Please use this identifier to cite or link to this item:
Title: Vitamin D status in young adults in Hong Kong : a biomarker approach to a public health concern
Authors: Wang, Weilan Erica
Advisors: Benzie, Iris (HTI)
Keywords: Vitamin D
Vitamin D deficiency.
Youth -- China -- Hong Kong.
Issue Date: 2016
Publisher: The Hong Kong Polytechnic University
Abstract: Low vitamin D status is very common across the world, mostly due to the modern "indoor" lifestyle that leads to low exposure to sunshine. Low vitamin D status is clearly associated with bone disease, and there is accumulating evidence of links with various non-communicable diseases (NCDs), which are the leading causes of death and disability globally. However, the link between vitamin D deficiency and NCDs is not yet confirmed. It is noted that most NCDs become obvious in late adulthood, but the process of disease development begins at a much younger age. The underlying biological changes such as poor glycaemic control, poor lipid profile, inflammation, DNA damage, and oxidative stress, form a "common soil" for NCD development. If the link between vitamin D deficiency and the elements of the "common soil" is confirmed, public health strategies to improve vitamin D status are warranted. In Hong Kong, local studies indicate that vitamin D deficiency is highly prevalent, but data on young people are lacking. Therefore, this study aimed to determine the vitamin D status in a group of young, apparently healthy adults living in Hong Kong, and to investigate the inter-relationships between vitamin D status and the risk of NCD through a biomarker approach in a two-part study. In part 1 (the observational study), 196 (63 males and 133 females) young (18-26y), healthy, non-obese, non-smoking subjects were recruited with their written informed consent. Fasting venous blood and urine samples were collected from each subject. Plasma 25(OH)D concentration was measured as the indicator of vitamin D status, and a panel of sensitive biomarkers for glycaemic control, lipid profile, inflammation, DNA damage, and oxidative stress were measured. In part 2, a pilot supplementation trial was performed in a sub-group of those who were identified as being vitamin D deficient: 16 subjects received 2,400 IU vitamin D3/day for 12 weeks, while 11 received matching placebo. The improvement of vitamin D status and biomarker response were determined.
The vitamin D status was found to be low: mean(SD) plasma 25(OH)D in the 196 subjects studied was 42(13) nmol/l, nearly all (194/196, 99%) had vitamin D insufficiency (defined as plasma 25(OH)D <75 nmol/l). Plasma 25(OH)D was found to be inversely associated with fasting plasma glucose and directly associated with the FRAP value ('total' and corrected for urate) for total antioxidant power (p<0.05). For those with plasma 25(OH)D <25 nmol/l (severe deficiency), significantly higher HbA1c, and total cholesterol/high density lipoprotein cholesterol ratio and lower high density lipoprotein cholesterol was seen (all p<0.05), in comparison with those with 25(OH)D≥25<50 nmol/l and those with 25(OH)D≥50 nmol/l. No significant association was seen between vitamin D status and DNA damage or any other biomarker. In the supplementation arm, correction of deficiency was linked to lower DNA damage (p<0.05), but no significant improvement was seen in any other biomarker. In addition, 146/196 of the subjects studied were found to have least one cardiometabolic disease related biomarker in the high risk category. In conclusion, this study provides new data on the vitamin D status of apparently healthy young adults in Hong Kong, and presents novel findings on the association between vitamin D status and well-established biomarkers related to NCD risk in this group. The high prevalence of low vitamin D status in our young people is an important public health concern in Hong Kong, as this may have long-term impact on their health, and results provide support for adoption of public health strategies to improve their vitamin D status through, for example education, food fortification schemes, and health screening programmes to identify vitamin D deficient individuals for appropriate supplementation.
Description: PolyU Library Call No.: [THS] LG51 .H577P HTI 2016 Wang
xx, 291 pages :color illustrations
Rights: All rights reserved.
Appears in Collections:Thesis

Files in This Item:
File Description SizeFormat 
b2950028x_link.htmFor PolyU Users208 BHTMLView/Open
b2950028x_ira.pdfFor All Users (Non-printable)3.37 MBAdobe PDFView/Open
Show full item record
PIRA download icon_1.1View/Download Contents

Page view(s)

Last Week
Last month
Citations as of Sep 16, 2018


Citations as of Sep 16, 2018

Google ScholarTM


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.