Free fatty acids are one of the outcomes of the food digestion process. These acids are described as "free" because they can be transported in the bloodstream without the aid of any other carriers.
The human diet is categorized into three subdivisions: carbohydrates, proteins, and fats. It is the digestion of fats that leads to the further process known as hydrolysis, which creates a number of different fatty acids in the body, each with a unique and specific function.
Essential fatty acids are those necessary to a particular aspect of human metabolic function; these fatty acids are not otherwise created through the body's natural processes. The most crucial function of these fatty acids is the absorption of the fat-soluble vitamins necessary to the processes of bone building, blood clotting, and central nervous system maintenance. These vitamins are A, D, E, and K. Similar to the essential fatty acids are those found in fish oils and similar foods, the omega-3 group.
On the negative side of the health ledger, some fats ingested by the body and broken down through hydrolysis are the trans fatty acids, which are created in the hydrogenation, the rendering of liquid fats into solid form oils that contain saturated fats such as animal fats and lard. The trans fatty acids are a proven facilitator of the presence of unhealthy low density lipoproteins (LDLs), which are believed to contribute to the formation of plaque in blood vessels, a leading cause of arteriosclerosis, stroke, and other cardiovascular ailments.
Fats are a source of fuel that the body can utilize to produce energy. As fats are not capable of being processed by the body in their natural state, the fat molecules must be altered to permit absorption into the body after digestion. The body has mechanisms that permit it to recognize fats and to store them for future energy purposes; each fatty acid molecule, possessed of two carbon atoms, will ultimately generate a total of 17 units of adenosine triphosphate (ATP), the energy product created by the body; approximately four times as much ATP can be realized from a similar amount of the carbohydrate energy source, glucose. It is for this reason that the body is equipped with special storage areas known as adipose tissue, each of which is a sophisticated series of cells equipped to both store and to release fat when signaled to do so.
Adipose tissues store fat in the same manner in which it naturally occurs in food. However, the fats are broken down on digestion within the body, and they are reformed into the storage form known as triglycerides, a term that describes a collection of three fatty acid molecules bound together with a glycerol molecule. Each fatty acid molecule is an extended chain of carbon and hydrogen atoms. The process of hydrolysis separates the stored fats into its two separate compounds, fatty acids and glycerol. Glycerol has properties similar to alcohol and sugar; after the release by the adipose tissue, the glycerol is passed through the bloodstream for return to the liver for a conversion into a useful energy source, glucose.
The free fatty acids released from adipose tissue can be utilized anywhere there is an energy need within the body. The process of releasing these compounds begins with a signal from the pancreas, the organ responsible for the monitoring of glucose concentrations in the blood. When a low glucose level is detected, the glucagon hormone is released to stimulate glucose release from the stores of glycogen in the liver. If the blood level of glucose is too high, the body releases the hormone insulin. In this circumstance, fatty acid production will be stimulated through the further trigger of the chemical lipase in the adipose tissue. The ultimate destination of the released fatty acids is the mitochondria of the subject cells that require energy. The mitochondria is the powerhouse of every cell.
There is a well-known correlation between the consumption of caffeine and the metabolizing of free fatty acids. Caffeine promotes the process of lipolysis, the breakdown of the triglycerides stored in the adipose cells. There is also a scientifically established linkage between the increased presence of fatty acids in the bloodstream and the onset of diabetes, the disease whereby the body produces insufficient amounts of insulin to properly regulate the level of blood sugars (glucose).
While fat, in the form of fatty acids, is a very desirable energy source, it is dependent on the presence of oxygen to be useful. In circumstances where energy is required by the body more quickly than oxygen can be delivered to the required location, the body will switch to its less energy efficient anaerobic system. When the body is using one of its anaerobic energy systems, it cannot burn fat, but it will simply generate less energy and will sustain a greater glucose depletion.