Vitamin D status and current policies to achieve adequate vitamin D intake in the Nordic countries.

Aims: Nordic countries share fairly similar food culture and geographical location as well as common nutrition recommendations. The aim of this paper was to review the latest data on vitamin D status and intake and to describe the national supplementation and food fortification policies to achieve adequate vitamin D intake in the Nordic countries. Methods: The data are based on results derived from a literature search presented in a workshop held in Helsinki in November 2018 and completed by recent studies. Results: Vitamin D policies and the implementation of the recommendations differ among the Nordic countries. Vitamin D fortification policies can be mandatory or voluntary and widespread, moderate or non-existent. Vitamin D supplementation recommendations differ, ranging from all age groups being advised to take supplements to only infants. In the general adult population of the Nordic countries, vitamin D status and intake are better than in the risk groups that are not consuming vitamin D supplements or foods containing vitamin D. Non-Western immigrant populations in all Nordic countries share the problem of vitamin D insufficiency and deficiency. Conclusions: Despite the common nutrition recommendations, there are differences between the Nordic countries in the implementation of the recommendations and policies to achieve adequate vitamin D intake and status. There is a need for wider Nordic collaboration studies as well as strategies to improve vitamin D status, especially in risk groups.

New advice on vitamin D supplements and cod liver oil for infants. / Nye råd om D-vitamintilskudd og tran til spedbarn.

Until recently, all parents have been advised to give cod liver oil to their infants. Now, cod liver oil is no longer recommended during the first year of life, but breastfed infants still need vitamin D supplements.

Effect of Vitamin D on Thyroid Autoimmunity: A Randomized, Double-Blind, Controlled Trial Among Ethnic Minorities.

CONTEXT: Autoimmune thyroid disorders have been linked to vitamin D deficiency, but an effect of vitamin D supplementation is not established. OBJECTIVE: Our objective was to test whether vitamin D compared with placebo could reduce thyroid autoantibodies. DESIGN: Predefined additional analyses from a randomized, double-blind, placebo-controlled trial. SETTING: The study was conducted in different community centers in Oslo, Norway. PARTICIPANTS: A total of 251 presumed healthy men and women, aged 18 to 50 years, with backgrounds from South Asia, the Middle East, and Africa were included. INTERVENTION: Daily supplementation with 25 µg (1000 IU) vitamin D3, 10 µg (400 IU) vitamin D3, or placebo for 16 weeks. OUTCOME MEASURE: Difference in preintervention and postintervention antithyroid peroxidase antibody (TPOAb) levels. Additional outcomes were differences in thyroid-stimulating hormone (TSH) and free fraction of thyroxine (fT4). RESULTS: There were no differences in change after 16 weeks on TPOAb (27 kU/L; 95% CI, -17 to 72; P = 0.23), TSH (-0.10 mU/L; 95% CI, -0.54 to 0.34; P = 0.65), or fT4 (0.09 pmol/L; 95% CI, -0.37 to 0.55; P = 0.70) between those receiving vitamin D supplementation or placebo. Mean serum 25(OH)D3 increased from 26 to 49 nmol/L in the combined supplementation group, but there was no change in the placebo group. CONCLUSION: Vitamin D3 supplementation, 25 µg or 10 µg, for 16 weeks compared with placebo did not affect TPOAb level in this randomized, double-blind study among participants with backgrounds from South Asia, the Middle East, and Africa who had low vitamin D levels at baseline.

Vitamin D supplementation and vitamin D status in children of immigrant background in Norway.

OBJECTIVE: Sufficient vitamin D status during infancy is important for child health and development. Several initiatives for improving vitamin D status among immigrant children have been implemented in Norway. The present study aimed to evaluate the vitamin D status and its determinants in children of immigrant background in Oslo. DESIGN: Cross-sectional study. SETTING: Child health clinics in Oslo. SUBJECTS: Healthy children with immigrant background (n 102) aged 9-16 months were recruited at the routine one-year check-up from two child health clinics with high proportions of immigrant clients. Blood samples were collected using the dried blood spot technique and analysed for serum 25-hydroxyvitamin D (s-25(OH)D) concentration using LC-MS/MS. RESULTS: Mean s-25(OH)D was 52·3 (sd 16·7) nmol/l, with only three children below 25 nmol/l and none below 12·5 nmol/l. There was no significant gender, ethnic or seasonal variation in s-25(OH)D. However, compared with breast-fed children, s-25(OH)D concentration was significantly higher among children who were about 1 year of age and not breast-fed. About 38 % of the children were anaemic, but there was no significant correlation between s-25(OH)D and Hb (Pearson correlation, r=0·1, P=0·33). CONCLUSIONS: Few children in the study had vitamin D deficiency, but about 47 % of the children in the study population were under the recommended s-25(OH)D sufficiency level of ≥50 nmol/l.

Nutritional rickets in Norway: a nationwide register-based cohort study.

OBJECTIVES: Poor vitamin D status has been reported to be highly prevalent in many non-western immigrant groups living in Norway and other western countries. However, data on rickets are scarce, and the aim of the current study was to identify new cases of nutritional rickets in Norway in the period 2008-2012 among children under the age of 5 years. DESIGN: Register-based cohort study. SETTING: The Norwegian population from 2008 to 2012. PARTICIPANTS: Children with nutritional rickets under the age of 5 years. MAIN OUTCOME MEASURE: Nutritional rickets. Patients with ICD10 (International Statistical Classification of Diseases and Related Health Problems, 10th revision) diagnosis code E55.0 (active rickets) treated at all Norwegian hospitals were identified in the Norwegian Patient Registry. We were able to review 85% of the medical records for diagnosis confirmation. In addition, we identified patients with the diagnoses E55.9, E64.3 and E83.3 to identify individuals with rickets who had been given other diagnoses. RESULTS: Nutritional rickets was confirmed in 39 children aged 0-4 years with the diagnosis of E55.0. In addition, three patients with the diagnosis of unspecified vitamin D deficiency (E55.9) were classified as having nutritional rickets, giving a total of 42 patients. Mean age at diagnosis was 1.40 years (range 0.1-3.5 years), and 93% had a non-western immigrant background. The incidence rate of rickets was estimated to be 0.3 per 10 000 person-years in the total Norwegian child population under the age of 5 years and 3.1 per 10 000 person-years in those with an immigrant background from Asia or Africa. CONCLUSION: The number of children with nutritional rickets in Norway remained low in the period 2008-2012. Nearly all children had a non-western immigrant background.

Effect of vitamin D3 supplementation on iron status: a randomized, double-blind, placebo-controlled trial among ethnic minorities living in Norway.

BACKGROUND: Both vitamin D and iron deficiencies are widespread globally, and a relationship between these deficiencies has been suggested. However, there is a paucity of randomised controlled trials assessing the effect of vitamin D supplementation on iron status. PURPOSE: We aimed to investigate whether 16 weeks of daily vitamin D3 supplementation had an effect on serum ferritin, haemoglobin, serum iron and transferrin saturation. METHODS: Overall, 251 participants from South Asia, Middle East and Africa aged 18-50 years who were living in Norway were randomised to receive daily oral supplementation of 10 µg vitamin D3, 25 µg vitamin D3, or placebo for 16 weeks during the late winter. Blood samples from baseline and after 16 weeks were analysed for serum 25-hydroxyvitamin D (s-25(OH) D), serum ferritin, haemoglobin and serum iron. In total, 214 eligible participants completed the intervention (86 % of those randomised). Linear regression analysis were used to test the effect of vitamin D3 supplementation combined (10 or 25 µg) and separate doses 10 or 25 µg compared to placebo on change (T2-T1) in each outcome variable adjusted for baseline s-25(OH)D values. RESULTS: There was no difference in change in the levels of s-ferritin (1.9 µg/L, 95 % CI: -3.2, 7.0), haemoglobin (-0.02 g/dL, 95 % CI: -0.12, 0.09), s-iron (0.4 µg/L, 95 % CI: -0.5, 1.3) or transferrin saturation (0.7 %, 95 % CI: -0.6.1, 2.0) between those receiving vitamin D3 or those receiving placebo. Serum 25-hydroxyvitamin D increased from 29 nmol/L at baseline to 49 nmol/L after the intervention, with little change in the placebo group. CONCLUSIONS: In this population of healthy ethnic minorities from South Asia, the Middle East and Africa who had low vitamin D status, 16 weeks of daily supplementation with 10 or 25 µg of vitamin D3 did not significantly affect the haemoglobin levels or other markers of iron status.

Vitamin D status in pre-school children in rural Nepal.

OBJECTIVE: Vitamin D plays a major role in Ca and bone metabolism, and its extraskeletal functions are being appraised. Although inadequate vitamin D concentrations have been reported in populations worldwide, too little is known about vitamin D status and its determinants among children in developing countries. We aimed to determine vitamin D status and its determinants in Nepalese children of pre-school age. DESIGN: A community-based, cross-sectional study. SETTING: Rural Nepal at latitude 27.39° N. SUBJECTS: Healthy children (n 280) aged 12-60 months, selected randomly from the records of a vitamin A supplementation programme. Blood samples were collected using the dried blood spot technique and analysed for serum 25-hydroxyvitamin D (s-25(OH)D) concentration using liquid chromatography-tandem mass spectrometry. Ca intake and background variables were assessed with a structured questionnaire. RESULTS: Hypovitaminosis D, defined as s-25(OH)D concentration less than 50 nmol/l, was found in 91.1% of the children. S-25(OH)D concentration was not related to gender, socio-economic indicators, sun exposure or nutritional status. Currently breast-fed children had higher s-25(OH)D concentrations (36.4 (sd 13.2) nmol/l) than those who were not (28.6 (sd 9.8) nmol/l, P<0.001). Adjustment for sociodemographic factors did not alter the results. CONCLUSION: There is widespread vitamin D deficiency among pre-school children in a rural area of Nepal. In our sample, sociodemographic factors did not affect the vitamin D status of children, but prolonged breast-feeding was associated with higher s-25(OH)D concentrations. Further research is required to investigate the health consequences of poor vitamin D status for this population.

Effect of vitamin D3-supplementation on bone markers (serum P1NP and CTX): A randomized, double blinded, placebo controlled trial among healthy immigrants living in Norway.

OBJECTIVE: Vitamin D is essential for the maintenance of calcium homeostasis and bone mineralization; and low serum 25-hydroxyvitamin D (s-25-(OH)D) concentrations are associated with increased bone turnover. However, there is a lack of randomized controlled trials that have investigated the effect of vitamin D treatment on bone turnover in immigrant populations. We aimed to investigate the effect of 16-week daily vitamin D3 supplementation on bone formation marker serum procollagen type 1 amino-terminal propeptide (P1NP) and bone resorption marker C-terminal crosslinked telopeptide of type I collagen (CTX). DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: Immigrant community centers in Oslo, Norway. PARTICIPANTS: 251 healthy adults aged 18-50 years with a non-Western immigrant background were recruited. INTERVENTION: 16 weeks of daily oral supplementation with either 10 µg vitamin D3, 25 µg vitamin D3, or placebo. MAIN OUTCOME MEASURES: Difference in change during the 16-week intervention between the intervention groups combined (10 or 25 µg of vitamin D3/day) and placebo, in serum P1NP and serum CTX. RESULTS: A total of 214 (85%) participants completed the study. S-25-(OH)D increased from 29 nmol/L at baseline to 49 nmol/L in the intervention group with no significant change in the placebo group. However, there was no difference in change of serum P1NP (mean difference: - 1.2 µg/L (95% CI: - 5.4, 2.9, P = 0.6)) and serum CTX (mean difference: - 0.005 µg/L (95% CI: - 0.03, 0.02, P = 0.7)) between those receiving vitamin D3 supplementation compared with placebo. The plasma PTH had decreased by a mean of - 1.97 pmol/L (95% CI: - 2.7, - 1.3, P < 0.0001) in the vitamin D3 group compared to placebo. CONCLUSIONS: Supplementation with 10 or 25 µg oral vitamin D3 during winter and spring for 16 weeks did not significantly affect serum P1NP and serum CTX, despite increasing s-25(OH)D and decreasing PTH in a healthy immigrant population with low baseline vitamin D status. Trial registration number: NCT01263288.

Effect of vitamin D3 supplementation on glycated hemoglobin (HbA1c), fructosamine, serum lipids, and body mass index: a randomized, double-blinded, placebo-controlled trial among healthy immigrants living in Norway.

OBJECTIVE: Despite the suggested role of vitamin D in the prevention of diabetes and cardiovascular disease or its risk factors, the evidence is not consistent and there is a paucity of randomized controlled trials in this field. We aimed to investigate the effect of 16-week daily vitamin D3 supplementation on glycated hemoglobin (HbA1c), fructosamine, body mass index (BMI), and serum lipids. DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: Immigrant community centers in Oslo, Norway. PARTICIPANTS: 251 healthy adults aged 18-50 years with a non-Western immigrant background. All participants performed the baseline test and 215 (86%) returned to the follow-up test. INTERVENTION: 16 weeks of daily oral supplementation with either 10 µg vitamin D3, 25 µg vitamin D3, or placebo. MAIN OUTCOME MEASURES: Difference in absolute change during the 16-week intervention between the intervention groups combined (10 or 25 µg of vitamin D3/day) and placebo, in HbA1c, fructosamine, serum lipids (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides), and BMI. RESULTS: A total of 215 (86%) participants completed the study. Serum 25-hydroxyvitamin D increased from 29 nmol/L at baseline to 49 nmol/L after intervention, with little change in the placebo group. However, there was no difference in change of HbA1c between those receiving vitamin D3 compared with placebo (mean difference: 0.01% (95% CI -0.04 to 0.06, p=0.7)). Neither did the vitamin D3 supplementation have any effect on the other end points: fructosamine, serum lipids, and BMI. CONCLUSIONS: 16-week vitamin D3 supplementation to healthy immigrants from South Asia, the Middle East, or Africa and now living in Norway with low vitamin D status did not improve HbA1c, fructosamine, lipid profiles, or BMI. An updated meta-analysis of similar published trials showed that our results were generally consistent with those of other studies. TRIAL REGISTRATION NUMBER: NCT01263288.

Effect of vitamin D on musculoskeletal pain and headache: A randomized, double-blind, placebo-controlled trial among adult ethnic minorities in Norway.

Immigrants from South Asia, the Middle East, and Africa living in Northern Europe frequently have low vitamin D levels and more pain compared to the native Western population. The aim of this study was to examine whether daily vitamin D3 (25 µg/d or 10 µg/d) supplementation for 16 weeks would improve musculoskeletal pain or headache compared to placebo. This randomized, double-blind, placebo-controlled, parallel-group trial recruited 251 participants aged 18 to 50 years, and 215 (86%) attended the follow-up visit. The pain measures were occurrence, anatomical localization, and degree of musculoskeletal pain, as measured by visual analogue scale (VAS) score during the past 2 weeks. Headache was measured with VAS and the Headache Impact Test (HIT-6) questionnaire. At baseline, females reported more pain sites (4.7) than males (3.4), and only 7% reported no pain in the past 2 weeks. During the past 4 weeks, 63% reported headache with a high mean HIT-6 score of 60 (SD 7). At follow-up, vitamin D level, measured as serum 25(OH)D3, increased from 27 nmol/L to 52 nmol/L and from 27 nmol/L to 43 nmol/L in the 25-µg and 10-µg supplementation groups, respectively, whereas serum 25(OH)D3 did not change in the placebo group. Pain scores and headache scores were improved at follow-up compared with baseline. The use of vitamin D supplements, however, showed no significant effect on the occurrence, anatomical localization, and degree of pain or headache compared to placebo.

Does vitamin D improve muscle strength in adults? A randomized, double-blind, placebo-controlled trial among ethnic minorities in Norway.

CONTEXT: The effect of vitamin D on muscle strength in adults is not established. OBJECTIVE: Our objective was to test whether vitamin D supplementation increases muscle strength and power compared with placebo. DESIGN: We conducted a randomized, double-blind, placebo-controlled trial. SETTING: The setting was immigrants' activity centers. PARTICIPANTS: Two hundred fifty-one healthy adult males and females aged 18-50 years with non-Western immigrant background performed the baseline test and 86% returned to the follow-up test. INTERVENTIONS: Sixteen weeks of daily supplementation with 25 µg (1000 IU) vitamin D3, 10 µg (400 IU) vitamin D3, or placebo. MAIN OUTCOME MEASURES: Difference in jump height between pre- and postintervention. Secondary outcomes were differences in handgrip strength and chair-rising test. RESULTS: Percentage change in jump height did not differ between those receiving vitamin D (25 or 10 µg vitamin D3) and those receiving placebo (mean difference -1.4%, 95% confidence interval: -4.9% to 2.2%, P=.44). No significant effect was detected in the subgroup randomized to 25 µg vitamin D or in other preplanned subgroup analyses nor were there any significant differences in handgrip strength or the chair-rising test. Mean serum 25-hydroxyvitamin D3 concentration increased from 27 to 52 nmol/L and from 27 to 43 nmol/L in the 25 and 10 µg supplementation groups, respectively, whereas serum 25-hydroxyvitamin D3 did not change in the placebo group. CONCLUSIONS: Daily supplementation with 25 or 10 µg vitamin D3 for 16 weeks did not improve muscle strength or power measured by the jump test, handgrip test, or chair-rising test in this population with low baseline vitamin D status.

Changes in the vitamin D endocrine system and bone turnover after oral vitamin D3 supplementation in healthy adults: results of a randomised trial.

BACKGROUND: There is uncertainty as to which intake of vitamin D is needed to suppress PTH and maintain normal bone metabolism throughout winter at northern latitudes. We aimed to investigate whether four weeks' daily supplementation with 10 µg vitamin D3 from fish oil produced a greater change in serum vitamin D metabolites, parathyroid hormone, and bone turnover in healthy adults compared with solid multivitamin tablets. Furthermore, it was studied whether age, gender, ethnic background, body mass index, or serum concentrations at baseline predicted the magnitude of change in these parameters. METHODS: Healthy adults aged 19-48 years living in Oslo, Norway (59°N) were randomised to receive a daily dose of 10 µg vitamin D3 given as fish oil capsules or multivitamin tablets during four weeks in late winter. Serum samples from baseline and after 28 days were analysed for 25-hydroxyvitamin D (s-25(OH)D), 1,25-dihydroxyvitamin D (s-1,25(OH)2D), intact parathyroid hormone (s-iPTH), and osteoclast-specific tartrate-resistant acid phosphatase 5b (s-TRACP). Fifty-five eligible participants completed the intervention (74% of those randomised). RESULTS: S-25(OH)D increased by mean 34.1 (SD 13.1) nmol/l, p < 0.001; s-iPTH decreased by mean 1.2 (SD 2.5) pmol/l, p = 0.001; s-1,25(OH)2D increased by mean 13 (SD 48) pmol/l, p = 0.057; and s-TRACP increased by mean 0.38 (SD 0.33) U/l, p < 0.001. For all these parameters, there was no difference between fish oil and multivitamin formulation. Baseline concentrations were the only independent predictors of changes in biochemical parameters. CONCLUSIONS: Four weeks of daily supplementation with 10 µg vitamin D3 decreased mean s-iPTH and increased s-TRACP concentration, and this did not differ by mode of administration. Our results suggest an increased bone resorption following vitamin D supplementation in young individuals, despite a decrease in parathyroid hormone levels. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01482689.

Vitamin D status among immigrant mothers from Pakistan, Turkey and Somalia and their infants attending child health clinics in Norway.

High prevalences of vitamin D deficiency have been reported in non-Western immigrants moving to Western countries, including Norway, but there is limited information on vitamin D status in infants born to immigrant mothers. We aimed to describe the vitamin D status and potentially correlated factors among infants aged 6 weeks and their mothers with Pakistani, Turkish or Somali background attending child health clinics in Norway. Eighty-six healthy infants and their mothers with immigrant background were recruited at the routine 6-week check-up at nine centres between 2004 and 2006. Venous or capillary blood was collected at the clinics from the mother and infant, and serum separated for analysis of 25-hydroxyvitamin D (s-25(OH)D) and intact parathyroid hormone (s-iPTH). The mean maternal s-25(OH)D was 25.8 nmol/l, with 57 % below 25 nmol/l and 15 % below 12.5 nmol/l. Of the mothers, 26 % had s-iPTH>5.7 pmol/l. For infants, mean s-25(OH)D was 41.7 nmol/l, with 47 % below 25 nmol/l and 34 % below 12.5 nmol/l. s-25(OH)D was considerably lower in the thirty-one exclusively breast-fed infants (mean 11.1 nmol/l; P < 0.0001). Use of vitamin D supplements and education showed a positive association with maternal s-25(OH)D. There was no significant association between mother's and child's s-25(OH)D, and no significant ethnic or seasonal variation in s-25(OH)D for mothers or infants. In conclusion, there is widespread vitamin D deficiency in immigrant mothers and their infants living in Norway. Exclusively breast-fed infants who did not receive vitamin D supplements had particularly severe vitamin D deficiency.

A randomised comparison of increase in serum 25-hydroxyvitamin D concentration after 4 weeks of daily oral intake of 10 microg cholecalciferol from multivitamin tablets or fish oil capsules in healthy young adults.

Many types of vitamin supplements are available on the market, but little is known about whether cholecalciferol obtained from fat-containing capsules differs in bioavailability from that of solid tablets. Our objective was to test whether 4 weeks of daily supplementation with 10 mug cholecalciferol given as a fish oil capsule produces a larger increase in serum 25-hydroxyvitamin D (s-25(OH)D) concentration compared with the same dose of cholecalciferol given as a multivitamin tablet. A total of seventy-four healthy subjects aged 19-49 years were initially included and fifty-five of these completed the study and fulfilled the inclusion criteria. After completing a self-administered questionnaire about diet and sunshine exposure and having a non-fasting venous blood sample drawn, participants were randomised to receive daily multivitamin tablets (n 28) or fish oil capsules (n 27), each containing equal doses of cholecalciferol. A second blood sample was drawn after 28 d. Mean baseline s-25(OH)D was 40.3 (sd 22.0) nmol/l in the multivitamin group and 48.5 (24.8) nmol/l in the fish oil group. When controlling for baseline s-25(OH)D, mean 4-week increase in s-25(OH)D was 35.8 (95 % CI 30.9, 40.8) nmol/l in the multivitamin group and 32.3 (95 % CI 27.3, 37.4) nmol/l in the fish oil group; the mean difference was 3.5 (95 % CI - 3.6, 10.6) nmol/l (P = 0.33). The results were unaltered by statistical adjustment for BMI, ethnic background, age and sex. We conclude that fish oil capsules and multivitamin tablets containing 10 microg cholecalciferol administered over a 4-week period produced a similar mean increase in s-25(OH)D concentration.