“Our hypothesis is that black garlic is able to attenuate the disbalance of lipid profile and improve endothelial function in the condition of hypercholesterolemia,” the team of Spanish researchers wrote. “Thus, the aim of the present study was to evaluate the effect of black garlic consumption on markers of cardiovascular function in hypercholesterolemic adult populations, compared to healthy subjects.”
The study, published in the journal Nutrients, was funded by the Andalusian Institute of Agricultural and Fisheries Research and Training (IFAPA) and the European Rural Development Fund (ERDF) through the project “Characterization, bioavailability and healthy potential of bioactive food compounds”.
Black garlic bioactive
Garlic (Allium sativum L.) possesses several bioactive compounds such as allicin, S-allylcysteine, ajoene, diallyl disulfide and S-methylcysteine sulfoxide, which have been shown to improve hypertension, insulin resistance, oxidative stress, lipid profile and hepatic steatosis.
When fermented at high temperature, garlic becomes black, sweet and odorless – making it more palatable and increasing the bio accessibility of certain compounds known for their anti-inflammatory, antioxidant and antidiabetic activities.
“[T]he elevated temperature required to produce black garlic is responsible for the changes in bioactive compounds, showing an increase in S-alkyl-cysteine compounds (SAC), coumaric acid, total phenols and flavonoids,” the researchers wrote.
They noted that previous human studies have shown contrasting results due to differences in study design, dosage, duration of supplementation, garlic supplement type and metabolic status of individuals. In their study, they evaluated the effects of black garlic on markers of cardiovascular function including lipid profile (as measured by TC/LDL cholesterol ratio), blood pressure and endothelial function (as measured by plasma levels of adhesion molecules VCAM-1, ICAM-1 and E-selectin, which are used to predict the onset and prognosis of chronic disease).
The study recruited a total of 31 men and 31 women between the ages of 40 and 64 years and divided them evenly between a hypercholesterolemia group (200–300 mg/dL total cholesterol and 135–175 mg/dL low-density lipoprotein (LDL)-cholesterol) or a healthy control group. Participants consumed four cloves of black garlic (12 g) a day for 12 weeks.
Blood samples, blood pressure and body composition measures were taken at the beginning and end of the test period. Physical activity and diet were also evaluated by survey.
Results indicated that HDL-cholesterol and LDL-cholesterol levels increased significantly in the healthy group post-consumption, but there was no significant variance found in the hypercholesterolemia group. LDL-cholesterol particles are associated with a worse progression of cardiovascular disease while HDL-cholesterol particles remove excess cholesterol from the tissues and bloodstream. No significant changes in blood pressure were observed in either group.
“Consumption of black garlic improved the ratio of TC/HDL-cholesterol in healthy subjects, and there was a tendency to decrease in the atherogenic index of apolipoproteins,” the study concluded. “Decreased levels observed of endothelial adhesion molecules, VCAM-1 and ICAM-1, may indicate a better prognosis for complications of hypercholesterolemia.”
The researchers called for future long-term study to confirm the relevance of the findings and to examine the effect of black garlic consumption in a cohort at increased cardiovascular risk, as well as the bioavailability of its bioactive compounds for correlation with effects.
“Effect of Black Garlic Consumption on Endothelial Function and Lipid Profile: A Before-and-After Study in Hypercholesterolemic and Non-Hypercholesterolemic Subjects”
Authors: Débora Villaño et al.