Squalene – Olive Oil Sharks
admin | July 4, 2010As a young lad I was a very keen saltwater fisherman. I vividly recall catching my first shark off a breakwater at Victor Harbour in South Australia. It was a young hammerhead – and a beautiful creature at that. I very carefully removed the hook while my younger brother bravely restrained it and we sent it on its way. I’ve caught quite a few sharks since then, and despite them being excellent quality table fish, I’ve released them all. They are just exceptional creatures.
Surprisingly sharks and olive oil do have something very special in common. They are the two richest dietary sources of a healthful substance called squalene. Olive oil contains between 0.4-0.7% squalene. That’s a massive 1 to 2 teaspoons in every litre of olive oil. More on the sharks later.
Squalene has been shown to be a chemopreventive cancer agent, especially effective against breast, pancreatic, and colon cancers (at least in mice). In combination with polyphenols, it also provides protection against coronary heart disease. Squalene also accumulates in high concentrations in the skin where it quenches skin damaging oxygen radicals. For this reason it is believed to protect skin against signs of aging. Squalene and one of its related compounds squalane (which is made from squalene) are easily absorbed by the skin protecting it against harmful UV rays and oxygen. Both are also very effective skin hydrators, and have the interesting physical property that their viscosity doesn’t change much across a very wide temperature range – something that is pretty useful in cosmetic formulations as you don’t want your hand cream to be like lard when cold and have the consistency of watery custard when warm.
Unfortunately, here is where the poor sharks get screwed!
Surprisingly, ¼ of a sharks body weight is made up of its liver – 50% by weight of that is oil – and of that oil, 50 to 80% is pure squalene. If you do the math – a typical deep sea shark that weighs 100kg will yield around 6-10 kgs of pure squalene.
On top the far superior yield compared with olive oil (one shark will yield the same amount of squalene as 200 litres of olive oil), it is easier and cheaper to purify shark liver oil to the 95% purity required. As a result shark derived squalene sells for around 1/3 the price of that obtained from olive oil. Although the EU has banned the use of shark derived squalene in cosmetics and health supplements, this hasn’t stopped an estimated 350,000 sharks being slaughtered each year in the Atlantic and Pacific oceans solely to harvest their livers for squalene production.
Scary, but better here than in a jar of hand lotion
So next time you eat extra virgin olive oil, you at least will know that no defenceless shark was harmed in making you healthy.
And as a post script. Squalene is a pretty stable substance provided that it is not exposed to light or heat – another reason to store your olive oil in a cool dark place or in your refrigerator.
Here’s some useful references:
Reddy, L.H. and Couvreur, P. (2009) Squalene: A natural triterpene for use in disease management and therapy. Advanced Drug Delivery Reviews 61, 1412–1426.
Camin, F. et al. (2010) Stable isotope ratios of carbon and hydrogen to distinguish olive oil from shark squalene-squalane. Rapid Commun. Mass Spectrom. 24, 1810–1816.
Eeep! Richard, sharks do get cancer! If you want the history on the myth to the contrary, there’s plenty of resources on the fact that sharks really do get cancer! Just Google the phrase (with quotes), “sharks do get cancer“, for more.
Even if they didn’t, of course, that wouldn’t be good evidence on whether squalene is chemopreventive or chemotherapeutic in humans, which is still unknown; most of the animal models are poor. Here’s a not-terribly-useful page on shark liver oil and squalene from the American Cancer Society.
Hi Michael
That’s a shame! So on top of having an undeserved reputation as being killers, and being slaughtered in their hundreds of thousands so people can eat shark fin soup, or for their squalene, or for bogus cancer cures, they get cancer as well. Bugger!
But thanks for the heads up on the matter. I’ve changed the post to reflect the facts.
Thanks
RG