What are Blood Lipids?

A lipid can basically be defined as a substance that is insoluble in water but is soluble in alcohol or some other type of solvent. Blood lipids are lipids, or fats, in the bloodstream. Some commonly known blood lipids are cholesterol, cholesterol complexes, and triglycerides. These molecules may occur freely in the blood, although they are most often packaged and transported in protein complexes.

In general, ingested lipids from food and drink are digested in the small intestine and transported to the liver in large complexes of lipid and protein known as chylomicrons. The liver is essentially responsible for ensuring that all tissues receive enough lipids for proper functioning and for normalizing the concentration of blood lipids. In the liver, triglycerides and cholesterol are packaged into complexes of varying densities, or lipoproteins, and then released into the blood stream.

There are three commonly known lipoproteins. Very low-density lipoproteins (VLDLs) consist primarily of triglycerides but will eventually become low-density lipoproteins (LDLs). The main ingredient of LDLs is cholesterol, and high blood levels of LDL are associated with a higher risk of heart disease. High-density lipoproteins (HDLs) also consist of cholesterol but additionally contain a large amount of protein and appear to serve as scavengers by cleaning excess cholesterol from the blood. In contrast to LDLs, a high proportion of HDLs in the bloodstream is associated with a protective effect against the development of heart disease.

The lipid hypothesis was first developed in the 1850s to describe the connection between high levels of blood cholesterol and heart disease. This hypothesis is accepted as fact by many researchers and clinicians today who claim that years of scientific research have confirmed this association, but a strong minority disagrees with this mainstream view. Opponents of the lipid hypothesis argue that less than half of heart attack patients have high cholesterol levels, and many propose that inflammatory processes are more to blame for heart disease than blood lipid levels.

Due to the generally wide acceptance of the lipid hypothesis, it is often recommended that people over the age of 20 get a blood lipid profile. This profile measures LDL, HDL, and triglycerides, and is a simple blood test that should be drawn after a 12-hour fast. The fast ensures that lipids obtained from the diet have been cleared out of the blood stream.

Although blood lipids are usually portrayed in a negative light, they have many important functions in a healthy body. They are necessary for formation of cell membranes, and they are the body’s main form of energy storage. In addition, lipids are processed in the body to become essential hormones.