Hyperlipidaemia, including hypercholesterolaemia and hypertriglyceridaemia, is a major risk factor in the development of cardiovascular diseases. Indeed, the Lipid Research Clinics Coronary Primary Prevention Trial has concluded that every 1% reduction in plasma total cholesterol (TC) leads to a 2% decrease in the risk of coronary heart disease. Elevated levels of plasma low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) as well as reduced levels of plasma high-density lipoprotein cholesterol (HDL-C) are often associated with an increased risk of coronary heart disease and fatty liver disease. Nowadays, a logical strategy to prevent or treat cardiovascular disease is to target hyperlipidaemia with drugs and/or dietary intervention. Recently, there has been a special focus on the hypolipidaemic effects of dietary plants, some of which have shown promising potential in lowering cholesterol levels in plasma.
Asparagus (Asparagus officinalis L.), a healthy and nutritious vegetable, is commonly consumed in many regions of the world. In addition to its edible value, this plant has been demonstrated to possess various biological activities such as antimutagenic (juice), hypolipidaemic (juice), antioxidant (edible parts of spears), antitumour (edible parts of spears), antifungal (roots), hepatoprotective (roots), hypoglycaemic (roots) and immunoprotective (roots) functions. However, during industrial processing, around half of the total length of each spear is discarded, which causes significant waste for producers. In fact, these by-products of asparagus contain many bioactive substances such as flavonoids, steroidal saponins and polysaccharides and might have potential use as food supplements for their therapeutic effects. Nevertheless, only a limited number of studies are available on the pharmacological effects of asparagus by-products so far. Therefore the active fractions of asparagus by-products and a detailed dosedependent study of their physiological effects remain to be validated.