Janette Walton

Vitamin D status of Irish adults: findings from the National Adult Nutrition Survey

Previous national nutrition surveys in Irish adults did not include blood samples; thus, representative serum 25-hydroxyvitamin D (25(OH)D) data are lacking. In the present study, we characterised serum 25(OH)D concentrations in Irish adults from the recent National Adult Nutrition Survey, and determined the impact of vitamin D supplement use and season on serum 25(OH)D concentrations. Of the total representative sample (n 1500, aged 18+ years), blood samples were available for 1132 adults. Serum 25(OH)D was measured via immunoassay. Vitamin D-containing supplement use was assessed by questionnaire and food diary. Concentrations of serum 25(OH)D were compared by season and in supplement users and non-users. Year-round prevalence rates for serum 25(OH)D concentration < 30, < 40, < 50 and < 75 nmol/l were 6.7, 21.9, 40.1 and 75.6 %, respectively (11.1, 31.1, 55.0 and 84.0 % in winter, respectively). Supplement users had significantly higher serum 25(OH)D concentrations compared to non-users. However, 7.5 % of users had winter serum 25(OH)D < 30 nmol/l. Only 1.3 % had serum 25(OH)D concentrations >125 nmol/l. These first nationally representative serum 25(OH)D data for Irish adults show that while only 6.7 % had serum 25(OH)D < 30 nmol/l (vitamin D deficiency) throughout the year, 40.1 % had levels considered by the Institute of Medicine as being inadequate for bone health. These prevalence estimates were much higher during winter time. While vitamin D supplement use has benefits in terms of vitamin D status, at present rates of usage (17.5 % of Irish adults), it will have only very limited impact at a population level. Food-based strategies, including fortified foods, need to be explored.

Impact of voluntary fortification and supplement use on dietary intakes and biomarker status of folate and vitamin B-12 in Irish adults

BACKGROUND Ireland has traditionally operated a liberal policy of voluntary fortification, but little is known about how this practice, along with supplement use, affects population intakes and status of folate and vitamin B-12. OBJECTIVE The aim was to examine the relative impact of voluntary fortification and supplement use on dietary intakes and biomarker status of folate and vitamin B-12 in Irish adults. DESIGN Folic acid and vitamin B-12 from fortified foods and supplements were estimated by using brand information for participants from the cross-sectional National Adult Nutrition Survey 2008-2010. Dietary and biomarker values were compared between 6 mutually exclusive consumption groups formed on the basis of folic acid intake. RESULTS The consumption of folic acid through fortified foods at low, medium, and high levels of exposure [median (IQR) intakes of 22 (13, 32), 69 (56, 84), and 180 (137, 248) μg/d, respectively]; from supplements [203 (150, 400) μg/d]; or from both sources [287 (220, 438) μg/d] was associated with significantly higher folate intakes and status compared with nonconsumption of folic acid (18% of the population). Median (IQR) red blood cell (RBC) folate increased significantly from 699 (538, 934) nmol/L in nonconsumers to 1040 (83, 1390) nmol/L in consumers with a high intake of fortified foods (P < 0.001), with further nonsignificant increases in supplement users. Supplement use but not fortification was associated with significantly higher serum vitamin B-12 concentrations relative to nonconsumers (P < 0.001). Two-thirds of young women had suboptimal RBC folate for protection against neural tube defects (NTDs); among nonconsumers of folic acid, only 16% attained optimal RBC folate. CONCLUSIONS The consumption of voluntarily fortified foods and/or supplement use was associated with significantly higher dietary intakes and biomarker status of folate in Irish adults. Of concern, the majority of young women remain suboptimally protected against NTDs.

Small Increments in Vitamin D Intake by Irish Adults over a Decade Show That Strategic Initiatives to Fortify the Food Supply Are Needed

BACKGROUND Food fortification could be an effective method of increasing vitamin D intakes and preventing deficiency with minimal risk of excessive dosing. OBJECTIVE Secular trends in vitamin D intakes were examined over a 10-y period. METHODS We compared vitamin D intakes among 18- to 64-y-old adults from the base diet, fortified foods, and supplements in 2 nationally representative dietary surveys in 1999 and 2009 implemented using the same methodology. RESULTS There was a slight increase in the median (IQR) intake of vitamin D from 2.9 (3.2) to 3.5 (3.7) μg/d (mean ± SD, 4.3 ± 4.0 to 5.0 ± 6.4 μg). The median (IQR) intake from the base diet was 2.3 (1.6) μg/d in 1999 and 2.1 (1.8) μg/d in 2009. In vitamin D supplement users, median (IQR) intakes were 7.6 (6.7) and 8.7 (7.2) μg/d and the prevalence of inadequacy decreased from 67% to 57% in 2009. Although the consumption of vitamin D-containing supplements was similar in the 2 surveys (17% and 16%), the use of calcium-vitamin D supplements increased from 3% to 10% among women aged 50-64 y. The prevalence of fortified food consumption was also similar at 60%, and median (IQR) vitamin D intakes in consumers were 2.9 (2.2) and 3.7 (2.9) μg/d in 1999 and 2009, respectively. Mathematical modeling of food fortification using modified vitamin D composition data showed that there is potential to increase vitamin D intakes at the lower end of the distribution, without increasing the risk of exceeding the Tolerable Upper Intake Level. CONCLUSIONS We report small increases in vitamin D intakes among Irish adults over a decade of focus on vitamin D and in the context of a voluntary fortification policy. Strategic management of vitamin D in the food supply is required to yield measurable benefits.

A review of sugar consumption from nationally representative dietary surveys across the world.

Abstract Background Government and health organisations worldwide have recently reviewed the evidence on the role of dietary sugars in relation to health outcomes. Hence, it is timely to review current intakes of dietary sugars with respect to this guidance and as a benchmark for future surveillance. Methods This review collates data from nationally representative dietary surveys across the world and reports estimates of intakes of total and added sugars, and sucrose in different population subgroups. Total sugars includes all mono‐ and disaccharides; namely, glucose, fructose, lactose, sucrose and maltose. Added and free sugars differ in the quantity of natural sugars included in their definitions. Free sugars include sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates, whereas added sugars typically only refer to those added during processing. Results Most countries reported intakes of total sugars, with fewer reporting intakes of added sugars and sucrose. No country reported intakes of free sugars. The available data suggest that total sugars as a percentage of energy were highest in the infant (<4 years), with mean values ranging from 20.0% to 38.4%, and decreased over the lifespan to 13.5–24.6% in adults. Intakes of added sugars were higher in school‐aged children and adolescents (up to 19% of total energy) compared to younger children or adults. Conclusions Further research into the dietary patterns contributing to added sugars intake in children and adolescents is warranted. It would also be beneficial to policy guidance if future dietary surveys employed a uniform way of expressing sugars that is feasible to measure and has public health significance.

The 3 Epimer of 25-Hydroxycholecalciferol Is Present in the Circulation of the Majority of Adults in a Nationally Representative Sample and Has Endogenous Origins

Fundamental knowledge gaps in relation to the 3 epimer of 25-hydroxycholecalciferol [3-epi-25(OH)D₃] limit our understanding of its relevance for vitamin D nutrition and health. The aims of this study were to characterize the 3-epi-25(OH)D₃ concentrations in a nationally representative sample of adults and explore its determinants. We also used data from a recent randomized controlled trial (RCT) of supplemental cholecalciferol (vitamin D₃) conducted in winter in older adults to directly test the impact of changes in vitamin D status on serum 3-epi-25(OH)D3 concentrations. Serum 25-hydroxycholecalciferol [25(OH)D₃] and 3-epi-25(OH)D₃ concentrations (via LC-tandem mass spectrometry) from our vitamin D₃ RCT in adults (aged ≥50 y) and data on dietary, lifestyle, and biochemical characteristics of participants of the recent National Adult Nutrition Survey in Ireland (aged 18-84 y; n = 1122) were used in the present work. In the subsample of participants who had serum 3-epi-25(OH)D₃ concentrations greater than the limit of quantification (n = 1082; 96.4%), the mean, 10th, 50th (median), and 90th percentile concentrations were 2.50, 1.05, 2.18, and 4.30 nmol/L, respectively, whereas the maximum 3-epi-25(OH)D₃ concentration was 15.0 nmol/L. A regression model [explaining 29.9% of the variability in serum 3-epi-25(OH)D₃] showed that age >50 y, vitamin D supplement use, dietary vitamin D, meat intake, season of blood sampling, and sun exposure habits were significant positive determinants, whereas increasing waist circumference and serum 25-hydroxyergocalciferol concentration were significant negative determinants. The RCT data showed that mean serum 25(OH)D₃ and 3-epi-25(OH)D₃ concentrations increased (49.3% and 42.1%, respectively) and decreased (-28.0% and -29.1%, respectively) significantly (P < 0.0001) with vitamin D₃ (20 μg/d) and placebo supplementation, respectively, over 15 wk of winter. In conclusion, we provide data on serum 3-epi-25(OH)D₃ in a nationally representative sample of adults. Our combined observational and RCT data might suggest that both dietary supply and dermal synthesis of vitamin D₃ contribute to serum 3-epi-25(OH)D₃ concentration.

The impact of voluntary food fortification on micronutrient intakes and status in European countries: a review

This review aims to assess the efficacy and safety of voluntary fortification as an option to address the occurrence of inadequate micronutrient intakes in population subgroups in Europe. Although legislation is harmonised across the European Union, fortification practices and patterns of consumption of fortified foods vary considerably between countries. While the proportion of children consuming fortified foods is greater than adults, the proportion of dietary energy obtained from fortified foods is generally low (<10% in Ireland, where fortified foods are widely consumed). There are a few systematic studies on the overall nutritional impact of voluntary fortification, but there are several studies on the impact of fortified ready-to-eat breakfast cereals. The available evidence indicates that voluntary fortification can reduce the risk of sub-optimal intakes of a range of micronutrients at a population level and can also improve status for selected micronutrients (e.g. folate, vitamin D and riboflavin) in children and adults. Although concerns have been raised regarding the potential of food fortification to lead to unacceptably high micronutrient intakes, particularly for those consuming higher amounts of fortified foods, data from national surveys on total micronutrient intakes (including fortified foods) in Europe show that small proportions of the population, particularly children, may exceed the upper intake level (UL) for some micronutrients. The risk of adverse effects occurring in these individuals exceeding the UL by modest amounts is low. In conclusion, voluntary fortification practices have been shown to improve intake and status of key micronutrients in European Union population groups and do not contribute appreciably to risk of adverse effects.

Modelling the impact of specific food policy options on coronary heart disease and stroke deaths in Ireland

Objective To estimate the potential reduction in cardiovascular (CVD) mortality possible by decreasing salt, trans fat and saturated fat consumption, and by increasing fruit and vegetable (F/V) consumption in Irish adults aged 25–84 years for 2010. Design Modelling study using the validated IMPACT Food Policy Model across two scenarios. Sensitivity analysis was undertaken. First, a conservative scenario: reductions in dietary salt by 1 g/day, trans fat by 0.5% of energy intake, saturated fat by 1% energy intake and increasing F/V intake by 1 portion/day. Second, a more substantial but politically feasible scenario: reductions in dietary salt by 3 g/day, trans fat by 1% of energy intake, saturated fat by 3% of energy intake and increasing F/V intake by 3 portions/day. Setting Republic of Ireland. Outcomes Coronary heart disease (CHD) and stroke deaths prevented. Results The small, conservative changes in food policy could result in approximately 395 fewer cardiovascular deaths per year; approximately 190 (minimum 155, maximum 230) fewer CHD deaths in men, 50 (minimum 40, maximum 60) fewer CHD deaths in women, 95 (minimum 75, maximum 115) fewer stroke deaths in men, and 60 (minimum 45, maximum 70) fewer stroke deaths in women. Approximately 28%, 22%, 23% and 26% of the 395 fewer deaths could be attributable to decreased consumptions in trans fat, saturated fat, dietary salt and to increased F/V consumption, respectively. The 395 fewer deaths represent an overall 10% reduction in CVD mortality. Modelling the more substantial but feasible food policy options, we estimated that CVD mortality could be reduced by up to 1070 deaths/year, representing an overall 26% decline in CVD mortality. Conclusions A considerable CVD burden is attributable to the excess consumption of saturated fat, trans fat, salt and insufficient fruit and vegetables. There are significant opportunities for Government and industry to reduce CVD mortality through effective, evidence-based food policies.

Nutritional adequacy of diets containing growing up milks or unfortified cow’s milk in Irish children (aged 12-24 months)

Background Growing up milks (GUM) are milk-based drinks with added vitamins and minerals intended for children aged 12–36 months. Few data are available on the consumption of GUM and their role in the diets of young children. Objective To determine the nutritional adequacy of two groups of 12–24-month-old Irish children by type of milk consumption (consumers or non-consumers of GUM). Design Using data from a cross-sectional study of Irish children, the National Pre-School Nutrition Survey (2010–2011), two groups of children were defined. The groups included children aged 12–24 months with an average daily total milk intake of at least 300 g and consuming GUM (≥100 g/day) together with cows milk (n=29) or cows milk only (n=56). Results While average total daily energy intakes were similar in both consumers and non-consumers of GUM, intakes of protein, saturated fat, and vitamin B12 were lower and intakes of carbohydrate, dietary fibre, iron, zinc, vitamins C and D were higher in consumers of GUM. These differences in nutrient intakes are largely attributable to the differences in composition between GUM and cows milk. For both consumers and non-consumers of GUM, intakes of carbohydrate and fat were generally in line with recommendations while intakes of protein, dietary fibre and most micronutrients were adequate. For children consuming cows milk only, high proportions had inadequate intakes of iron and vitamin D; however, these proportions were much lower in consumers of GUM. Conclusions Consumption of GUM reduced the risk of inadequacies of iron and vitamin D, two nutrients frequently lacking in the diets of young children consuming unfortified cows milk only.

A metabolomics approach to the identification of biomarkers of sugar-sweetened beverage intake

BACKGROUND The association between sugar-sweetened beverages (SSBs) and health risks remains controversial. To clarify proposed links, reliable and accurate dietary assessment methods of food intakes are essential. OBJECTIVE The aim of this present work was to use a metabolomics approach to identify a panel of urinary biomarkers indicative of SSB consumption from a national food consumption survey and subsequently validate this panel in an acute intervention study. DESIGN Heat map analysis was performed to identify correlations between ¹H nuclear magnetic resonance (NMR) spectral regions and SSB intakes in participants of the National Adult Nutrition Survey (n = 565). Metabolites were identified and receiver operating characteristic (ROC) analysis was performed to assess sensitivity and specificity of biomarkers. The panel of biomarkers was validated in an acute study (n = 10). A fasting first-void urine sample and postprandial samples (2, 4, 6 h) were collected after SSB consumption. After NMR spectroscopic profiling of the urine samples, multivariate data analysis was applied. RESULTS A panel of 4 biomarkers-formate, citrulline, taurine, and isocitrate-were identified as markers of SSB intake. This panel of biomarkers had an area under the curve of 0.8 for ROC analysis and a sensitivity and specificity of 0.7 and 0.8, respectively. All 4 biomarkers were identified in the SSB sample. After acute consumption of an SSB drink, all 4 metabolites increased in the urine. CONCLUSIONS The present metabolomics-based strategy proved to be successful in the identification of SSB biomarkers. Future work will ascertain how to translate this panel of markers for use in nutrition epidemiology.

Dietary vitamin D2 - a potentially underestimated contributor to vitamin D nutritional status of adults?

It has been suggested that vitamin D₂ is not very prevalent in the human food chain. However, data from a number of recent intervention studies suggest that the majority of subjects had measurable serum 25-hydroxyvitamin D₂ (25(OH)D₂) concentrations. Serum 25(OH)D₂, unlike 25(OH)D₃, is not directly influenced by exposure of skin to sun and thus has dietary origins; however, quantifying dietary vitamin D₂ is difficult due to the limitations of food composition data. Therefore, the present study aimed to characterise serum 25(OH)D₂ concentrations in the participants of the National Adult Nutrition Survey (NANS) in Ireland, and to use these serum concentrations to estimate the intake of vitamin D₂ using a mathematical modelling approach. Serum 25(OH)D₂ concentration was measured by a liquid chromatography-tandem MS method, and information on diet as well as subject characteristics was obtained from the NANS. Of these participants, 78.7 % (n 884) had serum 25(OH)D₂ concentrations above the limit of quantification, and the mean, maximum, 10th, 50th (median) and 90th percentile values of serum 25(OH)D₂ concentrations were 3.69, 27.6, 1.71, 2.96 and 6.36 nmol/l, respectively. To approximate the intake of vitamin D₂ from these serum 25(OH)D₂ concentrations, we used recently published data on the relationship between vitamin D intake and the responses of serum 25(OH)D concentrations. The projected 5th to 95th percentile intakes of vitamin D₂ for adults were in the range of 0.9-1.2 and 5-6 μg/d, respectively, and the median intake ranged from 1.7 to 2.3 μg/d. In conclusion, the present data demonstrate that 25(OH)D₂ concentrations are present in the sera of adults from this nationally representative sample. Vitamin D₂ may have an impact on nutritional adequacy at a population level and thus warrants further investigation.