1. Introduction

 
Osteoporosis and bone fractures cause from osteoporosis are major public health problems in the world, including in Thailand. Data from the World Health Organization found that the prevalence of osteoporosis worldwide in women was 4% in the 50-59 age group and increased to 8, 25 and 48% in the 60-69, 70-79 age group and over 80 years old, respectively. (1) For epidemiological studies in Thailand, in Thai women, the prevalence of osteoporosis increased with age. The prevalence of osteoporosis was 19.8% in the lumbar vertebrae 1-4 and 13.6% in the hip bone (3). The osteoporosis and bone fractures was found that it was affecting the quality of life. The quality of life after the fracture in Thai people is clearly reduced significantly. (4) Those who develop the hip fracture have a mortality rate of 28% in the first year, and after surgery, they also need someone to help them to live such as Walking, working and sociality (5). There are several risk factors (6-9) for osteoporosis and bone fractures cause from osteoporosis in postmenopausal women such as high age (more than 65 years old), female, white and Asian women, Menopause before the age of 45 or the deficiency of estrogen before menopause. Moreover the Small body build, parent or sister, osteoporosis or bone fractures cause from osteoporosis, and fragile fractures have a propensity to falls, such as impaired vision and inadequate or deficient of calcium intake.
Vitamin D is a vitamin that the body could synthesizes by itself when exposed to ultraviolet B (UVB). When vitamin D is low or inadequate vitamin D intake, it can cause vitamin D deficiency. The Vitamin D deficiency may increase the risk of osteoporosis in adults. From the past study, it found that the inadequate of Vitamin D associated with many health problems such as cancers (10-12), diabetes (13-17) and arteriosclerosis (18-20). The sufficient Vitamin D could prevent osteoporosis. Taking the Vitamin D 800-1000 IU daily is sufficient to prevent vitamin D deficiency. The vitamin D intake can be obtained from food, the sunlight exposure and from Vitamin D capsule (21-25). Thai population health survey in 2008 (26) which survey the Vitamin D status in Thailand found that the found that Thai people have vitamin D level of 31.8 + 8.5 (SD) ng / mL, Vitamin D levels in women aged 16-90 years in the northeastern region were found to be 30.7 ± 5.6 ng / mL and the prevalence of vitamin D deficiency was 51%. The prevalence of vitamin D deficiency was up to 44.3 percent in urban and rural postmenopausal women. The prevalence of vitamin D deficiency among the elderly in urban areas was 65.4%, followed by menopausal women (60%) and lowest in the rural women (15.4%). 
There are significantly difference in Vitamin D levels of the urban and rural population of Thailand. By saying that the People who living in urban areas have lower levels of vitamin D than those living outside of the city. Why is this? It is possible that the environmental and living conditions of people in urban societies are different from those in rural areas, for example, the social values in of white-skinned women was better than those of dark-skinned women such that they tend to have in-door activities, as well as, the use of sunscreen and the pollution in the city, which results to the people in urban areas to have less probability to the sunlight exposure than in the rural areas. The cause of vitamin D deficiency (24) is the reduction of skin synthesis, the use of sunscreen, skin color, age, season, latitude, time of day, as well as, the absorption’s abnormality, Obesity and Kidney Failure.
 
What is interesting is that the risk of vitamin D deficiency is higher, due to several metabolic changes in calcium and vitamin D content such as 7-dehydrocholesterol, which was the source of vitamin D in the skin, decreased in the elderly which result to the Reduction of vitamin D synthesis from the skin, especially, in people living in nursing homes or have the illness to stay in the house. The degradation of the kidney function resulting in the reduction of enzymes 1α-hydroxylase, which used to synthesis 1,25 (OH)2D. Moreover it could cause the degradation in calcium absorption in the intestine and the intestinal adaptation to low calcium in the blood.
 
According to a recent study conducted in Thailand, women in the Northeast had a high prevalence of vitamin D deficiency by 51 percent, and in older women, the risk of vitamin D deficiency was higher. Therefore, it is the main objective of the study, which to study the effect of sunlight exposure and the intake of vitamin D 2 and whether the combination of both could be able to increase the vitamin D levels in older women or menopausal women.