The connection between the gut and the skeleton offers the potential for novel strategies through nutrition modification.
By Diane Schneider, MD
The old saying You are what you eat rings true for bone health and your overall health. The impact of nutrition and lifestyle—positive and negative—on our bones is well known, but a different type of connection between the gut and the skeleton has recently been found that may surprise you.
This new area of research has examined the role of the bacteria in your intestine as a potentially important regulator of health and a contributor to a variety of diseases. The bacteria in the gut, referred to as the gut microbiome, may play a significant role in bone health. In some 2012 experiments with mice, researchers found that gut bacteria (microbiota) regulated bone mass.1
Since that time studies have looked for nutritional factors that would decrease bone loss. The animal model for postmenopausal women is estrogen-deficit mice. Modification of microbiota in mice with probiotic supplementation showed a beneficial effect on general bone health under nondiseased conditions and reduced bone loss in estrogen-deficit mice. Estrogen depletion was associated with decreased numbers and diversity of microbiota. The probiotic supplementation contained different bacteria that modified the gut microbiome of the mice. The probiotics restored a greater number and diversity of bacteria. The research suggests that decreased diversity contributes to bone loss induced by the loss of estrogen.
One Yogurt a Day Boosts Bone Density
A real-world example of the benefit of probiotics can be found in the impact of yogurt consumption on the gut microbiome. Yogurt is a calcium-rich food. Depending on the type of yogurt, one serving may provide 200 to 450 milligrams of calcium. Recent research suggests that the beneficial effects of yogurt may go beyond just the calcium content. Yogurt also contains fermented dairy products and probiotics, which were found to be beneficial for bone health in animal laboratory experiments. Bacteria in yogurt ferments the milk.
The possible protective effect of fermented dairy products on postmenopausal bone loss led Swiss researchers to examine yogurt consumption in healthy men and women who were recruited at the age of 65.2 This study included 733 healthy postmenopausal women who underwent a bone mineral density (DXA, or dual-energy X-ray absorptiometry) scan at baseline and again three years later. At the beginning of the study, women who consumed yogurt had higher bone density and were thinner than women who did not consume yogurt.
At the follow-up assessment three years later, women who ate at least one serving of yogurt per day had less bone loss than those who did not eat yogurt. These findings were independent of any other factors that could account for differences in bone density, such as physical activity, protein consumption, and total calcium intake. Also the number of fractures trended toward a lower rate: 19 percent among yogurt consumers versus 29 percent for non-consumers.
The researchers hypothesize that bacteria in yogurt populate the large intestine, where they improve calcium absorption and decrease inflammation. They suggested that the protective effect of yogurt on bone has to do with not only calcium and protein but also the fermentation that happens in yogurt—all three of which are believed to be beneficial to bone health.
Gut Microbiome: A New Frontier
Stay tuned to this exciting new area of research. These findings suggest that by optimizing the microbiome, you may be able to build and maintain stronger bone. The connection between the gut and the skeleton offers the potential for novel strategies through nutrition modification. Research methods to shift the gut microbiome by interventions open the door for the discovery of treatments to improve health and ameliorate disease, including osteoporosis. In the meantime you may just want to eat a serving of yogurt each day for good measure.
Want to Know Your Gut Microbiome?
You can find out what’s living in your gut through a crowd-funded research study at the University of California, San Diego.
Anyone can contribute to and participate in the American Gut Project. Enroll online at fundrazr.com/campaigns/4Tqx5. When you do, you get a kit; use it to swab your stool and mail it in. The American Gut Project team extracts the microbial DNA from the sample and uses a genetic-sequencing technique to map which types of bacteria are there and how many there are of each type.
American Gut participants not only get information about what’s living in their own bodies but they can also see how they compare with other participants with similar (or different) ages, diets, and exercise habits. What’s more, participants are also contributing valuable information (stripped of their personal identification data) to an open access database. Because the microbiome data is paired with lifestyle information such as diet and exercise, researchers can use these data to study how nutrition and activity influence the microbiome and how that microbial makeup is associated with health problems. For more information go to americangut.org.
1 Sjogren K, Engdahl C, Henning P, et al. The gut microbiota regulates bone mass in mice. Journal of Bone and Mineral Research. 2012 Jun; 27(6): 1357–1367. doi: 10.1002/jbmr.1588 Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3415623/. Accessed January 19, 2017.
2 Biver E, et al 2016 Yogurt consumption is associated with attenuated cortical bone loss independently of total calcium and protein intake and physical activity in postmenopausal women. J Bone Miner Res 31 (Suppl 1). Available at http://www.asbmr.org/education/AbstractDetail?aid=1c27565e-384d-44cb-a5c6-7973f82cd8a1. Accessed January 14, 2017.