@kfhoz Study Report: https://pmc.ncbi.nlm.nih.gov/articles/PMC8441532/
After reading the study you referenced (see above) I have a different understanding of the results. To me, the results showed that Fortibone, called "specific collagen peptides" in the report, was compared to a different powder as a "placebo", and the results showed improvements in bone mineral density in the Fortibone group ("specific collagen peptides") whereas those taking the placebo showed decreases in bone mineral density.

From the report:
"3. Investigational product
The same bioactive collagen peptides (FORTIBONE®) from the main randomised control trial with a high safety (GRAS status) were used for this intervention."

"2.7. Protein Supplementation
For this study, a mixture of specific bioactive collagen peptides (SCP) with a mean molecular weight of approx. 5 kDa, derived from a complex multi-step hydrolysis of collagen, was used (FORTIBONE®, GELITA AG, Eberbach, Germany). The sachets containing 5 g SCP or placebo (maltodextrin, CARGILL, Paris, France) were identical in appearance and the products were equal in flavor and texture."

So, my takeaway is that the study found that women who took the SCP (Fortibone) showed increases in BMD, while the women who took a placebo showed decreases in BMD:
"The analysis showed that bone density significantly increased in the spine and the femoral neck after SCP treatment compared to placebo. In the SCP group, BMD increased by almost 3.0% in the spine and 6.7% in the femoral neck, whereas, in the same period, bone density decreased in the placebo group (−1.3% for spine and −1.0% in the femoral neck)."

The conclusion also stated the benefits of using "specific collagen peptides" -- which was Fortibone in the study.
"4. Discussion
The main outcome of this randomized, double-blinded and placebo-controlled study in postmenopausal women was that specific collagen peptides significantly increased bone mineral density (BMD) in both the lumbar spine and femoral neck. In contrast, no significant changes for these parameters were determined in the placebo group. Considering the decrease in BMD in the control group, subjects in the SCP group showed a 4.2% higher BMD in the spine and a 7.7% higher BMD in the femoral neck, suggesting a clinically relevant effect of the 12-month treatment with SCP
."

So, if I am going to take a collagen powder I will use a Fortibone product.