## 4 Discussion  
The present study was designed to examine the effects of micronutrient supplementation in bone health indicators and other health biomarkers as well as in whole-body BMD, in postmenopausal women, with high risk of osteopenia or osteoporosis, after one year (groups I, II and III) and five months (group IV) intervention. Various bone health indicators and other non-traditional bone metabolism biomarkers can provide valuable information about the participants' bone health and metabolism and were measured in the present study. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Physical Activity Levels** & **Total Bone Density (rho)** & \(p\)**-Value \({}^{*}\) \\ \hline moderate & & \\ Group I & - & - \\ Group II & - & - \\ Group III & - & - \\ Group IV & 3.20 \(\pm\) 0.28 & 0.726 \\ \(p\)-value & - & - \\ intense & & \\ Group I & 2.65 \(\pm\) 0.48 & 0.032 \\ Group II & 2.83 \(\pm\) 0.38 & 0.032 \\ Group III & 2.61 \(\pm\) 0.50 & 0.032 \\ Group IV & - & - \\ \(p\)-value & - & - \\ \hline \hline \end{tabular} \({}^{*}\) Association is significant at the 0.05 level with the ANOVA test.  
\end{table} 
Table 6: Correlation of physical activity with whole-body BMD. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Beginning of Study** & **End of Study** & **\% Change** & \(p\)**-Value \({}^{*}\)** \\ \hline Whole-body BMD (g/cm\({}^{2}\)) & & & & \\ Group I & 1.38 \(\pm\) 0.49 & 1.85 \(\pm\) 0.5 & 3.46\% & 0.027 \\ Group II & 1.29 \(\pm\) 0.45 & 1.31 \(\pm\) 0.47 & 1.55\% & 0.036 \\ Group III & 1.39 \(\pm\) 0.5 & 1.56 \(\pm\) 0.51 & 12.23\% & 0.043 \\ Group IV & 1.67 \(\pm\) 0.48 & 1.87 \(\pm\) 0.35 & 11.98\% & 0.003 \\ \(p\)-value \({}^{\ddagger}\) & 0.298 & 0.187 & & \\ \hline \hline \end{tabular} \({}^{*}\)Values presented at baseline and at the end of the study are presented as means \(\pm\) SD. \({}^{*}\) Level of significance for differences observed within the same group, between the two measurements. Repeated measures ANOVA was used to define significant differences in all variables tested for each study group, at baseline and at the end of the study. \({}^{\ddagger}\) Level of significance for differences in means between groups at each interval.  
\end{table} 
Table 5: Changes in whole-body BMD. Reductions in parathyroid hormone (PTH) levels were observed in groups II and III, indicating an inverse correlation with 25-hydroxyvitamin D3 (25(OH)D3) levels. This documented inverse relationship between decreased serum 25(OH)D3 levels and PTH, crucial for calcium homeostasis and bone health, is well recognized [43]. However, the precise threshold at which 25(OH)D3 affects PTH levels remains uncertain [44]. Moreover, the optimal dose of calcium supplementation needed to inhibit PTH secretion is undefined, suggesting that inadequate supplementation may have contributed to elevated PTH levels in groups I and IV [45]. It is proposed that decreased PTH levels may result from increased 25(OH)D3 levels, especially with high calcium intake [45], potentially explaining the decrease in PTH levels in groups II and III. Further investigation is warranted to elucidate the metabolic response of PTH in postmenopausal women during calcium and vitamin D supplementation. Overall, although beneficial changes in 25(OH)D3 levels were observed in groups II, III, and IV, no significant differences were detected across the study groups. This suggests that the administered amount of 25(OH)D3 may have been insufficient to adequately elevate serum levels, and/or the study duration may have been too short. Additionally, for group IV, low 25(OH)D3 levels may have been influenced by seasonal variations, as the intervention period extended from October to February. This finding aligns with prior research indicating decreased 25(OH)D3 levels during winter months, potentially outweighing the impact of vitamin D supplementation [46]. Interestingly, vitamin D deficiency appears more prevalent in elderly populations in Mediterranean countries, compared to regions with less sunlight exposure.