We normally don’t think about our 206 bones that comprise our very foundation, and often, when we do, we tend to think they are rather static, just like a concrete foundation: just there, immobile, unchangeable.
But our bones are anything but – they are living tissue that is constantly changing, which is normal. The process is called bone remodeling. And as with anything else attributed to aging, getting older doesn’t just slow down the remodeling activity, it reverses it.
Researchers in one study describe bone as “a dynamic organ that undergoes constant remodeling during all stages of life. This remodeling process requires the coordinated actions from two cell types, osteoclasts and osteoblasts. Osteoclasts carry out the action of bone resorption, while osteoblasts take part in the formation of new bone.
Ca, D and K2
As you well know, calcium and vitamin D (as well as working out with weights) all help to preserve the balance of breakdown and remodeling, keeping bones strong and resistant to outside forces (eg, bumping into things, running, etc.).
Briefly, calcium is a critical and abundant part of bone and when there is not enough of this mineral, the parathyroid gland resorbs bone to try to attain more; after time, this leaching of calcium from bones causes them to become brittle and lose resilience. Vitamin D, calcium’s BFF for bones, is used by your body to mineralize newly forming bone; and if you accidentally break or fracture a bone, vitamin D comes to the rescue to help mineralize/form and repair the break.
Vitamin K2 has joined the dynamic duo of calcium and vitamin D to support healthy bone structure, and more research is being performed to validate its ability to do so by switching on dormant osteocalcin, an important protein secreted by osteoblasts (the bone-building cells) to keep bone forming or rebuilding in a youthful manner.
Bone: A Living Organism
Probiotics and managing the microbiome is an area of keen interest and study as they relate to ensuring bone health optimization – a cogent clinical term meaning “the process of bone status assessment, identification and correction of metabolic deficits, and initiation of treatment, when appropriate, for skeletal structural deficits.”
The gut microbiota (just the bacterial populations) is increasingly recognized as a critical factor in determining bone health status. In one review, researchers commented, “Recently, the role of gut bacteria in bone health … has received more significant attention…. “We propose an emerging field of the gut-brain-bone axis, in which the gut drives bone physiology via regulation of key hormones that are originally synthesized in the brain.”
Through the absorption of calcium, the gut has a role to paly in the regulation of mineralization.
Bone dynamism is also affected by ubiquitous inflammation, and several studies showed a benefit of probiotics on inflammation observed in various conditions in bone. In a murine study, for example, Lactobacillus casei administration reduced both production if pro-inflammatory compounds TNF-alpha and IL6 production while increasing production of the anti-inflammatory cytokine IL-10.
According to researchers, “Osteoblasts and osteoclasts are the main bone cells and balance between their activities indicates bone health. Several mechanisms influence the bone turnover and RANKL/RANK/OPG pathway is one of them. “
Studies in humans have shown, overall, that probiotics may have noteworthy value in promoting healthy bone turnover.
In a human study, researchers explained how probiotics’ inflammation-mediated effects can influence healthy bone turnover. They explained, “Probiotic administration may reduce the expression of several pro-inflammatory and osteolytic cytokines (TNF-a and IL-1b). The cytokines alter expression of the OPG as an anti-osteoclastogenic cytokine, which is responsible for the altered RANKL/OPG ratio. This leads to enhanced activity and formation of osteoclasts and suppressed bone formation by osteoblasts, which results in bone loss.”
Several randomized placebo-controlled trials have assessed the effects of probiotics on bone metabolism in healthy postmenopausal women, the primary population that exhibits age-induced porosity of bones. Several studies that used different probiotics between six to 12 months of supplementation showed measures of decreased bone resorption (breakdown).
Three studies showed that probiotic species (Lactobacillus reuteri, Bacillus subtilis, or a combination) halted rate of bone loss at the distal tibia (larger of the forearm bones), at the lumbar spine, or at the hip, respectively.
In 2018, what is called the first study in which probiotics were used to reduce bone loss in older people provided strong evidence that probiotics are a valuable tool in a healthy lifestyle for extending well-being. In this study, 90 older women (average age of 76 years), consumed either placebo or the strain Lactobacillus reuteri 6475 for one year. "When we finished the study after a year, we measured the women's bone loss in their lower legs with a CT scan and compared it with the measurements we made when the study began. (The supplement group) had lost only half as much bone in the skeleton compared with those who received inactive powders," stated study co-author Anna Nilsson.
Another study evaluated how a supplement containing several species of probiotics affected bone biomarkers and bone density in post-menopausal women. The six-month randomized double-blind placebo-controlled clinical trial on healthy 50 women aged 50–72 years with a high rate of osteoclastic activity found that those who consumed a seven-species probiotic (GeriLact) exhibited slower rates of bone turnover than those on placebo.
Prebiotics seem to have a positive role in bone structure, as well. One 24-month randomized, double-blind, controlled trial looked at the influence of consumption of the prebiotic fructooligosaccharides (FOS) and bone status in post-menopausal women, finding a “more favorable bone health profile after supplementation with calcium and short-chain fructooligosaccharide. Supplementation with CaFOS slowed the rate of total-body and spinal bone loss in postmenopausal women.”
A synbiotic was investigated in one murine study for its role in potentially helping to preserve bone health. The researchers gave Bifidobacterium longum with or without prebiotic (yacon flour) to subjects, and found that the bone mineral content was statistically significantly higher in the synbiotic group although the probiotic by itself also yielded noticeable bone health benefit.
These represent the tip of a growing iceberg of scientific evidence demonstrating the value of consuming probiotics, prebiotics and synbiotics to ensure healthy bone structure. Researchers are positive about the future of this area of study, writing, “There is still much to learn regarding our understanding of the signaling pathways that link the microbiome and gut to skeletal health. We envision that modulation of the intestine-microbiome interaction to improve bone health will play an important role in human health.”