Lecithin

DESCRIPTION

Lecithin is a fatty substance which is made by the liver (synthesised from choline). It is also present in certain foods. Lecithin was named after the Greek word for egg yolk (‘leci-thos’). Lecithin is comprised of phosphatidylcholines - a group of phospholipids each made up of glycerol, Phosphorus, choline and two fatty acids of varying identity.

However, the term lecithin usually encompasses a wider group of substances - namely, phosphatidylcholine together with phosphatidylinositol, phosphatidylethanolamine, Phosphatidylserine, and free fatty acids, choline and inositol.

Lecithin is made internally by the liver and is also present in certain foods.

FUNCTIONS

Lecithin is a very rich precursor source of choline, which is needed to make acetylcholine - a neurotransmitter that is essential for normal brain function.

The phosphatidylcholine component of lecithin functions structurally as a component of cell membranes and is also an emulsifying component of bile.

Lecithin increases the faecal excretion of neutral steroid molecules. This may reduce the absorption of dietary cholesterol from the intestinal contents whilst restricting the re-absorption of endogenously produced cholesterol into the bloodstream.

SUPPLEMENTAL USES

High Cholesterol:
Lecithin may be effective in lowering high blood lipid levels, but to have a substantial effect, high levels are needed (1).

Gallstones:
Lecithin is able to increase the capacity of the bile to solubilise cholesterol and may be useful in the prevention of Gallstones (2). At a minimum dose of 2g per day, lecithin can help to normalise the low phospholipid to cholesterol ratios.

Senile Dementia:
There are many conflicting trials on the use of lecithin in senile dementia. A trial in 1996 reported that Phosphatidylserine, derived from soyabean lecithin improves cognitive disorders of cholesterol ratios (3).

Tardive Dyskinesia:
Tardive dyskinesia is characterised by repetitive and uncontrollable movements, caused by the long-term use of "neuroleptic" or antipsychotic medications. Preliminary reports suggest that some patients may benefit from large levels of either lecithin or choline. Further work in this area is warranted (4,5,6).

Multiple sclerosis:
There is some evidence that the phospholipid content of myelin is depleted in Multiple sclerosis sufferers (7). Lecithin or choline supplements may help to slow the deterioration of the nerve coverings.

SAFETY

Lecithin does not have any reported side effects at levels up to 100g per day for up to four months.
Higher dosages may cause minor abdominal discomfort, Diarrhoea, and nausea.

Safety in young children, pregnant or nursing women, and patients with severe liver or kidney disease has not been determined.

INTERACTIONS AND CONTRA-INDICATIONS

There are no known drug interactions or other contra-indications for lecithin.

FOOD SOURCES

Food (mg/100g)
Wheat 2820
Soya bean 1480
Peanuts 1113
Maize 953
Liver 850
Oats 650
Rice 580
Trout 580
Meat 450-750
Eggs (each) 350
Butter 150

Supplements of lecithin are usually produced either from eggs or from soya, but soya lecithin is nutritionally to be preferred as the fatty acids contained in this lecithin have a higher polyunsaturated to saturated ratio.

Importance of Unbleached Lecithin Products

The manufacturing of unbleached lecithin is slower and more labour-intensive than conventional lecithin. The process does not use solvents and results in a more stable product.

REFERENCES

1. Polichetti E, et al. Cholesterol-lowering effect of soyabean lecithin in normolipidaemic rats by stimulation of biliary lipid secretion. British J Nutrition, 75;3:471-478 1996.
2. Ochi H, Tazuma S, Kajiyama G. Lecithin hydrophobicity modulates the process of cholesterol crystal nucleation and growth in supersaturated model bile systems. Biochem J, 318 Pt 1:139-144 1996.
3. Sakai M, Yamatoya H, Kudo S. Pharmacological effects of Phosphatidylserine, enzymatically synthesized from soybean lecithin on brain functions in rodents. J Nutr SCi Vitaminol, 42;1:47-54 1996.
4. Davis KL, Hollister LE, Barchas JD, Berger PA. Choline in tardive dyskinesia and Huntington’s disease: preliminary results from a pilot study. Am J Psychiatry 1979;136:772-76.
5. Gelenberg, AJ, Doller-Wojcik JC, Growdon JH. Choline and lecithin in the treatment of tardive dyskinesia: preliminary results from a pilot study. Am J Psychiatry 1979;136:772-76.
6. Anderson BG, Reker D, Ristich M, et al. Lecithin treatment of tardive dyskinesia—a progress report. Psychopharmacol Bull 1982;18:87-88.
7. Tong XW, Xue QM. Alterations of serum phospholipids in patients with multiple sclerosis. Clin Med J, 106;9:650-654 1993.