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

Aiswarya Raj; Shreya Cherian; Shuba Srinivasan

doi:10.4103/jcrsm.jcrsm_81_21

ORIGINAL ARTICLE

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

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

Aiswarya Raj, Shreya Cherian, Shuba Srinivasan
Department of General Medicine, DM WIMS Medical College, Wayanad, Kerala, India

Date of Submission	21-Oct-2021
Date of Decision	27-Jan-2022
Date of Acceptance	28-Jan-2022
Date of Web Publication	8-Jul-2022

Correspondence Address:
Dr. Shuba Srinivasan
Room 703, RB 2, DM Wayanad Institute of Medical Sciences, Naseera Nagar, Meppadi, Wayanad - 673 577, Kerala
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jcrsm.jcrsm_81_21

Abstract

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

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

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:

Recall approximate hours of exposure to sunlight per day
Whether they consume milk or diary daily along with the approximate amount
If a mixed or vegetarian diet was followed
Any history of chronic liver or kidney diseases, diabetes, and HTN
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

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

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.

Limitations

Cross-sectional studies have limitations in determining associations between variables
For diseases such as diabetes and HTN and association with vitamin levels ideal method is a case-control or cohort study
The use of a single value of Vitamin D level may not be ideal
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
The small sample size of the study might have affected the determination of association of several variables.

Conclusions

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

Nil.

Conflicts of interest

There are no conflicts of interest.

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