Probiotics, which are live microorganisms, can provide health benefits when consumed in sufficient quantities. Known for supporting gut health, research explores their role in systemic health, including cardiovascular well-being and cholesterol levels. The gut microbiome, a community of microorganisms, influences host metabolism and can be affected by beneficial bacteria like Lactobacillus and Bifidobacterium.
The Role of the Gut Microbiome in Cholesterol Regulation
Cholesterol balance involves synthesis in the liver, absorption in the intestines, and excretion. The gut microbiota can influence this process. When probiotics, especially Lactobacillus and Bifidobacterium, colonize the intestines, they can influence the body's lipid profile. The mechanisms are complex and can vary depending on the strain.
Mechanisms Responsible for Cholesterol-Lowering Effects
- Bile Salt Hydrolase (BSH) Activity: The liver creates bile acids from cholesterol, stored in the gallbladder, and released into the small intestine to aid fat digestion. The body usually recycles these bile acids. Some probiotic strains have the BSH enzyme, which deconjugates bile acids in the gut. Deconjugated bile acids are less soluble and are excreted. The liver uses more cholesterol to synthesize new bile acids to compensate, lowering serum cholesterol.
- Cholesterol Assimilation and Binding: Some probiotic bacteria can assimilate cholesterol, incorporating it into their cellular membranes. Both live and heat-killed probiotic cells can bind to cholesterol in the intestinal lumen. This binding prevents cholesterol absorption, increasing excretion via feces.
- Production of Short-Chain Fatty Acids (SCFAs): Gut microbes, including probiotics, produce SCFAs by fermenting indigestible carbohydrates. These SCFAs can go to the liver, where they can inhibit the enzyme HMG-CoA reductase, which is involved in cholesterol synthesis. This results in less liver cholesterol production.
- Modulation of Intestinal Transporters: Some probiotics can down-regulate the intestinal cholesterol transporter Niemann-Pick C1-Like 1 (NPC1L1), which absorbs dietary cholesterol. By inhibiting this transporter, probiotics can reduce cholesterol entering the bloodstream.
Effective Probiotic Strains and Research Findings
Studies have investigated the cholesterol-lowering potential of probiotic strains, with meta-analyses confirming reductions in total cholesterol (TC) and LDL-C. Some strains and findings include:
- Lactobacillus plantarum: Several strains have shown efficacy. A 2013 study found that three specific L. plantarum strains (CECT 7527, 7528, and 7529) significantly reduced TC and LDL-C in hypercholesterolemic adults over 12 weeks. Another study highlighted L. plantarum ECGC13110402, which significantly reduced TC and LDL-C in dyslipidemic individuals.
- Lactobacillus reuteri: The strain L. reuteri NCIMB 30242 has demonstrated effectiveness in lowering LDL-C and TC. It has high bile salt hydrolase activity, which is key for its cholesterol-lowering effect.
- Bifidobacterium lactis: Often used with Lactobacillus species, B. lactis strains like Bb12 have shown benefits in some studies, particularly in lowering LDL-C and improving the LDL-C/HDL-C ratio. Multi-strain supplements containing Bifidobacterium tend to show stronger results.
Factors Influencing Probiotic Effectiveness
- Dosage: The number of viable bacteria, measured in Colony-Forming Units (CFU), is a critical factor. Studies have shown that dosages exceeding 10⁹ CFU/day are often more effective in reducing LDL-C. A higher dose can maximize colonization and benefits.
- Duration: The length of intervention is also important. Meta-analyses indicate that longer treatment durations (typically >6-8 weeks) lead to more pronounced reductions in TC and LDL-C.
- Baseline Health Status: Probiotics appear to have a more significant effect in individuals with higher baseline cholesterol levels. For instance, reductions in TC were more pronounced in patients with baseline TC levels above 5.7 mmol/L.
Comparison: Probiotics vs. Statins
Both probiotics and statins can lower cholesterol through different mechanisms. The following table highlights key differences:
| Feature | Probiotics | Statins (e.g., Atorvastatin) |
|---|---|---|
| Mechanism | Multi-faceted: Bile acid deconjugation, cholesterol assimilation, SCFA production, intestinal transporter regulation. | Primary: Inhibit HMG-CoA reductase, the rate-limiting enzyme in hepatic cholesterol synthesis. |
| Effectiveness | Modest and highly strain-specific. More effective with higher baseline levels. | High effectiveness in reducing LDL-C. Considered the gold standard for high-risk patients. |
| Side Effects | Generally safe for healthy individuals; minor side effects like gas and bloating can occur. Serious risks are rare and typically limited to immunocompromised individuals. | Can cause significant side effects, including muscle pain, digestive issues, and liver dysfunction in some patients. |
| Application | Non-pharmacological, used as a supplement or functional food for primary prevention and management. | Pharmacological intervention for managing high cholesterol and reducing cardiovascular risk. |
| Cost | Varies widely by brand, strain, and dosage. | Varies by drug and insurance coverage. |
Beyond Probiotics: A Holistic Approach
Managing cholesterol effectively requires a broader approach with diet, exercise, and lifestyle choices. Many natural strategies can complement probiotic supplementation:
- Soluble Fiber Intake: Foods rich in soluble fiber, such as oats, barley, beans, and certain fruits (apples, citrus), can bind to cholesterol in the digestive tract, preventing its absorption.
- Healthy Fats: Replacing saturated and trans fats with healthier monounsaturated and polyunsaturated fats (found in avocados, nuts, seeds, and olive oil) can help lower LDL-C levels.
- Plant Sterols and Stanols: These naturally occurring compounds, found in many plants, nuts, and legumes, and also added to fortified foods like margarines and orange juice, can block cholesterol absorption.
- Regular Physical Activity: Aerobic exercise, such as walking, swimming, or cycling, helps to raise HDL ('good') cholesterol and improve overall cardiovascular health.
- Omega-3 Fatty Acids: Found in oily fish like salmon and mackerel, omega-3s can help reduce triglyceride levels and support heart health.
Risks and Considerations
Probiotics are generally safe for healthy individuals. The most common side effects are mild digestive symptoms like gas and bloating. However, caution is advised for high-risk groups, including those who are severely ill, immunocompromised, have had recent surgery, or have central venous catheters. There is a rare, increased risk of systemic infection in these cases. The quality and labeling of probiotic products can vary, and not all commercial products contain the viable, effective strains listed. Consult a healthcare provider before starting a new supplement regimen, especially if you have pre-existing health conditions.
Conclusion
The gut microbiome plays a role in cholesterol metabolism, and specific probiotic strains have shown promise in managing cholesterol levels. The mechanisms behind this effect, including bile acid regulation and cholesterol assimilation, are well-documented. Their impact is typically modest, strain-specific, and depends on factors like dosage and duration. Probiotics offer a valuable and safe option for cholesterol management, but they are not a replacement for statins in high-risk individuals. The most effective strategy involves a comprehensive approach, combining probiotic supplementation with a heart-healthy diet, regular exercise, and medical guidance.
MedlinePlus, "How to lower cholesterol with diet," National Library of Medicine
