Soy Lecithin

Latin Name - Glycine max

Pharmacopeial Name - Lecithinum ex soya

Overview

The Commission E has published two positive monographs (in 1988 and in 1994) on soy lecithin, which consists of soybean phospholipids, and soy phospholipid containing 73;79% (3-sn-phosphatidyl)choline. The monographs differ in that the former refers to phospholipids extracted from soybeans, while the latter pertains to preparations consisting of a specific concentration of those phospholipids: 73;79%. Generally, lecithin removed from soybeans contains about 76% phosphatidylcholine (Schulz et al., 1998).

Phospholipids contain mostly linoleic acid (LA), a fatty acid essential to cell membrane formation. Linoleic acid is obtained primarily from food; a small amount is synthesized in the liver. When liver function is compromised, linoleic acid is deficient. Dietary supplementation with soy phospholipids may help patients with liver disease, alcoholism, or chronic parenteral nutrition reduce their risk of LA deficiency. Soy phospholipid 73;79% (3-sn-phosphatydyl)choline products, in addition, are reported to reduce symptoms of liver disease, chronic hepatitis, or liver dysfunction due to malnutrition, such as loss of appetite and abdominal pain (Schulz et al., 1998).

Soy may also lower blood lipids. Soy is recommended for hypercholesteremia in patients whose cholesterol levels do not respond to exercise or weight loss regimens. A recent meta-analysis of 38 studies noted that when dietary meat protein was supplanted with vegetable protein, risks for coronary artery disease were reduced (Anderson et al., 1995). The soy-based diets reduced serum levels of total cholesterol, LDL cholesterol, and triglyceride, without affecting HDL cholesterol (Manson et al., 1992; Anderson et al., 1995). The full extent of soy phospholipid effects has not been determined. Published studies suggest that phospholipids may be useful in the treatment of menopause and post-menopausal conditions, cancer, hypertension, aging, and benign prostatic hyperplasia (Holt, 1996).

Soy cultivation is believed to have begun in China; the emperor Shen-nong, who compiled the Medical Bible of the Yellow Emperor (Huang-di nei jing) sometime between 2967 and 2597 B.C.E., counted soybean among the five sacred crops. Since then, both ancient Chinese and contemporary Chinese medical literature have claimed health benefits from soy. During the Ming Dynasty (1368;1644 B.C.E.), in his 52-volume Chinese Materia Medica, Li-Shi Zhen recommended soybeans for the treatment of kidney disease, edema, and poisoning. Today soy may be recommended for skin diseases, gastrointestinal disorders, leg ulcer, vitamin deficiency, and pregnancy toxemia (Holt, 1996).

Description

Soy lecithin consists of the phospholipids extracted from the seeds of Glycine max (L.) Merrill [Fam. Fabaceae] and its preparations in effective dosage. Soy lecithin contains (3-sn-phosphatidyl)choline, phosphatidylethanolamine, and phosphatidylinositol.

Chemistry and Pharmacology

The main constituents are a natural mixture of phosphatides, mainly phosphatidylcholine (20;31.6%), phosphatidylethanolamine and phosphatidylinositol, in combination with fatty acids, carbohydrates, and other substances (DAB, 1998; Der Marderosian, 1999; Der Marderosian et al., 1988; FCC III, 1981; CFR 21, 1998). Soybean lecithin contains 11.7% palmitic, 4% stearic, 8.6% palmitoleic, 9.8% oleic, 55.0% linoleic, 4.0% linolenic, and 5.5% C20 to C22 acids (Budavari, 1996; Der Marderosian, 1999). Pharmacopeial grade soy lecithin must contain a minimum 20% and maximum 31.6% phosphatidyl choline, calculated on the dried substance. Its iodine number value must be between 76 and 85, its acid value maximum 35, and peroxide value maximum 10 (DAB, 1998). The Commission E reported lipid-lowering activity.

The Merck Index reported its therapeutic category as lipotropic (Budavari, 1996). Soy lecithin is reported to act as an emulsifier aiding in the absorption of fats (Ringer, 1998). It appears to act by improving the metabolism of cholesterol in the digestive system (Der Marderosian, 1999).

Uses

The Commission E approved soy lecithin for moderate disturbances of fat metabolism, especially hypercholesterolemia if dietary measures are not sufficient. Lecithin has been used as a treatment in cases of poor nutrition, rickets, anemia, diabetes, and tuberculosis (Taber, 1962). Lecithin is used to treat hypercholesterolemia, neurologic disorders, and liver disorders, including diabetic fatty liver and toxic liver damage (Der Marderosian, 1999). The FDA permits the use of lecithin in food with no limitations other than its production by current good manufacturing practice (CFR 21, 1998).

Contraindications: None known.

Side Effects: None known.

Use During Pregnancy and Lactation: No restrictions known.

Interactions with Other Drugs: None known.

Dosage and Administration (Unless otherwise prescribed): Preparations from soy beans for oral intake containing total phospholipids in their natural mixture composition corresponding to 3.5 g (3-sn-phosphatidyl)choline per day.

References:

Anderson, J.W., B.M. Johnstone, M.E. Cook-Newell. 1995. Meta-analysis of the effects of soy protein intake on serum lipids. N Engl J Med 333(5):276;282.
Budavari, S. (ed.). 1996. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 12th ed. Whitehouse Station, N.J.: Merck & Co, Inc.
CFR 21. See U.S.A. Dept. of Health and Human Services: Food and Drug Administration.
Der Marderosian, A. (ed.). 1999. The Review of Natural Products. St. Louis: Facts and Comparisons.
Der Marderosian, A. et al. 1988. Natural Product Medicine. Philadelphia: George F. Stickley Co. 121;122, 140, 313;315.
Deutsches Arzneibuch (DAB 1998). 1998. Stuttgart: Deutscher Apotheker Verlag.
Food Chemicals Codex, 3rd ed. (FCC III). 1981. Washington, D.C.: National Academy of Sciences. 166;167. Holt, S. 1996.
Soya for Health: The Definitive Medical Guide. New York: Mary Ann Liebert, Inc.
Manson, J.E. et al. 1992. The primary prevention of myocardial infarction. N Engl J Med 326(21):1406;1416.
Ringer, D.L. 1998. Physicians' Guide to Nutriceuticals;. Omaha, NE: Nutritional Data Resources, L.P. 193.
Schulz, V., R. Hänsel, V.E. Tyler. 1998. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. New York: Springer.
Taber, C.W. 1962. Taber's Cyclopedic Medical Dictionary, 9th ed. Philadelphia: F.A. Davis Company. L-15.

U.S.A. Dept. of Health and Human Services: Food and Drug Administration. 1998. Code of Federal Regulations 21 (CFR 21). Part 184.1400. Washington, D.C.: Office of the Federal Register National Archives and Records Administration. 488.

Additional Resources:

Emmert, J.L., T.A. Garrow, D.H. Baker. 1996. Development of an experimental diet for determining bioavailable choline concentration and its application in studies with soybean lecithin. J Anim Sci 74(11):2738;2744.
Guarini, P. et al. 1998. Effects of dietary fish oil and soy phosphatidylcholine on neutrophil fatty acid composition, superoxide release, and adhesion. Inflammation 22(4):381;391.
Hänsel, R., K. Keller, H. Rimpler, G. Schneider (eds.). 1992;1994. Hagers Handbuch der Pharmazeutischen Praxis, 5th ed. Vol. 4;6. Berlin-Heidelberg: Springer Verlag.
Jannace, P.W., R.H. Lerman, J.I. Santos, J.J. Vitale. 1992. Effects of oral soy phosphatidylcholine on phagocytosis, arachidonate concentrations, and killing by human polymorphonuclear leukocytes. Am J Clin Nutr 56(3):599;603.
Oosthuizen W. et al. 1998. Lecithin has no effect on serum lipoprotein, plasma fibrinogen and macro molecular protein complex levels in hyperlipidaemic men in a double-blind controlled study. Eur J Clin Nutr 52(6):419;424.
Renaud, C., C. Cardiet, C. Dupont. 1996. Allergy to soy lecithin in a child. J Pediatr Gastroenterol Nutr 22(3):328;329.
Sirtori, C.R. et al. 1985. Cholesterol-lowering and HDL-raising properties of lecithinated soy proteins in type II hyperlipidemic patients. Ann Nutr Metab 29(6):348;357. Steinegger, E. and R. Hänsel. 1992. Pharmakognosie, 5th ed. Heidelberg: Springer Verlag.
Teuscher, E. 1997. Biogene Arzneimittel, 5th ed. Stuttgart: Wissenschaftliche Verlagsgesellschaft.
Tompkins, R.K. and L.G. Parkin. 1980. Effects of long-term ingestion of soya phospholipids on serum lipids in humans. Am J Surg 140(3):360;364.
Wilson, T.A., C.M. Meservey, R.J. Nicolosi. 1998. Soy lecithin reduces plasma lipoprotein cholesterol and early atherogenesis in hypercholesterolemic monkeys and hamsters: beyond linoleate. Atherosclerosis 140(1):147;153.

Note:

This material was adapted from The Complete German Commission E Monographs-Therapeutic Guide to Herbal Medicines. M. Blumenthal, W.R. Busse, A. Goldberg, J. Gruenwald, T. Hall, C.W. Riggins, R.S. Rister (eds.) S. Klein and R.S. Rister (trans.). 1998. Austin: American Botanical Council; Boston: Integrative Medicine Communications.

1) The Overview section is new information.
2) Description, Chemistry and Pharmacology, Uses, Contraindications, Side Effects, Interactions with Other Drugs, and Dosage sections have been drawn from the original work. Additional information has been added in some or all of these sections, as noted with references.
3) The dosage for equivalent preparations (tea infusion, fluidextract, and tincture) have been provided based on the following example:
- Unless otherwise prescribed: 2 g per day of [powdered, crushed, cut or whole] [plant part]
  Infusion: 2 g in 150 ml of water
  Fluidextract 1:1 (g/ml): 2 ml
  Tincture 1:5 (g/ml): 10 ml

4) The References and Additional Resources sections are new sections. Additional Resources are not cited in the monograph but are included for research purposes.

Excerpt from Herbal Medicine: Expanded Commission E Monographs

Published by Integrative Medicine Communications

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