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Topical Area: Obesity

Obesity (Poster Session)

(P31-010-23) Calcium Deficiency and High-Fat Diet-Induced Obesity Are Detrimental to Bone Structure in Ovariectomized Rats

Monday, July 24, 2023
12:45 PM – 1:45 PM ET
Location: Poster Board 233

    Presenting Author(s)

  • JC

    Jay J. Cao, PhD

    Research Nutritionist
    Grand Forks Human Nutrition Research Center
    Grand Forks, North Dakota, United States

    • Co-Author(s)

  • BG

    Brian R. Gregoire, M.Sc

    Grand Forks Human Nutrition Research Center
    Grand Forks, North Dakota, United States

Disclosure(s):
Jay J. Cao, PhD: No relevant financial relationship(s) with ineligible companies to disclose.


Objectives: Obesity induced by high-fat (HF) diets increases bone resorption and/or decreases bone formation resulting in reduced bone mass and strength in various animal models. Inadequate dietary calcium intake and decreased production of estrogen are two main factors that contribute to the onset of osteoporosis and bone fracture. Whether calcium deficiency exacerbates bone structure in HF induced obese animals has not yet been investigated. We hypothesize that inadequate calcium intake decreases bone mass in HF-induced obese ovariectomized (OVX) rats.

Methods: Forty-seven OVX and 12 sham-operated Sprague Dawley rats at 6-mo-old were used. OVX rats were randomly assigned to four groups in a 2x2 factorial design: normal-fat (NF, 10% fat as energy) diet or HF (45% fat as energy) diet and low calcium (1 g/kg) or normal calcium (5 g/kg). Sham rats were fed a NF normal calcium diet as a control for OVX. Rats were on the respective experimental diet for 4 months.

Results: OVX increased body weight (290 ± 8 vs 340 ± 4 g, for sham and OVX respectively, P < 0.01). Compared to sham, OVX rats had lower bone volume/total volume (BV/TV), connectivity density (Conn.D), trabecular number (Tb.N), trabecular thickness (Tb.Th), and higher structural model index (SMI) and trabecular separation (Tb.Sp), all at P < .01). Compared to NF, HF decreased BV/TV (P < 0.05), Tb.N (P < 0.05), and increased Tb.Sp (P < 0.05). Calcium deficiency resulted in lower BV/TV (P < 0.01), Conn.D (P < 0.01), Tb.N (P < 0.01), and higher Tb.Sp (P < 0.01), compared to normal calcium diets.

Conclusions: These data indicate that inadequate calcium intake and obesity are detrimental to bone in ovariectomized rats.

Funding Sources: Agricultural Research Service of the United States Department of Agriculture, #3062-51000-053-00D