Condition category
Nutritional, Metabolic, Endocrine
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Altered vitamin D levels are associated with an increased risk of obesity, high blood pressure and diabetes (also known as metabolic syndrome). Low levels of vitamin D (hypovitaminosis D) are also a risk factor for heart disease and death. The northern Chinese population have an increased risk of hypovitaminosis D due to their darker skin pigmentation and living at a northern latitude. Few studies have focused on the effect of vitamin D supplements on obesity and related metabolic disorders in Chinese populations. The aims of this study are to examine the relationship between vitamin D levels and obesity and other metabolic risk factors, and to find out whether vitamin D supplements improve metabolic disorders in patients with metabolic syndrome and hypovitaminosis D.

Who can participate?
People aged 35-60 who visit the healthcare department of Jinan Central Hospital for their annual health examination

What does the study involve?
Participants’ weight, height, waist circumference and blood pressure are measured. A blood sample is collected for measurement of vitamin D, glucose (sugar), insulin, fat and cholesterol levels. Participants with metabolic syndrome and hypovitaminosis D are randomly allocated to take either vitamin D and calcium supplements or a placebo (dummy drug) for 12 weeks. Both groups receive a lifestyle intervention provided by a dietitian. The dietitian meets the participants at 2-week intervals to assess their compliance with the lifestyle intervention program and provide additional study products (vitamin D, calcium or placebos). At the end of the 12 weeks, the two groups undergo the same tests as at the start of the study.

What are the possible benefits and risks of participating?
All participants receive a lifestyle intervention which may improve their health and physical function. The participants who receive vitamin D and calcium supplements may improve their vitamin D levels. There are no known risks to participants.

Where is the study run from?
Jinan Central Hospital (China)

When is the study starting and how long is it expected to run for?
January to April 2012

Who is funding the study?
1. Science and Technical Bureau of Jinan (China)
2. Health Department of Shandong (China)

Who is the main contact?
Dr Xiao Yin

Trial website

Contact information



Primary contact

Dr Xiao Yin


Contact details

Shandong University
27 Shanda Nanlu

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Effect of vitamin D treatment on the improvement of metabolic syndrome: a randomized single-blind trial


Study hypothesis

1. Are the vitamin D levels associated with indices of adiposity and metabolic risk factors in a representative sample of the urban young and middle-aged non-diabetic adults residing in northern China?
2. Evaluate the prevalence of subclinical vitamin D deficiency in this cohort
3. Does vitamin D supplementation, in a randomized double-blind intervention trial, improve metabolic disorders in metabolic syndrome individuals with hypovitaminosis D.

Ethics approval

Ethics Committee of Shandong University Affiliated Jinan Central Hospital, China, 14/12/2011 ref: 2011026

Study design

Cross-sectional cohort single-center interventional randomised double blind placebo-controlled crossover study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Metabolic syndrome


Anthropometric measures (weight, height, waist circumference) and blood pressure will be measured on all participants. A fasting blood sample will be collected for measurement of serum 25-hydroxy vitamin D, plasma glucose, insulin, triglyceride, low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol concentrations.

For the randomized treatment portion of the study, 40-50 metabolic syndrome patients with hypovitaminosis D will be assigned, in a random double-blind manner, to receive either vitamin D treatment (vitamin D treatment group) or placebo (control group). Those in the vitamin D treatment group receive an oral dose of 500 IU vitamin D3 (cholecalciferol) and 1200mg calcium daily for 12 weeks. Both groups will be provided lifestyle intervention by a dietitian, At the end of the 12 weeks, subjects in the two groups will be re-evaluated for the same parameters measured at baseline.

Intervention type



Not Applicable

Drug names

Primary outcome measure

1. Weight, height, waist circumference and blood pressure
2. Body mass index (BMI)
3. Serum 25(OH)D and insulin, measured by double antibody radioimmunoassay
4. Plasma glucose, triglycerides, and HDL cholesterol, measured by enzymatic colorimetric assay

Secondary outcome measures

LDL cholesterol, calculated using the Friedwald equation

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Male and female participants
2. Aged 35-60 years old
3. Living in Jinan, China for more than 5 years
4. Employed in an office setting
5. Has had more than 13 years of education

Participant type


Age group




Target number of participants

500-600 participants will be enrolled in the observation study, then from the same cohort, 40-50 participants will be enrolled in interventional trial.

Participant exclusion criteria

1. Use of vitamin D and calcium supplementation within 60 days of screening
2. Current use of cigarettes (self-report)
3. Alcohol abuse (defined as >14 drinks/week for men, >7 drinks/week for women)
4. Diagnosis of overt diabetes, cardiovascular disease or other systematic disease
5. Use of medications that influence vitamin D, glucose, lipid profiles or blood pressure
6. Engaging in more than 20 minutes of strenuous physical activity or exercise that causes excessive breathing and sweating more than once per week

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Shandong University

Sponsor information


Shandong University (China)

Sponsor details

Jinan Central Hospital
Jiefang road 105

Sponsor type




Funder type


Funder name

Jinan Technology Star Program, Science and Technical Bureau of Jinan (China)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Shandong Province Medical and Health Development Program (China)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2012 results in:

Publication citations

  1. Results

    Yin X, Sun Q, Zhang X, Lu Y, Sun C, Cui Y, Wang S, Serum 25(OH)D is inversely associated with metabolic syndrome risk profile among urban middle-aged Chinese population., Nutr J, 2012, 11, 68, doi: 10.1186/1475-2891-11-68.

Additional files

Editorial Notes

16/09/2016: Plain English summary added.