Poster Topical Area: Dietary Bioactive Components

Location: Hall D

Poster Board Number: 353

P08-095 - Effects of the low and high daidzein diet on bone density and osteogenic gene expression in female obese Zucker rats

Monday, Jun 11
8:00 AM – 3:00 PM

Objective: Phytoestrogens, including isoflavones found in soybeans and other legumes, are nonsteroidal plant compounds with conspicuously similar chemical structures to mammalian estrogen thus capable of mimicking estrogen's effects in selective tissues. A diet rich in phytoestrogens is associated with a variety of health benefits including reduced symptoms of menopause, decreased risks for heart disease, breast cancer, and osteoporosis in lean population. Obesity and osteoporosis are two chronic conditions that have been increasing in prevalence in the US and worldwide. Daidzein, an isoflavone from soy, has been shown to improve bone health in lean animal models of osteoporosis but not in obese animals.

To investigate the effect of daidzein, a soy isoflavone, on bone health in an obese population, 19 five-week-old female obese Zucker rats (OZR) after one week of acclimation on an AIN-93G diet, were randomly assigned to a modified AIN-93G diet containing either high daidzein (HD, 0.12g/kg feed) or low daidzein (LD, 0.01g/kg feed). After 8 weeks, tibias and femurs were removed and true density measured using Archimedes' principle. Additionally, femoral mRNA expression of various genes related to bone health were measured by reverse transcription polymerase chain reaction (RT-PCR).

Results: Our results indicated that there were no significant differences between the tibial or femoral true density measures (p=0.834 and p=0.299, respectively) of the rats in the HD and LD diet groups. Similarly, there were no significant differences found in gene expressions related to bone health, including RANKL (p=0.439), OPG (p=0.363), NOX4 (p=0.429), BGLAP (p=0.173), SOST (p=0.909), DKK1 (p=0.502), CTNNB1 (p=0.931), WNT3A (p=.097), AXIN1 (p=0.485), RUNX2 (p=0.761), and LRP5 (p=0.990).

It can be concluded that daidzein in soy may not be responsible for the bone health in obese population.

Funding Source: The project was funded by the Arkansas Childrens Research Institute's University Medical Group Fund grant program.

CoAuthors: Brooke Wickman – San Diego State University; Changqi Liu, Ph.D – San Diego State University ; Andrea Bell, MS – Department of Dietetics and Nutrition, University of Arkansas for Medical Sciences; Christy Bekkevold – University of Arkansas for medical sciences; Shirin Hooshmand, Ph.D – San Diego State University ; Reza Hakkak, Ph.D – University of Arkansas for Medical Sciences

Eric Rochester

Grad Student
San Diego State University School of Exercise and Nutritional Sciences
San Diego, California