Journal of Obesity & Metabolic Syndrome

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J Obes Metab Syndr 2018; 27(2): 128-129

Published online June 30, 2018 https://doi.org/10.7570/jomes.2018.27.2.128

Copyright © Korean Society for the Study of Obesity.

Nonalcoholic Fatty Liver Disease and Abdominal Fat Accumulation According to Vitamin D Status in Patients with Type 2 Diabetes (J Obes Metab Syndr 2018;27:53-60)

Bo-Yeon Kim* , Dug-Hyun Choi, Chan-Hee Jung, Ji-Oh Mok, Sung Koo Kang, and Chul-Hee Kim

Division of Endocrinology and Metabolism, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea

Correspondence to:
Bo-Yeon Kim,
https://orcid.org/0000-0002-3658-2351,
Division of Endocrinology and Metabolism,
Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, 170 Jomaru-ro, Wonmi-gu, Bucheon 14584, Korea,
Tel: +82-32-621-5157,
Fax: +82-32-621-5018,
E-mail: byby815@schmc.ac.kr

Received: May 31, 2018; Reviewed : June 7, 2018; Accepted: June 18, 2018

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

The association between vitamin D level and nonalcoholic fatty liver disease (NAFLD) has not yet been established. However, several studies suggest that vitamin D deficiency is associated with NAFLD and obesity and abdominal obesity.13 Our study evaluated the association between NAFLD and abdominal fat accumulation according to vitamin D status in patients with type 2 diabetes. Ours is a clinic-based study showing that low vitamin D level is associated with NAFLD and abdominal visceral fat accumulation in Korean patients with type 2 diabetes, as reported in Journal of Obesity & Metabolic Syndrome.4

As a reader mentioned, the association between vitamin D level and visceral adiposity/prevalence of NAFLD could be influenced by the different treatments, and the contradicting findings observed in this study might be affected by antidiabetic medications, antihypertensive medications, and other drugs. Insulin resistance is a very important contributor to the pathogenesis of NAFLD. Therefore, we plan to analyze the effect on abdominal fat accumulation of each antidiabetic medication in future study including these participants.

The other question was about the effect of vitamin D level on the prevalence of NAFLD independent of visceral fat thickness in the logistic regression model. When we analyzed further as the reader mentioned, vitamin D deficiency was associated with the prevalence of NAFLD after adjusting for visceral fat thickness in addition to the given logistic regression model. Because vitamin D is known to be involved in immune regulation and inflammatory responses, low vitamin D is thought to play a role in the pathogenesis of NAFLD by hepatic inflammation through adipocytokines.5 We thank you for your very important comment on this and plan to evaluate whether visceral adiposity is an important factor in the association of vitamin D status with NAFLD in the next study. Because of the lack of data, outdoor activity, dietary habits, and seasonal variations in vitamin D were also not included in our study. This is a limitation of our current study.

Lastly, our finding showed that the vitamin D deficiency group has increased visceral fat accumulation compared with the vitamin D sufficient group. However, in our study, body mass index (BMI) was not statistically different among the three groups (24.4± 4.0 kg/m2 in the vitamin D deficient group, 24.8±4.2 kg/m2 in the vitamin D insufficient group, and 25.2±3.8 kg/m2 in the vitamin D sufficient group; P=0.378). Unlike our study, several previous studies showed an inverse association between vitamin D level and BMI.6,7 However, another Korean study showed that vitamin D level is not correlated with BMI in men and is negatively correlated with visceral fat in both sexes, similar to our study.8 These inconsistencies may be due to race, nutrition status, and BMI in the patients. Recent studies have reported that vitamin D may affect glucose metabolism and adipose tissue distribution. I agree with the reports, but I plan to obtain more information such as physical activity, sun exposure, and nutrition status of participants to explain why the vitamin D deficiency group had increased visceral fat accumulation compared with the vitamin D sufficient group. I agree that further, large prospective studies are required to elucidate the associations between vitamin D level and NAFLD and abdominal fat. Finally, we thank you for the letter and giving us an opportunity to respond it.

The authors declare no conflict of interest.

  1. Angelico F, Del Ben M, Conti R, Francioso S, Feole K, Fiorello S, et al. Insulin resistance, the metabolic syndrome, nonalcoholic fatty liver disease. J Clin Endocrinol Metab 2005;90:1578-82.
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  2. Bhatt SP, Misra A, Sharma M, Guleria R, Pandey RM, Luthra K, et al. Vitamin D insufficiency is associated with abdominal obesity in urban Asian Indians without diabetes in north India. Diabetes Technol Ther 2014;16:392-7.
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  3. Hannemann A, Thuesen BH, Friedrich N, Völzke H, Steveling A, Ittermann T, et al. Adiposity measures and vitamin D concentrations in northeast Germany and Denmark. Nutr Metab (Lond) 2015;12:24.
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  4. Choi DH, Jung CH, Mok JO, Kim CH, Kang SK, Kim BY. Nonalcoholic fatty liver disease and abdominal fat accumulation according to vitamin D status in patients with type 2 diabetes. J Obes Metab Syndr 2018;27:53-60.
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  5. Kwok RM, Torres DM, Harrison SA. Vitamin D and nonalcoholic fatty liver disease (NAFLD): is it more than just an association?. Hepatology 2013;58:1166-74.
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  6. Drincic AT, Armas LA, Van Diest EE, Heaney RP. Volumetric dilution, rather than sequestration best explains the low vitamin D status of obesity. Obesity (Silver Spring) 2012;20:1444-8.
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  7. Young KA, Engelman CD, Langefeld CD, Hairston KG, Haffner SM, Bryer-Ash M, et al. Association of plasma vitamin D levels with adiposity in Hispanic and African Americans. J Clin Endocrinol Metab 2009;94:3306-13.
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  8. Park D, Kwon H, Oh SW, Joh HK, Hwang SS, Park JH, et al. Is vitamin D an independent risk factor of nonalcoholic fatty liver disease? A cross-sectional study of the healthy population. J Korean Med Sci 2017;32:95-101.
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