from food and dietary supplements prior to simple correction for within-person variation (first add then shrink) may produce estimates of habitual total micronutrient intake so badly biased as to be smaller than estimates of habitual intake from food sources only. A 3-part model using a first shrink then add approach is proposed to estimate the habitual micronutrient intake from food among nonsupplement users, food among supplement users, and supplements. The population distribution of habitual total micronutrient intake is estimated by combining these 3 habitual intake distributions, accounting for possible interdependence between Eq. 2 and 3. The new model is an extension of a model developed by the USA National Cancer Institute. Habitual total vitamin D intake among young children was estimated using the proposed model and data from the Dutch food consumption survey (n = 1279). The model always produced habitual total intakes similar to or higher than habitual intakes from food sources only and also preserved the multimodal shape of the observed total vitamin D intake distribution. This proposed method incorporates several sources of covariate information that should provide more precise estimates of the habitual total intake distribution and the proportion of the population with intakes below/above cutpoint values. The proposed methodology could be useful for other complex situations, e.g. where high concentrations of micronutrients appear in episodically consumed foods.

Isotope dilution liquid chromatography - mass spectrometry methods for fat- and water-soluble vitamins in nutritional formulations

Vitamins are essential to human health, and dietary supplements containing vitamins are widely used by individuals hoping to ensure they have adequate intake of these important nutrients. Measurement of vitamins in nutritional formulations is necessary to monitor regulatory compliance and in studies examining the nutrient intake of specific populations. Liquid chromatographic methods, primarily with UV absorbance detection, are well established for both fat- and water-soluble measurements, but they do have limitations for certain analytes and may suffer from a lack of specificity in complex matrices. Liquid chromatography-mass spectrometry (LC-MS) provides both sensitivity and specificity for the determination of vitamins in these matrices, and simultaneous analysis of multiple vitamins in a single analysis is often possible. In this work, LC-MS methods were developed for both fat- and water-soluble vitamins and applied to the measurement of these analytes in two NIST Standard Reference Materials. When possible, stable isotope labeled internal standards were employed for quantification.

Developing a database of vitamin and mineral supplements (ViMiS) for the Norfolk arm of the European Prospective Investigation into Cancer (EPIC-Norfolk)

OBJECTIVE

Supplements are an important source of micronutrient intake, which, unless taken into account, can misclassify individuals with regard to levels of nutrient exposure. A label-based vitamin and mineral supplements (ViMiS) database was developed to contain manufacturers' information and to enter supplement use by participants in the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk). The ViMiS database contains information on all ingredients, broken down into nutrient information in order to be combined with nutrient intake derived from food consumption.

DESIGN

Development of the ViMiS database and cross-sectional analysis of supplement use in a population-based study.

SETTING

Men and women aged 40-79 years from the general population participating in the EPIC-Norfolk study between 1993 and 1997, with data available from 7 d diet diaries (7dDD).

SUBJECTS

A subset of 19 330 participants with available 7dDD and known supplement status.

RESULTS

To date, the ViMiS database includes 2066 supplements, which altogether contain 16 586 ingredients, with a median of eleven nutrient/ingredients per supplement. Forty per cent of the cohort took a supplement, of which cod liver oil was the most common (24·5 %).

CONCLUSIONS

The ViMiS database provides a flexible tool for estimating total nutrient intake. The high prevalence of supplement use in the general population indicates that supplement use needs to be taken into account when examining the relationship of intake of particular nutrients to health outcomes.

Total folate and folic acid intakes from foods and dietary supplements of US children aged 1-13 y

BACKGROUND

Total folate intake includes naturally occurring food folate and folic acid from fortified foods and dietary supplements. Recent reports have focused on total folate intakes of persons aged > or =14 y. Information on total folate intakes of young children, however, is limited.

OBJECTIVE

The objective was to compute total folate and total folic acid intakes of US children aged 1-13 y by using a statistical method that adjusts for within-person variability and to compare these intakes with the Dietary Reference Intake guidelines for adequacy and excess.

DESIGN

Data from the 2003-2006 National Health and Nutrition Examination Survey, a nationally representative cross-sectional survey, were analyzed. Total folate intakes were derived by combining intakes of food folate (naturally occurring and folic acid from fortified foods) on the basis of 24-h dietary recall results and folic acid intakes from dietary supplements on the basis of a 30-d questionnaire.

RESULTS

More than 95% of US children consumed at least the Estimated Average Requirement (EAR) for folate from foods alone. More than one-third (35%) of US children aged 1-13 y used dietary supplements, and 28% used dietary supplements containing folic acid. Supplement users had significantly higher total folate and folic acid intakes than did nonusers. More than half (53%) of dietary supplement users exceeded the Tolerable Upper Intake Level (UL) for total folic acid (fortified food + supplements) as compared with 5% of nonusers.

CONCLUSIONS

Total folate intakes of most US children aged 1-13 y meet the EAR. Children who used dietary supplements had significantly higher total folate intakes and exceeded the UL by >50%.

Estimation of total usual calcium and vitamin D intakes in the United States

Our objective in this study was to estimate calcium intakes from food, water, dietary supplements, and antacids for U.S. citizens aged >or=1 y using NHANES 2003-2006 data and the Dietary Reference Intake panel age groupings. Similar estimates were calculated for vitamin D intake from food and dietary supplements using NHANES 2005-2006. Diet was assessed with 2 24-h recalls; dietary supplement and antacid use were determined by questionnaire. The National Cancer Institute method was used to estimate usual nutrient intake from dietary sources. The mean daily nutrient intake from supplemental sources was added to the adjusted dietary intake estimates to produce total usual nutrient intakes for calcium and vitamin D. A total of 53% of the U.S. population reported using any dietary supplement (2003-2006), 43% used calcium (2003-2006), and 37% used vitamin D (2005-2006). For users, dietary supplements provided the adequate intake (AI) recommendation for calcium intake for approximately 12% of those >or=71 y. Males and females aged 1-3 y had the highest prevalence of meeting the AI from dietary and total calcium intakes. For total vitamin D intake, males and females >or=71, and females 14-18 y had the lowest prevalence of meeting the AI. Dietary supplement use is associated with higher prevalence of groups meeting the AI for calcium and vitamin D. Monitoring usual total nutrient intake is necessary to adequately characterize and evaluate the population's nutritional status and adherence to recommendations for nutrient intake.

Total folate and folic acid intake from foods and dietary supplements in the United States: 2003-2006

BACKGROUND

The term total folate intake is used to represent folate that occurs naturally in food as well as folic acid from fortified foods and dietary supplements. Folic acid has been referred to as a double-edged sword because of its beneficial role in the prevention of neural tube defects and yet possible deleterious effects on certain cancers and cognitive function. Previous monitoring efforts did not include folic acid from dietary supplements and are therefore not complete.

OBJECTIVE

Our objective was to combine data on dietary folate (as measured by two 24-h recalls) and folic acid from dietary supplements (collected with a 30-d frequency questionnaire) with the use of the bias-corrected best power method to adjust for within-person variability.

DESIGN

The National Health and Nutrition Examination Survey (NHANES) is a nationally representative, cross-sectional survey. Linear contrasts were constructed to determine differences in dietary and total folate intake for age and racial-ethnic groups by sex; prevalence of inadequate and excessive intakes is presented.

RESULTS

In 2003-2006, 53% of the US population used dietary supplements; 34.5% used dietary supplements that contained folic acid. Total folate intake (in dietary folate equivalents) was higher for men (813 +/- 14) than for women (724 +/- 16) and higher for non-Hispanic whites (827 +/- 19) than for Mexican Americans (615 +/- 11) and non-Hispanic blacks (597 +/- 12); 29% of non-Hispanic black women had inadequate intakes. Total folate and folic acid intakes are highest for those aged > or =50 y, and 5% exceed the Tolerable Upper Intake Level.

CONCLUSIONS

Improved total folate intake is warranted in targeted subgroups, which include women of childbearing age and non-Hispanic black women, whereas other population groups are at risk of excessive intake.

Development of a supplement composition database for the SURE Study

The Supplement Reporting (SURE) study is one of the first to systematically examine the accuracy of collection of dietary supplement use data for population-based studies of diet. In 2005-2007, the SURE study collected data from 444 participants in Hawaii and Los Angeles. Several methods of collecting data were compared, including an inventory of supplements, a recall, a daily diary, and a one-page supplement frequency questionnaire. Considerable effort was put into developing an extensive supplement composition database. To quantify intakes, we extended the existing supplement composition table (SCT) used at the Cancer Research Center of Hawaii. The original SCT contained default codes for multivitamin/multimineral products to be used when insufficient detail was available to assign an existing code. However, the default concept needed to be expanded for the SURE study to include additional multivitamin/multimineral default codes, as well as single nutrients and other components. Approximately 1800 new codes were created, including 211 new default codes. Roughly 130 nutrients and 870 other components were included in the SCT at the conclusion of the study. To accurately quantify intakes from supplements, it is crucial to maintain a comprehensive supplement composition database. Future improvements to our SCT include incorporation of analytic values from the US Department of Agriculture to replace composition data taken from supplement labels.

Assessing the vitamin D status of the US population

This article describes the information currently available in the National Nutrition Monitoring System that is relevant to assessing the vitamin D status of US population groups, the strengths and limitations of this information, and selected results of vitamin D nutritional status assessments. The National Health and Nutrition Examination Survey (NHANES) provides information on vitamin D intakes only from 1988 to 1994. NHANES collected information on supplement use and circulating 25-hydroxyvitamin D [25(OH)D] concentrations from 1988 through current surveys. The National Nutrient Database for Standard Reference started providing limited data on the vitamin D content of foods in 2002 and continues to update these values. The Food Label and Package Survey provides 2006-2007 label information on vitamin D fortification of marketed foods. Despite limitations in the available data and controversies about appropriate criteria for evaluating vitamin D status among population groups, we can make some useful comparisons of vitamin D status among life-stage groups. In general, males have higher vitamin D intakes and 25(OH)D concentrations than do females. Children tend to have higher vitamin D status than adults. The increasing use of multivitamin-mineral dietary supplements in younger to older adults is not associated with a corresponding increase in serum 25(OH)D concentrations. In general, leaner individuals have higher circulating concentrations of 25(OH)D and supplement use than do heavier individuals. Finally, non-Hispanic whites tend to have higher vitamin D status than do non-Hispanic blacks and Mexican Americans.

Application of FDA Adverse Event Report Data to the Surveillance of Dietary Botanical Supplements

Background:

Concerns have been raised about the sufficiency of dietary botanical supplement (DBS) surveillance in the US. The Food and Drug Administration's Center for Food Safety and Applied Nutrition's Adverse Event Reporting System (CAERS) represents one of the few existing surveillance mechanisms, but it has not been well characterized with respect to DBS adverse effects.

Objective:

To characterize data on DBSs associated with adverse event reports submitted to CAERS.

Methods:

We requested and obtained CAERS data from 1999 to 2003 involving adverse effects associated with the 6 most frequently used DBSs: Echinacea, ginseng, garlic, Ginkgo biloba, St. John's wort, and peppermint. We summarized and characterized the adverse event reports received, focusing on the composition of the DBSs and the nature of associated adverse events. We also cross-referenced reported single-ingredient DBSs with corresponding available product information. A sample of CAERS cases associated with signal DBSs was also characterized in detail.

Results:

CAERS reports involving ginseng DBSs were most frequently reported during the study period, whereas reports involving St. John's wort were the least frequently reported. Most CAERS reports involved multiple-ingredient DBSs, and 3-13% of reports involved multiple DBSs. Gastrointestinal and neurologic problems were the most common clinical outcomes among single-ingredient DBS-associated adverse events.

Conclusions:

CAERS surveillance of DBS adverse effects is potentially as effective as other passive surveillance methods, but the number of reports is relatively small, validation is incomplete, and some inconsistencies within reports were found. Reports in CAERS may underrepresent DBS adverse events associated with DBS consumption.

Progress in developing analytical and label-based dietary supplement databases at the NIH Office of Dietary Supplements

Although an estimated 50% of adults in the United States consume dietary supplements, analytically substantiated data on their bioactive constituents are sparse. Several programs funded by the Office of Dietary Supplements (ODS) at the National Institutes of Health enhance dietary supplement database development and help to better describe the quantitative and qualitative contributions of dietary supplements to total dietary intakes. ODS, in collaboration with the United States Department of Agriculture, is developing a Dietary Supplement Ingredient Database (DSID) verified by chemical analysis. The products chosen initially for analytical verification are adult multivitamin-mineral supplements (MVMs). These products are widely used, analytical methods are available for determining key constituents, and a certified reference material is in development. Also MVMs have no standard scientific, regulatory, or marketplace definitions and have widely varying compositions, characteristics, and bioavailability. Furthermore, the extent to which actual amounts of vitamins and minerals in a product deviate from label values is not known. Ultimately, DSID will prove useful to professionals in permitting more accurate estimation of the contribution of dietary supplements to total dietary intakes of nutrients and better evaluation of the role of dietary supplements in promoting health and well-being. ODS is also collaborating with the National Center for Health Statistics to enhance the National Health and Nutrition Examination Survey dietary supplement label database. The newest ODS effort explores the feasibility and practicality of developing a database of all dietary supplement labels marketed in the US. This article describes these and supporting projects.