330 J Contemp Med Sci | Vol. 7, No. 6, November-December 2021: 330–333 Original The Prevalence of Vitamin D Deficiency and Associated Risk Factors among General Populations in Duhok Province, Kurdistan Region, Iraq Lina Y. Mohammed, Shaker A. Jamal, Nawfal R. Hussein, Ibrahim A. Naqid* Introduction Vitamin D, a lipid-soluble prohormone, plays a key role in human health by promoting the absorption and metabolism of calcium and phosphate1,2 especially in bone formation and skeletal development. Vitamin D deficiency is associated with a wide variety of other health conditions, including cardiovas- cular disease,3 type 1 and 2 diabetes,4 chronic kidney disease, rheumatoid arthritis,5 increased risk of cancer, as well as cog- nitive dysfunction, schizophrenia and depression,6 rickets in children and osteomalacia in adults.7 Vitamin D may also be implicated in the risk of miscarriage due to its function as an immune modulator8 and its potential importance for the maternal-fetal immunologic response.9 Several studies have been conducted in Iraq about the potential causes of miscar- riage among pregnant women, but have not reported the impact of Vit. D on pregnancy.10–12 The most studied types among five forms of vitamin D (D1 to D5) are vitamin D2 and D3 Vitamin.13 D2, ergocalcif- erol is synthesized in plants and invertebrates and is consumed in the human’s diet and as supplements while D3 (cholecalcif- erol) comes from vertebrate animals such as fatty fish and meat, eggs. The major source of vitamin D is formed in the skin after exposure of 7-dehydrocholesterol to ultraviolet sun rays (vitamin D3) while minor source of vitamin D comes from food (vitamin D3, cholecalciferol) and from dietary sup- plements (vitamin D2, ergocalciferol) for synthesize a signifi- cant amount of vitamin D requirements.14 Vitamin D (D2 and D3) from the skin and diet are transported and metabolized in the liver to produce 25(OH) vitamin D3 which is used to determine the level of vitamin D in patients, then the kidney converted it by 25-hydroxyvitamin D-1α- hydroxylase enzyme to its to its active form 1,25(OH)2 vitamin D.15 In Iraq including Kurdistan Region, with sunlight throughout the year, vitamin D serum levels are expected to be adequate, yet studies from different Arab countries showed high prevalence levels of vitamin D deficiency and insuffi- ciency.16,17 The prevalence of vitamin D deficiency level is very high and varies from 70% to 90% in different populations, globally.18 There is limited data on the prevalence of Vitamin D defi- ciency among the general population in Kurdistan Region- Iraq. Determination of vitamin D status in different age-groups and gender in a community and in different climates of a country is necessary and has important implications for gen- eral public health. Therefore, the main objective of this study was to determine the levels of vitamin D 25(OH) among Zakho and Dohuk populations and determine associated risk factors as age and gender. Materials and Methods Study Design and Sampling A cross sectional study was conducted in Azadi and Bedari hospitals in Dohuk and Zakho cities, Kurdistan region, Iraq. The study was conducted over a period of nine months from January 2019 to September 2019. A total of 1143 serum sam- ples were collected (632 patients from Bedari hospital, Zakho city and 511 patients from Azadi hospital, Dohuk city). The ages of participants ranged from 9 months to 86 years old (36.31 ± 17.61). An overnight fasting blood sample (5 ml) was obtained for each patient by venepuncture. Serum 25(OH)D3 levels were measured within 24 hrs of blood collection in the hospital clin- ical laboratory using an enzyme-linked immunosorbent assay (ELISA) method supplied by (Bioactivia diagnostic GmbH). The patients were classified into three diagnostic groups Abstract Objectives: This study aimed to determine the serum levels of 25(OH)D3 and associated risk factors in Duhok province, Kurdistan Region, Iraq. Methods: A cross-sectional study was performed from January 2019 to September 2019 among the general population in Dohuk and Zakho cities. 1143 of subjects were recruited in this study and aged ranged from 9 months to 86 years old (36.31 ± 17.61). Serum 25(OH) D3 levels were measured using an enzyme-linked immunosorbent assay (ELISA) method. Results: Of 1143 subjects, 229 (44.9%) people were suffered from vitamin D deficiency in Duhok city and 241(38.19%) from Zakho city. There was significant difference between the incidence of vitamin D in both cities (P < 0.067). The prevalence of vitamin D deficiency was 152 (37.8%) in male and 318 (43.03%) in females. There was no significantly associated with low level of vitamin D between genders (P < 0.133). The low level of Vitamin D was more frequently found in age group between 20–40 years old (46.23%), with sufficient differences between age group (P < 0.001). Conclusion: The prevalence of vitamin D deficiency is much predominant in Duhok province, younger adults and female population. Our finding also found that the low level of vitamin D deficiency in older people. Further studies are required to investigate the pathophysiology of hypovitaminosis D and its clinical consequences. Keywords: Vitamin D deficiency, general population, Duhok province, Kurdistan, Iraq ISSN 2413-0516 Department of Biomedical Sciences, College of Medicine, University of Zakho, Zakho Kurdistan Region, Iraq. *Correspondence to: Ibrahim A Naqid (E-mail: ibrahim.naqid@uoz.edu.krd) (Submitted: 10 September 2021 – Revised version received: 06 October 2021 – Accepted: 19 October 2021 – Published online: 26 December 2021) 331J Contemp Med Sci | Vol. 7, No. 6, November-December 2021: 330–333 L.Y. Mohammed et al. Original Prevalence of Vitamin D deficiency in Duhok Province, Iraq according to their serum concentrations of 25(OH)D3 by increasing the order of severity as follows: vitamin D defi- ciency, 15 ng/mL or less, vitamin D deficiency, (16–30 ng/mL); and vitamin D deficiency greater than 30 ng/mL. Ethical Approval The study proposal was approved by the ethics committee of the College of the Medicine/University of Zakho, Kurdistan Region, Iraq. Informed written consent was obtained from all the participants before samples collection. Statistical Analysis The result of this study was analysed using the GraphPad Prism software package, version 8. The results were expressed as the mean ± standard deviation or as simple percentages as appropriate. Comparisons were made using the Chi-Square and Fisher Exact Test. The results were considered significant if P ≤ 0.05. Results A total of 1141 participants were recruited in this study. Table 1 summarises the demographic characteristics of the total population. Of 1143 individuals, 402 (35.23%) were male and 739 (65%) of them were female. 510 (45%) of participants were from Dohuk residency and 63 (55%) from Zakho residency. The majority of participants 491 (43%) were from 20–40 years old, followed by 40–60 years 332 (29%), less than 20 years 188 (16%) and greater than 60 years 130 (11%). The mean age was 36.31 ± 17.61 years (ranged from 9 months to 86 years old). According to the patient’s serum 25 OHD concentrations, three diagnostic categories were found in both Dohuk’s and Zakho’s population (Table 2). The incidence of vitamin D defi- ciency among Dohuk population was 229 (44.9%) with mean value (8.26 ± 3.63). On the other hand, 241(38.19%) of Zakho study group were vitamin D deficient with mean value (9.68 ± 2.99). There was significant difference between the status of vitamin D level and their current residency when analysed using the Fisher Exact Test (P = 0.067). The prevalence of Vitamin D deficiency levels in serum among gender in studied population are presented in Table 3. It was found that the prevalence of this nutritional deficiency in male was 152 (37.8%) with the mean concentration (8.97 ± 3.51), 165 (41%) were vitamin D insufficient with the mean concentration (21.23 ± 4.19) while only 85 (21.1%) of partici- pants were vitamin D sufficient. Analysis of vitamin D levels regarding female participants revealed that 318 (43.03%) of them were deficient with the mean concentration (9.03 ± 3.33) while 261 (35.31%) of female were vitamin D insufficient with the mean level concentration (22.43 ± 4.42). 160 (21.65%) of female cases had vitamin D sufficient with the mean concen- tration (44.18 ± 16.62). Using Fisher Exact Test, the differ- ences between genders were statistically not significant (P = 0.133). Associations between 25(OH)D level and age groups were also investigated (Table 4). Majority of them were between 20–40 years, 227 (46.23%) of them were vitamin D deficient with the mean level (9.12 ± 3.42). The next age group were 40–60 years, 121 (36.44%) of them were vitamin D deficient with the mean level (8.74 ± 3.37). The age group less than 20 years came in third order regarding to vitamin D levels, accounting for 83 (44.14%) were vitamin D deficient with the mean level (9.11 ± 3.32). Of all participants in this study, least were in greater than 60 years age group accounting for 39 (30%) of them were vitamin D deficient with the mean level (8.78 ± 3.48). Our results showed that there was a significant Table 1. Demographic characteristic of the participants Variables Frequency Percentage Gender Male 402 35.23% Female 739 65% Residence Duhok 510 45% Zakho 631 55% Age group (Year) <20 188 16% 20–40 491 43% 40–60 332 29% >60 130 11% Table 2. Comparison of serum level of vitamin D in nanogram/dl according to residency Variable Deficient Number (%) Mean ± SD Insufficient Number (%) Mean ± SD Sufficient Number (%) Mean ± SD *P value Residence Duhok 229 (44.9%) (8.26 ± 3.63) 177 (34.70%) (21.54 ± 4.27) 103 (20.19%) (45.85 ± 18.27) 0.067 Zakho 241 (38.19%) (9.68 ± 2.99) 249 (39.46%) (21.31 ± 4.38) 141 (22.34%) (44.19 ± 19.06) SD, Standard deviation. *P value was determined by Chi-Square (Fisher Exact Test). Table 3. Comparison of serum level of vitamin D in nanogram/dl according to gender Variable Deficient Number (%) *Mean ± SD Insufficient Number (%) *Mean ± SD Sufficient Number (%) *Mean ± SD P value Gender Male 152 (37.8%) (8.97 ± 3.51) 165 (41%) (21.23 ± 4.19) 85 (21.1%) (47.61 ± 21.9) 0.133 Female 318 (43.03%) (9.03 ± 3.33) 261 (35.31%) (22.43 ± 4.42) 160 (21.65%) (44.18 ± 16.62) 332 J Contemp Med Sci | Vol. 7, No. 6, November-December 2021: 330–333 Prevalence of Vitamin D deficiency in Duhok Province, Iraq Original L.Y. Mohammed et al. Table 4. Comparison of serum level of vitamin D in nanogram/dl according to age group Variable Deficient Number (%) *Mean ± SD Insufficient Number (%) *Mean ± SD Sufficient Number (%) *Mean ± SD P value Age group (Year) <20 83 (44.14%) (9.11 ± 3.32) 70 (37.23%) (21.11 ± 4.22) 35 (18.61%) (43.73 ± 17.82) 0.001 20–40 227 (46.23%) (9.12 ± 3.42) 162 (32.99%) (21.17 ± 4.19) 102 (20.77%) (48.98 ± 20.19) 41–60 121 (36.44%) (8.74 ± 3.37) 145 (43.67%) (21.71 ± 4.52) 66 (19.87%) (40.65 ± 19.51) >60 39 (30%) (8.78 ± 3.48) 49 (37.69%) (21.72 ± 4.41) 42 (32.30%) (42.60 ± 11.65) difference in serum 25(OH)D level between age subgroups (P < 0.001), indicating that the age can be considered as a risk factor of vitamin D deficiency. Discussion The roles vitamin D have found in many physiological func- tions. It facilitates the absorption of calcium and phosphorus, which is important to prevent osteoporosis or fragility frac- tures development. Vitamin D deficiency and insufficiency is a worldwide common health issue and nowadays is linked with many diseases therefore measuring circulating levels of 25 OHD provides evidence of a person’s deficiency/insuffi- ciency of vitamin D.1 Therefore, the purpose of this study was to evaluate the prevalence of vitamin D deficiency and insufficiency among Dohuk and Zakho population and fur- ther to investigate whether age and sex variations in serum 25 OHD are evident among these population in Kurdistan Region, Iraq. In the present study, the status of vitamin D is measured in 1141 blood samples of both genders. It was observed in our population that vitamin D was deficient in 41.19% popula- tion while the 37.33% had insufficient vitamin D levels. Fur- thermore, vitamin D deficiency was found in 43.03% of females while 35.31% of females were having insufficient vitamin D levels. This showed that females are more deficient to vitamin D than males. However, there is no statistical dif- ference seen in vitamin D deficiency between men and women. Our study is in agreement with study done by Wei, et al.19 A study conducted in 2007–2010 by NHANES recorded no major gender gaps between adults in the United States,20 while another study in 1998–2004 also done by NHANES found that men had a higher 25-OHD level than women.21 In Middle East countries, many studies have demonstrated the incidence of vitamin D levels. For example, in Saudi Arabian population, 25–37% of healthy Saudi men with low vitamin D have been reported although sunny days are abundant almost year around.21 This study is more com- parable to our result as 35.23% of men in our population had a low 25(OH)D level. The fact that there was no significant difference between genders due to sun avoidance behaviour is limited by lifestyle and other choices as most females in our society spend more of their time at home rather than in other places. Additionally, wearing a Hijab, full body covered clothes and using sunscreen, and sunglasses makes it difficult to get enough vitamin D only from diet as well as gender dif- ferences may also be caused by differences in hormone levels leading to effect on this value. Therefore, long-term supplementation is possibly needed for patients with this nutritional deficiency and they should change their lifestyle behaviour. Our findings reported that there was significant differ- ence in 25(OHD) levels between the Dohuk and Zakho pop- ulation. People are more likely to live in cities due to the rapid urbanization phase and higher socioeconomic status, and higher population density areas have contributed to reduced exposure to natural sunlight. Moreover, air contam- ination in urban areas may influence too by acting as a boundary to UV light but this suggested pathway has not elu- cidated clearly.22 The factor of race, ethnicity, country of res- idence and skin colour could explain the differences of 25(OHD) levels among the population. In our society, these factors can be ignored as most of our population are Kurdish sharing the same culture and tradition. On the other hand, many studies have shown racial differences could contribute to different 25(OHD) concentrations. Population from the UK, Australia, Canada, and the Middle East has lower 25(OHD) levels compared to white population.23,24 More- over, African American have lower levels of vitamin D than their white population due to skin pigmentation that decreases vitamin D production.25 Furthermore, in this study, we found that there was also a significant difference between different age groups related to serum 25(OHD) levels (P < 0.001). Maximum incidence of vitamin D deficiency was observed in younger age group between 20–40 years old (46.23%) followed by aged 40–60 years (36.44%) while in older people the incidence of vitamin D deficiency was lower than the other groups (30%) vitamin D levels decline with age,26 these studies found that production of this vitamin in the skin, calcium absorption of circulated 1,25(OH)2D, and renal production of 1,25(OH)2D decrease after the sixth decade of life.27 It could be due to supplementation of vitamin D among elderly people, especially female, who are getting used to taking vitamin D supplementation or they depend on regular and adequate amount of food rich in vitamin D and spend more time in the sun. In addition to clothing habit/lifestyle, mod- ification among younger people partly could explain the results. Younger people prefer living in apartments and have less outdoor physical activity whereas older people prefer living in houses and have had more outdoor physical activity when they were younger. We concluded that the low incidence of vitamin D in older adults might be subject to vitamin D supplementation in this group or have more dietary supplements or maybe have more varied sources of vitamin D nutrients. Younger adults 333J Contemp Med Sci | Vol. 7, No. 6, November-December 2021: 330–333 L.Y. Mohammed et al. Original Prevalence of Vitamin D deficiency in Duhok Province, Iraq and females had a higher prevalence of vitamin D deficiency compared to older people and male. Our study is in agreement with the study which is done by Maldonado, et al.28 who demonstrated that the level of vitamin D in older adults is lower than other age groups. Competing Interests The authors declare that there are no competing interests. Funding/Support No funding or support. 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