Researchers studied over 1,200 people to understand why some adults lose muscle mass and strength as they age—a condition called sarcopenia. They discovered that people with higher levels of a special protein called klotho had stronger muscles and were less likely to experience this muscle loss. This finding suggests that klotho might be important for keeping muscles healthy, and doctors might one day use klotho measurements to identify people at risk of losing muscle strength before it becomes a serious problem.

The Quick Take

  • What they studied: Whether a protein in the blood called klotho is connected to muscle loss and weakness in adults
  • Who participated: 1,250 adults from different backgrounds who participated in a large U.S. health survey between 2011 and 2016
  • Key finding: People with higher klotho levels had stronger grip strength and were less likely to have sarcopenia (muscle loss), though the connection became less clear when researchers adjusted for other health factors
  • What it means for you: Klotho may play a role in keeping muscles strong, but more research is needed before doctors can use klotho tests to predict or prevent muscle loss. This is promising early evidence, not yet a proven treatment or prevention strategy.

The Research Details

Scientists used information from the National Health and Nutrition Examination Survey (NHANES), a large study that tracks the health of Americans. They looked at data from 1,250 people and divided them into four groups based on how much klotho protein they had in their blood. They measured muscle strength using a handgrip test and calculated muscle mass using body measurements. Then they used statistical tools to see if people with more klotho had stronger muscles and less muscle loss.

This type of study is called a cross-sectional study, which means researchers looked at everyone at one point in time rather than following them over years. It’s like taking a snapshot instead of a video. This approach is good for finding connections between things, but it can’t prove that one thing directly causes another.

This research approach is important because it uses real-world data from thousands of Americans rather than just laboratory experiments. By looking at actual people’s health information, scientists can see if klotho levels matter in everyday life. However, because it’s a snapshot in time, researchers had to be careful about other factors (like age, weight, and vitamin D levels) that might also affect muscle strength.

The study used a large, diverse group of people from across the United States, which is a strength. However, the findings became less clear when researchers accounted for other health factors, suggesting that klotho’s role in muscle health is more complicated than it first appeared. The study is observational, meaning it shows connections but cannot prove cause-and-effect relationships. More research, particularly long-term studies, would be needed to confirm these findings.

What the Results Show

The researchers found that people with the lowest klotho levels had the highest risk of sarcopenia (muscle loss and weakness). When they first analyzed the data without adjusting for other factors, higher klotho levels were clearly linked to lower sarcopenia risk. However, when they added other health factors into their analysis—like age, sex, weight, vitamin D levels, and existing diseases—the connection became weaker and was no longer statistically significant.

This pattern suggests that klotho doesn’t work alone. Instead, it appears to work together with other health factors. For example, people with higher klotho might also have better overall health, which could be why they have stronger muscles. The researchers also found that grip strength (a measure of muscle strength) was negatively correlated with klotho levels in some groups, meaning the relationship was more complex than expected.

The study revealed that several factors significantly influence the relationship between klotho and muscle health, including biological sex, ethnicity, alcohol use, body weight, vitamin D levels, and whether someone has kidney disease. This means that klotho’s effect on muscles isn’t the same for everyone—it varies depending on a person’s individual characteristics and health status. The findings were particularly interesting in older adults, where the connection between klotho and grip strength was also observed.

This research adds to growing evidence that klotho, a protein known for its anti-aging properties, may play a role in muscle health. Previous studies have suggested klotho helps regulate vitamin D and minerals important for bone and muscle function. This study is one of the first to examine this connection in a large, diverse U.S. population using national health data, making it a valuable addition to the scientific literature.

The study has several important limitations. First, it’s a snapshot in time, so researchers couldn’t follow people to see if low klotho actually caused muscle loss. Second, the connection between klotho and sarcopenia disappeared when other health factors were considered, suggesting the relationship is more complicated than initially thought. Third, the study couldn’t prove that klotho directly causes stronger muscles—only that they’re associated. Finally, while the sample was diverse, it only included people who participated in the health survey, which might not represent all Americans perfectly.

The Bottom Line

Based on this research, there is not yet enough evidence to recommend measuring klotho levels as a routine screening tool for muscle loss. However, the findings suggest klotho may be important for muscle health and warrant further investigation. If you’re concerned about muscle loss, focus on proven strategies: regular strength training, adequate protein intake, and maintaining a healthy weight. Consult your doctor about your individual risk factors.

This research is most relevant to older adults concerned about muscle loss, people with kidney disease (since klotho is involved in kidney function), and healthcare providers looking for new ways to identify people at risk of sarcopenia. It’s less immediately relevant to younger, healthy adults, though the findings may eventually apply to them as they age.

This is early-stage research. Even if klotho testing becomes available, it would likely take 5-10 years of additional research before doctors could confidently use it to predict or prevent muscle loss. In the meantime, proven strategies like exercise and good nutrition remain your best approach to maintaining muscle strength.

Want to Apply This Research?

  • Track grip strength monthly using a hand dynamometer (available inexpensively online) and record results in the app. Also track weekly strength training sessions and daily protein intake in grams. This creates a personal baseline to monitor muscle health over time.
  • Set a goal to perform resistance exercises (weights, bands, or bodyweight) 2-3 times per week, and ensure daily protein intake meets recommended levels (0.8-1.0 grams per pound of body weight for older adults). Log these activities in the app to build consistency.
  • Create a quarterly review where you compare grip strength measurements, exercise frequency, and protein intake trends. If grip strength declines or exercise consistency drops, use the app to send reminders and adjust goals. Share trends with your healthcare provider during annual checkups.

This research is preliminary and does not establish klotho testing as a clinical diagnostic tool. The findings show associations, not proven cause-and-effect relationships. Do not make health decisions based solely on this study. If you’re concerned about muscle loss or sarcopenia, consult with your healthcare provider for personalized evaluation and recommendations. This information is for educational purposes only and should not replace professional medical advice.