Effect of a Black Garlic Extract on Cholesterol LDL Levels

Overview

One of the most characteristic components of the Mediterranean diet is garlic (Allium sativum L.), food to which has been attributed protective properties against cardiovascular diseases (CVD). Recently, several methods of garlic processing have been developed to obtain derivatives with milder organoleptic characteristics and a longer shelf life than habitual garlic derivates. One of these strategies is the aging of the garlic by high temperatures treatment that eliminates the taste and characteristic odor of garlic and gives it a dark color, a sweet taste and a slimy texture. Because the changes in the visual and organoleptic characteristics, the garlic obtained by aging at high temperatures is named black garlic. Interestingly, these modifications translate into an increase in their antioxidant power and their protective capacity against the development of CVDs, mainly due to the formation of melanoidins and to the content of organosulfur derivatives of cysteine compounds, such as S-allyl-cysteine (SAC) and alliin. Hypothesis of the study: The daily administration of a new extract of aged black garlic (SANE), with a higher concentration of bioactive compounds and lower unwanted compounds will lower cholesterol levels of low density lipoproteins (LDL-c), and will produce favorable changes on other markers of cardiovascular risk in individuals with moderate hypercholesterolemia. Each 250 mg of SANE contains 0.5% in SAC, which will mean an amount of 1.25 mg of SAC per day, about 5 times more than SAC levels present in many of the black garlic products marketed. The main objective was to evaluate the effect of the daily intake of a SANE with a higher concentration of bioactive compounds, SAC and alliin, and minor unwanted compounds such as simple sugars and furfural derivatives, in combination with dietary recommendations, on LDL-c levels in individuals with moderate hypercholesterolemia.

Chronic, randomized, crossover, placebo-controlled and double-blind nutritional intervention trial. The 60 participants in the study will be randomly divided into two groups of 30 participants, as they begin the study taking the SANE or placebo for 6 weeks. At the end of study week 6, when the first treatment is finished, a 3-week washout period will be carried out, and then the treatment that will take place during another 6 weeks will be exchanged. Total study duration of 15 weeks. The dose of SANE will be 250 mg daily, presented in a tablet of 550 mg / unit. The placebo will be microcrystalline cellulose. The consumption of SANE and placebo will be in the form of tablets with the same appearance, of 550 mg / tablet, guaranteeing that the study is blind both for the researchers of the project and for the participants (double blind). The tablets will be presented in recipients of 45 units, so that with one recipient the participants will be able to carry out the entire intervention for each of the products. Adverse effects will be controlled: body odor, halitosis, flatulence, nausea, abdominal distension, reflux and allergic reactions. During the study, volunteers will perform 7 visits, according to the cross-type study design. * a pre-selection visit (to check inclusion / exclusion criteria) (V0) and, in case of meeting the inclusion criteria, * three study visits during the consumption of SANE, which will take place in weeks 1 (start of the study), 3 and 6 (end point) (V1, V2, V3). * three study visits during the consumption of the placebo, which will take place in weeks 1 (start of the study), 3 and 6 (end point) (V4, V5, V6). In all the visits the participants must present themselves in fasting conditions of 8 hours to obtain blood. In addition, at each visit (except in the case of V0) a questionnaire will be conducted to determine the presence / absence of adverse effects. Main variable: LDL-c concentrations. Secondary variables: * Measures of body composition (in all study visits, V0-V6): * Body weight. * Height. * Body mass index (BMI) (Kg / m2). * Waist circumference. * Blood pressure (in all study visits, V0-V6): * Systolic blood pressure (SBP). * Diastolic blood pressure (DBP). * Parameters in plasma: * Total cholesterol, High density lipoproteins cholesterol (HDL-c) and triglycerides (TG) (in all study visits, V0-V6). * From these values the atherogenic indices (AIs) will be calculated: * Total cholesterol / HDL-c; * LDL-c / HDL-c * Plasma atherogenic index, which combines the values of triglycerides and HDL-c, calculated as the logarithm of the TG / HDL-c ratio, which is considered a good indirect indicator of the size of the LDL-c particles and of the subclinical atherosclerosis. * Glucose (in all the visits of the study, V0-V6). * Insulin and Non esterified free fatty acids (NEFAs) (at the beginning and end of the study period visits with each of the two products (SANE or placebo). * From the glucose and insulin values, the Homeostatic Model Assessment for insulin resistance index (HOMA-IR) and the revised-Quantitative insulin sensitivity index (R-QUICKI) will be calculated. * The pro-inflammatory cytokines Monocyte chemoattractant protein 1 (MCP-1), Interleukin 6 (IL-6) and (Tumor necrosis factor alpha (TNF-α) (at the beginning and end of the study period visits with each of the two products (SANE or placebo). * Apolipoprotein (Apo) B, a protein present in the potentially atherogenic particles present in plasma and that reflects the number of particles that contain cholesterol and triglycerides (in the visits of the beginning and end of the study period with each of the two products (SANE or placebo). * Apo A1, the major protein present in HDL-c and that initiates the reverse transport of cholesterol (in the visits of the beginning and end of the study period with each of the two products (SANE or placebo). * Based on the ApoB and ApoA1 values, the Apo B / Apo A1 ratio will be calculated as an indicator of cardiovascular disease risk. This ratio reflects the balance between proatherogenic and CVD protective particles. * Oxidized LDL-c (oxLDL) (at the beginning and end of the study period visits with each of the two products (SANE or placebo). * Phospholipid transfer protein (PLTP) (at the start and end visits of the study period with each of the two products (SANE or placebo).