The Hidden Link Between Gut Microbiota and Cholesterol: When Your Health Checkup Report Shows Red Flags for LDL

When your health check report shows a red flag for LDL, is your first thought, "I need to eat less oil"?

Diet control is certainly important, but the process of cholesterol metabolism might not just be a matter of "how much you eat." This article, based on two double-blind clinical trials conducted in the UK, will help you understand the connection between gut microbiota and cholesterol metabolism, including specific research figures and the limitations of current evidence. (Related products can be found at the end of the article...)

The enterohepatic circulation of bile acids, and what happens when it's interrupted

The liver converts cholesterol into bile acids, which help digest fats. After use, most bile acids are reabsorbed in the intestines and return to the liver for recirculation – this pathway is called "enterohepatic circulation."

What if this recycling process is interrupted?

Some probiotic strains carry an enzyme called BSH (Bile Salt Hydrolase). Research has observed that BSH can break down the chemical bonds of bile salts, making bile acids less likely to be reabsorbed by the intestines, and thus excreted in feces.

When the liver's cholesterol reserves are reduced as a result, liver cells increase the number of "LDL receptors" on their surface. These receptors then capture LDL cholesterol from the bloodstream to replenish the raw materials needed for synthesizing new bile acids. This is one of the mechanisms currently theorized by research to potentially affect LDL levels.

How this strain was discovered

One of the most thoroughly researched strains is Lactobacillus plantarum (scientific name ECGC 13110402, trade name LPLDL). According to a study published in PLoS ONE in 2017, this strain was selected by a research team from 353 systematically screened Lactobacillus strains, based on in vitro BSH activity, gastric acid resistance, and bile salt resistance, ultimately choosing a dairy isolate.

Two independent double-blind clinical trials conducted in the UK have tested this strain.

6-week short-term trial (2022, Journal of Functional Foods)

This trial, conducted by a team from the University of Reading in the UK, enrolled 16 adults with elevated total cholesterol (TC ≥ 6 mmol/L). Participants were randomly assigned to a supplement group and a placebo group, with daily supplementation of 4×10⁹ CFU capsules. After 6 weeks, compared to the placebo group, the supplement group showed:

• Average total cholesterol decrease of 34.6% (statistically significant, p=0.001)
• Average LDL-C decrease of 28.4% (p=0.001)
• Non-HDL-C decrease of 17.6% (p=0.001)
• ApoB (another lipoprotein indicator related to cardiovascular risk) decrease of 28.6% (p=0.008)

The research team also tracked liver function indicators and vitamin D levels, observing no significant changes during the supplementation period. However, after a 3-week washout period (cessation of supplementation), the inter-group differences in the aforementioned cholesterol indicators disappeared, indicating that the effects were related to continuous supplementation.

12-week longer-term trial (2017, PLoS ONE)

The same PLoS ONE study (which described the strain screening process), conducted by a team from the University of Roehampton in the UK, enrolled 49 adults with normal to mildly hypercholesterolemic levels, followed for 12 weeks with an additional 4-week washout period. The research team analyzed participants stratified by baseline cholesterol concentration, age, and sex, with results showing:

• In the normal baseline total cholesterol group (TC<5mM), LDL-C significantly decreased by 13.9% (p=0.03)
• In the sub-group of subjects over 60 years old, systolic blood pressure decreased by an average of 6.6% (p=0.003)
• Also in the sub-group over 60 years old, HDL (good cholesterol) increased by an average of 14.7% (p=0.007)
• Triglycerides in the over 60 age group also significantly decreased by 53.9% (p=0.002)

It's important to note that the positive changes in blood pressure, HDL, and triglycerides were observed in specific age sub-groups, not consistently across all participants. As these were small sample analyses after stratification, the research team themselves cautioned in the article that the statistical power of these sub-group results is limited, and further validation requires larger, specifically designed studies.

This study also performed fecal microbiota sequencing and metabolome analysis. The results did not observe significant differences in gut microbiota structure between the treatment and placebo groups, suggesting that LPLDL's effects might stem more from "transient metabolic action" rather than long-term colonization altering the gut microbiota itself.

Several points to honestly explain

• The sample sizes of both studies were not large – the 6-week trial had only 16 participants, and the 12-week trial had 49. Both are considered pilot studies, and the results require further validation through larger-scale research.
• The positive changes in blood pressure, HDL, and triglycerides were observed in specific age sub-groups (over 60 years old), which does not mean that all users will experience the same results.
• Probiotics are not medicine, nor are they statins (cholesterol-lowering drugs), and cannot replace cholesterol-lowering treatments prescribed by a doctor.
• If you are already taking cholesterol-lowering medication, please do not adjust your dosage or stop taking it on your own. Any adjustments should be discussed with your doctor.
• These research findings are more suitable as reference information for individuals with mildly elevated LDL who are still in the lifestyle modification stage, to be evaluated in conjunction with diet and exercise, rather than relying solely on them.

European Perspective: Gut Microbiota is a Common Topic in Integrative Medicine

In Taiwan, discussions about cholesterol predominantly focus on diet and medication. However, from a European integrative medicine perspective, adjustments to the gut microbiota are usually discussed as part of overall metabolic health management, rather than just a black-and-white issue of "what to eat and what not to eat." This is why topics like BSH-active strains and bile acid metabolism have gained some traction in the health product markets of the UK and Germany, but are relatively less mentioned in Taiwan.

References

1. Keleszade E, Kolida S, Costabile A. The cholesterol lowering efficacy of Lactobacillus plantarum ECGC 13110402 in hypercholesterolemic adults: a double-blind, randomized, placebo controlled, pilot human intervention study. Journal of Functional Foods. 2022;89:104939. https://doi.org/10.1016/j.jff.2022.104939
2. Costabile A, Buttarazzi I, Kolida S, Quercia S, Baldini J, Swann JR, Brigidi P, Gibson GR. An in vivo assessment of the cholesterol-lowering efficacy of Lactobacillus plantarum ECGC 13110402 in normal to mildly hypercholesterolaemic adults. PLoS ONE. 2017;12(12):e0187964. https://doi.org/10.1371/journal.pone.0187964

Disclaimer: The content of this article is a compilation of health education information, not medical advice, and cannot replace the individual diagnostic and treatment recommendations of a professional physician or nutritionist. If you have any related health concerns, please consult a professional healthcare provider. The research results mentioned in the article are from publicly published academic literature, and individual responses may vary due to physique, diet, and lifestyle.