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 Table of Contents  
Year : 2022  |  Volume : 8  |  Issue : 1  |  Page : 20-24

Vitamin D levels among adults in a tertiary care hospital in Wayanad

Department of General Medicine, DM WIMS Medical College, Wayanad, Kerala, India

Date of Submission21-Oct-2021
Date of Decision27-Jan-2022
Date of Acceptance28-Jan-2022
Date of Web Publication8-Jul-2022

Correspondence Address:
Dr. Shuba Srinivasan
Room 703, RB 2, DM Wayanad Institute of Medical Sciences, Naseera Nagar, Meppadi, Wayanad - 673 577, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcrsm.jcrsm_81_21

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Background: Vitamin D insufficiency affects nearly 50% of the population worldwide. Inadequate serum Vitamin D levels are associated with multiple conditions such as secondary hyperparathyroidism and increased fracture risk. Multiple studies carried out also showed a correlation between Vitamin D deficiency and occurrence of diabetes and hypertension (HTN) in these deficient individuals. This study aimed to determine the serum levels of Vitamin D among patients frequenting a tertiary care hospital in Wayanad and the associations with sunlight exposure, gender, dietary factors, and diabetes and HTN.
Settings and Design: Cross-sectional study.
Materials and Methods: Hundred patients were randomly selected from the outpatient department over 6 months and asked to fill up a questionnaire. Vitamin D analysis was done by Elecsys Vitamin D total assay. Statistical analysis used was IBM SPSS statistics for Windows, version 20.0: Association between continuous data was determined using t-test/Mann–Whitney test depending on normality of data and association between categorical variables was determined using Pearson's Chi-square test.
Results: Fifty-seven percentage of patients had Vitamin D deficiency. Significantly lower values of Vitamin D were seen among women.
Conclusions: The median Vitamin D levels in men were 22.785 ng/ml and 17.81 ng/ml in women. No association was established between >1 h of daily sunlight exposure, the prevalence of diabetes and HTN, and daily consumption of dairy products and Vitamin D deficiency.

Keywords: Diabetes, gender, hypertension, sunlight exposure, Vitamin D

How to cite this article:
Raj A, Cherian S, Srinivasan S. Vitamin D levels among adults in a tertiary care hospital in Wayanad. J Curr Res Sci Med 2022;8:20-4

How to cite this URL:
Raj A, Cherian S, Srinivasan S. Vitamin D levels among adults in a tertiary care hospital in Wayanad. J Curr Res Sci Med [serial online] 2022 [cited 2023 May 30];8:20-4. Available from: https://www.jcrsmed.org/text.asp?2022/8/1/20/350142

  Introduction Top

Vitamin D deficiency (VDD) affects nearly 50% of the population worldwide[1] and is associated with increased fracture risk[2] and diabetes and hypertension (HTN).[3],[4],[5] Vitamin D, mainly produced in the skin by exposure to sunlight, undergoes hydroxylation in the liver and kidney to become biologically active.[6] The main cause for VDD is inadequate sunlight exposure.[7],[8] and is associated with increased cardiovascular mortality, multiple sclerosis,[9] diabetes mellitus as it affects beta-cell function and insulin sensitivity,[10] higher blood pressure (BP) levels in cross-sectional studies,[4],[5] and incident HTN.[11]

Hence, we decided to do a cross-sectional study to determine Vitamin D levels among 100 patients.

Our objectives were to determine the serum levels of Vitamin D among patients frequenting a tertiary care hospital in Wayanad and to identify its association with gender, sunlight exposure, dietary consumption of dairy products, and comorbidities such as diabetes and HTN.

  Materials and Methods Top

We conducted a cross-sectional study on outpatients at our Institution and Hospital, Wayanad, Kerala. To study the association between HTN and Vitamin D levels, 105 subjects had to be recruited. (independent sample t-test, clinical significance 5 units, level of significance 5%, power 80%). Hence, 100 patients were randomly selected from the general medicine outpatient department (OPD) at our institution over a total study duration of 6 months.

Exclusion criteria were all pregnant and lactating women and patients <18 years of age and patients already on Vitamin D supplementation. All study participants gave written informed consent after being notified of the benefits of early detection of hypovitaminosis D, and the study was approved by the ethics committee at our institution and hospital, Wayanad (IEC/DMWIMS/April/2009–009).

The study took place over 6 months between November 1, 2018, and May 1, 2019. The enrolled participants were asked to fill up a questionnaire. The following questions were included:

  1. Recall approximate hours of exposure to sunlight per day
  2. Whether they consume milk or diary daily along with the approximate amount
  3. If a mixed or vegetarian diet was followed
  4. Any history of chronic liver or kidney diseases, diabetes, and HTN
  5. Whether they had a history of chronic diarrhea, with it being defined as diarrhea persisting for more than 4 weeks.

While interviewing the patients, we had specifically asked the female patients verbally whether they wore a burqa when they were exposed to sunlight, and all subjects affirmed sunlight exposure without a burqa/headscarf. In all patients, exposure to sunlight was during the morning hours.

The principle of the test used for analyzing serum concentrations of Vitamin D was the competition principle, using Elecsys Vitamin D total assay, which employs a Vitamin D binding protein as capture protein. VDD was taken as a serum 25-hydroxyvitamin D (OH-D) concentrations <20 ng/mL. Levels equal to and more than 20 ng/ml were considered adequate.

The obtained data were analyzed using IBM SPSS Statistics for Windows, version 20.0 (IBM Corp, Armonk, New York., USA). We represented Vitamin D levels in the participants as mean and standard deviation/median with interquartile ranges (IQR). Association between continuous data was determined using t-test/Mann–Whitney test depending on normality of data. Association between categorical variables was determined using Pearson's Chi-square test. P < 0.05 was considered statistically significant. As the Chi-square test was done, the confidence interval was not calculated.

  Results Top

Among the randomly selected patients from the general medicine OPD at our Institution, 30 were male and 70 were female with a mean age of 50.7 ± 15.37. Among the total 100 patients assessed, 57% of patients in total were found to have Vitamin D deficiency.

Among the 30 males assessed, 12 were found to have Vitamin D deficiency, while among the 70 females, 46 had Vitamin D deficiency. The median (IQR) Vitamin D levels in men were 22.785 ng/ml (10.0875) and 17.81 ng/ml (10.1025) in women (P = 0.005), respectively [Figure 1].
Figure 1: Distribution of Vitamin D levels concerning sex among the participants (1 – Males, 2 – Females)

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A 2018 study conducted among men in Pune, India, showed that >1 h of casual midday sunlight exposure daily was required to maintain serum 25 (OH) D concentrations above 50 nmol/L (20 ng/ml)[18] Hence, using a cutoff of 1 h or less as inadequate daily exposure, we assessed the serum Vitamin D levels between the two categories [Table 1]. A Chi-square test was performed (P = 0.061, df = 1). Although not mentioned in the question, while making the patient fill up the questionnaire, verbally, we had asked specifically whether they were exposed to sunlight outside the house (external sunlight exposure).
Table 1: Association of vitamin D status with dairy intake, sunlight, diabetes and hypertension

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Among 100 participants, only 36 participants consumed milk and dairy products daily. However out of these 36 participants, only 11 participants had Vitamin D levels of more than 20 ng/dl [Table 1]. Chi-square test was performed (P = 0.082, df = 1).

A total of 77 patients were nondiabetic and 23 patients were diabetic among the randomly selected patients. Forty six of the nondiabetic patients were found to have VDD and 12 among the diabetics were found to be deficient [Table 1] A Chi-square test was performed, and the P value obtained was 0.519 (df = 1).

A total of 69 patients were nonhypertensives and 31 patients were hypertensive among the randomly selected patients. Forty-two of the nonhypertensive patients were found to have VDD and 16 among the hypertensive population were found to be deficient [Table 1]. Chi-square test was performed (P = 0.386, df = 1).

  Discussion Top

An estimated 1 billion people across the world, all age groups, have a VDD.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13] Vitamin D is essential for bone. Osteoporosis is the most common metabolic bone disease in the world, and low Vitamin D level is an established risk factor for osteoporosis.[12]

VDD was taken as a serum 25OHD concentrations <20 ng/mL. According to multiple studies, 25OHD concentrations were found to be significantly higher in males compared to females.[14],[15]

Similarly, the findings of our study also suggest that females had a lower concentration compared to males living in the same area. This could probably be attributed to the men working outside and poor sun exposure among women as they tend to spend more time indoors and use cultural practices like veils. The difference in body composition may also play a role, with women having more fat mass as body fat may represent a reservoir for Vitamin D storage, reducing its bioavailability.[16]

When our skin is exposed to sunlight, 7-dehydrocholesterol in the skin absorbs ultraviolet B radiation and is converted to previtamin D3 which then converts to Vitamin D3. It then undergoes sequential metabolism in the liver and kidneys into 25-OH-D and then to 1,25-di OH-D which is the biologically active form[6] In fact, in a pilot study conducted on Arab women of childbearing age, women who were exposed to sunlight for 15 min/day twice a week for 4 weeks and who avoided changes to dietary Vitamin D intake had significantly higher postintervention (23.0 nmol/L) than preintervention values (17.6 nmol/L).[17] A 2018 study conducted among men in Pune, India, showed that >1 h of casual midday sunlight exposure daily was required to maintain serum 25 (OH) D concentrations above 50 nmol/L (20 ng/ml).[18]

However, in our study, comparing the average Vitamin D levels among the two populations (adults with an approximate daily exposure to sunlight >1 h and those without), no association could be established between sunlight exposure and prevention of Vitamin D deficiency. Our study is in line with a meta-analysis done in 2017 in apparently healthy Indians living in different regions of India, which specified VDD is prevalent whether there is adequate or inadequate exposure to sunlight. This is probably due to darker skin, use of sunscreen, and indoor lifestyle.[19]

Milk is a natural source of calcium and Vitamin D. In the 1960s, Vitamin D content in cow milk was determined to be 0.125–1 g/L[20] Yoghurt also has 0.1 g/L, whereas cheddar cheese contains 0.3–0.6 g/L, and butter has 1.5 g/L. However, more than dairy products, egg yolk was found to contain 4.9–5.4 g/L, and Wild Salmon has between 13.1 and 24.7 g/L.[21] In a study conducted in the US,[22] Using the 24-h recall method, milk intake (especially reduced-fat, low-fat, and no-fat milk) was positively associated with serum Vitamin D status. In conclusion, the results indicate that milk consumers consistently have higher serum Vitamin D levels and a higher probability of meeting recommended levels. In our study also, the patients were asked to recall how many of them consumed milk and dairy products daily. No association was found between daily consumption of milk and dairy products with the levels of Vitamin D.

In a study conducted in Andhra Pradesh, involving 80 patients with Type 2 DM, hypovitaminosis D was observed in more than half of the patients.[23] In our study, we attempted to assess if there was any correlation between Vitamin D status and the prevalence of Type 2 diabetes among our participants. However, no association was found between VDD and the prevalence of Type 2 diabetes mellitus.

In a cross-sectional study conducted by the Department of Physiology, Amrita School of Medicine, Amrita Institute of Medical Sciences in 2019, severe VDD was found to be more prevalent in people with HTN than in people without HTN.[24] Another study conducted by King George's Medical University Lucknow in 2017 also positively affirmed the same, concluding that VDD is more prevalent with HTN, and low levels tend to correlate with elevated systolic BP. However, larger studies are needed to confirm this association.[25] Comparing the prevalence of VDD among hypertensives and nonhypertensives, our study concluded that there was no association between the prevalence of VDD and HTN.


  1. Cross-sectional studies have limitations in determining associations between variables
  2. For diseases such as diabetes and HTN and association with vitamin levels ideal method is a case-control or cohort study
  3. The use of a single value of Vitamin D level may not be ideal
  4. Determining sunlight exposure, dairy consumption, etc., may be subjective and if patients are aware of the aim of the study are likely to be biased – wanting to report that they have good sunlight exposure
  5. The small sample size of the study might have affected the determination of association of several variables.

  Conclusions Top

Hence, from our study, we concluded that among the 100 participants from a tertiary care hospital in Wayanad, more than half had Vitamin D deficiency. Significantly lower values of Vitamin D were seen among women when compared to men among our study participants. No association could be established between >1 h of daily sunlight exposure, the prevalence of diabetes and HTN, daily consumption of dairy products, and Vitamin D deficiency.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Lakkireddy M, Mudavath SV, Karra ML, Arora AJ. Hypovitaminosis D in patients with osteoporotic hip fractures. J Clin Orthop Trauma 2019;10:768-73.  Back to cited text no. 2
Song Y, Wang L, Pittas AG, Del Gobbo LC, Zhang C, Manson JE, et al. Blood 25-hydroxy vitamin D levels and incident type 2 diabetes: A meta-analysis of prospective studies. Diabetes Care 2013;36:1422-8.  Back to cited text no. 3
Scragg R, Sowers M, Bell C. Serum 25-hydroxyvitamin D, ethnicity, and blood pressure in the Third National Health and Nutrition Examination Survey. Am J Hypertens 2007;20:713-9.  Back to cited text no. 4
Fraser A, Williams D, Lawlor DA. Associations of serum 25-hydroxyvitamin D, parathyroid hormone and calcium with cardiovascular risk factors: Analysis of 3 NHANES cycles (2001-2006). PLoS One 2010;5:e13882.  Back to cited text no. 5
Lips P, Hosking D, Lippuner K, Norquist JM, Wehren L, Maalouf G, et al. The prevalence of vitamin D inadequacy amongst women with osteoporosis: An international epidemiological investigation. J Intern Med 2006;260:245-54.  Back to cited text no. 6
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Munger KL, Åivo J, Hongell K, Soilu-Hänninen M, Surcel HM, Ascherio A. Vitamin D status during pregnancy and risk of multiple sclerosis in offspring of women in the finnish maternity cohort. JAMA Neurol 2016;73:515-9.  Back to cited text no. 9
Stivelman E, Retnakaran R. Role of vitamin D in the pathophysiology and treatment of type 2 diabetes. Curr Diabetes Rev 2012;8:42-7.  Back to cited text no. 10
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Muscogiuri G, Barrea L, Somma CD, Laudisio D, Salzano C, Pugliese G, et al. Sex differences of vitamin D status across BMI classes: An observational prospective cohort study. Nutrients 2019;11:3034.  Back to cited text no. 14
Al-Horani H, Abu Dayyih W, Mallah E, Hamad M, Mima M, Awad R, et al. Nationality, gender, age, and body mass index influences on vitamin D Concentration among elderly patients and young Iraqi and Jordanian in Jordan. Biochem Res Int 2016;2016:8920503.  Back to cited text no. 15
Wortsman J, Matsuoka LY, Chen TC, Lu Z, Holick MF. Decreased bioavailability of vitamin D in obesity. Am J Clin Nutr 2000;72:690-3.  Back to cited text no. 16
Dawodu A, Kochiyil J, Altaye N. Pilot study of sunlight exposure and vitamin D status in Arab women of childbearing age. East Mediterr Health J 2011;17:570-4.  Back to cited text no. 17
Patwardhan VG, Mughal ZM, Chiplonkar SA, Webb AR, Kift R, Khadilkar VV, et al. Duration of casual sunlight exposure necessary for adequate vitamin D status in Indian men. Indian J Endocrinol Metab 2018;22:249-55.  Back to cited text no. 18
Selvarajan S, Gunaseelan V, Anandabaskar N, Xavier AS, Srinivasamurthy S, Kamalanathan SK, et al. Systematic review on vitamin D level in apparently healthy Indian population and analysis of its associated factors. Indian J Endocrinol Metab 2017;21:765-75.  Back to cited text no. 19
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O'Mahony L, Stepien M, Gibney MJ, Nugent AP, Brennan L. The potential role of vitamin D enhanced foods in improving vitamin D status. Nutrients 2011;3:1023-41.  Back to cited text no. 21
Torres-Gonzalez M, Cifelli CJ, Agarwal S, Fulgoni VL 3rd. Association of milk consumption and vitamin D status in the US population by ethnicity: NHANES 2001-2010 analysis. Nutrients 2020;12:3720.  Back to cited text no. 22
Kumar PS, Vinapamula KS, Suchitra MM, Sachan A. Study on the association of Vitamin D with glycaemic control in patients with type 2 diabetes mellitus. J Clin Sci Res 2019;8:188-192. [doi: 10.4103/JCSR.JCSR_96_19]. Available from: https://www.jcsr.co.in. [Last accessed on 2022 Jul 02].  Back to cited text no. 23
Vatakencherry RM, Saraswathy L. Association between vitamin D and hypertension in people coming for health check up to a tertiary care centre in South India. J Family Med Prim Care 2019;8:2061-7.  Back to cited text no. 24
[PUBMED]  [Full text]  
Priya S, Singh A, Pradhan A, Himanshu D, Agarwal A, Mehrotra S. Association of vitamin D and essential hypertension in a North Indian population cohort. Heart India 2017;5:7-11. [doi: 10.4103/heartindia.heartindia_36_1]. Available from: https://www.heartindia.net. [Last accessed on 2022 Jul 02].  Back to cited text no. 25


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