Researchers tested a traditional Japanese herbal medicine called Ninjin’yoeito on aging mice to see if it could help with dry mouth—a common problem in older people. After four months of treatment, mice taking the herb produced significantly more saliva and showed signs of better overall health, including reduced inflammation and improved nutrition. The herb appeared to work by boosting the immune system and reducing aging-related damage to cells, rather than by changing how the mouth’s water channels work. While these results are promising, this research was done in mice, so scientists will need to test it in humans before recommending it as a treatment.

The Quick Take

  • What they studied: Whether a traditional Japanese herbal medicine could help restore saliva production in older individuals experiencing dry mouth
  • Who participated: Male laboratory mice bred to age quickly (called SAMP1 mice), which naturally develop dry mouth as they get older. The mice were divided into two groups: one eating normal food and one eating food mixed with 3% of the herbal extract for four months
  • Key finding: Mice treated with the herb produced significantly more saliva when their salivary glands were stimulated, and their glands showed less cellular damage compared to untreated mice. The treated mice also had better nutrition levels, stronger immune function, and lower inflammation markers
  • What it means for you: This research suggests that Ninjin’yoeito may help with age-related dry mouth by improving overall body health rather than just fixing the mouth itself. However, since this was tested only in mice, people should not start using this herb without talking to their doctor first. More human studies are needed before it can be recommended as a treatment

The Research Details

Scientists used specially bred mice that naturally develop aging-related problems, including dry mouth, much faster than regular mice. They divided these mice into two groups: one group ate regular food while the other group ate the same food but with 3% of Ninjin’yoeito (a traditional Japanese herbal medicine) mixed in. This continued for four months. After the treatment period, researchers tested how much saliva the mice could produce when their salivary glands were stimulated, similar to how a doctor might test human saliva production.

The researchers didn’t just measure saliva—they also looked at the actual structure of the salivary glands under a microscope to see if the herb changed how the glands looked. They took blood samples to check nutrition levels and immune cell counts. They also used advanced genetic testing to measure which genes were turned on or off in the salivary glands, specifically looking at genes related to inflammation and aging.

This type of study is called a controlled experiment because it compares two similar groups that receive different treatments, allowing researchers to see what effect the herb actually had.

Using mice that age quickly allowed researchers to study a problem that normally takes decades to develop in humans. This approach lets scientists test whether a treatment might work before spending years and money on human studies. The combination of measuring saliva production, looking at gland structure, checking blood health, and analyzing genes gave researchers multiple ways to understand how the herb worked, making the results more reliable and complete

This study was published in a peer-reviewed scientific journal, meaning other experts reviewed it before publication. The researchers used multiple methods to measure their results (saliva tests, microscopy, blood work, and genetic analysis), which strengthens their findings. However, the study was conducted only in mice, not humans, so results may not directly apply to people. The sample size of mice was not specified in the abstract, which makes it harder to judge how reliable the results are. Additionally, this is a single study, so the findings would be stronger if other research groups could repeat and confirm these results

What the Results Show

The main finding was that mice receiving the herbal treatment produced significantly more saliva when their glands were stimulated compared to mice eating regular food. This is important because the ability to produce saliva is the core problem in dry mouth.

When researchers looked at the salivary glands under a microscope, they found that treated mice had fewer vacuoles (empty spaces or damage) in their acinar cells—the cells responsible for making saliva. This suggests the herb helped protect these cells from age-related damage.

Blood tests showed that mice receiving the herb had better nutrition, with higher albumin levels (a protein that indicates good nutritional status) and a healthier balance of immune cells. This suggests the herb improved overall body health, not just mouth health.

Genetic testing revealed that the herb reduced the activity of genes related to inflammation and cellular aging. In other words, the herb appeared to calm down the body’s inflammatory responses and slow down aging-related changes at the cellular level.

Interestingly, the herb did not change how two important water-channel proteins worked in the salivary glands (transmembrane protein 16A and aquaporin 5). These proteins are responsible for moving water into saliva. This finding suggests the herb improved saliva production through a different mechanism—by improving overall health and reducing inflammation—rather than by directly fixing these water channels

Dry mouth in older adults is a well-known problem caused by aging, inflammation, and sometimes medications. Previous research has shown that reducing inflammation and improving immune function can help with age-related health problems. This study supports that idea by showing that an herb that reduces inflammation and boosts immunity also helps restore saliva production. The finding that the herb works through general health improvement rather than targeting specific mouth proteins is consistent with how traditional herbal medicines are thought to work

The biggest limitation is that this research was done in mice, not humans. Mice age differently than people, and results in mice don’t always translate to humans. The abstract doesn’t specify how many mice were used in each group, making it difficult to assess whether the sample size was large enough to draw solid conclusions. The study lasted four months in mice, which is a reasonable timeframe for mouse studies but doesn’t tell us how long humans would need to take the herb to see benefits. The study doesn’t compare this herb to other treatments for dry mouth, so we don’t know if it’s better or worse than existing options. Finally, this appears to be a single study, and scientific findings are more trustworthy when multiple independent research groups confirm the same results

The Bottom Line

Based on this research alone, Ninjin’yoeito cannot be recommended as a treatment for dry mouth in humans. The evidence is promising but preliminary—it comes from mouse studies only. Anyone experiencing dry mouth should talk to their doctor about proven treatments first, such as staying hydrated, using saliva substitutes, or addressing underlying causes. If someone is interested in trying traditional herbal medicines, they should discuss this with their healthcare provider to ensure it won’t interfere with other medications or conditions. Future human studies would be needed to determine safe and effective doses, potential side effects, and how well it actually works in people

This research is most relevant to older adults experiencing age-related dry mouth, as well as researchers studying traditional medicines and aging. Healthcare providers who treat dry mouth should be aware of this emerging research. People interested in complementary and alternative medicine may find this interesting, but they should not use it as a reason to self-treat without medical guidance. This research is less relevant to younger people or those without dry mouth problems

In the mouse study, benefits appeared after four months of continuous treatment. If this herb were to be tested in humans, it would likely take several months to see noticeable improvements. However, this is speculative—human studies would need to be conducted to determine realistic timelines. People should not expect immediate results if they were to try this herb

Want to Apply This Research?

  • Users could track saliva production by noting daily dry mouth symptoms (using a 1-10 scale), frequency of needing water or saliva substitutes, and any changes in mouth comfort during eating or speaking. This would provide measurable data to discuss with healthcare providers
  • If a user’s doctor approves trying this herb, the app could help them remember to take it consistently (since the mouse study showed benefits after four months of continuous use) and track any changes in dry mouth symptoms over time. The app could also remind them to stay hydrated and maintain good oral hygiene
  • Long-term tracking would involve monthly check-ins on dry mouth severity, changes in saliva production, and any side effects. Users could photograph or describe changes in mouth comfort, eating ability, and overall quality of life. This data would be valuable to share with healthcare providers to assess whether the treatment is working

This research was conducted in laboratory mice, not humans. The findings are preliminary and should not be used as a basis for self-treatment. Dry mouth can have multiple causes, some of which require medical attention. Anyone experiencing persistent dry mouth should consult with a healthcare provider for proper diagnosis and treatment recommendations. Before using any herbal supplement, including Ninjin’yoeito, discuss it with your doctor or pharmacist, as it may interact with medications or underlying health conditions. This article is for educational purposes only and does not constitute medical advice.