Nutraceutical approach for the management of cardiovascular risk – a combination containing the probiotic Bifidobacterium longum BB536 and red yeast rice extract: results from a randomized, double-blind, placebo-controlled study

Atherosclerosis-related cardiovascular (CV) diseases are associated with greater disability, morbidity for concomitant severe conditions and mortality [1]. In addition to some subjects with severe hypercholesterolemia, mostly related to genetic conditions [2], the majority of subjects with low or medium CV risk actually show moderate cholesterol elevation, together with moderate rise of related biomarkers [1]. This CV risk is often underdiagnosed and undertreated, thus representing a significant burden for the individual, especially in combination with unhealthy lifestyle habits [3]. In this field, statins are an established and widely used therapeutic option and their use has led to relevant improvements in the outcome of CV diseases [4]. However, statins are also well-known to be associated with important side-effects, such as muscle symptoms of different entity [5] and, to a lower extent, de novo diabetes mellitus development [6] indicating the need for additional drug and nutraceutical treatment options.

In all these conditions, nutraceutical approach may be a reasonable option, since in several instances a moderate-intensity (multi)treatment may offer relevant advantages over the no-treatment option or the presence of inadequate adherence to a drug therapy, due for example to adverse effects [7] or even as an add-on to low dose statins in secondary prevention patients intolerant to high dose statin [8]. Several nutraceutical compounds have been evaluated both alone and in combination in the context of moderate dyslipidemia [9, 10]. Among these, the most widely tested and used are extracts of red yeast rice (RYR), berberine, phytosterols, and stanols [11]. Interestingly, comparative studies between RYR and statins observed a smaller incidence of muscular side effects with the former treatment [12].

Recent evidence indicates that alterations of gut microbiota may be involved in the pathogenesis of systemic diseases related to CV risk, including hypercholesterolemia [13], suggesting that the use of selected probiotics with specific biological activities may be proposed for these systemic conditions. Indeed, available data suggest that the intake of selected probiotics, incorporated into a food matrix like yogurt or fermented milk, may lead to a significant reduction of total cholesterol (TC) (up to − 5.4%) and low-density lipoprotein-cholesterol (LDL-C) (up to − 16%) [14‐16]. More specifically, probiotic strains showing high biliary salt hydrolase (BSH) activity [17, 18], such as Bifidobacterium longum BB536, may contribute to lower circulating TC and LDL-C by reducing intestinal cholesterol reabsorption [19]. As such food matrices may not be very practical for a long-term use, the incorporation of these probiotics into pharmaceutical forms, also in association with other nutraceuticals, may result in better adherence and efficacy for the management of low CV risk subjects.

This double-blind RCT conducted in subjects with low CV risk was aimed at exploring the efficacy and safety of a novel nutraceutical association, combining the Bifidobacterium longum BB536, a probiotic with high BSH activity (18), with a RYR extract, niacin and coenzyme Q10 (Lactoflorene Colesterolo®). This nutraceutical combination is well accepted, safe and effective in terms of significant improvement of the atherogenic lipid profile. The primary endpoint was met with a − 25.7% drop in LDL-C; significant reductions were also found for TC (− 16.7%), ApoB (− 17%) and non-HDL-C (− 24%). Since a similar reduction of the lipid atherogenic markers was already achieved after 6 weeks of treatment, this could be a practical timeframe for assessing the individual response in the clinics. The LDL-C goal recommended by the EAS guidelines (LDL-C < 115 mg/dL) [25] was reached by 4/16 subjects, whereas in 7/16 participants LDL-C was lower than 130 mg/dL, after nutraceutical treatment, although an expected variability due to individual responsiveness has been observed. The efficacy of this nutraceutical combination in terms of improvement of clinical lipid markers is comparable or even better than that of several other widely used nutraceuticals, evaluated by RCT studies [26‐28].

The intake of selected probiotics incorporated into milk or milk derivatives, as mentioned before, has been found to improve the lipid profile of moderately hypercholesterolemic subjects, with a significant (− 5/18%) reduction of TC and LDL-C [15, 19], indicating that this approach is relevant and needs to be further pursued. In these studies, however, the amount of food containing the probiotics was quite high (300–350 g or mL of fermented milk or yogurt per day), making such approach less practical for long-term treatments. On the other hand, we show here that is reasonably simpler, safe and even more effective, for a long-term treatment, to propose a nutraceutical combination containing a probiotic in a specific pharmaceutical form (granules for oral suspension), packaged into a 2-compartment sachet to preserve probiotic integrity. Interestingly, the extent of LDL-C modifications with this nutraceutical combination is similar to the average reduction observed in some of the earlier statin clinical trials, reported in the CTT meta-analysis [29]. Clinical trials with statins and, in general, with lipid-modifying drugs, included very large cohorts and long-term follow-ups and enabled to appreciate the reduction of major adverse CV events. This important aspect has not yet been addressed by clinical trials with nutraceuticals and remains a relevant challenge for the future. The effects of the combination of another probiotic (L. fermentum ME-3) with RYR and other active components on the lipid profile has also been recently evaluated in an open-label preliminary study, leading to the observation of a significant − 18% reduction of LDL-C [30]. The use of this nutraceutical combination was associated with a slight reduction of oxLDL levels. Interestingly, the circulating levels of PCSK9, the main regulator of LDL-C, were not affected by this nutraceutical combination, possibly counteracting the known stimulatory effect of RYR alone on this protein [31, 32]. Another RCT evaluating a nutraceutical mix including RYR titrated, like in the present study, at 10 mg/day monacolin K, and the antioxidant compound hydroxytyrosol, reported a significant − 20% reduction of oxLDL [33].

The potential advantage of this nutraceutical combination is that it is supposed to activate two separate mechanisms to promote LDL-C and TC reduction: inhibition of cholesterol synthesis in the liver by RYR extract and reduction of intestinal cholesterol absorption by the Bifidobacterium longum BB536, through its high BSH activity. The analysis of circulating levels of sterols allowed to estimate the relative contribution of the two mechanisms to the observed LDL-C and TC reduction. As expected, a marked lathosterol:TC reduction indicates a strong inhibition of cholesterol synthesis. We found no changes of campesterol:TC and sitosterol:TC upon active treatment. While this may be viewed as a negative finding, it should be noted that treatment with statins, including lovastatin, structurally identical to monacolin K, in addition to reduce liver cholesterol synthesis, with lathosterol:cholesterol reduction, tends to increase intestinal cholesterol absorption, shown by increased campesterol:cholesterol and beta-sitosterol:cholesterol ratios [26, 34].

Although no data on specific RYR-sterols interactions are available, since monacolin K is structurally identical to lovastatin, one may predict that RYR extract may behave like a statin concerning the modulation of circulating sterol levels. Our findings therefore through an indirect mechanism suggest that Bifidobacterium longum BB536 may effectively act to minimize a possible monacolin K-driven increase of cholesterol absorption, as suggested by the unchanged campesterol and beta-sitosterol levels. Future studies should assess the potential usefulness of probiotics like Bifidobacterium longum BB536 on top of cholesterol synthesis inhibitors like statins. This nutraceutical combination appears to be safe also in terms of glucose metabolism, since no changes were observed regarding insulin resistance and FGF19 and FGF21 levels [35, 36].

The strengths of this study include some novel aspects in the field of nutraceuticals for CV risk: i) the inclusion of a probiotic with a specific biological activity (BSH) in a nutraceutical combination, ii) the evaluation of experimental markers of CV and metabolic risk, in addition to clinical biomarkers, and iii) the assessment, for the first time, of biomarkers of cholesterol synthesis and absorption in a RCT with nutraceuticals. A limitation of the study is that we could not evaluate additional treatment arms with, for example, the RYR extract or the probiotic alone. On the other end, a nutraceutical formulation may be advantageous (or disadvantageous) because of its complexity and studying each single component in a clinical trial may not be very informative.