European Journal of Clinical Nutrition (2015) 69, 405–407 © 2015 Macmillan Publishers Limited All rights reserved 0954-3007/15 www.nature.com/ejcn
SHORT COMMUNICATION
Association of body fat and vitamin D status and the effect of body fat on the response to vitamin D supplementation in Pakistani immigrants in Denmark IM Grønborg1, IM Lundby1, C Mølgaard2, J Jakobsen3, L Ovesen4 and R Andersen1 Vitamin D deficiency and obesity are both prevalent conditions in the northern countries, especially among immigrants. The aims were to assess the possible relationship between body fat and vitamin D status, and to investigate the effect of body fat on the response to oral vitamin D supplementation in Pakistani immigrants in Denmark. Data were obtained from a 1-year double-blind randomised controlled trial with oral vitamin D supplementation. A total of 122 women and men received either vitamin D3 supplementation (10 or 20 μg/day) or placebo. No association was found between body fat percentage and vitamin D status in a multiple linear regression model (P o 0.001). No effect of body fat was seen on the vitamin D status response following the intervention with vitamin D. In conclusion, there was no baseline association between body fat percentage and vitamin D status, and body fat percentage had no effect on the response to vitamin D supplementation. European Journal of Clinical Nutrition (2015) 69, 405–407; doi:10.1038/ejcn.2014.254; published online 3 December 2014
INTRODUCTION Vitamin D deficiency is prevalent throughout the world, particularly in populations living at high latitudes where the rate of cutaneous vitamin D production is affected by season.1 Low vitamin D status is especially prevalent among immigrants from countries of lower latitudes living in northern countries. The lower levels of vitamin D in these populations are mainly attributed to increased skin pigmentation, different sun and clothing habits and a low intake of vitamin D-containing foods and supplements, compared with ethnic Nordic populations.2 Another health issue receiving much attention is the global obesity epidemic.3 Obesity seems to be more prevalent among immigrants living in northern countries than in ethnic Nordic populations.4 Immigrants in Denmark are therefore a vulnerable group—both when it comes to vitamin D status and the prevalence of overweight and obesity. Owing to the fat-soluble properties of vitamin D, and the high prevalence of both vitamin D deficiency and obesity, several studies have investigated the possible link between vitamin D status and body fatness.5,6 This study aimed at assessing the possible relationship between body fat and vitamin D status and at investigating the effect of body fat on the response to oral vitamin D supplementation in a Pakistani immigrant population living in Denmark.
SUBJECTS AND METHODS The study was a 1-year randomised double-blind placebocontrolled intervention with two doses of oral vitamin D (10 and
20 μg/day). It was performed in 2002 as a part of the EU project OPTIFORD.7 The baseline population consisted of Pakistani women (n = 87) and men (n = 77) living in Copenhagen, Denmark. Data were collected before and after the intervention. The study was conducted in accordance with the Declaration of Helsinki with written informed consent from all participants. Fasting blood samples were analysed for vitamin D status measured as serum 25(OH)D using high-performance liquid chromatography. Further information about recruitment, tablets, sampling, compliance and biochemical analyses is described elsewhere.8 Two different measures of body fat were used: body mass index (BMI) was calculated on the basis of anthropometric measures of weight and height (kg/m2) and used as an indirect measure of body fat. Body fat mass and lean mass were measured by wholebody DXA scans from which the body fat percentage (fat mass/ (total weight) × 100%) was calculated.5 All statistical analyses were performed using R for Windows (version 2.15.3, Vienna, Austria), with a significance level of α = 0.05. The baseline characteristics are presented with medians and percentiles (25th and 75th) due to non-normally distributed data. A parametric analysis of variance and a Kruskal–Wallis test were applied when comparing the three supplementation groups. Serum concentrations of 25-hydroxyvitamin D (25(OH)D) were logarithmically transformed, using the natural logarithm, to approximate normal distribution. Multiple linear regression analyses were performed on baseline and intervention data to assess associations between vitamin D status and body fat, and to assess whether body fat influenced the effect of vitamin D supplementation on status. We tested possible interactions between gender and body fat, supplementation group (10 or
1 Division of Nutrition, National Food Institute, Technical University of Denmark, Søborg, Denmark; 2Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark; 3Division of Food Chemistry, National Food Institute, Technical University of Denmark, Søborg, Denmark and 4Department of Medicine, Slagelse Sygehus, Slagelse, Denmark. Correspondence: Miss IM Grønborg, Division of Nutrition, National Food Institute, Technical University of Denmark, Mørkhøj bygade 19, Søborg DK-2860, Denmark. E-mail: [email protected] Received 18 February 2014; revised 16 October 2014; accepted 18 October 2014; published online 3 December 2014
Vitamin D and body fat IM Grønborg et al
406
20 μg/day) and body fat on both baseline 25(OH)D and the change in 25(OH)D following the intervention; none were significant (all P40.05). The population assessed after the intervention was reduced to 62 women and 60 men because of drop-outs. The drop-outs did not differ from the remaining population in age, vitamin D status, body fat percentage, BMI and dietary vitamin D intake (P40.05). Table 1.
RESULTS Baseline characteristics of those who completed the intervention are shown in Table 1. No significant differences were found between the supplementation groups in any of the variables for neither men nor women (P40.05). The regression model included the following variables: gender, season of recruitment, age, body fat percentage, vitamin D intake from diet and supplements,
Baseline characteristics of all participants in placebo and supplemented groups completing the study
Total n = 164
10 μg
Placebo n 54
% Female Age (years)b BMI (kg/m2)b Body fat (%)b Vitamin D intakec,d 25(OH)D (nmol/l)c
Median (25th; 75th)a 38.3 27.1 28.5 1.7 17.5
n 52
35.2 (29.2; 47.5) (23.7; 30.1) (24.3; 35.2) (1.3; 2.9) (10.1; 23.1)
20 μg
Median (25th; 75th)a 34.8 27.0 27.9 1.7 13.5
n 58
40.4 (28.7; 45.8) (24.9; 29.7) (23.7; 35.2) (1.4; 2.6) (8.5; 24.7)
Median (25th; 75th)a 38.1 26.6 29.8 2.1 16.4
37.9 (33.1; 47.7) (23.5; 30.6) (23.9; 36.6) (1.5; 4.0) (9.8; 23.5)
Abbreviations: BMI, body mass index; Body fat, percentage body fat; 25(OH)D, 25-hydroxyvitamin D. a(25th; 75th) percentiles. bNo significant difference between treatment groups (parametric ANOVA), P40.05. cNo significant difference between treatment groups (Kruskal–Wallis), P40.05. dFrom diet (μg/day).
Table 2.
Multiple linear regression models for baseline and intervention data. Values are back-transformed from the natural logarithm
Dependent variable: 25(OH)D Explanatory variables: Baseline (n = 164) Male Female Body fat percentage Summera Winterb Age ⩽ 33 years Age 33 to 45 years Age445 years Vitamin D from the diet Vitamin D from own supplements High frequency of sun exposurec Low frequency of sun exposure Short sleeves and long trousers Long sleeves and long trousers Dependent variable: The change in 25(OH)D Explanatory variables: Intervention (n = 122) Male Female Baseline vitamin D status Body fat percentage No supplementation (placebo) Supplementation group 10 μg/day Supplementation group 20 μg/day Summera Winterb Age ⩽ 33 years Age 33 to 45 years Age445 years Vitamin D from the diet High frequency of sun exposurec Low frequency of sun exposure Short sleeves and long trousers Long sleeves and long trousers
Effect
95% CI
Standard error
P-value
1.39 1.00 1.00 1.72 1.00 1.00 1.17 1.24 1.01 1.12 1.22 1.00 1.10 1.00
0.60–3.25 — 0.98–1.01 1.48–2.01 — — 0.96–1.43 0.93–1.65 0.98–1.05 1.06–1.76 1.06–1.41 — 0.94–1.30 —
0.51 — 0.01 0.09 — — 0.12 0.17 0.02 0.03 0.08 — 0.10 —
0.526 — 0.783 o 0.001 — — 0.184 0.218 0.521 o 0.001 0.019 — 0.297 —
Effect
95% CI
Standard error
P-value
3.45 1.00 0.96 1.00 1.00 4.47 4.01 0.86 1.00 1.00 0.44 0.24 0.97 1.00 1.00 1.11 1.00
1.26–9.44 — 0.95–0.97 0.97–1.02 — 1.58–12.66 1.39–11.59 0.72–1.02 — — 0.27–0.73 0.11–0.51 0.94–1.01 0.86–1.17 — 0.93–1.32 —
0.61 — 0.01 0.02 — 0.63 0.64 0.11 — — 0.23 0.46 0.02 0.09 — 0.11 —
0.045 — o 0.001 0.819 — 0.019 0.032 0.149 — — 0.008 0.002 0.268 0.984 — 0.351 —
Abbreviation: CI, confidence interval. aJune, July, August, September, October, November. bDecember, January, February, March, April, May. cMore than 6 times/ week during summer between 1000 hours and 1300 hours for minimum 30 min.
European Journal of Clinical Nutrition (2015) 405 – 407
© 2015 Macmillan Publishers Limited
Vitamin D and body fat IM Grønborg et al
frequency of sun exposure and clothing habits. Table 2 (baseline) shows the regression model assessing the association between vitamin D status and body fat. No association was found between baseline vitamin D status and body fat percentage, and the same was seen when BMI was used as the measure for body fat. In the intervention analysis, the model included the following variables: gender, body fat percentage, supplementation group, season of recruitment, age, vitamin D intake from the diet, frequency of sun exposure and clothing habits. The model with the change in vitamin D status as the dependent variable showed that body fat did not have a significant influence on the effect of supplementation on vitamin D status in this population, as only baseline vitamin D status, supplementation group, season of recruitment, older age and male gender significantly influenced the change in vitamin D status. DISCUSSION The results showed no association between vitamin D status and body fat percentage. The same conclusion was reached when using BMI as the measure of body fat. After a 1-year intervention on the same population, neither body fat percentage nor BMI had a significant effect on the response in serum status to vitamin D supplementation. Most studies show an inverse association between vitamin D status and body fat.5,6 Few studies have been conducted with immigrant populations.5 In accordance with our results, other intervention studies9,10 did not find an effect of body fat on the response to oral vitamin D supplementation, but it may be questioned whether the same conclusion will be reached if the sample size is increased in future studies. In conclusion, body fat does not seem to affect the response to 1 year of oral vitamin D supplementation in a Pakistani population living in northern latitudes. Intervention studies with more participants are needed to further clarify whether the response to oral vitamin D supplementation is similar in overweight/obese individuals compared with normal-weight individuals in immigrant populations, as well as in other populations.
ACKNOWLEDGEMENTS We thank Karin Hess Ygil, Dorthe Strange and Nighat Kwajada for the sampling and Birgitte Hermansen for assisting the DXA-scans. This study is an addition to the OPTIFORD-project ‘Towards a strategy for optimal vitamin D fortification’, financed by EU, the Fifth Framework Programme (QLK1-CT-2000-00623) and by the National Food Institute, Technical University of Denmark. This study is an addition to the OPTIFORDproject ‘Towards a strategy for optimal vitamin D fortification’, financed by EU, the Fifth Framework Programme (QLK1-CT-2000-00623) and by the National Food Institute, Technical University of Denmark
AUTHOR CONTRIBUTIONS RA collected the data; IMG and IMN undertook the statistical analyses and wrote this paper; RA, CM and LO designed the study; and JJ analysed the S-25(OH)D. All authors contributed to the manuscript.
REFERENCES
The authors declare no conflict of interest.
1 Holick MF. Resurrection of vitamin D deficiency and rickets. J Clin Invest 2006; 116: 2062–2072. 2 Holvik K, Meyer HE, Haug E, Brunvand L. Prevalence and predictors of vitamin D deficiency in five immigrant groups living in Oslo, Norway: the Oslo Immigrant Health Study. Eur J Clin Nutr 2005; 59: 57–63. 3 WHO Overweight. 2013. http://www.who.int/gho/ncd/risk_factors/overweight_ text/en/. Accessed on 17 April 2013 4 Kumar BN, Meyer HE, Wandel M, Dalen I, Holmboe-Ottesen G. Ethnic differences in obesity among immigrants from developing countries, in Oslo, Norway. Int J Obes 2006; 30: 684–690. 5 Sulistyoningrum DC, Green TJ, Lear SA, Devlin AM. Ethnic-specific differences in vitamin D status is associated with adiposity. PLoS One 2012; 7: 1–6. 6 Lenders CM, Feldman HA, Von Scheven E, Merewood A, Sweeney C, Wilson DM et al. Relation of body fat indexes to vitamin D status and deficiency among obese adolescents. Am J Clin Nutr 2009; 90: 459–467. 7 Andersen R, Brot C, Ovesen L. Towards a strategy for optimal vitamin D fortification (OPTIFORD). Nutr Metab Cardiovasc Dis 2001; 11: 74–77. 8 Andersen R, Mølgaard C, Skovgaard LT, Brot C, Cashman KD, Jakobsen J et al. Effect of vitamin D supplementation on bone and vitamin D status among Pakistani immigrants in Denmark: a randomised double-blinded placebocontrolled intervention study. Br J Nutr 2008; 100: 197–207. 9 Nelson ML, Blum JM, Hollis BW, Rosen C, Sullivan SS. Supplements of 20 μg/d cholecalciferol optimized serum 25-hydroxyvitamin D concentrations in 80% of premenopausal women in winter. J Nutr 2009; 139: 540–546. 10 Canto-Costa MHS, Kunii I, Hauche OM. Body fat and cholecalciferol supplementation in elderly homebound individuals. Braz J Med Biol Res 2006; 39: 91–98.
© 2015 Macmillan Publishers Limited
European Journal of Clinical Nutrition (2015) 405 – 407
CONFLICT OF INTEREST
407
SHORT COMMUNICATION
Association of body fat and vitamin D status and the effect of body fat on the response to vitamin D supplementation in Pakistani immigrants in Denmark IM Grønborg1, IM Lundby1, C Mølgaard2, J Jakobsen3, L Ovesen4 and R Andersen1 Vitamin D deficiency and obesity are both prevalent conditions in the northern countries, especially among immigrants. The aims were to assess the possible relationship between body fat and vitamin D status, and to investigate the effect of body fat on the response to oral vitamin D supplementation in Pakistani immigrants in Denmark. Data were obtained from a 1-year double-blind randomised controlled trial with oral vitamin D supplementation. A total of 122 women and men received either vitamin D3 supplementation (10 or 20 μg/day) or placebo. No association was found between body fat percentage and vitamin D status in a multiple linear regression model (P o 0.001). No effect of body fat was seen on the vitamin D status response following the intervention with vitamin D. In conclusion, there was no baseline association between body fat percentage and vitamin D status, and body fat percentage had no effect on the response to vitamin D supplementation. European Journal of Clinical Nutrition (2015) 69, 405–407; doi:10.1038/ejcn.2014.254; published online 3 December 2014
INTRODUCTION Vitamin D deficiency is prevalent throughout the world, particularly in populations living at high latitudes where the rate of cutaneous vitamin D production is affected by season.1 Low vitamin D status is especially prevalent among immigrants from countries of lower latitudes living in northern countries. The lower levels of vitamin D in these populations are mainly attributed to increased skin pigmentation, different sun and clothing habits and a low intake of vitamin D-containing foods and supplements, compared with ethnic Nordic populations.2 Another health issue receiving much attention is the global obesity epidemic.3 Obesity seems to be more prevalent among immigrants living in northern countries than in ethnic Nordic populations.4 Immigrants in Denmark are therefore a vulnerable group—both when it comes to vitamin D status and the prevalence of overweight and obesity. Owing to the fat-soluble properties of vitamin D, and the high prevalence of both vitamin D deficiency and obesity, several studies have investigated the possible link between vitamin D status and body fatness.5,6 This study aimed at assessing the possible relationship between body fat and vitamin D status and at investigating the effect of body fat on the response to oral vitamin D supplementation in a Pakistani immigrant population living in Denmark.
SUBJECTS AND METHODS The study was a 1-year randomised double-blind placebocontrolled intervention with two doses of oral vitamin D (10 and
20 μg/day). It was performed in 2002 as a part of the EU project OPTIFORD.7 The baseline population consisted of Pakistani women (n = 87) and men (n = 77) living in Copenhagen, Denmark. Data were collected before and after the intervention. The study was conducted in accordance with the Declaration of Helsinki with written informed consent from all participants. Fasting blood samples were analysed for vitamin D status measured as serum 25(OH)D using high-performance liquid chromatography. Further information about recruitment, tablets, sampling, compliance and biochemical analyses is described elsewhere.8 Two different measures of body fat were used: body mass index (BMI) was calculated on the basis of anthropometric measures of weight and height (kg/m2) and used as an indirect measure of body fat. Body fat mass and lean mass were measured by wholebody DXA scans from which the body fat percentage (fat mass/ (total weight) × 100%) was calculated.5 All statistical analyses were performed using R for Windows (version 2.15.3, Vienna, Austria), with a significance level of α = 0.05. The baseline characteristics are presented with medians and percentiles (25th and 75th) due to non-normally distributed data. A parametric analysis of variance and a Kruskal–Wallis test were applied when comparing the three supplementation groups. Serum concentrations of 25-hydroxyvitamin D (25(OH)D) were logarithmically transformed, using the natural logarithm, to approximate normal distribution. Multiple linear regression analyses were performed on baseline and intervention data to assess associations between vitamin D status and body fat, and to assess whether body fat influenced the effect of vitamin D supplementation on status. We tested possible interactions between gender and body fat, supplementation group (10 or
1 Division of Nutrition, National Food Institute, Technical University of Denmark, Søborg, Denmark; 2Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark; 3Division of Food Chemistry, National Food Institute, Technical University of Denmark, Søborg, Denmark and 4Department of Medicine, Slagelse Sygehus, Slagelse, Denmark. Correspondence: Miss IM Grønborg, Division of Nutrition, National Food Institute, Technical University of Denmark, Mørkhøj bygade 19, Søborg DK-2860, Denmark. E-mail: [email protected] Received 18 February 2014; revised 16 October 2014; accepted 18 October 2014; published online 3 December 2014
Vitamin D and body fat IM Grønborg et al
406
20 μg/day) and body fat on both baseline 25(OH)D and the change in 25(OH)D following the intervention; none were significant (all P40.05). The population assessed after the intervention was reduced to 62 women and 60 men because of drop-outs. The drop-outs did not differ from the remaining population in age, vitamin D status, body fat percentage, BMI and dietary vitamin D intake (P40.05). Table 1.
RESULTS Baseline characteristics of those who completed the intervention are shown in Table 1. No significant differences were found between the supplementation groups in any of the variables for neither men nor women (P40.05). The regression model included the following variables: gender, season of recruitment, age, body fat percentage, vitamin D intake from diet and supplements,
Baseline characteristics of all participants in placebo and supplemented groups completing the study
Total n = 164
10 μg
Placebo n 54
% Female Age (years)b BMI (kg/m2)b Body fat (%)b Vitamin D intakec,d 25(OH)D (nmol/l)c
Median (25th; 75th)a 38.3 27.1 28.5 1.7 17.5
n 52
35.2 (29.2; 47.5) (23.7; 30.1) (24.3; 35.2) (1.3; 2.9) (10.1; 23.1)
20 μg
Median (25th; 75th)a 34.8 27.0 27.9 1.7 13.5
n 58
40.4 (28.7; 45.8) (24.9; 29.7) (23.7; 35.2) (1.4; 2.6) (8.5; 24.7)
Median (25th; 75th)a 38.1 26.6 29.8 2.1 16.4
37.9 (33.1; 47.7) (23.5; 30.6) (23.9; 36.6) (1.5; 4.0) (9.8; 23.5)
Abbreviations: BMI, body mass index; Body fat, percentage body fat; 25(OH)D, 25-hydroxyvitamin D. a(25th; 75th) percentiles. bNo significant difference between treatment groups (parametric ANOVA), P40.05. cNo significant difference between treatment groups (Kruskal–Wallis), P40.05. dFrom diet (μg/day).
Table 2.
Multiple linear regression models for baseline and intervention data. Values are back-transformed from the natural logarithm
Dependent variable: 25(OH)D Explanatory variables: Baseline (n = 164) Male Female Body fat percentage Summera Winterb Age ⩽ 33 years Age 33 to 45 years Age445 years Vitamin D from the diet Vitamin D from own supplements High frequency of sun exposurec Low frequency of sun exposure Short sleeves and long trousers Long sleeves and long trousers Dependent variable: The change in 25(OH)D Explanatory variables: Intervention (n = 122) Male Female Baseline vitamin D status Body fat percentage No supplementation (placebo) Supplementation group 10 μg/day Supplementation group 20 μg/day Summera Winterb Age ⩽ 33 years Age 33 to 45 years Age445 years Vitamin D from the diet High frequency of sun exposurec Low frequency of sun exposure Short sleeves and long trousers Long sleeves and long trousers
Effect
95% CI
Standard error
P-value
1.39 1.00 1.00 1.72 1.00 1.00 1.17 1.24 1.01 1.12 1.22 1.00 1.10 1.00
0.60–3.25 — 0.98–1.01 1.48–2.01 — — 0.96–1.43 0.93–1.65 0.98–1.05 1.06–1.76 1.06–1.41 — 0.94–1.30 —
0.51 — 0.01 0.09 — — 0.12 0.17 0.02 0.03 0.08 — 0.10 —
0.526 — 0.783 o 0.001 — — 0.184 0.218 0.521 o 0.001 0.019 — 0.297 —
Effect
95% CI
Standard error
P-value
3.45 1.00 0.96 1.00 1.00 4.47 4.01 0.86 1.00 1.00 0.44 0.24 0.97 1.00 1.00 1.11 1.00
1.26–9.44 — 0.95–0.97 0.97–1.02 — 1.58–12.66 1.39–11.59 0.72–1.02 — — 0.27–0.73 0.11–0.51 0.94–1.01 0.86–1.17 — 0.93–1.32 —
0.61 — 0.01 0.02 — 0.63 0.64 0.11 — — 0.23 0.46 0.02 0.09 — 0.11 —
0.045 — o 0.001 0.819 — 0.019 0.032 0.149 — — 0.008 0.002 0.268 0.984 — 0.351 —
Abbreviation: CI, confidence interval. aJune, July, August, September, October, November. bDecember, January, February, March, April, May. cMore than 6 times/ week during summer between 1000 hours and 1300 hours for minimum 30 min.
European Journal of Clinical Nutrition (2015) 405 – 407
© 2015 Macmillan Publishers Limited
Vitamin D and body fat IM Grønborg et al
frequency of sun exposure and clothing habits. Table 2 (baseline) shows the regression model assessing the association between vitamin D status and body fat. No association was found between baseline vitamin D status and body fat percentage, and the same was seen when BMI was used as the measure for body fat. In the intervention analysis, the model included the following variables: gender, body fat percentage, supplementation group, season of recruitment, age, vitamin D intake from the diet, frequency of sun exposure and clothing habits. The model with the change in vitamin D status as the dependent variable showed that body fat did not have a significant influence on the effect of supplementation on vitamin D status in this population, as only baseline vitamin D status, supplementation group, season of recruitment, older age and male gender significantly influenced the change in vitamin D status. DISCUSSION The results showed no association between vitamin D status and body fat percentage. The same conclusion was reached when using BMI as the measure of body fat. After a 1-year intervention on the same population, neither body fat percentage nor BMI had a significant effect on the response in serum status to vitamin D supplementation. Most studies show an inverse association between vitamin D status and body fat.5,6 Few studies have been conducted with immigrant populations.5 In accordance with our results, other intervention studies9,10 did not find an effect of body fat on the response to oral vitamin D supplementation, but it may be questioned whether the same conclusion will be reached if the sample size is increased in future studies. In conclusion, body fat does not seem to affect the response to 1 year of oral vitamin D supplementation in a Pakistani population living in northern latitudes. Intervention studies with more participants are needed to further clarify whether the response to oral vitamin D supplementation is similar in overweight/obese individuals compared with normal-weight individuals in immigrant populations, as well as in other populations.
ACKNOWLEDGEMENTS We thank Karin Hess Ygil, Dorthe Strange and Nighat Kwajada for the sampling and Birgitte Hermansen for assisting the DXA-scans. This study is an addition to the OPTIFORD-project ‘Towards a strategy for optimal vitamin D fortification’, financed by EU, the Fifth Framework Programme (QLK1-CT-2000-00623) and by the National Food Institute, Technical University of Denmark. This study is an addition to the OPTIFORDproject ‘Towards a strategy for optimal vitamin D fortification’, financed by EU, the Fifth Framework Programme (QLK1-CT-2000-00623) and by the National Food Institute, Technical University of Denmark
AUTHOR CONTRIBUTIONS RA collected the data; IMG and IMN undertook the statistical analyses and wrote this paper; RA, CM and LO designed the study; and JJ analysed the S-25(OH)D. All authors contributed to the manuscript.
REFERENCES
The authors declare no conflict of interest.
1 Holick MF. Resurrection of vitamin D deficiency and rickets. J Clin Invest 2006; 116: 2062–2072. 2 Holvik K, Meyer HE, Haug E, Brunvand L. Prevalence and predictors of vitamin D deficiency in five immigrant groups living in Oslo, Norway: the Oslo Immigrant Health Study. Eur J Clin Nutr 2005; 59: 57–63. 3 WHO Overweight. 2013. http://www.who.int/gho/ncd/risk_factors/overweight_ text/en/. Accessed on 17 April 2013 4 Kumar BN, Meyer HE, Wandel M, Dalen I, Holmboe-Ottesen G. Ethnic differences in obesity among immigrants from developing countries, in Oslo, Norway. Int J Obes 2006; 30: 684–690. 5 Sulistyoningrum DC, Green TJ, Lear SA, Devlin AM. Ethnic-specific differences in vitamin D status is associated with adiposity. PLoS One 2012; 7: 1–6. 6 Lenders CM, Feldman HA, Von Scheven E, Merewood A, Sweeney C, Wilson DM et al. Relation of body fat indexes to vitamin D status and deficiency among obese adolescents. Am J Clin Nutr 2009; 90: 459–467. 7 Andersen R, Brot C, Ovesen L. Towards a strategy for optimal vitamin D fortification (OPTIFORD). Nutr Metab Cardiovasc Dis 2001; 11: 74–77. 8 Andersen R, Mølgaard C, Skovgaard LT, Brot C, Cashman KD, Jakobsen J et al. Effect of vitamin D supplementation on bone and vitamin D status among Pakistani immigrants in Denmark: a randomised double-blinded placebocontrolled intervention study. Br J Nutr 2008; 100: 197–207. 9 Nelson ML, Blum JM, Hollis BW, Rosen C, Sullivan SS. Supplements of 20 μg/d cholecalciferol optimized serum 25-hydroxyvitamin D concentrations in 80% of premenopausal women in winter. J Nutr 2009; 139: 540–546. 10 Canto-Costa MHS, Kunii I, Hauche OM. Body fat and cholecalciferol supplementation in elderly homebound individuals. Braz J Med Biol Res 2006; 39: 91–98.
© 2015 Macmillan Publishers Limited
European Journal of Clinical Nutrition (2015) 405 – 407
CONFLICT OF INTEREST
407
