Squalene

Squalene, a 30-carbon isoprenoid, is a lipid found in large quantities in shark liver oil and in smaller amounts (0.1 to 0.7 %) in olive oil, wheat germ oil, rice bran oil and yeast. It is a key intermediate in the biosynthesis of cholesterol. Squalene is an all-trans isoprenoid containing six isoprene units. Chemically, it is known as (all-E)-2, 6, 10, 15, 19, 23-Hexamethyl-2, 6, 10, 14, 18, 22-tetracosahexaene.

It is represented structurally as:

It is also known as spinacene and supraene. Squalene is also found in human sebum. Squalene has the ability to absorb oxygen.

ACTIONS AND PHARMACOLOGY

ACTIONS

Squalene has demonstrated proliferative activity in cancer studies.

Squalene may have some radioprotective effects.

Other studies suggest that squalene may also have a cholesterol-lowering effect.

MECHANISM OF ACTION

Squalene is a key precursor in the biosynthesis of cholesterol. It inhibits 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, thus reducing farnesyl pyrophosphate availability for prenylation of the ras oncogene, an activity that could account for its anti-proliferative effect. Apoptosis inhibition may also play a role in the anti-tumor effects of squalene. The mechanism of the radioprotective effect of squalene is unknown.

PHARMACOKINETICS

Over 60 % of ingested squalene is absorbed from the small intestine; from there it is carried in the lymph in the form of chylomicrons into the systemic circulation. In the blood, squalene is carried mainly in very-low-density lipoproteins and distributed to the various tissues of the body. A large percentage of squalene gets distributed to the skin. Squalene is metabolized to cholesterol.

INDICATIONS AND USAGE

Studies suggest that indications could one day emerge for squalene in the prevention and treatment of some cancers, for immune enhancement and possibly for lowering cholesterol. It is not indicated for gastritis, joint pain and inflammation or to improve lung function.

RESEARCH SUMMARY

Squalene is being investigated as an adjunctive therapy in some cancers. In some models, it has proved effective in inhibiting lung tumors. It has also demonstrated chemopreventive effects against colon cancer in other models. Supplementation of squalene in mice has produced enhanced immune function and, in other studies, it has reduced cholesterol levels, prompting one researcher to suggest that it might be used to potentiate cholesterol-lowering drugs.

Animal studies showed squalene to confer radioprotection against lethal whole-body radiation.

CONTRAINDICATIONS, PRECAUTIONS, ADVERSE REACTIONS

CONTRAINDICATIONS

None known.

PRECAUTIONS

Squalene supplementation should be avoided in infants, children, pregnant women and nursing mothers.

ADVERSE REACTIONS

Those taking squalene supplements may have mild gastrointestinal symptoms such as diarrhea.

INTERACTIONS

None known.

OVERDOSAGE

There have been no reports of overdosage.

DOSAGE AND ADMINISTRATION

Squalene is a liquid that is available in capsules for oral use. Doses of 500 milligrams to 4 grams are used; the higher doses are used by some cancer sufferers. The source of squalene is usually from shark liver oil and sometimes from olive oil.

Squalene should not be confused with squalamine, which is an unusual steroid found in the dogfish shark and which has antibiotic properties.

HOW SUPPLIED

Capsules - 450 mg, 500 mg, 1000 mg

LITERATURE

Kelly GS. Squalene and its potential clinical uses. Altern Med Rev. 1999; 4:29-36.

Newmark HL, Squalene, olive oil, and cancer risk: a review and hypothesis. Cancer Epidemiol Biomarkers Prev. 1997; 6:1101-1103.

Rao CV, Newmark HL, Reddy BS. Chemopreventive effect of squalene on colon cancer. Carcinogenesis. 1998; 19:287-290.

Smith TJ, Yank GY, Seril DN, et al. Inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorogenesis by dietary olive oil and squalene. Carcinogenesis. 1998; 19:703-706.

Storm HM, Oh SY, Kimler BF, Norton S. Radioprotection of mice by dietary squalene. Lipids. 1993; 28:555-559.