Sometimes I wish I had been born into a simpler time when foods that were good and bad were pretty much laid out in black and white. You were supposed to drink your milk, eat your vegetables, and avoid eating excessive amounts of chocolate if you wanted to grow up to be healthy. Nowadays, even the foods that have long since been touted as healthy for you are no longer construed as such.

If you don't believe me, just look at how many times that researchers have flip-flopped their view on the risks versus benefits of eggs. As comedian Lewis Black put it in 2000, "They said they're good, they're bad, they're good, the whites are good, the yolks are bad.... Make up your mind! It's breakfast; I've gotta eat!"

For those of you men who adhere to strictly healthier foods, or use various dietary supplements to improve your health, you may have had your bubble burst yet again in a study published online Wednesday by The Journal of the National Cancer Institute with regard to the effects of fish oil on the body over the long term.

Something fishy is brewing
According to the study conducted by Seattle's Fred Hutchinson Cancer Research Center, patients who took omega3 fish oil supplements -- or who ate more fish on a weekly basis than those people who didn't take the supplements or eat as much fish -- had an elevated risk of acquiring prostate cancer. The study points to a 71% increased chance of developing the most aggressive form of prostate cancer and a 43% elevated risk of developing the slower growing form of prostate cancer if you have elevated omega3 fatty acids in your system. 

Source: Pixabay.

If you recall, scientifically questioning the benefits of omega3 fatty acids has been going on for some time now. As my Foolish colleague Brian Orelli pointed out in May, a study published in The New England Journal of Medicine showed no conclusive evidence that omega3 fatty acids play a role in lowering stroke or heart attack risk. A considerably more encompassing study was published by The Journal of the American Medical Association last year that analyzed nearly 20 clinical studies and concluded little benefit to heart attack, stroke, or death prevention from omega3 fatty acids.

Are fish oil drug developers in trouble?
We are getting to a point where these mounting studies could begin to have a negative effect on fish oil sales and companies like Amarin (AMRN -2.11%), GlaxoSmithKline (GSK 0.12%), and AstraZeneca (AZN 5.38%).

Amarin's Vascepa, approved in July 2012, is only now beginning to see sales of its potential blockbuster take off, and the last thing it needs is studies that show otherwise. You can see from its short sales history below how quickly Vascepa prescriptions are ramping up:


Source: Flyonthewall. *June results exclude final two days of the month. 

Amarin is expecting big things from Vascepa and recently announced a nearly 22 million share secondary offering, which I can only assume it will use to expand its production capacity for the drug. With no other FDA-approved drugs, Amarin has a lot riding on Vascepa.

That isn't quite the case for GlaxoSmithKline's Lovaza, which generated $923 million in sales last year. While certainly dominating this space, any fall back in sales will hardly be noticeable in Glaxo's diverse pipeline.

The same can be said for Omthera Pharmaceuticals' shareholders who have little care in the world with AstraZeneca agreeing to purchase the company for $323 million in May to get a hold of Omthera's late-stage fish oil drug, epanova. With the option to receive an additional $120 million in pipeline sales incentives on top of the $323 million buyout price, Omthera shareholders are still on cloud nine, and development of the drug is continuing as planned.

Don't throw in the towel just yet
While the news has been overwhelmingly bad of late, I don't feel it's time to throw in the towel just yet on fish oil supplements.

To begin with, the target audience -- should fish oil be proven effective -- is gigantic. Fish oil supplements tout a number of positive effects, most notably in that they lower cholesterol, which can, in turn, reduce blood pressure and improve cardiovascular health. High cholesterol and high blood pressure are two of the most common ailments of the some 35.7% of U.S. citizens who are considered to be obese by the Centers for Disease Control and Prevention. This sector has only reached the tip of the iceberg in terms of hitting its target audience, meaning that the pie is more than big enough to make room for Lovaza, Vascepa, and epanova should it be approved.

The studies are also another potential bright spot for fish oil developers. True, the data hasn't exactly worked in their favor, but it's not as if researchers have a good understanding as to why fish oil has been linked to prostate cancer. Wednesday's study threw around theories that fish oil may dampen our immune system, damage our DNA, or even help tumors spread and grow -- but right now, it's nothing more than that, a theory, and may wind up being wholly coincidental. Until there's concrete data that demonstrates a link between omega3 fatty acids and cancer, I'm not sure you'll see physicians paring back their prescriptions of these supplements.

In the meantime, I'd suggest letting the sales data do the talking. With GlaxoSmithKline and AstraZeneca, you're getting a considerably more diversified product pipeline, so the effects (good or bad) from these studies will tend to be muted. As for Amarin, the fish oil pure play, sequential monthly sales growth is beginning to slow, but is still on a double-digit pace. Encouraged by its progress, I have had added it to my watchlist and would suggest you do the same.