Scientists discovered that bacteria in your gut produce a chemical called trimethylamine (TMA) that acts like a messenger to control your body’s internal clock. When your body receives this message through a special receptor called TAAR5, it helps regulate your sleep-wake cycle, metabolism, and even your gut bacteria balance. This research in mice suggests that the food you eat influences your gut bacteria, which then sends signals that affect your daily rhythms and overall health. Understanding this connection could help explain why an imbalance in gut bacteria is linked to weight gain and heart disease.

The Quick Take

  • What they studied: How a chemical messenger produced by gut bacteria affects your body’s 24-hour rhythms (circadian rhythms) and whether a specific receptor in your body that detects this chemical is important for maintaining healthy daily patterns.
  • Who participated: Laboratory mice with different genetic modifications—some missing the ability to produce the chemical messenger, some missing the receptor that detects it, and normal control mice for comparison.
  • Key finding: Mice without the ability to sense the bacterial chemical (TMA) through the TAAR5 receptor showed disrupted daily rhythms in gene activity, hormone levels, gut bacteria composition, and behavior patterns. This suggests the chemical messenger is essential for keeping your body’s clock running properly.
  • What it means for you: Your gut bacteria may play a bigger role in controlling your daily rhythms than previously thought. This could eventually lead to new ways to prevent weight gain and heart disease by managing gut bacteria through diet, though more research in humans is needed before making specific recommendations.

The Research Details

Researchers used genetically modified mice to test whether a chemical called trimethylamine (TMA) produced by gut bacteria affects the body’s internal clock. They created mice missing different parts of this system: some couldn’t produce TMA, some couldn’t sense TMA, and some couldn’t convert TMA into its related form (TMAO). They then measured how these changes affected the mice’s daily patterns in gene activity, hormone levels, sleep-wake behavior, and gut bacteria composition.

The study built on previous research showing that lowering TMA and TMAO levels helped mice stay at a healthy weight. Instead of just looking at the end product (TMAO), these scientists focused on the initial chemical (TMA) and the specific receptor (TAAR5) that detects it in the body.

This approach allowed them to pinpoint exactly which part of the system was responsible for controlling circadian rhythms, rather than just observing that the chemicals were involved.

Understanding the specific mechanism—how TMA communicates with TAAR5 to control daily rhythms—is important because it identifies a potential target for treatment. If scientists can develop ways to influence this TMA-TAAR5 communication through diet or medication, it might help prevent obesity and heart disease. This research also shows that the bacteria in your gut aren’t just passive passengers; they actively communicate with your body to regulate fundamental processes.

This research was published in eLife, a respected peer-reviewed scientific journal. The study used multiple approaches (genetic knockouts) to test the same question from different angles, which strengthens confidence in the findings. However, this work was conducted in mice, so results may not directly apply to humans. The researchers measured multiple outcomes (genes, hormones, behavior, bacteria) rather than relying on a single measurement, which provides more comprehensive evidence.

What the Results Show

Mice that lacked the TAAR5 receptor (the part that detects TMA) showed significant disruptions in their circadian rhythms. These mice had abnormal patterns in which genes were active at different times of day, unusual hormone levels throughout the day, and irregular sleep-wake behaviors. Their gut bacteria composition was also different from normal mice, suggesting the TMA-TAAR5 system helps maintain a healthy bacterial community.

Mice that couldn’t produce TMA in the first place (because their gut bacteria lacked the necessary enzymes) also showed altered circadian rhythms, though in different ways. Similarly, mice that couldn’t convert TMA to TMAO (missing the host enzyme) had disrupted daily patterns. This shows that multiple steps in this system are important for maintaining normal circadian rhythms.

The findings suggest that TMA acts as a communication signal between your gut bacteria and your body. When this signal is blocked or absent, your body loses an important cue for regulating its daily rhythms.

The research revealed that the TMA-TAAR5 system affects multiple aspects of daily regulation simultaneously—not just one process. The changes in circadian rhythms were accompanied by changes in metabolic hormones (chemicals that control energy use), suggesting the system influences how your body processes food and energy throughout the day. The altered gut bacteria composition in mice lacking TAAR5 indicates that this receptor may also help maintain a balanced microbial community, which is important for overall health.

Previous research had focused mainly on TMAO (the end product after TMA is further processed) and its link to heart disease. This study shifts attention to TMA itself and shows it plays a direct role in controlling daily rhythms. Earlier work showed that drugs lowering both TMA and TMAO protected mice from obesity, but didn’t explain the mechanism. This research provides that missing explanation: the protection works partly by maintaining normal circadian rhythms through the TMA-TAAR5 system. The findings also expand our understanding of how gut bacteria influence host health beyond just producing metabolites—they actively regulate fundamental biological processes.

This research was conducted entirely in mice, so we cannot yet confirm these findings apply to humans. The study didn’t test whether changing diet (which would change TMA production) could restore normal rhythms in mice lacking TAAR5, so the practical implications remain unclear. The researchers measured circadian changes but didn’t directly test whether these changes cause the health problems (like obesity) associated with high TMAO levels. Additionally, the study focused on one specific bacterial metabolite and receptor; other gut bacteria chemicals likely also influence circadian rhythms through different mechanisms.

The Bottom Line

Based on this research, there are no direct recommendations for humans yet. However, the findings suggest that maintaining a healthy gut bacteria balance through diet (eating foods like fiber and fermented foods) may help keep your circadian rhythms stable. This is a moderate-confidence recommendation based on animal research. People with circadian rhythm disorders or metabolic issues should continue following their doctor’s advice, as this research is still preliminary.

This research is most relevant to people interested in understanding how gut health affects overall wellness, particularly those concerned about weight management or heart health. It may eventually be important for people with circadian rhythm disorders (like shift workers or those with sleep problems) and those with metabolic diseases. People taking medications for heart disease or obesity should not change their treatment based on this research alone. Researchers studying gut bacteria, circadian biology, and cardiometabolic disease should pay close attention to these findings.

This is very early-stage research. Even if these findings are confirmed in humans, it would likely take 5-10 years before any new treatments based on this mechanism become available. In the near term (1-2 years), we might see follow-up studies in humans to confirm the TMA-TAAR5 system works similarly in people. Any practical applications would come much later.

Want to Apply This Research?

  • Track your sleep-wake consistency (bedtime and wake time) and energy levels throughout the day for 2-4 weeks. Note any patterns with your diet, particularly intake of choline-rich foods (eggs, meat, dairy) and fiber. This baseline data could help identify whether dietary changes affect your daily rhythms.
  • Gradually increase fiber intake from vegetables, whole grains, and legumes to support healthy gut bacteria. Maintain a consistent sleep schedule (same bedtime and wake time daily) to support your natural circadian rhythms. Log these changes in the app to track correlations between diet consistency and sleep quality or energy patterns.
  • Over 8-12 weeks, monitor whether consistent dietary patterns (particularly fiber intake) correlate with improvements in sleep quality, energy consistency, and overall well-being. Use the app to identify your personal patterns and whether maintaining gut-healthy foods affects your daily rhythm stability. Share trends with your healthcare provider if you have metabolic or sleep concerns.

This research was conducted in mice and has not yet been tested in humans. The findings are preliminary and should not be used to diagnose, treat, or prevent any disease. If you have concerns about your circadian rhythms, sleep, weight, or heart health, consult with your healthcare provider before making any dietary or lifestyle changes. This article is for educational purposes only and does not replace professional medical advice. Do not stop or change any medications based on this research.