A mineral-rich extract from the red marine algae Lithothamnion calcareum preserves bone structure and function in female mice on a Western-style diet

Abstract

The purpose of this study was to determine whether a mineral-rich extract derived from the red marine algae Lithothamnion calcareum could be used as a dietary supplement for prevention of bone mineral loss. Sixty C57BL/6 mice were divided into three groups based on diet: the first group received a high-fat Western-style diet (HFWD), the second group was fed the same HFWD along with the mineral-rich extract included as a dietary supplement, and the third group was used as a control and was fed a low-fat rodent chow diet (AIN76A). Mice were maintained on the respective diets for 15 months. Then, long bones (femora and tibiae) from both males and females were analyzed by three-dimensional micro-computed tomography (micro-CT) and (bones from female mice) concomitantly assessed in bone strength studies. Tartrate-resistant acid phosphatase (TRAP), osteocalcin, and N-terminal peptide of type I procollagen (PINP) were assessed in plasma samples obtained from female mice at the time of sacrifice. To summarize, female mice on the HFWD had reduced bone mineralization and reduced bone strength relative to female mice on the low-fat chow diet. The bone defects in female mice on the HFWD were overcome in the presence of the mineral-rich supplement. In fact, female mice receiving the mineral-rich supplement in the HFWD had better bone structure/function than did female mice on the low-fat chow diet. Female mice on the mineral-supplemented HFWD had higher plasma levels of TRAP than mice of the other groups. There were no differences in the other two markers. Male mice showed little diet-specific differences by micro-CT.

Fig. 1

Micro-CT cross-sectional images through cortical (mid-diaphysis) and trabecular (distal metaphysis) ROIs of femora from female mice on three different diets. Differences in cortical thickness and in trabecular number, thickness, and space are evident

Fig. 2

Bone strength measurements from female mice in the three diet groups. Femora were tested to failure in four-point bending. Values for each parameter are means and standard deviations for females. Statistical significance of each parameter was assessed by ANOVA followed by paired group comparisons. Asterisks are placed on the HFWD + supplement group: * statistically significant improvement relative to the AIN76A group, ** statistically significant improvement relative to both AIN76A and HFWD (P < 0.05). Data are based on eight mice in the AIN76A diet group, four mice in the HFWD group, and 10 mice in the HFWD + supplement group

Fig. 3

Osteocalcin, PINP, and TRAP levels in plasma from female mice in the three diet groups. Plasma levels of osteocalcin, PINP, and TRAP 5b were assessed by ELISA from animals killed at the end of the 15-month study. Statistical significance of each parameter was assessed by ANOVA followed by paired group comparisons. ** Statistically significant difference relative to both AIN76A and HFWD (P < 0.05). Data are based on eight mice in the AIN76A diet group, four mice in the HFWD group, and 10 mice in the HFWD + supplement group