Breige A. McNulty

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.

Women's compliance with current folic acid recommendations and achievement of optimal vitamin status for preventing neural tube defects

BACKGROUND The timing of folic acid supplement usage is critical to preventing pregnancies affected by neural tube defects (NTDs) because the neural tube closes by Day 28 post-conception. We investigated compliance of pregnant women with current folic acid recommendations (400 µg/day from preconception to 12 weeks) in relation to achieving a folate status associated with lowest risk of NTDs. METHODS From a sample of 296 women with singleton uncomplicated pregnancies attending an antenatal clinic in Northern Ireland, those who reported taking folic acid in the first trimester (n = 226) were investigated. Samples were taken at 14 weeks gestation to measure serum concentrations of folate and vitamin B12 (related to folate and an independent predictor of NTD), and dietary B-vitamin intake and folic acid usage were investigated. RESULTS Although the majority of the overall sample (84%) reported taking folic acid supplements in the first trimester, only 19% had started before conception, as recommended. Multigravidae compared with primigravidae women were less likely to have followed the recommendations correctly (P= 0.001). At 14 weeks, red cell folate (considered a reliable biomarker of previous 3 months, covering time of neural tube closure) was correlated (r = 0.320, P < 0.001) with the reported duration of folic acid usage, and was lower (P< 0.0001) in women who started folic acid after conception. CONCLUSIONS Red cell folate concentrations in women not complying with recommendations were suboptimal in relation to NTD risk. The findings generally support the recent official recommendation to the Chief Medical Officer for mandatory fortification of food with folic acid in the UK.

Impact of continuing folic acid after the first trimester of pregnancy: findings of a randomized trial of Folic Acid Supplementation in the Second and Third Trimesters

BACKGROUND Supplementation with folic acid (FA) is recommended worldwide before and during early pregnancy because of its proven effect in preventing neural tube defects, but the role of FA after the 12th gestational week (GW) is much less clear. OBJECTIVE We investigated maternal folate and homocysteine responses and related effects in the newborn that resulted from continued FA supplementation after the first trimester of pregnancy. DESIGN Pregnant women, aged 18-35 y, who were attending an antenatal clinic in Northern Ireland with singleton uncomplicated pregnancies and reported taking FA supplements in the first trimester, were randomly assigned at the start of trimester 2 to receive 400 μg FA/d or a placebo capsule. RESULTS A total of 119 women (60 women in the placebo group; 59 women in the treatment group) completed the trial. From GWs 14-36, mean (±SD) serum folate decreased (from 45.7 ± 21.3 to 19.5 ± 16.5 nmol/L; P < 0.001) in unsupplemented women, whereas plasma homocysteine increased (6.6 ± 2.3 to 7.6 ± 2.3 μmol/L; P < 0.001). However, FA supplementation prevented these changes and resulted in a significant increase in red blood cell folate concentrations from 1203 ± 639 to 1746 ± 683 nmol/L (P < 0.001; GWs 14-36). Cord blood folate was significantly higher in the FA group than in the placebo group (red blood cell concentrations of 1993 ± 862 and 1418 ± 557 nmol/L, respectively; P = 0.001). CONCLUSIONS Continued supplementation with 400 μg FA/d in trimesters 2 and 3 of pregnancy can increase maternal and cord blood folate status and prevent the increase in homocysteine concentration that otherwise occurs in late pregnancy. Whether these effects have benefits for pregnancy outcomes or early childhood requires additional study.

The use of cluster analysis to derive dietary patterns: methodological considerations, reproducibility, validity and the effect of energy mis-reporting

Over the last three decades, dietary pattern analysis has come to the forefront of nutritional epidemiology, where the combined effects of total diet on health can be examined. Two analytical approaches are commonly used: a priori and a posteriori. Cluster analysis is a commonly used a posteriori approach, where dietary patterns are derived based on differences in mean dietary intake separating individuals into mutually exclusive, non-overlapping groups. This review examines the literature on dietary patterns derived by cluster analysis in adult population groups, focusing, in particular, on methodological considerations, reproducibility, validity and the effect of energy mis-reporting. There is a wealth of research suggesting that the human diet can be described in terms of a limited number of eating patterns in healthy population groups using cluster analysis, where studies have accounted for differences in sex, age, socio-economic status, geographical area and weight status. Furthermore, patterns have been used to explore relationships with health and chronic diseases and more recently with nutritional biomarkers, suggesting that these patterns are biologically meaningful. Overall, it is apparent that consistent trends emerge when using cluster analysis to derive dietary patterns; however, future studies should focus on the inconsistencies in methodology and the effect of energy mis-reporting.

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.

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.

Use of metabotyping for the delivery of personalised nutrition

SCOPE Personalised nutrition can be defined as dietary advice that is tailored to an individual. In recent years, the concept of targeted nutrition has evolved, which involves delivering specific dietary advice to a group of phenotypically similar individuals or metabotypes. This study examined whether cluster analysis could be used to define metabotypes and developed a strategy for the delivery of targeted dietary advice. METHOD AND RESULTS K-means clustering was employed to identify clusters based on four markers of metabolic health (triacylglycerols, total cholesterol, direct HDL cholesterol and glucose) (n = 896) using data from the National Adult Nutrition Survey. A decision tree approach was developed for the delivery of targeted dietary advice per cluster based on biochemical characteristics, anthropometry and blood pressure. The appropriateness of the advice was tested by comparison with individualised dietary advice manually compiled (n = 99). A mean match of 89.1% between the methods was demonstrated with a 100% match for two-thirds of participants. CONCLUSION Good agreement was found between the individualised and targeted methods demonstrating the ability of this framework to deliver targeted dietary advice. This approach has the potential to be a fast and novel method for the delivery of targeted nutrition in clinical settings.

Dietary intake of four artificial sweeteners by Irish pre-school children

ABSTRACT In spite of rigorous pre- and post-market reviews of safety, there remains a high level of debate regarding the use of artificial sweeteners in foods. Young children are of particular interest when assessing food chemical exposure as a result of their unique food consumption patterns and comparatively higher exposure to food chemicals on a body weight basis when compared with the general population. The present study examined the intakes of four intense sweeteners (acesulfame K, aspartame, saccharin, sucralose) in the diets of children aged 1–4 years using food consumption and sweetener presence data from the Irish National Pre-school Nutrition Survey (2010–11) and analytical data for sweetener concentration in foods obtained from a national testing programme. Four exposure assessment scenarios were conducted using the available data on sweetener occurrence and concentration. The results demonstrated that the mean daily intakes for all four sweeteners were below the acceptable daily intake (ADI) (17–31%), even considering the most conservative assumptions regarding sweetener presence and concentration. High consumer intakes (P95) were also below the ADI for the four sweeteners when more realistic estimates of exposure were considered. Both sweetener occurrence and concentration data had a considerable effect on reducing the estimated intake values, with a combined reduction in intakes of 95% when expressed as a proportion of the ADI. Flavoured drinks were deemed to be a key contributor to artificial sweetener intakes in this population cohort. It was concluded that there is no health risk to Irish pre-school children at current dietary intake levels of the sweeteners studied.

High saturated-fat and low-fibre intake: a comparative analysis of nutrient intake in individuals with and without type 2 diabetes

Objective:The aim of dietary modification, as a cornerstone of type 2 diabetes (T2DM) management, is to optimise metabolic control and overall health. This study describes food and nutrient intake in a sample of adults with T2DM, and compares this to recommendations, and to intake in age, sex, body mass index (BMI) and social-class matched adults without T2DM.Design:A cross-sectional analysis of food and nutrient intake in 124 T2DM individuals (64% male; age 57.4±5.6 years, BMI 32.5±5.8 kg m−2) and 124 adults (age 57.4±7.0 years, BMI 31.2±5.0 kg m−2) with no diabetes (ND) was undertaken using a 4-day semiweighed food diary. Biochemical and anthropometric variables were also measured.Results:While reported energy intake was similar in T2DM vs ND (1954 vs 2004 kcal per day, P=0.99), T2DM subjects consumed more total-fat (38.8% vs 35%, P⩽0.001), monounsaturated-fat (13.3% vs 12.2%; P=0.004), polyunsaturated-fat (6.7% vs 5.9%; P<0.001) and protein (18.6% vs 17.5%, P⩽0.01). Both groups exceeded saturated-fat recommendations (14.0% vs 13.8%). T2DM intakes of carbohydrate (39.5% vs 42.9%), non-milk sugar (10.4% vs 15.0%) and fibre (14.4 vs 18.9 g) were significantly lower (P<0.001). Dietary glycaemic load (GL) was also lower in T2DM (120.8 vs 129.2; P=0.02), despite a similar glycaemic index (59.7 vs 60.1; P=0.48). T2DM individuals reported consuming significantly more wholemeal/brown/wholegrain breads, eggs, oils, vegetables, meat/meat products, savoury snacks and soups/sauces and less white breads, breakfast cereals, cakes/buns, full-fat dairy, chocolate, fruit juices, oily fish and alcohol than ND controls.Conclusion:Adults with T2DM made different food choices to ND adults. This resulted in a high saturated-fat diet, with a higher total-fat, monounsaturated-fat, polyunsaturated-fat and protein content and a lower GL, carbohydrate, fibre and non-milk sugar content. Dietary education should emphasise and reinforce the importance of higher fibre, fruit, vegetable and wholegrain intake and the substitution of monounsaturated for saturated-fat sources, in energy balanced conditions.