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Background: Data from a nationally representative sample of 18- to 64-y-old Irish adults conducted in 1999 highlighted low phylloquinone intakes. That survey, however, did not include older adults (aged ≥65 y), a subgroup that is potentially at higher risk of low phylloquinone intakes, or a biomarker of vitamin K status.Objectives: The objectives of this work were to measure the phylloquinone intake and its adequacy and the serum percentage of undercarboxylated osteocalcin (%ucOC), a vitamin K status biomarker, in a nationally representative sample of Irish adults aged 18-90 y, and to compare these newer data on dietary phylloquinone in adults aged 18-64 y with those from the previous survey.Methods: Data and biobanked serum samples from the National Adult Nutrition Survey, a randomly selected sample of Irish adults aged 18-90 y (N = 1500), were accessed. Phylloquinone intakes were estimated from 4-d food diary data and were compared across age groups (18-35, 36-50, 51-64, and ≥65 y). Serum %ucOC was assessed by immunoassay (n = 692).Results: The mean ± SD intake of phylloquinone from all sources was 85.2 ± 59.1 μg/d, 99% of which was derived from food. Phylloquinone intakes and serum %ucOC were significantly (P < 0.05) lower (14-25%) and higher (27-39%), respectively, in the 18- to 35-y age group than in the 36- to 50-y, 51- to 64-y, and ≥65-y age groups (no differences between these 3 groups; P > 0.2 in all cases). Mean phylloquinone intakes had increased (P < 0.01) modestly (6 μg/d) in 18-64-y-olds across a decade. Of the total study population, 55% had phylloquinone intakes below the United Kingdom recommended intake of 1 μg ⋅ kg body weight-1 ⋅ d-1 CONCLUSION: Our study shows that younger adults (aged 18-35 y) appear to be at higher risk of inadequate vitamin K intake and lower vitamin K status, the health implications of which are unclear and warrant further investigation. [ABSTRACT FROM AUTHOR]

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 serum3-epi-25(OH)D3 concentrations. Serum25-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 serum3-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 serum3-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 serum3-epi-25(OH)D3 concentration. [ABSTRACT FROM AUTHOR]

Two separate, identical, double-blind, randomized, placebo-controlled intervention studies were carried out in the south and north of Ireland (51-55°N). Men and women aged 20-40 y (n = 202) and ≥64 y (n = 192) received cholecalciferol at doses of 0 (P), 5 (D3-5), 10 (D3-10), or 15 (D3-15) &mgr;g/d (0-600 lu) during wintertime. Serum 25-hydroxyvitamin D [s25(OH)D], intact parathyroid hormone, systolic and diastolic blood pressure, fasting lipids, glucose and insulin, HOMA-IR, high-sensitivity CRP, matrix metalloproteinase-9, and its inhibitor (tissue inhibitor metalloproteinase-1) were measured at baseline (October) and 22 wk later at endpoint (March). Vitamin D receptor Fok I and Taq I genotypes were analyzed and dietary intakes of vitamin D and calcium were assessed. In young adults, s25(OH)D decreased from baseline to endpoint (P< 0.001), except in the D3-15 group, who maintained the baseline concentration of ∼70 nmol/L Older adults had lower s25(OH)D at baseline (median, 54.2 nmol/L) and concentrations increased in the D3-10 and D3-15 groups (P < 0.001). There were no significant effects of supplementation on cardiovascular disease (CVD) risk biomarkers in either age group. Fasting glucose and total and HDL cholesterol were lower (P< 0.05) in older adults with the Fok 1 ffgenotype than in those with FFor Ff. Putative effects of vitamin D on cardio-metabolic health will only be evident at higher intakes than the current PDA and possibly in individuals at particular risk of low s25(OH)D and/or CVD risk. [ABSTRACT FROM AUTHOR]

Epidemiological studies have shown that low vitamin D status results in impaired immune function and is associated with the prevalence of autoimmune and inflammatory conditions. Vitamin D supplementation has been shown to reduce circulating concentrations of inflammatory markers in such conditions. However, the possible beneficial effect of vitamin D supplementation in the general population, particularly for those individuals living at high latitudes where hypovitaminosis D is common during wintertime, remains unclear. The aim of this study was to assess the effect of vitamin D supplementation using doses of 5, 10, and 15 μg/d cholecalciferol (D3) compared with placebo on cytokine concentrations throughout winter in apparently healthy younger (aged 20-40 y) and older (aged ≥64 y) adults. A total of 211 younger and 202 older adults completed the 22-wk intervention (from October to March) with >85% compliance. Serum concentrations of 25-hydroxycholecalciferol [25)OH)D3], high sensitivity C-reactive protein, IL-6, IL-10, soluble CD40 ligand, TGFβ, TNFα, and fibrinogen were measured using ELISA. 25(OH)D3 concentrations significantly decreased in the placebo and 5 and 10/d μg D3 groups in the younger cohort and in the placebo group in the older cohort. Whereas 15 μg/d D3 supplementation maintained 25(OH(D3 concentrations in the younger cohort (baseline, 75.9 nmol/L; postintervention, 69.0 nmol/L) and significantly increased concentrations in the older cohort (baseline, 55.1 nmol/L; postintervention, 73.9 nmol/L), it had no significant effect on cytokine concentrations (ANCOVA, P> 0.05). The long-term effects of low vitamin D status remain to be elucidated and optimization of vitamin D status in otherwise healthy individuals may potentially have lasting beneficial effects on the immune system. [ABSTRACT FROM AUTHOR]

Although there have been several studies of the effect of vitamin D status on bone turnover in the elderly, the findings are unclear, and, furthermore, to date very few have investigated this in young adults. The objective of these randomized, placebo-controlled, double-blind, 2-center intervention studies was to investigate the effect of cholecalciferol supplementation (0, 5, 10, and 15 μg cholecalciferol/d) throughout wintertime on indices of vitamin D status and bone turnover in young (aged 20-40 y; n = 215( and elderly (aged ⩾64 y; n = 204( adults, with relatively high mean calcium intakes of 976 and 874 mg/d, respectively. Fasting serum concentrations of 25-hydroxyvitamin D [25(OH(D], parathyroid hormone (PTH), osteocalcin, bone-specific alkaline phosphatase, and carboxyterminal collagen crosslinks were measured by enzyme immunoassays at baseline and endpoint. Fok I and Taq I vitamin D receptor (VDR( genotypes were determined by real-time PCR. Endpoint serum 25(OH)D increased (P< 0.0001) in a dose-related manner with increasing supplemental cholecalciferol (up to 15 μg/d( in 20-40-y olds and up to 10 μg/d in ⩾64-y olds. Endpoint serum PTH was lower (P < 0.051 in the 3 cholecalciferol-supplemented groups compared with that in the placebo group in ⩾64-y olds, but cholecalciferol supplementation did not affect other markers in either cohort and there was no significant interaction with VDR genotype. In conclusion, cholecalciferol supplementation alone throughout winter did not affect bone turnover markers in apparently healthy young and elderly adults, even when stratified by VDR genotype. [ABSTRACT FROM AUTHOR]