Background
Cardiovascular disease (CVD) performs the number one cause of death worldwide and continues to be a major economic and health burden globally [
1]. Atherosclerosis is the pathophysiological process underlying CVD. The signals starting the diseases are not ultimately understood and a role of an unbalanced intestinal microbiota in atherosclerosis pathogenesis is discussed [
2]. Among the risk factors of CVD hypercholesterolemia and an elevated level of blood triglycerides (TG) are generally accepted. An elevated level of low-density lipoprotein (LDL) is a major measurable risk factor for CVD thus blood lipid lowering strategy has been a primary target for both in primary and secondary cardiovascular disease prevention to date [
3]. The role of an elevated level of oxidized LDL (oxLDL) in the pathogenesis of atherosclerosis is also stressed [
4] thus all mechanisms leading to extensive oxidation of the LDL particles are unfavorable from the point of view of CVD.
Inflammation and non-specific haemoglobin (Hb) glycation are important pathogenetic factors of CVD and diabetes. Abnormal Hb glycation (an elevated HbA1c%) is linked to the pathophysiology of type 2 diabetes mellitus (T2DM) effect on CVD. A permanent low-grade (or high-normal) inflammation (LGI) and an advanced glycation both can enhance the development of CVD as demonstrated in the ATTICA study that supported a positive association between LGI and diabetes [
5]. LGI occurs typically in the vasculature and adipose tissue of a subject and is chronic in its nature. The parameter universally accepted to measure LGI is hsCRP [
6]. It has been shown that triglyceride/HDL-cholesterol ratio can be used as a marker of insulin resistance (a prediabetes/ diabetes related marker) [
7].
Although the study presented here is the first with RegActive Cholesterol formula, the probiotic strain L.
fermentum ME-3 has been extensively tested both in humans and animals.
Lactobacillus fermentum ME-3 (DSM 14241) (LFME-3) is a strain of human origin isolated from a healthy child [
8]. The strain has both antimicrobial and antioxidative functional properties including the complete glutathione system [
9‐
11]. Several benefits for health of fermented products containing LFME-3 have been demonstrated in various clinical studies including a favorable impact on postprandial lipemia and oxidative stress status [
12‐
15]. Reg’Activ Cholesterol™ (VF Bioscience) has been formulated for promoting cardiovascular health. This innovative formulation combines LFME3 with others functional ingredients that are listed and described in the Materials section.
The aim of the study was to establish if a special formulation of Reg’Activ Cholesterol (RAC) comprising also LFME3 has a positive influence to the human body cardiovascular, inflammatory and diabetic parameters LDL cholesterol, TG, oxLDL, hsCRV, IL-6 and glycated haemoglobin (HbA1c%).
Discussion
The limitations of our study design are mainly attributable to the lack of using a standardized diet prior and during the intervention. By using quite strict exclusion criteria we tried to minimize the influence of diet.
The elevated LDL cholesterol and blood triglyceride levels are well accepted risk factors of CVD [
3]. Inflammation and elevation of HbA1c% are related to pathogenesis of both CVD and diabetes [
5]. An elevated level of oxLDL has a role in the pathogenesis of atherosclerosis [
4]. Thus additional good tools to control blood lipoprotein, oxidative stress and inflammatory profile are needed. This study investigated a special formulation of food supplement RAC and established positive effects on blood lipid profile, oxidized LDL level, inflammatory signature, HbA1c% and TG/HDL cholesterol ratio.
The creation of an innovative formulation RAC with different bioactive components was based on the previously obtained scientific information.
Gut microbiota forms an essential part of the complex ecosystem of the host that is involved in nutrition and health. A wide variety of host, microbiological, dietary and environmental factors affect the metabolic interrelations between gut mucosal epithelial cells and microbiota [
22‐
25]. Organisms obtain a portion of cholesterol through nutrition and the major part is produced by highly-regulated biosynthesis in human body while dominating amount of cholesterol is eliminated from the organism as bile acids [
26]. Among normal microbiota of gastrointestinal tract some species and strains of lactic acid bacteria are able to assimilate cholesterol from provided dietary products [
27]. A meta-analysis of 13 probiotic studies indicates that a diet rich in probiotics decreases total cholesterol and LDL cholesterol concentration in plasma for participants with high, borderline high and normal cholesterol levels [
28]. However, its relation to temporal colonization of digestive tract by probiotic strains and the duration of treatment remains to be evaluated.
Earlier studies have shown that the impact of probiotics on lipid metabolism markers of the host can be quite strain and host specific [
29,
30]. The anti-oxidative and anti-atherogenic effect of LFME3 has been described previously in numerous in vitro and human trials with different dairy products such as goat milk, cheese and yoghurt [
9,
12,
13,
15].
Insulin resistance is associated with cardiovascular disease pathogenesis. The evidence is piling up that he TG/HDL ratio can be used as a parameter to evaluate insulin resistance [
7,
31‐
33]. After consumption of RAC capsules the TG/HDL cholesterol ratio decreased significantly.
Our previous data from 8 weeks versus data from 4 weeks showed that consumption of LFME3 enriched kefir, but not the placebo kefir, significantly decreased the level of LDL cholesterol [
34]. Next, only the probiotic kefir in 8 weeks decreased significantly the ratio of TG/HDL cholesterol.
Thus, these data together show that compositions comprising LFME-3 help to prevent risk, alleviate the symptoms and treat metabolic syndrome related conditions (prediabetes, diabetes, cardiovascular disease).
Recently we found that using LFME3 causes a decline of blood level of myeloperoxidase (data not published) accepted as one of the main factors causing production of dysfunctional HDL particles [
35].
Probably, there exist different mechanisms which lead to the positive effects of lactobacilli on various markers of lipid metabolism in human body [
2,
36].
It is well known that during the passage of the upper part of intestinal tract probiotics have an ability to bind a certain amount of bile acids which leads to the loss of this amount from the enterohepatic recirculation. As a consequence, the liver elevates
de novo production of new bile acids from cholesterol favoring a reduction of cholesterol levels. Some other possible mechanisms are as follows: LFME3 is characterized by a good activity of glycosyl-hydrolases, like alpha-galactosidase, beta-galactosidase, alpha-glycosidase, beta-glycosidase and beta-glycoronidase [
37]. When LDL cholesterol levels are elevated a part of it is oxidized and subsequently taken up by the arterial wall to form atherosclerotic plaques. However, the cholesterol transport system based on HDL is responsible for facilitating the movement of cholesterol from tissues back to the liver.
The RAC contains monacolin K that is an inhibitor of cholesterol synthesis key-enzyme [
38,
39]. The RAC formula also contains vitamin E and ubiquinol (vitamin Q), both working in the human body as powerful antioxidants. A study by Ceriello and colleagues also demonstrated the beneficial effects of targeting hyperglycemia and oxidative stress (OxS) and endothelial dysfunction simultaneously using insulin and an antioxidant (vitamin C) [
40]. Targeting hyperglycemia and OxS simultaneously may help to ameliorate lipid abnormalities (e.g., elevated LDL levels) [
41], and improve OxS which increases the susceptibility of LDLs to oxidation and glycation. This may prevent atherosclerosis and endothelial dysfunction. Food cysteine is the rate-limiting factor in cellular glutathione (GSH) biosynthesis. GSH, a well known cellular antioxidant and regulator of many body functions, is synthesized in the body from the amino acids L-cysteine, L-glutamic acid, and glycine. The sulfhydryl group of cysteine serves as a proton donor and is responsible for its biological activity. Thus, RAC contains L-cysteine and besides that LFME3 can transport and synthesise glutathione and has the ability of redox cycling of glutathione [
11,
42]. Vitamins B1, B6, B9 and B12 have several widely known effects in human body, including improvement of overall energy workout, carbohydrate, lipid and amino acids (e.g. homocysteine) metabolism.
The capsule RAC has been specially formulated to improve cardiovascular health. The decline of IL-6 and hsCRP refer to an improvement of blood inflammatory status. However, it seems that such formula/composition might have an impact on cardiometabolic risk involving also prediabetes/diabetes. The triglyceride/HDL cholesterol ratio is a marker of insulin resistance (a prediabetes, diabetes related marker). We found that after consumption of RAC capsules the TG/HDL-Chol ratio decreased significantly. The data of our preliminary study show that there was also a decline in HbA1c%, a well accepted marker for prediabetes/diabetes. Of course the antidiabetic effect should be verified using longer randomized placebo controlled double blind trials.
Gastrointestinal OxS is associated with the non-specific glycation, which in turn may influence the long term level of blood sugar. Through the OxS and inflammation on the cellular level the up-regulation of pro-inflammatory cytokines may reduce glucose transporter type 4 (GLUT4) expression and translocation to the plasma membrane in human adipocytes and muscle cells, which may lead to the decreased insulin-stimulated glucose uptake [
43,
44].
There are limitations of intensive treatment of hyperglycemia in preventing diabetic complications, because of adverse effects, which are linked to OxS. Maybe the simultaneous targeting of hyperglycemia and OxS could be more effective than intensive treatment of hyperglycemia in the management of T2DM [
45]. A reduction in OxS and simultaneous cardiovascular risk factor control seems to be an ideal treatment strategy in T2DM patients [
46]. Aside pharmaceutical and lifestyle correcting measures there is definitely room for food supplements and functional foods in the complex management of CVD and T2DM [
4,
28].
Acknowledgements
The authors would like to express their gratitude to M. Mikelsaar and J. Saatre for their participation in the discussions about the composition of RAC and their inspiring remarks to the work. We thank the VF Bioscience company for donating the RAC capsules used in this work.