Scientists tested whether adding selenium (a nutrient your body needs) to probiotic bacteria would help them grow better and absorb more of this mineral. They studied two types of helpful bacteria called Lactiplantibacillus plantarum and tested them with different amounts of selenium. The results showed that a little bit of selenium helped the bacteria grow, but too much actually slowed them down. One type of bacteria was better at quickly grabbing selenium, while the other type could store more selenium over time. This research could help create better probiotic supplements that contain extra selenium for your health.

The Quick Take

  • What they studied: Whether adding selenium to probiotic bacteria would help them grow better and absorb more selenium, which could make probiotic supplements more nutritious.
  • Who participated: Laboratory experiments with two strains of beneficial bacteria (Lactiplantibacillus plantarum DSM24730 and 299v) grown in controlled conditions with varying amounts of selenium.
  • Key finding: Moderate amounts of selenium (5-10 mg per liter) helped both bacteria grow, but high amounts (50-100 mg per liter) actually slowed their growth. The 299v strain grabbed selenium quickly and made more bacteria, while DSM24730 stored more selenium overall after longer growth periods.
  • What it means for you: This research suggests that probiotic supplements could potentially be made with added selenium, but the amount matters—too much selenium could actually harm the beneficial bacteria. More research is needed before this becomes a real product you can buy.

The Research Details

Scientists grew two types of probiotic bacteria in laboratory dishes with different amounts of selenium added to their food (from zero to 100 mg per liter). They measured how much bacteria grew, how fast it grew, and how much selenium the bacteria absorbed. They also tested whether the bacteria could survive in liquids that mimicked stomach acid and intestinal fluids, since probiotics need to survive these harsh conditions to help your body.

The researchers tracked several measurements in real-time, including how much total bacteria was produced, the growth patterns over time, and the bacteria’s ability to handle stressful conditions similar to what happens in your digestive system. This allowed them to see exactly how selenium affected the bacteria at different stages of growth.

This type of laboratory study is important because it helps scientists understand how nutrients interact with beneficial bacteria before testing them in people. It’s like testing a recipe in a small batch before making it for a big party.

Understanding how selenium affects probiotic bacteria is important because probiotics are increasingly used to support digestive health. If scientists can create probiotics that contain extra selenium, it could provide additional health benefits since selenium is an important nutrient that helps protect your cells. However, they first need to make sure the selenium doesn’t harm the bacteria or make them unable to survive in your stomach and intestines.

This study was conducted in controlled laboratory conditions, which is good for understanding basic interactions but doesn’t tell us what happens in real human bodies. The researchers used standard scientific methods to measure bacterial growth and selenium content. However, the study doesn’t include human participants, so we can’t yet say whether selenium-enriched probiotics would actually help people. The findings are preliminary and would need to be tested in people before any new products could be recommended.

What the Results Show

When scientists added moderate amounts of selenium (5-10 mg per liter), both types of bacteria grew well and produced healthy amounts of biomass. However, when they added high amounts of selenium (50-100 mg per liter), the bacteria grew much more slowly. The DSM24730 strain was particularly affected by high selenium levels—its growth was delayed by up to 12 hours at the highest concentration.

The two bacterial strains showed different strengths. The 299v strain was faster at absorbing selenium and produced more total bacteria quickly. After 24 hours, it accumulated 0.45 mg of selenium per gram of bacteria. The DSM24730 strain was slower at first but accumulated more selenium overall (0.29 mg per gram) when given more time to grow.

When the bacteria were exposed to simulated stomach acid, both strains survived well. However, when exposed to simulated intestinal fluid with high selenium levels (10 mg per liter or more), the bacteria’s survival dropped significantly. This suggests that too much selenium could prevent the probiotics from reaching your intestines where they’re supposed to help.

The research revealed important differences in how the two strains responded to selenium stress. The 299v strain showed more consistent growth across different selenium levels, suggesting it might be more stable for creating supplements. The DSM24730 strain’s growth was more disrupted at high selenium levels, but it had the advantage of accumulating more selenium over time, which could be useful if you wanted a supplement with very high selenium content. Both strains showed that selenium concentration affects not just how much bacteria grows, but also when the bacteria enters its main growth phase and how long that phase lasts.

These findings align with other research on selenium-enriched probiotics, confirming that different bacterial strains respond differently to added selenium. The study supports the general principle that ‘more is not always better’—moderate amounts of nutrients typically support bacterial growth better than excessive amounts. This matches what scientists have observed with other nutrients and probiotics.

This study was conducted entirely in laboratory dishes, not in human bodies, so the results may not directly apply to how these bacteria would work as supplements in real people. The study didn’t test very long-term effects or what happens when these bacteria interact with other bacteria in your gut. Additionally, the exact amounts of selenium used in the lab (up to 100 mg per liter) may not reflect realistic supplement doses. The researchers also didn’t test whether the selenium actually stays in the bacteria when it’s processed into a supplement or whether it would be absorbed by your body if you took such a supplement.

The Bottom Line

Based on this research, it appears that probiotic supplements containing added selenium could potentially be developed, but the selenium amount would need to be carefully controlled—probably in the 5-10 mg per liter range based on these findings. However, this is preliminary laboratory research, and human studies would be needed before any such supplements could be recommended. If you’re interested in selenium, it’s better to get it from food sources like Brazil nuts, fish, and eggs, or take a supplement specifically designed for selenium rather than waiting for selenium-enriched probiotics to become available. Confidence level: Low to Moderate—this is early-stage research.

This research is most relevant to supplement manufacturers and scientists developing new probiotic products. If you have digestive issues and take probiotics, this research suggests that adding too much selenium to probiotics might actually harm them, so you shouldn’t try to add extra selenium to your probiotic supplements on your own. People who are interested in both probiotics and selenium nutrition may find this research interesting, but it’s not yet ready to change what anyone should actually do.

This is laboratory research, so there’s no timeline for personal benefits yet. If companies do develop selenium-enriched probiotics based on this research, it would likely take several years of human testing before they could be sold. Even then, any benefits would likely take weeks to months to notice, similar to regular probiotics.

Want to Apply This Research?

  • Track your current selenium intake from food sources (Brazil nuts, fish, eggs, whole grains) and your probiotic supplement use separately. Note the type and brand of probiotic you take and any digestive changes you notice. This baseline data will be useful if selenium-enriched probiotics become available in the future.
  • If you’re interested in both probiotics and selenium, focus on getting selenium from whole food sources first (a few Brazil nuts daily provides adequate selenium) while taking a standard probiotic supplement. Don’t attempt to add selenium supplements to your probiotic products, as this research suggests that high selenium levels could reduce probiotic effectiveness.
  • Keep a simple log of your probiotic use and any digestive symptoms you notice. If selenium-enriched probiotics become commercially available in the future, you could compare your digestive health before and after switching to them, tracking factors like bloating, regularity, and overall digestive comfort over 4-8 weeks.

This research is preliminary laboratory work and has not been tested in humans. The findings do not yet support any changes to current probiotic or selenium supplement recommendations. Selenium-enriched probiotics are not currently available as commercial products. If you have questions about probiotics or selenium supplementation, especially if you have existing health conditions or take medications, please consult with your healthcare provider before making any changes. This article is for educational purposes only and should not be considered medical advice.