Garlic is an essential vegetable, which is often boiled, stewed or roasted for culinary purposes. It has been known to have various health benefits, including lowering cholesterol and high triglycerides to protect the heart. Garlic also acts as an antioxidant to reduce the accumulation of free radicals in blood vessels, thereby reducing the risk of cardiovascular diseases and blood clots. Black garlic is a well-known preparation of raw garlic that has been subjected to an extended period of thermal processing at regulated humidity and temperature, which significantly improves its nutrient composition, organosulfur bioactive compounds and flavor values. It is also considered a functional food due to its multi-functional properties, which include anti-inflammatory, anti-obesity, anticancer and hepatoprotective effects.
Garlic contains a variety of biologically active substances, including allicin, allyl sulfides, phenolic acids and flavonoids. In particular, the allicin in raw garlic has been shown to improve cardiovascular health by lowering LDL cholesterol and high triglycerides, while raising HDL (good) cholesterol levels in the blood. In addition, it has been found to promote a healthy immune system, protect against certain cancers, and slow the progression of age-related neurodegeneration. The black color of black garlic is the result of a Maillard reaction between fructose/glucose and amino acids, similar to that in roasted coffee. This process results in the formation of the brown polyphenols cinnamate and coumarin, as well as the dark pigment tetrahydroxybutane and the monomeric dye tetrahydroquinone.
Another benefit of black garlic is its anti-obesity effect. In one study, black garlic was found to lower body weight, epididymal fat pad, total fat pad and liver weight in diet-induced obese mice. It was also found to downregulate the expression of transcription factors and enzymes associated with adipogenesis and lipogenesis, such as peroxisome proliferator-activated receptor g, acetyl-coA carboxylase, sterol regulatory element-binding protein 1c and fatty acid synthase.
Black garlic is also believed to have hepatoprotective properties. In one animal model, black garlic was able to decrease liver weight and liver damage, as well as the elevation of hepatic enzymes ALT, AST and alkaline phosphatase in chronic alcohol-induced hepatotoxicity. Black garlic was also found to inhibit the synthesis of pro-inflammatory cytokines and attenuate oxidative stress in the liver.
Besides hepatoprotective properties, black garlic is also known to have anticancer activity. In vitro experiments have indicated that black garlic extracts are able to inhibit the growth of several types of cancer cells, including colon cancer, leukemia and melanoma. This is thought to be the result of its phenolic compounds, which suppress the growth and spread of cancer cells by binding with them and blocking their cell cycle pathways.
Black garlic has also been found to help prevent and treat dementia, Alzheimer’s and Parkinson’s disease, thanks to its high concentration of nitric oxide (NO). NO is an important signaling molecule in the brain, which helps to improve memory by reducing inflammation and improving blood circulation. It is also known to increase cognitive function in aging animals.