L-Carnitine

Amino acids are the chemical units, or the “building blocks,” as they are popularly called, that make up proteins. Protein could not exist without the proper combination of amino acids. To understand how vital amino acids are, you must understand how essential proteins are to life. It is protein that provides the structure of all living things. Each organism, from the tiniest microbe to the largest animal is composed of protein. And in its various forms, it is protein that participates in the vital chemical processes that enable us to sustain life.

In the human body, protein substances make up the muscles, ligaments, tendons, organs, glands, nails, hair and body fluids (except for bile and urine). Proteins are essential for the growth of bones. Enzymes, hormones and genes are also comprised of various proteins. Next to water, protein makes up the greatest portion of our body weight. Consequently, it is easy to see why meeting our body’s protein requirements is so important to good health.

In order for protein to be complete, it must contain all of its particular amino acids. Amino acids may be linked together almost indefinitely to form more than 50,000 different proteins and 20,000 known enzymes. Because each type of protein is composed of different amino acids, each being tailored for a specific need, they are not interchangeable. Amino acids contain about 16 percent nitrogen. This distinguishes them from carbohydrates and fats in the body.

The central nervous system cannot function without amino acids, which act as neurotransmitters or as precursors to the neurotransmitters. They are necessary in order for the brain to receive and send messages. Unless all of the amino acids are present together, almost anything can go wrong with the transmission of the message.

There are approximately twenty-nine commonly known amino acids that account for the hundreds of different types of proteins present in all living things. In the human body, the liver produces about 80 percent of the amino acids we need. The remaining 20 percent must be obtained from outside sources. The amino acids that must be obtained from the diet are called essential amino acids.

Most of the amino acids can appear in two forms. These are called the D- and L-series. Because amino acids in the L-series are in the same natural form as amino acids found in living plant or animal tissue, they are considered to be more compatible to human biochemistry.

The process of assembling amino acids to make proteins for the body’s use is continuous. When we need more enzyme proteins, the body produces more enzyme proteins; when we need more cells, the body produces more protein for cells. These different types of proteins are produced as the need arises. Should the body deplete itself of its reserves of any of the amino acids, it would not be able to produce those proteins requiring such amino acids. The resulting protein shortage could easily lead to any number of disorders.

How could such a deficiency occur? Easier than you may think. If the diet contains inadequate amounts of the essential amino acids, or if the body is unable to manufacture adequate amounts, physical disorders will arise. In order to avoid such problems, we can take supplements containing essential amino acids.

L-carnitine has been found to have an important regulatory effect upon fat metabolism in both the heart and skeletal muscles. In 1972 researchers J.D. McGarry and D.W. Foster conducted a study in which L-carnitine was administered in tissue culture. Results showed that carnitine stimulates fat metabolism and encourages the clearance of triglycerides and fatty acids.

In addition to their other vital functions, amino acids enable vitamins and minerals to perform their jobs properly.

Function of L-Carnitine

L-carnitine is an unusual amino acid that is biosynthesized in the liver of humans and found highest in muscle and organ meats in the human diet. L-carnitine is not found in vegetable sources. In human metabolism it is utilized as a material which transfers fatty acids across the membranes of the mitochondria (which is like the engine of the cell) where they can be used as a source of fuel to generate energy. In the absence of proper carnitine levels within the cell, the fatty acids are poorly metabolized and can build up within the cell or the surrounding medium, thereby leading to elevated blood fat and triglyceride levels.

Recognizable deficiencies

A.G. Engel and C. Angelini reported the first carnitine deficiency in humans in 1972. In this case, they reported of infiltration of the liver with fat, depressed muscle carnitine levels, and generalized spleen and liver enlargement with muscle wasting. Human carnitine deficiencies which have been identified since 1972, range from actual deficiencies of carnitine due to dietary and biosynthetic unavailability, to transport problems of carnitine as it relates to the inability of individuals to transport carnitine in their blood to the cells in need.

P.R. Chapoy and coworkers recognized a carnitine deficiency which resembles Reyes syndrome. The case history was that of a 6-month-old boy who had heart failure, an enlarged liver, gross retardation, infections of the respiratory tract, with fatty liver and low carnitine levels. After a number of years of not knowing what was wrong with the boy it was finally recognized that he might be suffering from a carnitine deficiency. He was then given 4000 mg per day of carnitine and showed remarkable improvement almost immediately. Over a period of two years his health changed dramatically for the better, and it was determined that he was suffering from a defect in the enzyme responsible for the manufacture of carnitine from lysine and methionine. The effective treatment of this youngster led to the removal of fat from the heart and muscle, a diminution of the heart size, improved muscle strength and improved neurological function.

Therapeutic use of L-Carnitine

The most exciting recent advances in the use of carnitine in clinical nutrition is as an agent to improve fat metabolism and to reduce blood triglycerides when 1000 to 3000 mg of L-carnitine is taken daily. Elevated triglycerides can lead to increased risk to small vessel diseases, such as poor circulation in the hands and feet kidney problems, and the inability to walk without pain, called claudication. These problems are controllable by instituting a lower fat diet with low sugar and increased carnitine intake in supplemental form. Even those individuals with very high triglyceride levels have responded extremely well to these positive changes in diet.

Neuromuscular diseases such as certain types of myopathies or problems with the, muscular dystrophy, myotonic dystrophy and limb-girdle muscular dystrophy have all appeared to be aided or improved by supplementation of carnitine. There is indication that these neuromuscular diseases lead to an increased loss of carnitine in the urine, and therefore may require higher levels for adequacy.

Carnitine has also been found to be helpful in those people who want to improve fatty acid metabolism due to metabolic obesity problems. Many weight-loss diets cause a problem called ketosis, which is the accumulation of ketone bodies or fat waste products in the blood. These ketones can cause the blood to become acidic, and lead to the loss of calcium, magnesium and potassium in the urine. When uncontrolled, ketosis in poor weight-less diets or diabetes can be life-threatening. The use of carnitine in therapeutic doses as a food supplement can encourage the proper metabolism of fats and prevent ketones from building up in people who are susceptible to ketosis. Supplementing the weight-loss program with carnitine can mean the difference between a poorly controlled and well-controlled weight-loss diet.

The future of this important amino acid in clinical nutrition is very bright, and as studies are made to indicate specifically the various forms of neuromuscular and fatty acid diseases that may respond to supplements of carnitine, its application in health care will increase.