Researchers discovered that lutein, a natural substance found in leafy green vegetables, might make metformin (a common diabetes medicine) work even better at controlling blood sugar. In a study with diabetic mice, scientists found that combining lutein with metformin lowered blood sugar levels more effectively than metformin alone. The improvement appeared to happen through changes in gut bacteria and how the body uses energy. While these results are promising, they come from animal studies, so more research in humans is needed before we know if this works the same way for people with diabetes.

The Quick Take

  • What they studied: Whether adding lutein (a plant nutrient) to metformin could improve blood sugar control better than metformin alone
  • Who participated: 30 laboratory mice total: 24 mice with type 2 diabetes (divided into 4 treatment groups) and 6 healthy mice as a comparison group
  • Key finding: Mice receiving both lutein and metformin had significantly lower blood sugar levels and better insulin sensitivity compared to mice receiving only metformin after 8 weeks
  • What it means for you: This suggests lutein might be a helpful addition to diabetes treatment, but these are early results from animal studies. People with diabetes should not change their treatment without talking to their doctor, as human studies are still needed

The Research Details

Scientists created type 2 diabetes in mice using a high-fat diet combined with a chemical injection. They then divided the diabetic mice into four groups: one receiving no treatment, one receiving only metformin, one receiving only lutein, and one receiving both lutein and metformin together. A fifth group of healthy mice ate normal food and served as a comparison. The researchers measured blood sugar levels, insulin resistance, and changes in gut bacteria over 8 weeks.

This type of study is called a controlled animal experiment. It allows scientists to carefully control all conditions and test one variable at a time. By comparing multiple groups, researchers can see which treatments work best and understand how they work.

The study measured several important markers: blood sugar levels, how well the body responds to insulin, and the composition of bacteria living in the mice’s digestive systems. They also examined specific proteins involved in energy metabolism.

Animal studies like this help scientists understand how treatments might work before testing them in humans. By using mice with diabetes similar to human type 2 diabetes, researchers can test whether new combinations of treatments are safe and effective. This research provides a foundation for future human studies.

This study was published in Scientific Reports, a reputable scientific journal. The researchers used established methods to create diabetes in mice and measured multiple health markers to confirm their results. However, because this is an animal study, results may not work exactly the same way in humans. The sample size is relatively small, which is typical for preliminary animal research. The study was well-designed with proper control groups for comparison.

What the Results Show

After 8 weeks, mice receiving both lutein and metformin had significantly lower blood sugar levels compared to mice receiving only metformin. These mice also showed better insulin sensitivity, meaning their bodies responded better to insulin and could control blood sugar more effectively.

The researchers found that a substance called imidazole propionate (a chemical produced by gut bacteria) was lower in the combination treatment group. Interestingly, the reduction in blood sugar was directly related to the reduction in this bacterial chemical, suggesting this might be part of how the treatment works.

The gut bacteria composition also changed in the combination treatment group. Specifically, the ratio of two major types of bacteria shifted, and a particular bacteria species called Eggerthella lenta became less abundant. This bacterial change appeared connected to the improved blood sugar control.

At the cellular level, the combination treatment activated a protein called AMPK more effectively than metformin alone. AMPK is important for how cells use energy and regulate blood sugar.

The study showed that lutein alone (without metformin) had some beneficial effects on blood sugar, but not as strong as the combination treatment. The changes in gut bacteria composition appeared to be a key mechanism through which the treatment worked. The activation of the AMPK protein pathway was significantly greater in the combination group, suggesting this is an important part of how lutein enhances metformin’s effects.

Previous research has shown that metformin works by changing gut bacteria and affecting how the body uses energy. This study builds on that knowledge by showing that lutein, a nutrient known to have antioxidant properties, may enhance these effects. The finding that gut bacteria changes are involved aligns with growing scientific understanding that our gut microbiome plays an important role in diabetes management.

This study was conducted only in mice, not humans, so results may not translate directly to people. The sample size was small, which is typical for animal studies but limits how confident we can be in the results. The study lasted only 8 weeks, so we don’t know about long-term effects. The mice were given lutein as a supplement, not through food, which may work differently than eating lutein-rich foods. The study didn’t examine potential side effects or optimal dosing. More research in humans is needed before these findings can be applied to diabetes treatment.

The Bottom Line

Based on this animal research, lutein shows promise as a potential supplement to enhance diabetes treatment. However, confidence in this recommendation is LOW because the study was only in mice. People with type 2 diabetes should continue taking their prescribed medications as directed by their doctor. Eating lutein-rich foods like spinach, kale, and broccoli is generally healthy and safe, but should not replace prescribed diabetes medications. Anyone considering lutein supplements should discuss this with their healthcare provider first.

People with type 2 diabetes and their healthcare providers should be aware of this research as it may lead to future treatment options. Researchers studying diabetes and gut health should find this work interesting. People interested in plant-based approaches to health may find this encouraging, but should remember this is early-stage research. People without diabetes do not need to change their habits based on this single animal study.

In the mouse study, improvements appeared within 8 weeks. If similar effects occur in humans, benefits might take several weeks to months to become noticeable. However, human studies would be needed to determine realistic timelines for people. Any changes to diabetes treatment should be gradual and monitored by a healthcare provider.

Want to Apply This Research?

  • Track daily lutein intake (through foods like spinach, kale, broccoli, or supplements if approved by doctor) alongside blood sugar readings to monitor any patterns or correlations over 8-12 weeks
  • Add one lutein-rich vegetable to your daily meals (such as a handful of spinach in breakfast, kale in lunch salad, or broccoli with dinner) while maintaining your current diabetes medication routine
  • Log weekly average blood sugar readings, weekly servings of lutein-rich foods, and any changes in how you feel. Share this data with your healthcare provider at regular check-ups to assess whether dietary changes are having any effect on your diabetes management

This research was conducted in mice and has not been tested in humans. These findings should not be used to change, stop, or replace any diabetes medications or treatments. People with type 2 diabetes should continue following their doctor’s treatment plan. Before adding lutein supplements or making significant dietary changes, consult with your healthcare provider or registered dietitian, especially if you take diabetes medications, as interactions are possible. This article is for educational purposes only and is not medical advice.