A Randomized, Placebo-Controlled, Double-Blind Crossover Study to Assess a Unique Phytosterol Ester Formulation in Lowering LDL Cholesterol Utilizing a Novel Virtual Tracking Tool

Phytosterol supplementation in capsules or tablets as adjunctive treatment for hypercholesterolemia: A systematic review of randomized controlled trials

BACKGROUND

The exploration of lipid-lowering resources, such as phytosterols, for the complementary nutritional treatment of hypercholesterolemia is relevant to reduce cardiovascular risk. The use of phytosterols in capsules or tablets can bring advantages in the context of diet therapy, but such format is still less studied when compared to fortified foods.

OBJECTIVE

Systematically review randomized clinical trials on the effects of phytosterol supplementation, in capsules or tablets, on the lipid profile and its use in the treatment of hypercholesterolemia in adults.

DESIGN

A systematic review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, with a PROSPERO protocol registered under number CRD42021249539. The process was conducted by two independent reviewers. Only randomized clinical trials with phytosterol supplementation in adult individuals with hypercholesterolemia were included. The terms were searched in the databases: PubMed/MEDLINE, Cochrane Library/CENTRAL, Embase, LILACS and Web of Science, without restriction of time and language. The manual search was also performed through the list of references of articles included in this review.

RESULTS

The searches resulted in 977 articles. 22 articles were selected, whose full text was read, and according to the eligibility criteria 10 were incorporated into the review. The studies were separated into groups according to the association of the intervention with changes in lifestyle and the characteristics extracted from the studies were summarized and displayed in tables. Most studies have revealed a positive association between phytosterol supplementation and cholesterol reduction, despite the short duration of interventions.

CONCLUSION

The analyzed studies showed that phytosterol supplements can be useful to modulate the lipid profile, helping to reduce the plasma concentration of LDL cholesterol. However, more research with the aforementioned supplementation in such pharmaceutical formats should be encouraged.

Liposomal Phytosterols as LDL-Cholesterol-Lowering Agents in Diet-Induced Hyperlipidemia

The high blood level of low-density lipoprotein cholesterol (LDL-C) is a primary risk factor for cardiovascular disease. Plant sterols, known as phytosterols (PSs), can reduce LDL-C in a range of 8-14%. The extent of LDL-C reduction depends on its formulation. Encapsulation into liposomes is one formulation strategy to enhance the efficiency of PSs. PSs (campesterol, stigmasterol, and β-sitosterol) have frequently been assessed alone or in combination for their LDL-C-lowering ability. However, one naturally abundant PS, brassicasterol, has not yet been tested for its efficacy. We have previously developed a novel liposomal formulation containing the PS mixture present naturally in canola that is composed of brassicasterol, campesterol, and β-sitosterol. In this work, the efficacy of our novel liposomal PS formulation that includes brassicasterol was assessed in a hamster model. Animals were divided into five groups: (i) liposomal PS in orange juice, (ii) liposomal PS in water, (iii) marketed PS in orange juice, (iv) control orange juice, and (v) control water. The animals were fed a high-fat, cholesterol-supplemented (0.5%) diet to induce hypercholesterolemia. The treatment was administered orally once daily for 4 weeks. Fasting blood samples were collected at baseline, week 2, and week 4. The extent of the reduction of total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglycerides was compared among the groups. Liposomal PSs in both orange juice and water significantly reduced LDL-C compared to their controls. Furthermore, the liposomal PS was as effective as a marketed PS-containing product in reducing LDL-C. Liposomal PSs in both orange juice and water showed similar efficacy in LDL-C reduction, highlighting that these vehicles/food matrices do not affect the efficacy of PSs. The liposomal formulation of a natural PS mixture extracted from canola oil, with brassicasterol as a major component, exhibited a significant LDL-C reduction in a hamster model.

Curcumin suppresses cell proliferation and reduces cholesterol absorption in Caco-2 cells by activating the TRPA1 channel

BACKGROUND

Curcumin (Cur) is a bioactive dietary polyphenol of turmeric with various biological activities against several cancers. Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths. Intestinal cholesterol homeostasis is associated with CRC. Chemotherapy for CRC is related to varied adverse effects. Therefore, natural products with anti-cancer properties represent a potential strategy for primary prevention of CRC.

METHODS

The present study used Cur as a therapeutic approach against CRC using the Caco-2 cell line. The cells were treated with different concentrations of Cur for different duration of time and then the proliferation ability of cells was assessed using Cell Counting Kit-8 and 5-Ethynyl-2'-deoxyuridine assays. Oil red O staining and cholesterol assay kit were used to evaluate cellular lipid content and cholesterol outward transportation. Finally, the protein expressions of cholesterol transport-related protein and signal transduction molecules were assessed using Western blot assay.

RESULTS

Cur inhibited cell proliferation in Caco-2 cells in a dose- and time-dependent manner by activating the transient receptor potential cation channel subfamily A member 1 (TRPA1) channel. Activation of the TRPA1 channel led to increased intracellular calcium, peroxisome proliferator-activated receptor gamma (PPARγ) upregulation, and the subsequent downregulation of the specificity protein-1 (SP-1)/sterol regulatory element-binding protein-2 (SREBP-2)/Niemann-Pick C1-like 1 (NPC1L1) signaling pathway-related proteins, and finally reduced cholesterol absorption in Caco-2 cells.

CONCLUSIONS

Cur inhibits cell proliferation and reduces cholesterol absorption in Caco-2 cells through the Ca²⁺/PPARγ/SP-1/SREBP-2/NPC1L1 signaling by activating the TRPA1 channel, suggesting that Cur can be used as a dietary supplement for the primary prevention of CRC. In Caco-2 cells, Cur first stimulates calcium influx by activating the TRPA1 channel, further upregulates PPARγ and downregulates SP-1/SREBP-2/NPC1L1 signaling pathway, and finally inhibits the absorption of cholesterol. TRPA1, transient receptor potential cation channel subfamily A member 1; NPC1L1, Niemann-Pick C1-like 1; PPARγ, peroxisome proliferator-activated receptor gamma; SP-1, specificity protein-1; SREBP-2, sterol regulatory element-binding protein-2; Cur, curcumin.

The Bioavailability and Biological Activities of Phytosterols as Modulators of Cholesterol Metabolism

Phytosterols are natural sterols widely found in plants that have a variety of physiological functions, and their role in reducing cholesterol absorption has garnered much attention. Although the bioavailability of phytosterols is only 0.5–2%, they can still promote cholesterol balance in the body. A mechanism of phytosterols for lowering cholesterol has now been proposed. They not only reduce the uptake of cholesterol in the intestinal lumen and affect its transport, but also regulate the metabolism of cholesterol in the liver. In addition, phytosterols can significantly reduce the plasma concentration of total cholesterol, triglycerides, and low-density lipoprotein cholesterol (LDL-C), with a dose-response relationship. Ingestion of 3 g of phytosterols per day can reach the platform period, and this dose can reduce LDL-C by about 10.7%. On the other hand, phytosterols can also activate the liver X receptor α-CPY7A1 mediated bile acids excretion pathway and accelerate the transformation and metabolism of cholesterol. This article reviews the research progress of phytosterols as a molecular regulator of cholesterol and the mechanism of action for this pharmacological effect.

Effects of Daily Consumption of an Aqueous Dispersion of Free-Phytosterols Nanoparticles on Individuals with Metabolic Syndrome: A Randomised, Double-Blind, Placebo-Controlled Clinical Trial

Metabolic syndrome (MS) affects up to 40% of the population and is associated with heart failure, stroke and diabetes. Phytosterols (PS) could help to manage one or more MS criteria. The purpose of this study was to evaluate the therapeutic effect of daily supplementation of an aqueous dispersion of 2 g of free-phytosterols nanoparticles in individuals with MS over six months of intervention, compared with placebo. This double-blind study included 202 participants with MS randomly assigned into phytosterol (n = 102) and placebo (n = 100) groups. Participants were assessed at baseline, 4, 12 and 24 weeks. General health questions, anthropometric measurements and blood parameters were analysed. At week 24, the proportion of participants with high triglycerides (≥150 mg/dL) in the phytosterol group was 15.65% lower than in the placebo group (p-value = 0.023). Similarly, half of the participants in the phytosterol group decreased their waist circumference up to 4 cm compared with 0 cm in the placebo group (p-value = 0.0001). We reported no adverse effects (diarrhoea or vitamin D reduction); nonetheless, almost 70% of participants in the phytosterol group self-reported an improvement in bowel habits. Daily intake of free-PS nanoparticles improved some MS criteria; therefore, it might be a promising adjuvant therapy for individuals with MS (NCT02969720).