Association of Bone Mineral Density and Lifestyle in Men

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Association of Bone Mineral Density and Lifestyle in Men
   Iranian J Publ Health, 2007, A supplementary issue on Osteoporosis, pp.51-56 51 Association of Bone Mineral Density and Lifestyle in Men  A Hossein-nezhad, Z Maghbooli, F Bandarian, S Mortaz, A Soltani, *  B Larijani  Endocrinology & Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran Abstract Background: Recently, osteoporosis is an increasingly important public health problem in men. The aim of this study was to investigate relationship between life style and bone mineral density in men. Methods:  Among the 20-76 year-old men of Tehran, 325 persons were selected randomly from 50 clusters. The persons suffering from rheumatoid arthritis, thyroid diseases, fractures or other conditions which effect bone metabolism were excluded. All participants underwent clinical examinations and lumbar and spinal densitometry using DXA method. Results:  In lumbar spine, peak bone density was seen between ages 25 and 40 yr and in hip, between 20 and 30. In men older than 50 yr, prevalence of osteoporosis and osteopenia, were 3.9% and 50%, respectively. Bone mineral density was significantly correlated to calcium and vitamin D intake, physical activity and smoking. Conclusion:  Nutritional intake and physical activity are important   factors in maintaining bone mineral density.   Peak bone density in 20-40 year-old population and its relation to life style could be useful in policy-making for the prevention of osteoporosis. Keywords:    Bone mineral density, Life style, Nutrition, Osteoporosis   Introduction   Osteoporosis is a common problem of health care systems and in other words it is a hidden epidemy of today world. Osteoporosis is associ-ated with bone loss and increase in bone fragil-ity. Bone Mineral densitometry (BMD) has an essential role in the evaluation of osteoporosis and fracture risk (1). BMD is the most impor-tant risk factor for fracture and is believed that  bone mineral density acts as an intermediary variable on the biological path way, linking endocrine hormones, lifestyle and dietary risk factors with fractures (2). Health care promotion in recent decades has  been associated with increase in life span and life expectancy, but industrialization and changes in life style and environmental factors have changed burden of disease patterns (3). In this regard, WHO in 2002 reported that 60% of mortality and 49% of burden of diseases is re-lated to chronic diseases, which in 79% of cases occurs in developing countries. Changes in die-tary habits, decreased physical activity and smoking are essential risk factors of these dis-eases. It has been reported that 20%- 50% of  bone mass changes are related to life style, especially nutrition. Nutrition has the essential role in maintaining peak bone density in growth  period (4). Appropriate diet, with provision of vitamin D and calcium, has an effective role in  bone metabolism. Supplying enough calcium for maintaining peak bone mass in growth pe-riod and for protection against bone loss in adolescence is essential (4-6). Osteoporosis prevention based on increasing  peak bone mass and delay in the beginning of  bone loss age, has been more noticed recently. These prevention programs have been designed  based on individual characteristic and effective factors indicative of osteoporosis and its following fractures (7). Especial variables of lifestyle which affect bone mass are physical activity (8), smoking (9), alcohol drinking (10) and calcium and vitamin D intake (4-6).    Iranian J Publ Health, 2007, A supplementary issue on Osteoporosis, pp.51-56 * Corresponding author : Tel: +98 21 88026902-3, Fax: +98 21 88029399, E-mail:      A Hossein-nezhad et al: Association of Bone… 52 The aim of this study was to investigate the relationship between life style and bone mineral density in men. Materials and Methods In this cross sectional study, 20- 76 year old males of Tehran (capital of Iran) population were assessed. Subjects were selected by ran-dom cluster sampling. Persons with rheumatoid arthritis, thyroid, parathyroid and adrenal dys-function, diabetes mellitus, renal failure, severe liver failure, cancer, smoking more than 10 ciga-rettes per day, alcohol drinking for more than 5 year, and one glass per day, addiction, profes-sional sporting, vertebral fracture, fracture due to simple falling, vertebral column deformity, hos -  pital admission in last 2 wk due to a disease, and complete bed rest were excluded from the study. The study protocol was approved in re-search ethic committee of the Endocrinology & Metabolism Research Center (EMRC). Selected subjects were invited to hospital for  bone mineral densitometry. After obtaining in-formed consent, special questionnaires were completed. The physical examination for bone deformity, muscle tenderness and vertebral col-umn deformity was performed, and weight and height were measured. For the subjects who had received radioactive material, radio opaque or calcium supplements, BMD assessment was  postponed to at least five days later. Bone mineral density was measured by dual x-ray absorptiometry (DXA), using a Lunar DPXMD densitometer (Lunar, 7164, USA) which was calibrated daily, using appropriate fantoms. BMD was assessed in lumbar verte- brae (L 2 -L 4 ) and femur (neck, ward and tro-chanter) in gr/cm 2 . A questionnaire, including general information, medical history, drug history, duration of physi-cal activity (h/wk), and period of sunlight expo-sure (min/d) was completed for each partici- pant. Also food frequency questionnaire was used to estimate the amount of daily calcium (mg/d) and vitamin D intakes (IU/d). The data analysis was done by SPSS software (version11), using paired t- test; Man-Whitney and variance analysis were used for mean com- parison. Linear and Logistic regression were used for assessment of correlation between variables. Results Three hundred twenty five males, 20-76 yr old, enrolled in the study. Mean age and BMI of  participants were 44.93±14.65 (yr) and 26.2± 4.18 (kg/m 2 ), respectively. Mean vitamin D and calcium intakes were 61.23 (54.05-68.42) (IU/ day) and 678.69 (638.43-718.96) (mg/day), res- pectively. 7.1% of cases were smoker, 5.2% alcohol drinker, and 23.4% did some kind of sports 2- 3 times in a wk. Daily sunlight exposure in 44.4% of cases were less than 45 min, in 25.9% less than 30 min and in 13.7%, less than 15 min. Peak bone mass of lumbar spine and hip region occurred between ages 25-40 and 20-30 yr, re-spectively. Osteoporosis was diagnosed in 3.9% and osteopenia in 50% of men older than 50. In linear regression, there was a significant correlation among bone mineral density in lum- bar spine and hip region and age and BMI. In one way analysis of variance there was no significant difference in calcium intake between different age groups but vitamin D intake had significant difference in different age groups and its intake decreased as the age increased. In cases with vitamin D intakes less than 100 (IU/day) and more than 100(IU/day), mean BMD of spine were 1.15±0.16 (gr/cm 2 ) and 1.22±0.14 (gr/cm 2 ), respectively. These measurements in hip region were 1±0.14 and 1.05±0.14 (gr/cm 2 ), re-spectively. The differences in both regions were significant between two groups. After age, BMI and vitamin D and calcium intake matching, BMD in hip and spine in 20- 40 yr old men, who exercised 2 or more times in a week was more than the others. Also in the same age group, lumbar spine BMD, in cases with calcium in-take of more than 800 (mg/day), was higher than cases with intake of less than 800 (mg/day).   Iranian J Publ Health, 2007, A supplementary issue on Osteoporosis, pp.51-56 53 After age, BMI and vitamin D intake matching in 20-40 yr-old men who exercised less than 2 times a week, spine and hip BMD was higher in cases with more than 800 (mg/day) calcium in-take (Fig. 1), but calcium had no effect on BMD in cases that exercised 2 or more times a week. Also sport had no effect on BMD in cases with less than 800 (mg/day) calcium in-take but hip BMD was higher in cases with more than 800 (mg/day) calcium intake and ex-ercising 2 or more times a week (Fig. 2). Overall hip BMD in cases that received more than 800 (mg/day) calcium and did some kind of sports 2 or more times in a week were higher than the others (Fig. 3). After age, BMI and calcium and vitamin D in-take matching in smokers, BMD in lumbar spine of subjects with older than 50 year was lower than non smokers (Fig. 4). In osteoporosis risk assessment among older than 50 yr subjects, calcium and vitamin D in-take and sunlight exposure were significantly different between osteoporotic and non osteo- porotic cases (Table 1). Table 1 :  Comparison of osteoporosis risk factors between normal and osteoporotic cases  P  value Osteoporotic group   Normal group   Parameters 0.7 58.2 ± 6.3 58.46 ± 6.6 Age (year) 0.05 24.99 ± 6.57 28.34 ± 3.7 BMI (Kg/m 2 ) 0.02 18.51 ± 14.2 44.7 ± 52.4 Vitamin D intake (IU/d) 0.04 413.4 ± 447 623.5 ± 378 Calcium intake (mg/d) 0.02 28.2 ± 17 77.41 ± 71.6 Sunlight exposure (min/d) Age Daily calcium intake > 800mg and less than 2 times a week sport Daily calcium intake < 800mg and less than 2 times a week sport Fig. 1:  BMD in hip region in 20-40 year-old according to daily calcium intake    B   M   D  o   f   H   i  p   (  g   /  c  m    2    )   A Hossein-nezhad et al: Association of Bone… 54 Age Daily calcium intake < 800mg and more than 2 times a week sport Daily calcium intake < 800mg and less than 2 times a week sport Fig. 2:   BMD in hip region in 20-40 year-old according to the frequency of weekly exercise Age Daily calcium intake > 800mg and more than 2 times a week sport Daily calcium intake < 800mg and less than 2 times a week sport   Fig. 3:   BMD in hip region in 20-40 year-old according to the daily calcium intake and frequency of weekly exercise    B   M   D  o   f   H   i  p   (  g   /  c  m    2    )   B   M   D  o   f   H   i  p   (  g   /  c  m    2    )   Iranian J Publ Health, 2007, A supplementary issue on Osteoporosis, pp.51-56 55 Age Cigarette smoking more than 5 years (at least 5 cigarettes daily)  Non smokers Fig. 4:  BMD in hip region in 50-70 year-old in smokers and non smokers Discussion Some of the studies have shown that, prevalence of osteoporosis and osteopenia in men older than 50 yr is 4%-6% and 33%-47% respectively, which is in concordance with our study (11, 12). Daily calcium and vitamin D intake only provide 60% and 15% of what is recommended, respec-tively. Up to age of 40, calcium intake has an effect on bone mass changes but in older ages, it has no independent correlation with bone mass. Effectiveness of calcium intake in older ages is controversial. Some studies have shown that in males, calcium intake up to 1200 (mg/day) has no effect on bone loss pattern. In other studies, it has been reported that cal-cium intake in older ages did not change bone mineral density significantly (13). Similar re-sults have been reported about vitamin D. It should be mentioned that vitamin D intake was inadequate and this make analysis difficult. Significant difference was found between osteo- porotic and non osteoporotic cases in sunlight exposure. Because of little intake of vitamin D, skin synthesis is the only source of it. Therefore high prevalence of vitamin D deficiency shows that this endogenous vitamin D is not sufficient to provide daily requirement. Other studies in various countries confirm these results (14-17). Different results have been reported about the role of alcohol in BMD changes (10). In our study there was no correlation between BMD and Alcohol drinking which can be justified by our culture, religious beliefs and lower preva-lence of drinking alcohol. Considering the results, smoking and its dura-tion have an effect on BMD, which has been re- ported in other studies (8, 9). Although osteoporosis in men is primarily asso-ciated with age and genetic factors, most stud-ies have shown that in 30%- 60% of cases, it is associated at least with one risk factor (12, 13, 18) .  According to the results, paying more attention to lifestyle improvement in young age may in-crease the peak bone mass, and decrease the    B   M   D  o   f   H   i  p   (  g   /  c  m    2    )
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