Ultraviolet B sunlight exposure is a primary source of vitamin D. There have been reports of low vitamin D status amongst the Malaysian population despite it being a tropical country. This study was conducted to determine the influence of sun exposure on 25(OH)D concentrations in urban and rural women in Malaysia and factors predicting 25(OH)D concentrations. Women aged above 45 years were recruited from urban (n=107) and rural areas (n=293). Subjects were interviewed regarding their outdoor activities and usual outdoor attire over the previous week. 25(OH)D concentrations were analyzed using the vitamin D3 (25-OH) electrochemiluminescence immunoassay. Median (Q1-Q3) age of the participants was 57 (53-61) years old. Median (Q1-Q3) 25(OH)D concentration of rural women was significantly higher [69.5 (59.0-79.1) nmol/L] compared to urban women [31.9 (26.1- 45.5) nmol/L] (p<0.001). Rural women spent more time in the sun compared to urban women (7.83 (3.67-14.7) vs 2.92 (1.17-4.92) hours, p<0.001), although the fraction of body surface area (BSA) exposed to sunlight was significantly higher in the urban group [0.21 (0.21-0.43) vs 0.12 (0.07-0.17), p<0.001]. The calculated sun index (hours of sun exposure per week × fraction of BSA) was significantly higher in rural [0.89 (0.42-1.83)] compared to urban women [0.72 (0.26-1.28)], p=0.018. In the stepwise linear regression, rural dwelling increased the serum 25(OH)D by 31.74 nmol/L and 25(OH)D concentrations increased by 1.93 nmol/L for every unit increment in sun index. Urban women in Malaysia had significantly lower vitamin D status compared to rural women. Rural dwelling and sun index were key factors influencing vitamin D status in Malaysian women.
維生素D 的主要來源，是由陽光中紫外線B 照射皮膚所合成。儘管馬來西亞屬於 熱帶國家，仍有研究指出部分馬來西亞人口處於低維生素D 的狀態。本研究目的 為評估陽光曝曬對於居住在都市與鄉村的馬來西亞婦女，血液25-羥基維生素D 的影響，及其濃度的預測因子。共招募400 位45 歲以上女性，其中107 位居住於 都市，293 位居住於鄉村。面訪參與者以詢問過去一個禮拜的戶外活動情形及通 常的戶外衣著。利用電化學發光免疫分析法，測定血清25-羥基維生素D 的濃 度。參與者的年齡中位數為57 歲(53-61 歲)。鄉村女性維生素D 的中位數值顯著 高於都市女性(69.5 nmol/L 比上31.9 nmol/L；p<0.001)。儘管都市女性暴露在陽光 下的面積較高(0.21 比上0.12；p<0.001)，但陽光曝曬的時間顯著低於鄉村女性 (2.92 比上7.83 小時；p<0.001)。比起都市女性，鄉村女性有顯著較高的陽光曝曬 指數(每週陽光曝曬時數×曝曬體表面積)。逐步線性迴歸顯示居住於鄉村者，血 清25-羥基維生素D 濃度高出31.7 nmol/L；每增加一單位陽光曝曬指數，血清 25-羥基維生素D 濃度升高1.93 nmol/L。馬來西亞都市婦女的維生素D 狀態，顯 著較差於鄉村女性。居住於鄉村及陽光曝曬指數，是影響馬來西亞婦女維生素D 狀態的主要因素。