Sharks Can Kill Suddenly and Maybe Slowly Too

Today’s Daily Mail shocker headline: “Taking omega-3 fish oil supplements may increase the risk of aggressive prostate cancer by 70%”  I tend not to rely on the Mail for science and health news, but note that The Telegraph reports on the same research study from Fred Hutchinson researchers in Seattle in it’s story “Omega-3 supplements ‘could raise prostate cancer risk’“

So what’s the connection to marine natural resources? Well, Omega-3 supplements come from the sea, and an earlier Mail article focuses on the Omega-3 supplement enthusiasm and deep-water shark overfishing. This October 2012 article is titled: “Demand for Omega 3 supplements sees huge increase in overfishing of sharks,” noting in a picture caption: “Deep sea sharks, including the goblin shark (pictured), are being killed for the oils found within their livers.”

The Telegraph story begins:

Omega-3 fatty acids, which are found naturally in oily fish, are widely hailed for their anti-inflammatory properties which are thought to protect against a raft of maladies including heart attacks and strokes, arthritis and various cancers. 

But a study found that men with high levels of omega-3 in their blood were at 43 per cent greater risk of prostate cancer than those with low concentrations, while less common aggressive “high-grade” tumours were 71 per cent more likely than in those not taking supplements.

So aggressive prostate cancer is linked, according to the study, to consuming too much oily fish or Omega-3 supplements. This seems good news for those concerned about shark overfishing. For those like me who just purchased Trader Joe’s Wild Salmon Oil, the news is not so good. Do I just consume one tablet a week? Or none if salmon is on the menu?

The Mail articles reports on the size of the fish oil supplement market: “fish oils accounts for a fifth of the [1 billion dollars] spent each year on dietary supplements in the UK.”

And the article reports: “Conservationists warn that the demand for these pills has let to rampant fishing of deep-sea sharks whose livers contain valuable oils?”

Trader Joe’s Wild Salmon Oil with its Omega-3 doesn’t come from deep-sea sharks. Still, given past Mail articles critical of Omega-3 supplement consumption causing shark over-fishing, and the interest on saving endangered species, it seems worth digging a little deeper into the story.

Here is a key background observation from the article:

The team from the Fred Hutchinson Cancer Research Centre in Seattle warned: ‘There is really no evidence that taking dietary supplements is beneficial to health, and there is increasing evidence that taking high doses is harmful.’

So the background for the research study authors starts with: “There is really no evidence that taking dietary supplements is beneficial to health…” Well, it is true that many in the medical profession believe this. Many believe that the $34 billion or so spent each year by Americas on vitamins and supplements (including fish oil) is wasted. (Consumer Reports article here.)

An article on the Fred Hutchinson Cancer Research Center site quotes study author Alan Kristal: “We’ve shown once again that use of nutritional supplements may be harmful,”

I don’t claim to know whether eating salmon or salmon oil supplements is overall good for you, or for me. Consuming Omega-3 from deep-sea shark livers may very well be as bad for you as it is was for the sharks.