Serum 1,25-dihydroxy vitamin D is inversely associated with body mass index

Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway.
European Journal of Nutrition (Impact Factor: 3.47). 04/2008; 47(2):87-91. DOI: 10.1007/s00394-008-0700-4
Source: PubMed


Based on in vitro studies, it has been hypothesized that 1,25-dihydroxy vitamin D (1,25-vit D) may promote weight gain in humans, but previous studies have demonstrated conflicting results regarding the association between serum 1,25-vit D and body mass index (BMI).
To evaluate the relation between serum 1,25-vit D and BMI.
Two thousand one hundred and eighty-seven subjects, recruited from a metabolic and medical lifestyle management clinic, were included in a cross-sectional study. BMI, 25-hydroxy vitamin D (25-OH-vit D) and 1,25-vit D were measured. The cohort was divided according to BMI in five groups (<25, 25-29.9, 30-34.9, 35-39.9 and >39.9 kg/m(2)). Statistical analyses were performed with multiple linear regression models. Age and gender were used as explanatory covariates.
With increasing BMI group, there was a significant decrease in both serum 25-OH-vit D and 1,25-vit D (P<0.001). Those with BMI >39.9 kg/m(2) had 24% lower serum 25-OH-vit D levels and 18% lower 1,25-vit D levels than those with BMI <25 kg/m(2).
There is an inverse association between BMI and the serum levels of 25-OH-vit D and 1,25-vit D. This makes it highly unlikely that high levels of circulating 1,25-vit D contribute to the development of obesity.

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    • "Moreover , a number of parameters were investigated in this cohort, and the possibility that some of the significant findings are by chance should be taken into account. Several reports have found a correlation between circulating levels of vitamin D and obesity (Konradsen et al., 2008; Wortsman et al., 2000). There was however no evidence for this in our cohort. "

    • "However, increased serum 1,25(OH) 2 D levels along with high serum PTH levels have been reported in obese humans [7] [12]. Conversely, an inverse association between serum 1,25(OH) 2 D levels and BMI was observed in other studies [13] [14]. This evidence suggests that vitamin D metabolism is altered in obesity; however, precise mechanisms have not been elucidated. "
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    ABSTRACT: Low serum 25(OH)D concentrations have been reported in obese humans. Inadequate sun exposure and impaired hepatic 25-hydroxylation have been suggested as possible reasons for obesity-associated vitamin D deficiency; however, the underlying mechanism has not been elucidated. We investigated the effects of high fat diet-induced obesity on vitamin D status and vitamin D metabolizing enzyme expression. Male C57BL mice (4 weeks old) were fed control diet containing 10% energy from fat (control group) or high fat diet containing 45% energy from fat (obese group) for 18 weeks. There were no differences in serum 25(OH)D concentrations between two groups, while serum 1,25(OH)2 D concentrations were significantly higher in obese mice. Hepatic mRNA levels of 25-hydroxylases (Cyp2r1, Cyp27a1, and Cyp2j3) were lower in the obese group (31, 30, and 48% lower, respectively). Renal 1α-hydroxylase (Cyp27b1) mRNA levels were higher and 24-hydroxylase (Cyp24) mRNA levels were lower in the obese group. Serum 1,25(OH)2 D concentrations correlated positively with renal Cyp27b1 expression levels and negatively with renal Cyp24 expression levels. Serum PTH concentrations were higher in obese mice. In visceral adipose tissue, Cyp27a1, Cyp2j3, and vitamin D receptor mRNA levels were higher in obese mice. Overall, vitamin D metabolizing enzyme expression was influenced by high fat diet-induced obesity, which might partly explain the mechanisms of the altered vitamin D endocrine system associated with obesity. Higher serum PTH and 1,25(OH)2 D concentrations in obese mice suggest abnormal regulation of serum 1,25(OH)2 D concentrations due to hyperparathyroidism, which might have contributed to lower hepatic 25-hydroxylase mRNA levels. © 2015 International Union of Biochemistry and Molecular Biology, Inc. © 2015 International Union of Biochemistry and Molecular Biology.
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    • "Also 1,25-hydroxyvitamin D modulates adipogenesis through vitamin D receptor-dependent inhibition of critical molecular components of adipogenesis such as peroxisome proliferator-activated receptor í µí»¾ [48]. Data on 1,25(OH) 2 D level are controversial in obese subjects; they are reported to be increased or decreased, probably due to the heterogeneity of the technique used in measuring 1,25(OH) 2 D by immunoassay, which is not totally specific and measures other vitamin D metabolites in serum [49] [50]. The complex biochemical interactions between adipose tissue and vitamin D in vitro raise the question as to whether hypovitaminosis D, itself, may contribute to obesity or inhibit weight loss in vivo. "
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    ABSTRACT: The skin synthesis of vitamin D represents the first step of a metabolic pathway whose features have been extensively studied and clarified in the last decades. In particular, the production of active and inactive forms of the hormone and the actions of the corresponding enzymes have offered new insights into the knowledge of vitamin D metabolism. Additionally, the description of the different organs and tissues expressing the vitamin D receptor and its possible functions, as well as its genetic determinants, have allowed focusing on the interrelationship between vitamin D and many physiological and pathological functions. In this context, many studies reported the association between vitamin D and adipose tissue metabolism, as well as the possible role of the hormone in obesity, weight, and fat mass distribution. Finally, many reports focused on the vitamin D-related effects on skeletal muscle, particularly on the mechanisms by which vitamin D could directly affect muscle mass and strength. This paper is mainly aimed to review vitamin D metabolism and its relationship with obesity and skeletal muscle function.
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