A large study of nearly 9,400 American adults found that people who eat more foods that are good for their gut bacteria—like fiber-rich plants and fermented dairy—had fewer broken bones and less osteoporosis than those who didn’t. Researchers created a simple scoring system to measure how “gut-friendly” people’s diets were, then compared it to their bone health. The results suggest that taking care of your gut through diet might also be taking care of your bones, though scientists say more research is needed to fully understand this connection.

The Quick Take

  • What they studied: Whether eating foods that support healthy gut bacteria is connected to stronger bones and fewer fractures
  • Who participated: 9,385 American adults aged 20 and older who participated in a national health survey between 2009 and 2020
  • Key finding: For every point increase on the gut-friendly diet score (out of 13 possible points), people had about 10% lower chances of fractures and 6% lower chances of osteoporosis
  • What it means for you: Eating more plant fiber and fermented foods while limiting red meat, processed foods, and refined grains may help protect your bones, though this study shows a connection rather than proof of cause-and-effect

The Research Details

This was a cross-sectional study, which means researchers looked at information from a large group of people at one point in time rather than following them over years. The study used data from NHANES (National Health and Nutrition Examination Survey), a program that regularly checks the health of Americans. Researchers calculated a “Dietary Index for Gut Microbiota” score for each person based on two days of food records. The score measured how much people ate foods that help gut bacteria (like vegetables, whole grains, and yogurt) versus foods that don’t help gut bacteria (like red meat, processed foods, and sugary items). They then compared these scores to each person’s bone health information, including whether they’d had fractures, whether they had osteoporosis, and their bone density measurements.

This approach is important because it looks at real-world eating patterns and their connection to bone health in a large, representative group of Americans. By using actual food intake data rather than just asking people about their diet, the researchers could be more precise about what people were really eating. The study also measured bone health in multiple ways—fractures, osteoporosis diagnosis, and bone density—which gives a more complete picture.

This study has several strengths: it included a very large, nationally representative sample of Americans, used standardized bone density measurements, and adjusted for many other factors that affect bone health. However, because it’s cross-sectional, it shows associations rather than proof that gut-friendly diets cause stronger bones. The study relied partly on people remembering and reporting their own fractures and osteoporosis diagnoses, which can be less accurate than medical records. The results are also from a snapshot in time, so we can’t know if the diet caused the bone health or if people with better bones simply tend to eat better.

What the Results Show

The main finding was that people with higher gut-friendly diet scores had significantly fewer fractures. Specifically, each point increase in the diet score (on a scale of 0-13) was linked to a 10% lower chance of having had a fracture. This pattern held true for fractures at different body sites and for both men and women. The study also found that higher diet scores were connected to 6% lower odds of having osteoporosis. These associations were consistent and statistically significant, meaning they’re unlikely to be due to chance.

When researchers looked at bone density measurements, they found that higher diet scores were linked to slightly higher bone density at the hip (femoral neck), though the increase was small. Interestingly, this connection was stronger in men than in women. The connection to spine bone density was very weak and not statistically significant, suggesting the gut-friendly diet may be more protective for hip bones than spine bones.

The study found that the benefits of a gut-friendly diet appeared consistent across different groups. Men and women both showed lower fracture risk with higher diet scores. Different types of fractures (hip, wrist, spine, and others) all showed the same protective pattern. This consistency across different populations and fracture types strengthens confidence in the findings.

This is the first study to directly examine the connection between a gut-microbiota-focused diet score and bone health outcomes. Previous research has shown that gut bacteria influence bone health through various biological pathways, and that diet shapes which bacteria live in our gut. This study bridges those two areas by showing that eating patterns known to support healthy gut bacteria are associated with better bone outcomes in a large population.

This study shows associations but cannot prove that eating gut-friendly foods causes stronger bones—people with stronger bones might simply choose to eat healthier. The study relied on people self-reporting fractures and osteoporosis diagnoses, which may be inaccurate. The diet information came from just two days of food records, which may not represent someone’s typical eating pattern. The study was conducted in the U.S., so results may not apply to other countries with different food cultures. Finally, because this is a snapshot in time, we don’t know if the diet-bone connection holds up over many years.

The Bottom Line

Based on this research, eating more foods that support gut bacteria appears to be associated with better bone health. This means increasing fiber-rich plants (vegetables, fruits, whole grains, beans), fermented dairy products (yogurt, kefir, cheese), and other fermented foods while reducing red meat, processed foods, and refined grains. However, this is one study showing an association, not definitive proof. These dietary changes are generally healthy for many reasons beyond bone health, so they’re reasonable to try. Confidence level: Moderate—the findings are promising but need confirmation from longer-term studies.

This research is relevant to anyone concerned about bone health, especially older adults, women going through menopause, and people with family histories of osteoporosis or fractures. It’s also interesting for anyone wanting to optimize their gut health, since these dietary changes benefit digestion and overall health. People already following Mediterranean or plant-based diets are likely already eating in ways that support this pattern. However, people with specific medical conditions affecting bone health or gut function should consult their doctor before making major dietary changes.

Bone health changes happen slowly. You wouldn’t expect to see improvements in bone density for several months to a year of consistent dietary changes. Fracture risk reduction would take even longer to measure. Think of this as a long-term investment in your skeletal health rather than something that produces quick results.

Want to Apply This Research?

  • Track daily servings of gut-friendly foods: fiber sources (vegetables, fruits, whole grains), fermented foods (yogurt, kefir, sauerkraut), and legumes. Aim for at least 5 servings of plants daily and 1-2 servings of fermented foods. Also track foods to limit: red meat, processed meats, refined grains, and high-fat foods.
  • Start by adding one gut-friendly food to each meal: a vegetable with breakfast, legumes or whole grains at lunch, and fermented foods as a snack or side. Gradually increase these while reducing processed and red meat options. Use the app to log these additions and see your gut-friendly diet score improve over time.
  • Weekly review of your gut-friendly diet score and monthly tracking of how you feel (digestion, energy, joint comfort). If possible, get bone density scans every 1-2 years to monitor long-term changes. Note any changes in fracture history or bone-related symptoms.

This research shows an association between gut-friendly eating patterns and better bone health, but does not prove that diet changes will prevent fractures or osteoporosis in any individual. This study is observational and cannot establish cause-and-effect. Anyone with concerns about bone health, osteoporosis, or fracture risk should consult with their healthcare provider for personalized advice. This information is not a substitute for medical diagnosis or treatment. Before making significant dietary changes, especially if you have existing health conditions or take medications, speak with your doctor or a registered dietitian.