Researchers wanted to know if taking special bacteria supplements (probiotics) before weight loss surgery could help reduce inflammation and improve health markers afterward. They gave 110 people either probiotics or a placebo pill for 12 weeks before surgery, then checked their blood and health markers six months later. The probiotic group had lower levels of one inflammation marker (IL-6), but most other health measures were similar between groups. While the results suggest probiotics might help with inflammation, the effect was modest, and the study was too small to draw firm conclusions.

The Quick Take

  • What they studied: Whether taking probiotic supplements before weight loss surgery could reduce inflammation and improve health markers in the months after surgery.
  • Who participated: 110 people scheduled for weight loss surgery (either sleeve gastrectomy or gastric bypass). Only 42 people’s blood samples were fully analyzed (18 in the probiotic group, 24 in the placebo group).
  • Key finding: People who took probiotics had lower levels of IL-6 (an inflammation marker) six months after surgery compared to those who took placebo. However, most other health markers showed no difference between the groups.
  • What it means for you: Probiotics may help slightly reduce one type of inflammation after weight loss surgery, but the benefit appears modest. This is early-stage research, so don’t expect probiotics to be a game-changer for weight loss surgery recovery. Talk to your doctor before taking probiotics, especially if you’re planning surgery.

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of medical research. Participants were randomly assigned to receive either a probiotic mixture containing nine different beneficial bacteria strains or a placebo (fake pill) for 12 weeks before their weight loss surgery. Neither the participants nor the researchers knew who received which treatment until the study ended—this is called “double-blind” and helps prevent bias. The researchers measured various inflammation markers and other health indicators in blood samples taken before surgery and six months after surgery.

The double-blind, randomized design is important because it helps ensure that any differences between groups are due to the probiotics themselves, not expectations or other factors. By measuring multiple health markers, researchers could see if probiotics affected different aspects of inflammation and metabolism.

This study has some important limitations to consider: only 42 out of 110 participants had complete blood samples analyzed (38% completion rate), which is quite low and could affect the reliability of results. The small final sample size means the study may have missed real effects that exist. The study was well-designed with proper randomization and blinding, which are strengths. However, the high dropout rate and small final sample size mean results should be interpreted cautiously.

What the Results Show

The main finding was that people in the probiotic group had significantly lower IL-6 levels (an inflammation marker) six months after surgery compared to the placebo group. IL-6 is a chemical messenger in the body that signals inflammation. However, the researchers noted that the improvement in IL-6 from before to after surgery was similar in both groups—the difference only appeared when looking at the final measurements. This suggests the effect may be less clear-cut than it initially appears.

Both groups showed significant reductions in LPS (a bacterial toxin that triggers inflammation) after surgery, but there was no difference between the probiotic and placebo groups. This suggests that the surgery itself, rather than the probiotics, was responsible for this improvement.

Adipokines are hormones related to fat and metabolism. Adiponectin (a beneficial hormone) increased significantly in the placebo group but not the probiotic group. Leptin (a hormone that signals fullness) decreased in both groups equally. These unexpected results suggest probiotics may not provide additional metabolic benefits beyond what surgery alone provides.

Other inflammation markers (IL-2R and C-reactive protein) showed no significant differences between groups. Gastrointestinal peptides like GLP-1 (which helps regulate blood sugar) improved in both groups without differences between them. Gene expression for ghrelin (hunger hormone) and trefoil factor 2 (gut protection protein) showed no changes in either group at the genetic level.

Previous research suggested that disrupted gut bacteria contribute to obesity-related inflammation. This study’s finding that probiotics may reduce one inflammation marker (IL-6) aligns with this theory, but the modest effect and lack of impact on other markers suggest the relationship is more complex than initially thought. The fact that surgery itself produced major improvements in most markers suggests the surgical intervention is more powerful than probiotic supplementation.

The biggest limitation is that only 38% of participants had complete data analyzed (42 out of 110), which significantly reduces confidence in the results. The small final sample size means the study had low statistical power—it may have missed real but subtle effects. The study only followed participants for six months, so long-term effects are unknown. The probiotic mixture tested may not be representative of all probiotics. Finally, the researchers noted that the between-group difference in IL-6 improvement from baseline was not statistically significant, meaning the observed effect could partially be due to chance.

The Bottom Line

Based on this research, probiotics may provide a modest reduction in one inflammation marker after weight loss surgery, but the evidence is weak (low confidence level). Taking probiotics before weight loss surgery is unlikely to cause harm, but don’t expect major benefits. If you’re considering probiotics, discuss it with your surgeon or doctor first, as they can advise based on your specific situation. This is preliminary research, and more studies are needed before making strong recommendations.

People planning weight loss surgery might be interested in this research, as might their doctors. However, the weak evidence means this shouldn’t influence surgery decisions. People with certain digestive conditions, compromised immune systems, or those taking specific medications should consult their doctor before taking probiotics, as they may not be appropriate for everyone.

If probiotics do help, based on this study, benefits would appear over several months (this study measured at six months post-surgery). Don’t expect immediate improvements. Most of the health improvements in this study came from the surgery itself, which typically shows major benefits within the first few months.

Want to Apply This Research?

  • If using an app to track health after weight loss surgery, monitor inflammation markers like C-reactive protein (CRP) if your doctor orders blood work. Track this every 3-6 months post-surgery to see your overall inflammation trends, regardless of whether you take probiotics.
  • Users could use a health app to set a reminder to take probiotics consistently if their doctor recommends them (typically daily). However, focus the app’s primary tracking on post-surgery milestones like weight loss, energy levels, and how you feel—these are more likely to show meaningful changes than inflammation markers.
  • Create a long-term tracking system that monitors overall wellness after surgery rather than focusing solely on probiotics. Track weight, energy levels, digestion comfort, and any inflammation symptoms you notice. Share this data with your healthcare provider at follow-up appointments to assess whether probiotics are helping your individual situation.

This research is preliminary and should not replace medical advice from your doctor or surgeon. The study had a small final sample size and modest effects, so results should be interpreted cautiously. If you are considering weight loss surgery or probiotic supplementation, consult with your healthcare provider about whether probiotics are appropriate for your individual situation. Do not start, stop, or change any medications or supplements without medical guidance. This summary is for educational purposes only and does not constitute medical advice.