Semester

Fall

Date of Graduation

2010

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Human Nutrition and Foods

Committee Chair

Janet C.L. Tou.

Abstract

Bone loss may be lessened if bone mass and strength are increased by optimizing nutrition intervention. Omega-3 polyunsaturated fatty acids (o-3 PUFAs) have been suggested to improve bone mineralization and microarchitecture by affecting mineral balance and lipid peroxidation. However, the sources of the o-3 PUFA differ in the types of o-3 PUFA, ratios, and structural form. Therefore, the study objective was to determine the effect of o-3 PUFAs from different sources on bone mineral and microarchitecture and explore potential associations. Growing (28 day) female Sprague-Dawley rats were randomly assigned (n=10/group) to a high fat 12% (weight) diet consisting of either corn oil (CO) control or the o-3 fatty acid rich flaxseed (FO), krill (KO), menhaden (MO), salmon (SO), or tuna (TO). After 8-weeks of feeding, femur and tibia were collected. Bone morphometry, bone mineralization, and microarchitecture were measured. Bone mineralization and microarchitecture were measured by dual-energy x-ray absorptiometry (DEXA) and micro-computed tomography (microCT), respectively. Bone strength was measured using a 3-point bending test. Mineral balance was determined by inductively coupled plasma optical emission spectrophotometry. Bone turnover markers were measured by standard enzyme immunoassay (EIA). Lipid peroxidation was determined by measuring the amount of thiobarbituric acid reactive substances (TBARS) using EIA. In the tibiae, rats fed TO had longer (P<0.001) tibiae than rats fed CO, FO, KO, and MO. Tibiae bone mineral content was greater in rats fed TO or SO (P<0.001) than CO-fed rats. Tibiae bone mineral density in TO-fed rats was higher (P=0.006) compared to CO-fed rats. Trabecular microarchitecture in the femur and tibiae showed rats fed FO or MO had improved bone microarchitecture compared to rats fed CO or SO. There were no significant differences in bone strength. Serum osteocalcin was higher (P=0.03) in rats fed FO compared to rats fed TO or SO. There were no significant differences in mineral balance. Rats fed SO or TO had a lower (P<0.005) TBARS than CO, KO, and MO, indicating that rats fed SO or TO had lower lipid peroxidation. Based on the study results, different sources of o-3 PUFAs influenced bone differently. Rats fed FO or MO, rich in alpha-linolenic acid (ALA), promoted bone microarchitecture and rats fed TO, rich in docosahexaenoic acid (DHA), had increased bone mineralization. The study results suggest that rather than focusing on one source of o-3 PUFAs, perhaps a variety of sources of o-3 PUFAs should be consumed in order to improve bone health during the growth stage of rats.

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