Nutrients and Bone Mineral Density in Postmenopausal Women

Abstract

This dissertation’s three studies investigated the short and long-term relationships of bone-related nutrient intakes with bone mineral density (BMD) in postmenopausal women. This dissertation compared the equivalency of dietary intakes assessed by eight days of diet records (DR) and the Arizona Food Frequency Questionnaire (AFFQ) at one year. It also determined the association of one year (DR) and the average of four-year (AFFQ) dietary intakes with cross-sectional BMD. The dietary intake associations with BMD were further investigated by hormone therapy (HT). Participant’s BMD was measured at the lumbar spine (L2-L4), femur trochanter, femur neck, Ward's triangle and total body using dual energy X-ray absorptiometry. Separate multiple linear regression analysis (p≤0.05), controlled for various covariates, were used to examine the associations between dietary intakes and regional and total body BMD. In study number one (n=266), significant correlations (r=0.30-0.70, p≤0.05) between dietary assessment methods were found with all dietary intake variables. Iron, magnesium, zinc, dietary calcium, phosphorous, potassium, total calcium, and fiber intakes were positively associated with BMD at three or more of the same bone sites regardless of the dietary assessment method at one year. In study number two (n=266), femur trochanter, lumbar spine, and total body BMD had mostly significant inverse associations with dietary polyunsaturated fatty acid (PUFA) intake at one year. In the HT group (n=136), inverse associations with dietary PUFA intake were seen in the spine and total body BMD. In study number three (n=130), average dietary intake of selected bone-related nutrients, were significantly inversely associated with lumbar spine BMD and total body BMD at year four. In the HT group (n=92), inverse associations with dietary PUFA intake were seen in the spine and total body BMD. The DR and AFFQ are acceptable dietary tools used to determine the associations of particular nutrients and BMD sites in healthy postmenopausal women at one year. At one and four year, dietary PUFA intakes had mostly inverse associations with lumbar spine and total body BMD. When categorized by HT use the associations remained significant only in the HT groups, suggesting that HT may influence dietary intake associations with BMD.