Vitamin D Status in Females of Urban Population

Transcription

1 Original Article Vitamin D Status in Females of Urban Population Naghmi Asif 1, Saeed Alam 2, Shaheen Mehmood 3 and Rehan Uppal 4 1Associate Professor, Department of Pathology, Islamabad Medical and Dental College, Islamabad 2Professor of Pathology, Islamabad Medical and Dental College, Islamabad 3, 4Islamabad Diagnostic Centre, Islamabad ( 1,2 Bahria University, Islamabad) Abstract Introduction: Vitamin D deficiency is pan-endemic and is even common in our country despite of ample sun exposure. Various factors like dietary factors, religious and social factors may be responsible. Very few studies have been carried out to look into vitamin D status of females in our country. Objective: We carried out this study to see the vitamin D levels in females of different age groups of urban population. Methodology: This retrospective cross-sectional study was carried out at Islamabad Diagnostic Centre, Islamabad from 1 st March th June Females of all age groups coming for the first time for evaluation of vitamin D status were included in the study. Vitamin D levels of >30 IU were taken as sufficient, IU as insufficient and those less than 20 IU were labelled as deficient levels. Results were entered into SPSS version 17 for analysis. Results: Total number of females included in the study period was Age range of these cases was between years. In all cases Mean vitamin D level was SD. Among all cases 73% of females were deficient in vitamin D (vitamin D < 20IU), 13% had insufficient levels (20-30 IU); only14% had desirable vitamin D levels (>30IU). Vitamin D levels were relatively lower in younger females as compared to the older ones. Conclusion: Vitamin D levels were significantly low in females of urban population. Only 14% of females have desirable vitamin D levels. Larger studies taking into account causes and effects of Vitamin D deficiency including bone mineral density need to be conducted in our set-up. Key words: Cholecalciferol, Vitamin D deficiency, urban population, females Introduction The major source of vitamin D for most humans is exposure to sunlight. 1,2 Vitamin D is metabolized in the liver to 25(OH)D and then in the kidneys to 1,25(OH)2D. 3,4 1,25(OH)2D produced by the kidneys enters the circulation to its major target tissues, the intestine and bone, where it interacts with its vitamin D receptor and enhances intestinal calcium absorption. Apart from these organs many other tissues in the body, including macrophages, brain, colon, prostate, breast, and others, have the enzymes to locally produce 1,25(OH)2D. 5,6 The local production of 1,25(OH)2D in non-calcium regulating tissues such as the colon, prostate, and breast has been reported to regulate many genes, which helps to control cell growth and cellular differentiation and may be responsible for decreasing the risk of the cells being transformed into a malignant state. 7 Vitamin D deficiency is now recognized as a pandemic. The major cause of vitamin D deficiency is the lack of sun exposure. Very few foods naturally contain vitamin D. Vitamin D deficiency causes rickets in children and will precipitate and exacerbate osteopenia, osteoporosis, and fractures in adults. Muscle weakness has also been associated with vitamin D deficiency. Vitamin D receptors are also present in skeletal muscles, and vitamin D deficiency has been associated with proximal muscle weakness, increase in body sway, and an increased risk of falling. 8,9 Vitamin D deficiency in adults can also cause a skeletal mineralization defect. The unmineralized osteoid provides little structural support for the periosteal covering. As a result, patients often complain of isolated or generalized bone discomfort along with aches and pains in their joints and muscles. 10 Vitamin D deficiency has also been associated with increased risk of common cancers, autoimmune diseases, hypertension, and infectious diseases. The major source of vitamin D for humans is exposure to sunlight. 11,12 Anything that diminishes the transmission of solar UV radiation to the earth s surface or anything that interferes with the penetration of UVB (ultraviolet B radiation) radiation into the skin will affect the cutaneous synthesis of vitamin D3. 3 Melanin is extremely efficient in absorbing UVB radiation, and, thus, increased skin pigmentation markedly reduces vitamin D3 synthesis. Similarly, a 18

2 sunscreens absorb UV radiation, and, thus, when topically applied will decrease the synthesis of vitamin D3 in the skin. 13 The practice of purdah, whereby all skin is covered and prevented from being exposed to sunlight, is one of the high risk factor for vitamin D deficiency and explains why in the sunniest areas of the world vitamin D deficiency is very common. Aging is associated with decreased concentrations of 7-dehydrocholesterol, the precursor of vitamin D3 in the skin. 14 Because vitamin D is fat soluble, it is readily taken up by fat cells. Obesity is associated with vitamin D deficiency, and it is believed to be due to the sequestration of vitamin D by the large body fat pool. 15 Medications including anti-seizure medications and glucocorticoids and fat malabsorption are also common causes of deficiency. Numerous epidemiological studies have assessed the prevalence of low serum 25(OH)D concentrations and have indicated that vitamin D inadequacy is a common problem worldwide particularly among females. Various factors, including physiological changes with age, race, body mass index (BMI), sun exposure, latitude, and dietary vitamin D intake are considered responsible. In our country despite sunny climate very low levels of vitamin D have been observed. Very few studies have been carried out to look into vitamin D status in our females. We carried out this study to see the vitamin D levels in females of different age groups of urban dwelling. Material and Methods This retrospective cross-sectional study was carried out at Islamabad Diagnostic Centre, Islamabad from 1 st March 2013 to 30 th June Females of all age groups coming for the first time for evaluation of vitamin D status were included in the study. Vitamin D estimation was done on Cobas E-411. Vitamin D levels of >30 IU were taken as sufficient, IU as insufficient and those less than 20 IU were labelled as deficient levels. Results were entered into SPSS version 17 for statistical analysis. Females were divided into two groups; Group 1 included females between 15 and 45 years and Group 2 comprised of females more than 45 years. Both the groups were then divided into further groups depending upon their vitamin D levels. Mean median and ranges were calculated for all groups. Comparison of both the group was done; p value of less than 0.05 was taken as statistically significant. Results Total number of females included in the study period was Age range of these cases was between years. In all cases Mean vitamin D level was SD. Among all cases 73% of females were deficient in vitamin D (vitamin D < 20IU), 13% had insufficient levels (20-30IU) and 14% of the females had desirable vitamin D levels (> 30IU). Among two Groups vitamin D levels were relatively lower in group 1 (mean= IU) as compared to group 2 (mean= 16.51) but this difference was statistically insignificant with p value of Decade wise distribution has shown a notable finding with continuously increasing levels of vitamin D with increasing age (Table 2). In all age groups mean vitamin D levels are lower than 20 IU. Table 1: Vitamin D Levels in Different Groups All cases (n= 2657) Age range= years Vitamin D levels (Mean SD) < 20= 1942 (73%) 20-30= 344 (13%) > 30= 371 (14%) Group 1 (n=1527) Age range= years Vitamin D levels (Mean SD) < 20= 1181 (77.4%) 20-30= 156 (10.2%) > 30= 189 (12.4%) Group 2 (n= 1130) Vitamin D levels (Mean SD) < 20= 761 (67.4%) 20-30= 188 (16.6%) > 30= 181 (16 %) Discussion Vitamin D, also described as the Sun Vitamin is a steroid with hormone-like activity. It regulates the functions of over 200 genes and is essential for growth and development of the body. Hypovitaminosis D is considered responsible for rickets, birth defects, osteoporosis, osteoarthritis, osteomalacia, chronic bone and muscle pains. Recent research has associated vitamin D deficiency as a contributing factor in diseases, such as heart disease, hypertension, 19

3 neurological disorders, autoimmune disease, depression and cancer. 16 Vitamin D deficiency is now recognized as a pandemic. 17 Poor diet, cultural practices of the region and poverty are some of the important reasons for vitamin D deficiency. Numerous epidemiological studies have assessed the prevalence of low serum 25(OH)D concentrations. 18 and have indicated that vitamin D inadequacy is a common problem worldwide. 19 Differences in the prevalence of vitamin D inadequacy have been related to a variety of factors, including physiological changes with age, race, body mass index (BMI), sun exposure, and dietary vitamin D intake. 3 Table 2: Vitamin D levels in Different Decades Age Range (Yrs) Number of cases Vitamin D levels Range [Mean + SD] ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Vitamin D deficiency is prevalent all over the world. 20 Though our country gets lot of sunlight but vitamin D deficiency is endemic in our country. 21 There are multiple studies in different countries regarding the prevalence of vitamin D deficiency. These studies showed high prevalence of vitamin D deficiency in Asian countries. 16 In our study about 86% of females had low vitamin D levels and younger females had relatively lower levels than the older females. Almost similar findings were noted in a study done in Tehran. A high prevalence (81%) of vitamin D deficiency was noted in their study population. Moreover Vitamin D levels in young and middle aged females were significantly lower than the older group, (results comparable to our study). 22 Prevalence of Vitamin D deficiency has been identified in 70% and 97 % of healthy asymptomatic people in two different studies done in Pakistan. 23,24 Sunlight exposure promotes vitamin D synthesis and one expects this region to be free from vitamin D deficiency. Unfortunately, there is high prevalence of vitamin D deficiency due to lack of proper diet, poor calcium intake and social customs. 23 In another study done on prevalence of vitamin D deficiency on women with osteoporosis, it was observed that 64% of women had serum levels <30 ng ml. It was also noted in the same study that woman who were taking vitamin D supplements had better vitamin D levels and showed better results of bone mineral density. Seasonal variation in vitamin D levels have also been reported and somewhat lower serum 25(OH)D levels were observed in women during winter than those recruited during the summer months in some countries. 25 In our study 88% women below 45 years (reproductive age group) had insufficient vitamin D levels. There are multiple factors for vitamin D deficiency in our country. One of the reasons may be social and religious customs as most of our women do not go outside and even if they do, their body is covered. Moreover our dietary habits are not so good as we do not routinely take much of sea food and our food is not fortified as in western countries and also vitamin D supplements are not taken by most our females. There are relatively few foods that are natural sources of vitamin D and are eaten regularly. 26 The most common are oily fish and egg yolk. Dietary vitamin D supplements, in the form of fish liver oils or synthesized vitamin D or Vitamin D fortified foods can make significant contributions. Vitamin D supplements have been found to increase bone mineral density and thus reduces risk of fractures in females. 27 Similarly dark pigmentation has been found to decrease skin synthesis of vitamin D because UV light cannot reach the appropriate layer of the skin. Vitamin D deficiency is associated with secondary hyperparathyroidism with consequent ill effects on bone mineral density. 28 Marwah et al, studied vitamin D deficiency and its effects on bone mineral density in Indian adolescents of years of age and concluded that metabolic bone disorders secondary to vitamin D deficiency continue to be prevalent in the Indian subcontinent and are more prevalent in lower socio economic population. 29 Particularly postmenopausal women are known to be prone to vitamin D deficiency causing an early onset of osteoporosis. In different studies vitamin D deficiency has been found more prevalent in winters than in summer, more common in women who spend little time out-door, those who wear clothes that cover most of the body or frequently use sunscreen. This tendency to the deficiency is found in most part of the world. The mean serum concentration of 25(OH)D of 30 ng/ml is considered desirable for health. A level of 20 ng/ml is considered as minimum acceptable. 13 However these values are 20

4 insufficient especially for pregnant females, sick adults and older adults. Conclusions Vitamin D deficiency is highly prevalent, even in countries with abundant sun light, as skin exposure to sunlight is limited by lifestyle and other factors. We found that only 14% of females had desirable levels of Vitamin D and these belong to a population of urban dwelling. As this may be associated with increasing incidence of aches and pains and increased risk of fractures paticularly in postmenopausal females, it is suggested that these findings (as has been proved in different studies) are highlighted and conveyed to general public through awareness campaigns and media. Moreover government should implement a mandatory programme for vitamin D fortification of selected foodstuff. Larger studies taking into account causes and effects of Vitamin D deficiency including bone mineral density should be done in our set-up. References 1. Holick MF. Vitamin D: A millennium perspective. 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