Vitamin D status and its determinants in adolescents from the Northern Ireland Young Hearts 2000 cohort

Department of Food and Nutritional Sciences, University College, Cork, Republic of Ireland, UK.
British Journal Of Nutrition (Impact Factor: 3.45). 05/2008; 99(5):1061-7. DOI: 10.1017/S0007114507842826
Source: PubMed


Despite recent concerns about the high prevalence of sub-clinical vitamin D deficiency in adolescents, relatively few studies have investigated the underlying reasons. The objective of the present study was to investigate the prevalence and predictors of vitamin D inadequacy among a large representative sample of adolescents living in Northern Ireland (54-55 degrees N). Serum concentrations of 25-hydroxyvitamin D (25(OH)D) were analysed by enzyme-immunoassay in a subgroup of 1015 of the Northern Ireland Young Hearts 2000 cohort; a cross-sectional study of 12 and 15 year-old boys and girls. Overall mean 25(OH)D concentration throughout the year was 64.3 (range 5-174) nmol/l; 56.7 and 78.1 nmol/l during winter and summer, respectively. Reported intakes of vitamin D were very low (median 1.7 microg/d). Of those adolescents studied, 3 % and 36 % were vitamin D deficient and inadequate respectively, as defined by serum 25(OH)D concentrations < 25 and < 50 nmol/l. Of the subjects, 46 % and 17 % had vitamin D inadequacy during winter and summer respectively. Gender differences were also evident with 38 % and 55 % of boys and girls respectively classified as vitamin D inadequate during winter (P < 0.001). Predictors of vitamin D inadequacy during winter were vitamin D intake and gender. In conclusion, there is a high prevalence of vitamin D inadequacy in white-skinned adolescents in Northern Ireland, particularly during wintertime and most evident in girls. There is a clear need for dietary recommendations for vitamin D in this age group and for creative strategies to increase overall vitamin D status in the population.

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Available from: Liam Murray, Sep 08, 2014
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    • "[9]. However, since other studies report higher prevalence of vitamin D deficiency among girls, differences in lifestyle factors not captured by our questionnaire cannot be ruled out as an explanation for the lower serum 25(OH)D in boys [11] [12]. "
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    ABSTRACT: Aim: The aim was to study vitamin D status in a healthy adolescent Norwegian population at 69°N. Methods: The data presented come from The Tromsø Study: Fit Futures, during the school year 2010/2011 (not including the summer months), where 1,038 (92% of those invited) participated. Physical examinations, questionnaires and blood samples were collected, and serum 25-hydroxyvitamin D (25(OH)D) were analyzed using LC-MS/MS. Results: RESULTS are presented from 475 boys and 415 girls (15-18 years old) with available blood samples. A total of 60.2% had vitamin D deficiency or insufficiency (serum 25(OH)D <50 nmol/l), 16.5% were deficient (<25 nmol/l) and 1.6% had severe vitamin D deficiency (<12.5 nmol/l). Only 12.4% had levels >75 nmol/l. A significant gender difference with a mean (SD) serum 25(OH)D level of 40.5 (20.5) nmol/l in boys and 54.2 (23.2) nmol/l in girls (p <0.01) was present. Furthermore, 51.3% of girls had levels >50 nmol/l in comparison to 29.7% of boys (p <0.01). There was an inverse correlation between parathyroid hormone levels and 25(OH)D, rs= -0.30 (p<0.01). Explanatory factors that were significantly associated with serum 25(OH)D levels in multivariate models were use of snuff, consumption of vitamin D fortified milk, cod liver oil and vitamin/mineral supplements, physical activity, sunbathing holiday and use of solarium in boys, and vitamin/mineral supplements, physical activity, sunbathing holiday and use of solarium in girls . Conclusions: Vitamin D deficiency is prevalent during the school year among adolescents in northern Norway, particularly among boys.
    Full-text · Article · Jul 2014 · Scandinavian Journal of Public Health
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    • "Of particular concern, these new target values (even the lowest ones) are considerably beyond current intakes in adolescent (2, 27) and adult populations (in some cases even the high consumers (reflected by those in the 95 percentile of intake) have vitamin D intakes below 9 µg/d (19). As an example, 84–97% of adolescents (2) and 93% of adults (20) in the UK National Diet and Nutrition Survey do not reach an intake of 5 and 9 µg/d, respectively. "
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    ABSTRACT: There is little doubt that vitamin D deficiency across all age groups in Europe is a problem. Low vitamin D status arises due to limited, if any, dermal synthesis during the winter months at latitudes above 40°N, putting increased importance on dietary supply of the vitamin. However, dietary intakes by most populations are low due to the limited supply of vitamin D-rich foods in the food chain. Thus strategies that effectively address this public health issue are urgently required. It has been emphasized and re-emphasized that there are only a limited number of public health strategies available to correct low dietary vitamin D intake: (1) improving intake of naturally occurring vitamin D-rich foods, (2) vitamin D fortification (mandatory or voluntarily) of food, and (3) vitamin D supplementation. Recent evidence suggests that the levels of vitamin D added to food would need to be high so as to ensure dietary requirements are met and health outcomes optimized. In addition, knowledge of the most effective forms of vitamin D to use in some of these preventative approaches is important. There is still uncertainty in relation to the relative efficacy of vitamin D(2) versus D(3), the two main food derived forms and those used in vitamin D supplements. The major metabolite of vitamin D with biological activity is 1,25(OH)(2)D; however, this is usually used for pharmacological purposes and is not typically used in normal, healthy people. The other major metabolite, 25(OH)D, which has also been used for pharmacological purposes is present in certain foods such as meat and meat products (particularly offal) as well as eggs. This metabolite may have the potential to boost vitamin D status up to five times more effectively that native vitamin D(3) in foods. However, the exact bioactivity of this compound needs to be established.
    Full-text · Article · Apr 2012 · Food & Nutrition Research

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