Squalene is a
triterpene that is an intermediate of the
cholesterol biosynthesis pathway and it can be obtained from the diet.
Olive oil contains 0.2-0.7%
squalene. The average intake of
squalene is 30 mg/day in the United States, however, when consumption of
olive oil is high, the intake of
squalene can reach 200-400 mg/day as observed in Mediterranean countries. The decreased risk for various
cancers associated with high
olive oil consumption may be due to the presence of
squalene. Experimental studies have shown that
squalene can effectively inhibit chemically-induced colon, lung and skin tumourigenesis in rodents. The protective effect is observed when
squalene is given before and/or during
carcinogen treatment. The mechanisms involved for the chemopreventive activity of
squalene may include inhibition of Ras farnesylation, modulation of
carcinogen activation and anti-oxidative activities. However, several factors must be taken into consideration when the evidence for the inhibition of
carcinogenesis by
squalene is examined, these include the effective dose used and the time of exposure. The information obtained is from animal bioassays and the long-term effects from consuming increased levels of
squalene are not known. Although animal studies have enhanced our understanding of the possible action of
squalene in decreasing
carcinogenesis, one must apply caution in extrapolating the information obtained in animal studies to humans, because of possible species differences. In order to evaluate the overall implications of
squalene to human
cancer prevention, further studies are needed to fully identify its protective effects, as well as possible detrimental effects.