Determinants of Bone Mineral Density and Metabolic Syndrome in South Asian Indian Men

There is a rising minority population in the United States and South Asians make up the largest growing sub population. Health concerns in the minority population are several of which metabolic syndrome (MetS) and low bone mineral density (BMD) are important. Interestingly research in the past decade is beginning to suggest an interplay between bone and energy metabolism. Hormones, bone proteins and cytokines that play an important role in bone metabolism are also altered in metabolic syndrome, suggesting that both these

conditions may share a common etiology. Hence the primary question in this study would be to assess whether bone is altered in the South Asian population in the United States and whether hormones or other proteins regulating bone influence metabolic syndrome outcomes in the South Asians, specifically the South Asian Indian population. There is also an altered body composition in the South Asian Indian population with a greater visceral adiposity. Greater visceral adipose tissue (VAT) is associated in both the pathogenesis of metabolic syndrome and low BMD, possibly due to release of pro inflammatory cytokines. Interestingly several factors that are involved in the etiology of low BMD such as a greater visceral adiposity, high serum pro inflammatory cytokines, altered hormonal milieu such as low 25 hydroxy vitamin D (25OHD) and high parathyroid hormone (PTH), low osteocalcin levels, low calcium and high carbohydrate diet may share a relationship with MetS outcomes. The South Asian population has all the above-mentioned biochemical and metabolic alterations and it would be interesting to examine this in an immigrant Asian population residing in the USA. The investigators propose to examine 30 South Asian Indians between the ages of 30-50 years, using 30 resident Caucasian men as controls. Bone measures such as BMD and bone mineral content will be measured at radius, trochanter, hip and tibia and body composition including lean mass, fat mass, android fat and gynoid fat will be assessed using the Dual X ray energy absorptiometry (DXA). Biochemical measures including a complete metabolic panel, PTH, 25OHD, osteocalcin and other bone markers, and pro inflammatory cytokines will be measured in the serum. Investigators hypothesize that South Asian Indian men will have a lower BMD and higher MetS risk factors compared to age and BMI matched Caucasian men. Investigators further propose that common biochemical and metabolic alterations will underlie both low BMD and MetS outcomes in SAI population, but not in the Caucasian population. Identification of common determinants will help design a single future interventional trial that will target both MetS and bone health in the SA population

Specific Aim 1 To determine whether Bone Mineral Density (BMD) at weight-bearing and non weight-bearing sites is lower in age- and weight-matched SAI compared to white men.

It is hypothesized that SAI men will have lower BMD at weight-bearing sites compared to age and BMI-matched white men.

Specific Aim 2 To determine whether body composition influences Bone Mineral Density in SAI men.

It is hypothesized that greater abdominal adiposity, specifically visceral fat, influences BMD in SAI men compared to age- and BMI-matched white men.

Specific Aim 3 To examine the hormonal, inflammatory, and dietary determinants of Bone Mineral Density and MetS in SAI compared to white men.

It is hypothesized that the hormonal, inflammatory, and dietary determinants of both MetS and low BMD will be similar in the SAI men but not in the white men.

This study will involve one single visit. The following will be conducted during this visit:

• This visit will last for about 2 hours
• Blood draw- Four 5 ml tubes of blood will be collected via venipuncture
• Spot urine sample collection
• Measurement of height, weight, blood pressure, waist circumference
• Completion of study questionnaires
• DXA scan