An abnormal blood lipid profile is one crucial target in the risk-reduction, prevention and treatment of cardiovascular disease, the number one cause of death worldwide. Hypercholesterolemia, hypertriglyceridemia, increased low-density lipoproteins (LDL), and reductions in the levels of high-density lipoproteins (HDL) may respond well to medications, exercise and diet. Functional foods enriched with bioactive components such as fish oils, fibers, phytosterols are also effective risk-reduction interventions. Now researchers are looking more closely at a role for probiotics.
Lipid profile and microbiota
In the past several decades, research has revealed that the intestinal microbiota (IM) looks different in subjects with abnormal lipid profiles. For example, in referencing just one part of the profile, people with hypercholesterolemia have lower bacterial diversity in their IM when compared with normocholesterolemic control subjects. Also, the microorganisms that are present are different, which suggests that IM possibly play a role in development of hypercholesterolemia.
Thus, manipulating gut microbes with e.g. probiotics may potentially change certain risk factors for cardiovascular disease.
A 2019 systematic review published in Journal Vascular Brasileiro looked at the effects of probiotic supplementation on the prevention and treatment of changes to the lipid profile.
Fourteen clinical trials published from 2013 to 2018 were included in the analysis. An excellent summary is presented in this table from the review.
- Supplementation with specific probiotic strains significantly reduced total cholesterol, LDL-c, and triglycerides and increased HDL-c.
- Most often given strains were belonging to Lactobacillus (11 studies) and Bifidobacterium genera (six studies.) Other strains of probiotics used belonged to Saccharomyces, Streptococcus, and Enterococcus genera (1study each.) Note that about half of these studies used probiotic combinations of various species and strains.
- The estimated time needed to observe more definite results using probiotics in isolation appears to be 6 weeks.
- Reported dosages varied from 109 to 112 × 109 CFU/day. After 6 weeks, the largest dose demonstrated several beneficial effects and no adverse clinical effects, which may suggest that larger doses are safe.
- The effects of probiotics show that they are strain-dependent.
A few potential mechanisms for probiotic action
- Deconjugation of bile salts: When bile acids are deconjugated, they are less well reabsorbed from the small intestine, enter the colon and are excreted with the feces. The liver is therefore forced to make more bile acids, thus removing cholesterol from the blood. Deconjugated bile acids coprecipitate with dietary cholesterol, leading to lower absorption and increased excretion of cholesterol and cholesterol based components such as bile acids.
- Incorporation of cholesterol in the cell membrane of new microorganisms
- Specific probiotic organisms feed on prebiotic fibers, producing short chain fatty acids (SCFA) such as butyrate and propionate, both of which may inhibit liver cholesterol synthesis. Propionate may also inhibit the synthesis of fatty acids in the liver, thereby lowering the rates of triacylglycerol secretion.
There are in fact numerous proposed mechanisms, some of which are poorly understood.
Thus, further studies are required to examine the possible mechanisms, whereby probiotics can be utilized safely and considered for the treatment of dyslipidemia.
A chief conclusion from the review highlighted above:
Supplementation with probiotics may help improve blood lipid profiles.
Other cardiovascular disease risk factors were also impacted positively by probiotics in this review: inflammatory profile, glycemic control, body mass, and immunological markers.
Another recent meta-analysis supports the positive impact of probiotics on lipid profiles in overweight subjects. Yet further studies may clarify which probiotics are optimal as well as the influence of probiotics in combination with drug therapy.