Versatile lecithin keeps cholesterol in line – includes related information
Ralph M. Myerson
Versatile Lecithin Keeps Cholesterol In Line
Among its many functions, lecithin is essential for the breakdown and elimination of cholesterol.
Whether we like it or not, fats (or lipids) are essential components of our body and are present in some form or other in every one of our cells. We know from our experience with cooking oils and other oily substances, that fats are difficult to dissolve, and that, under certain conditions such as a drop in temperature, they will change from a liquid to a solid state. Fortunately for us, the fats within and outside of our cells are maintained in a fairly stable condition. We owe this to lecithin, a remarkable substance present in every living cell in both the plant and animal kingdoms.
Technically, lecithin is a phospholipid, closely related chemically to the triglycerides. Whereas the triglycerides have three fatty acids attached to a glycerol molecule, in the case of lecithin, one of the fatty acids has been replaced by a phosphate and choline group, resulting in the scientific name of phosphatidyl choline. (We’ll speak later about the important significance of lecithin’s choline content.)
The chemical structure of lecithin and the electrical charges it carries give it powerful detergent action. It is able to emulsify oils and hold them in solution. It also acts as a surfactant, eliminating surface tension on internal body surfaces – an action that is extremely important for the proper function of the lungs. Lecithin is an important constituent of bile. Together with cholesterol and bile salts it comprises the three major constituents of bile. Its function is to keep the bile in a liquid form so that gall stones will not form. Cholesterol and bile salts are in a delicate balance in bile and an absolute or relative increase of one over the other tends to result in stone formation. The detergent action of lecithin can prevent this stone formation.
Lecithin is synthesized within the body by a complex series of chemical reactions that probably begins with amino acids. We do not ingest lecithin as such and there are no recommended dietary allowances. It is, however, available as a dietary supplement usually as egg or ovalecithin or as vegetable lecithin derived from various vegetable sources, particularly leguminous seeds such as soya bean and nuts. Very high doses of lecithin have been administered without any apparent side effects.
Lecithin frequently has been incorporated into processed foods to keep their lipid content dispersed. The detergent properties of lecithin and its close relationship to lipids and cholesterol have prompted a number of clinical studies.
Lecithin has been used successfully to treat a form of anemia produced by a defect in the membrane of the red blood cell. This form of anemia is caused by an imbalance between cholesterol and other compounds and was corrected by the lecithin in clinical studies. Lecithin produced improvement in the quality of the cell membrane, a decrease in cell destruction, and an improvement in the anemia.
Lecithin is a component of the enzyme lecithin-cholesterol-acyl transferase which helps in the metabolism of cholesterol to its by-products. It is essential for the breakdown and elimination of cholesterol. Several investigators have studied the effect of lecithin in lowering blood cholesterol. Lecithin in a dose of 1.8 grams a day, administered to 67 patients receiving clofibrate (a cholesterol-lowering drug), prevented the increase in low-density lipoproteins (LDL) that is usually caused by clofibrate treatment.
The detergent action of lecithin is absolutely essential for the normal function of the lungs. The lungs are a collection of huge numbers of small air sacs, the alveoli (singular alveolus). The walls of the alveoli are not strong enough to allow the alveoli to maintain their shape against the surface tension of water. The surface tension is reduced by the secretion of lecithin and its surfactant action enables the lung to maintain its normal shape.
Since the fetus obtains its oxygen from the maternal circulation, it has no need for surfactant until exposure to the air at delivery. The fetus forms little lecithin prior to the 30th week of gestation. Infants that are born before the 35th week may not have secreted enough active surfactant in their lungs for normal respiratory function, and consequently may develop the acute fetal respiratory distress syndrome characterized by rapid, shallow breathing and cyanosis (blueness of skin and mucous membranes due to insufficient oxygen). This is the leading cause of distress and a major cause of death in premature infants. Several studies have reported the beneficial effects of an artificial lecithin-like lung surfactant in the treatment of the respiratory distress syndrome. In one study, a single dose of a prepared lung surfactant containing phosphatidyl choline was blown into the lungs of 22 very premature babies. Thirty-three control infants did not receive the preparation. Fewer treated infants required assisted ventilation compared to the controls. None of the treated infants died, but eight of the control infants did.
As mentioned previously, lecithin contains choline, a substance which contributes to many important processes within the body. Many nutritionists have classified choline as a vitamin. Choline deficiency has been recognized in animals and is characterized by deposits of fat in the liver and hemorrhages in the kidneys. However, no human counterpart has been recognized because choline is so widespread in our food supply. It is found in muscle meats and grains in amounts approximating 100 mg choline per 100 g. Egg yolks and organ meats such as liver have considerably greater choline concentrations, and legumes are also good sources. An average American diet contains an estimated 400 to 900 mg of choline per day. (These relatively large amounts available in the diet probably indicate that choline is not a true vitamin).
Because of its widespread occurrence in foods, it would be virtually impossible to eat a conventional diet low in choline that would not also be lacking in several other nutrients. Choline may even be manufactured within the body.
One of choline’s most important functions is its role in the manufacture of acetylcholine (ACh). Acetylcholine is a chemical released at certain nerve endings and in the brain that transmits the nervous impulse from the nerve ending to the tissue or organ that is the target of the nerve. ACh is the neurotransmitter for the part of the nervous system that controls the major organs, such as the heart, gastrointestinal tract, skin and bladder. ACh is also the neurotransmitter for nerve circuits within the brain.
Under activity of acetylcholine and the cholinergic mechanism has been postulated (but never definitely demonstrated) to be present in a number of neurological and psychiatric disorders, including Alzheimer’s Disease, tardive dyskinesia (a disorder of involuntary muscle movements), Huntington’s chorea, cerebellar ataxias, mania and depression, and schizophrenia. Researchers found that choline can raise the levels of ACh in the brain and this finding prompted a number of studies utilizing choline or lecithin as therapy for the above-mentioned disorders. Actually, lecithin has been shown to produce higher and more prolonged serum concentrations of choline than choline itself. The levels of choline in the spinal fluid are also increased, indicating that choline has access to the nervous system.
A number of lecithin and choline studies have produced good results in tardive dyskinesia, a disorder characterized by involuntary muscle movements, especially of the face, tongue and lips. In ten studies, a total of 50 patients were treated, and researchers noted improvement in 36 (72 percent). Daily doses of choline ranged from 10 to 20 grams. Lecithin dosage ranged from 40 to 105 grams per day.
Studies in both man and laboratory animals suggest that neurotransmission activated by ACh is defective in disorders of learning and memory. A primary symptom of Alzheimer’s disease is diminished memory function, which may be related to decreased ACh activity. Studies to demonstrate an improvement in Alzheimer’s disease are, however, difficult to perform and evaluate. Each patient with Alzheimer’s disease has features unique to that person and different form others with the disease. While some studies have shown lecithin or choline administration to beneficial, others have not. Recent studies have demonstrated that choline improves the learning performance of normal human subjects and animals. Further studies with lecithin and choline, alone or in combination with other agents, should be done in Alzheimer’s disease, perhaps with patients with similar disease patterns.
Finally, lecithin and choline used to treat certain psychiatric disorders, especially in disorders characterized by mania symptoms, have produced encouraging results. In one double-blind, placebo-controlled study, 30 grams of lecithin a day was administered to six patients in the manic stage of manic depressive disorder. Five of the six patients showed greater improvement with the lecithin than with the inactive placebo. Lecithin improved all the symptoms of mania, including hallucinations, delusions and incoherent speech. This exciting finding requires confirmation by other studies.
PHOTO : Start the day the right way with lecithin at breakfast.
PHOTO : Eggs and legumes are rich sources of lecithin.
Ralph M. Myerson, M.D., F.A.C.P., received a B.S. and M.D. from Tufts University School of Medicine, and postgraduate training in internal medicine from Boston City Hospital. He is a board-certified internist and a consultant in gastroenterology at Smith Kline Beckman Corporation. He holds the faculty appointment of Clinical Professor of Medicine at the Medical College of Pennsylvania and has had over 150 articles published in both lay and scientific media. He has edited or co-edited seven text books, including four on medicinal chemistry.
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