Probiotics can modestly lower cholesterol, though the effect depends heavily on which strains you take and how long you take them. Meta-analyses of randomized controlled trials show total cholesterol reductions averaging about 13 mg/dL compared to placebo, with certain strains performing significantly better than others. That’s a meaningful but moderate shift, roughly in the range of dietary changes like increasing soluble fiber.
How Gut Bacteria Influence Cholesterol
Probiotics lower cholesterol through two main pathways, both rooted in what specific bacteria do inside your gut.
The first involves bile acids. Your liver uses cholesterol to make bile acids, which it releases into your intestines to help digest fat. Normally, most of those bile acids get reabsorbed and recycled back to the liver. Certain probiotic bacteria, particularly Lactobacillus and Bifidobacterium species, produce an enzyme called bile salt hydrolase that chemically alters bile acids so they can’t be reabsorbed as easily. When that happens, your liver has to pull more cholesterol out of your blood to make fresh bile acids. The net result is less cholesterol circulating in your bloodstream.
The second pathway works through short-chain fatty acids, especially propionate. When probiotic bacteria ferment fiber in your gut, they produce these fatty acids, which travel to the liver and interfere with the same cholesterol-production pathway that statin drugs target. Propionate specifically slows down the rate-limiting step of cholesterol synthesis. Short-chain fatty acids also trigger the release of hormones from cells lining the intestine that play a role in fat metabolism and help clear lipids from the blood.
What the Clinical Evidence Shows
A meta-analysis of randomized controlled trials published in Medicine found that probiotic supplementation significantly reduced total cholesterol compared to placebo, with a pooled reduction of about 13 mg/dL. But the results varied widely depending on the strain used and the duration of treatment.
Lactobacillus plantarum stood out as one of the more effective species. When taken for longer than six weeks, L. plantarum was associated with total cholesterol reductions averaging about 22 mg/dL. At six weeks or less, the effect was minimal. A trial published in the British Journal of Nutrition tested a mixture of three L. plantarum strains in people with high cholesterol and found that those with the highest starting levels saw reductions of roughly 17% in total cholesterol, 17.6% in LDL cholesterol, and 15.6% in oxidized LDL after 12 weeks.
Lactobacillus reuteri NCIMB 30242 is another well-studied strain. In a randomized controlled trial, it reduced LDL cholesterol by 11.64% and total cholesterol by 9.14% compared to placebo. It also lowered a protein called apoB-100 by about 8%, which is a marker of the number of harmful cholesterol particles in your blood.
Combinations of Lactobacillus acidophilus and Bifidobacterium lactis showed more modest effects, with total cholesterol dropping around 8 mg/dL on average. A fermented milk product containing Enterococcus faecium and Streptococcus thermophilus reduced LDL by about 6% over 16 weeks.
How Long Before You See Results
Four weeks appears to be the minimum threshold for any measurable effect. A meta-analysis in PLOS ONE found that probiotic interventions lasting longer than four weeks produced statistically significant reductions in both total and LDL cholesterol, while shorter interventions did not. The average LDL reduction in longer-term studies was about 10 mg/dL.
The strongest results in clinical trials came at the 12-week mark, and the data on L. plantarum suggests the effect continues to build over time. If you’re taking a probiotic specifically for cholesterol, plan on at least two to three months before judging whether it’s working.
Dosage and Strain Selection
Not all probiotics are interchangeable. The cholesterol-lowering effect is strain-specific, meaning even closely related bacteria can perform very differently. The strains with the strongest clinical evidence include L. plantarum (various strains including CECT 7527, 7528, and 7529), L. reuteri NCIMB 30242, and combinations of L. acidophilus with B. lactis.
Effective doses in human trials have ranged widely, from around 50 million CFU per day on the low end to 1 billion CFU per day on the higher end. L. plantarum 299v at roughly 50 million CFU daily was enough to reduce LDL by 12% in one study, while other trials used products delivering hundreds of millions of CFU per gram. There’s no single established dose, but most successful trials used products in the range of 100 million to 1 billion CFU daily. More isn’t necessarily better, as the strain matters more than the raw count.
Taking Probiotics With Statins
If you’re already on a statin, probiotics appear to be safe to take alongside the medication. A randomized, double-blind clinical trial tested a combination of probiotics (containing L. casei, B. lactis, and L. plantarum strains) with 20 mg of atorvastatin against atorvastatin plus placebo. The combination was well-tolerated, and the researchers recommended using probiotics alongside statins for treating high cholesterol. However, the trial did not find a statistically significant additional benefit from the probiotic beyond what the statin achieved on its own, suggesting probiotics don’t meaningfully amplify statin effects in most people already taking them.
Realistic Expectations
Probiotics are not a replacement for statins or other lipid-lowering medications. The best probiotic results, around a 10 to 17% reduction in LDL, are comparable to what you might achieve through aggressive dietary changes like adopting a portfolio diet rich in plant sterols, soluble fiber, and nuts. For someone with mildly elevated cholesterol who isn’t yet at the threshold for medication, the right probiotic strain could be a reasonable addition to diet and exercise changes.
For people with significantly elevated cholesterol or existing cardiovascular disease, the effect size of probiotics alone is too small to serve as a primary treatment. Where they may add value is as one component of a broader lifestyle approach, stacked alongside dietary changes, exercise, and weight management. Major cardiovascular guidelines from organizations like the American Heart Association classify probiotics as complementary products rather than recommended therapies for cholesterol management, and no official lipid guidelines currently include probiotics as a standard intervention.
The people most likely to see a noticeable benefit are those with higher baseline cholesterol levels. In the L. plantarum trial, participants who started with total cholesterol above 251 mg/dL saw the largest reductions, while those with lower starting levels saw smaller changes. If your cholesterol is only mildly elevated, the effect may be too small to detect on a standard blood test.