Protective Effect of Virgin Coconut Oil on Osteopenia Induced by High Refined Carbohydrate-Containing Diet in Mice

Abstract

Background: Obesity leads to chronic low-grade inflammation, promoting detrimental effects on bone. The consumption of virgin coconut oil (VCO) is associated with benefits related to meta-inflammation. We evaluated the effect of VCO supplementation on osteopenia promoted by diet-induced obesity in mice.

Methods: Male BALB/c mice were fed a control (C) or highly refined carbohydrate-containing (HC) diet for eight weeks. After that, the HC diet group was supplemented with three doses of VCO for four weeks.

Results: The HC diet increased the adiposity and leptin levels associated with augmented systemic inflammatory cells improved with VCO supplementation. The HC diet reduced the trabecular bone in the tibia, lumbar vertebrae, distal and proximal femur, as well as the bone mineral density of the femur and alveolar bone. The VCO supplementation reverted bone osteopenia by increasing the trabecular bone in different sites and improving femur and alveolar bone microarchitecture. Although the reduced number of osteoblasts in the alveolar bone of the HC diet group was not significantly enhanced by VCO supplementation, the reduced Alp expression in the HC diet group was enhanced in the VCO group. These beneficial effects were associated with lowering the Rankl/Opg ratio.

Conclusion: VCO supplementation might be an effective strategy to attenuate bone osteopenic effects induced by obesity.

Keywords: alveolar bone; bone loss; high refined carbohydrate diet; metabolism; obesity; virgin coconut oil.

Figure 1

Effect of the HC diet and VCO supplementation on the percentage of trabecular bone in the proximal and distal femur. (A) The trabecular bone area and (B) histological sections of the proximal femur (scale bars represent 100 µm). (C) The trabecular bone area and (D) histological sections of the distal femur (scale bars represent 100 µm). Analyses were performed in mice fed a chow diet, high refined carbohydrate-containing (HC) diet, and HC diet supplemented with 1000 mg/kg (LVCO), 3000 mg/kg (MVCO), or 9000 mg/kg (HVCO) of body weight of virgin coconut oil (VCO). Values are means ± SEM (n = 8). * compared with the control (C) group (p < 0.05); # compared with HC group (p < 0.05).

Figure 2

Effect of the HC diet and VCO supplementation on the percentage of trabecular bone in the tibia and lumbar vertebrae. (A) The trabecular bone area and (B) histological sections of the proximal tibia (scale bars represent 100 µm). (C) The trabecular bone area and (D) histological sections of lumbar vertebrae (scale bars represent 100 µm). Analyses were performed in mice fed a chow diet, high refined carbohydrate-containing (HC) diet, and HC diet supplemented with 1000 mg/kg (LVCO), 3000 mg/kg (MVCO), or 9000 mg/kg (HVCO) of body weight of virgin coconut oil (VCO). Values are means ± SEM (n = 8). * compared with the control (C) group (p < 0.05); # compared with HC group (p < 0.05).

Figure 3

Micro-CT analysis of trabecular bone in the femur. (A) Representative femur images (small red squares represent the analyzed region on micro-CT). (B) Bone mineral density (BMD), (C) trabecular bone volume fraction (BV/TV), (D) trabecular thickness (Tb.Th), (E) trabecular number (Tb.N), (F) trabecular pattern factor (Tb.Pf), (G) bone maximum load and (H) stiffness of femur in mice fed chow diet (C), high refined carbohydrate-containing diet (HC), and HC diet supplemented with 3000 mg/kg body weight of virgin coconut oil (MVCO). Values are means ± SEM (n = 5). * compared with the control (C) group (p < 0.05); # compared with HC group (p < 0.05).

Figure 4

Micro-CT analysis of maxillary bone. (A) Bone mineral density (BMD), (B) representative images of maxillary (small red squares represent the analyzed region on micro-CT). (C) Alveolar bone loss, (D) representative images of the maxilla (the area outlined of CEJ-ABC represents the area of alveolar bone resorption). (E) Trabecular bone volume fraction (BV/TV), (F) trabecular thickness (Tb.Th), (G) trabecular number (Tb.N), (H) trabecular pattern factor (Tb.Pf) of the maxilla, (I) osteoblast number per bone perimeter (ObN/BPm) and (J) representative images of osteoblasts in mice fed a chow diet (C), high refined carbohydrate-containing diet (HC), and HC diet supplemented with 3000 mg/kg body weight of virgin coconut oil (MVCO). Values are means ± SEM (n = 5). * compared with the control (C) group (p < 0.05); # compared with HC group (p < 0.05).

Figure 5

Effect of dietary VCO supplementation in the mRNA expression in the maxilla. (A) mRNA expression of Opg, (B) receptor activator of nuclear factor κB (Rank) and (C) receptor activator of nuclear factor κB ligand (Rankl). (D) Rankl/Opg ratio. (E) Runx2 and (F) Alp. Analyses were performed in mice fed a chow diet (C), high refined carbohydrate-containing diet (HC), and HC diet supplemented with 3000 mg/kg body weight of virgin coconut oil (MVCO). Values are means ± SEM (n = 5). * compared with the control (C) group (p < 0.05); # compared with HC group (p < 0.05).