Oh, no! Does fish oil cause cancer?
This is the most explosive health news I’ve heard in a while. In terms of the alternative health world, it’s as big as killing Osama bin Laden.
A new study suggests one of the omega 3 fats found in fish oil might actually increase a man’s risk of developing prostate cancer!
As you’d expect, there are a lot of problems with this study. It’s a long way from being the final word, and in fact it may mean nothing at all.
Let’s pick our way through this new minefield. . .
Toxic chemical condemned 8 men to die of prostate cancer
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I hesitate to even tell folks about this study. It may be wrong (very likely is). But I don’t see myself as a cheerleader for what everbody “knows” is true. If something runs contrary to my cherished beliefs, I’m inclined to look into it.
According to the study, published in the American Journal of Epidemiology1, men with higher levels of docosahexaenoic acid (DHA) were two-and-a-half times more likely to have an aggressive form of prostate cancer.
The results get even crazier!
Something else stunned the research team: men with the highest amounts of trans-fatty acids in their blood appeared to have a 50 percent reduction in their risk of developing prostate cancer!
Trans-fatty acids are synthetic “fake” fats found in thousands of processed food products. They’ve been linked to inflammation and heart disease. There’s even talk of passing laws against them and removing them from the food supply altogether.
Now along comes this study that seems to show trans-fatty acids DECREASED cancer risk.
The researchers found similar results for omega-6 fats. These have been associated with inflammation — and they tend to be seen as harmful. (But omega-6 acids aren’t really evil. More on this in a moment.) In this study, omega-6 fats, like trans-fatty acids, were found to be linked to a LOWER cancer risk.
If you take this study at face value, the “bad” fatty acids were good, while the “good” omega-3 fats — thought to protect your body from inflammation — were bad.
The scientists were stunned!
Lead researcher Theodore M. Brasky, Ph.D. and colleagues at Seattle’s Fred Hutchinson Cancer Research Center based their conclusions on data gathered from 3,461 participants in the Prostate Cancer Prevention Trial.
The researchers wanted to determine whether high concentrations of omega-6 fats and trans-fatty acids in the bloodstream could be linked to the development of prostate cancer.
But the latest findings were the total opposite of what the researchers expected!
Commenting in a group statement2, Brasky said the surprising results seem to “shine a light on the complexity of studying the association between nutrition and the risk of various chronic diseases.”
Is one of the most popular supplements a deadly danger?
As you probably know, thousands of Americans swallow fish oil capsules daily. You may well be one of them. I am. Fish oil supplements are reputed to help:
1. Prevent cardiovascular disease…
2. Boost your immune system…
3. Stop progression of psychotic disorders in high-risk children…
4. Guard against inflammation…
5. Reduce prostate cancer tumors…
Is all this now out the window? Not at all. . .but fat metabolism has always been more complicated than most people think — and it just got MORE complicated.
Odd sample may have led to odd result
The people who participated in this study were not a “random” sample. The study was conducted ONLY on males and only on males over the age of 55. What’s more, the roughly 3,400 men in this study were just a subset of about 19,000 men taking part in a study of the drug finasteride, prescribed to prevent prostate cancer.
Of the 3,400 men in the fatty acid study, half developed prostate cancer while the study was in progress. That’s a very high cancer rate.
Long story short, this was not a typical group selected from the whole population. The researchers said very few of the men in the study even took fish oil supplements. Those who got any omega-3 in their diet at all got it from eating fish — most likely salmon, I’d guess.
Right off the bat, this makes me wonder how much mercury those fish eaters were taking in. Personally, I don’t eat a lot of omega-3-rich fish for that very reason. I take a liquid fish oil supplement (not the capsules) which the manufacturer claims is completely uncontaminated by mercury.
I also wonder how many of these men were taking the drug finasteride (since that’s what the main study was all about). The drug could easily have played a role in the results. As could the lack of the drug, in those participants who DIDN’T take it.
Finally, a lot of people don’t start taking fish oil and/or eating a lot of salmon until AFTER they’re told they have prostate cancer. That’s late in the game, and certainly no basis for decided whether the omega-3’s prevented or caused their cancer.
Remember that half the men in this study came down with prostate cancer. Consider someone who’s never bothered much with supplements and then learns he has cancer. In a panic he starts taking lots of vitamin C, vitamin E — the whole gamut of supplements, including fish oil. It’s a good thing to do. But it seems to me it would be very easy for a researcher to misread the data: takes fish oil, has cancer; never touches the stuff, doesn’t have cancer.
So don’t go tossing your cod liver oil or other fish oil supplements just yet! These study results could be a legitimate warning—or a red herring (speaking of fish).
Brasky’s team emphasized the need for further research to better understand the relationship between prostate cancer risk and omega-3 and omega-6 fatty acids.
Plus, there are other omega-3s that were not linked to a possible increase in prostate cancer risk. So if you’re deciding on whether to use or continue using omega 3s-here’s some information you might find helpful…
Here’s what omega-3s are—and AREN’T…
According to the American Cancer Society, there are three fatty acids in the omega-3 family:
1. Alpha-linolenic acid — found in English walnuts, in some types of beans, and in canola, soybean, flaxseed/linseed, and olive oils. Olive oil would be the preferred source; avoid canola and soybean.
2. Docosahexaenoic acid (DHA) — found in seaweed and cold water, fatty fish — this is the one implicated in the recent study
3. Eicosapentaenoic acid (EPA) — found in mackerel, salmon, trout and other cold water, fatty fish
Recent dietary guidelines from the American Cancer Society (ACS) recommend a balanced diet with five or more daily servings of vegetables and fruit. They also suggest you limit intake of red meats and animal fats, including dairy fats, in order to reduce cancer risk.
A good way to do this is by eating more fish, poultry or beans instead of beef, pork or lamb. The ACS says that while studies suggest eating more servings of fish for their omega-3 fats can help lower heart disease risk—the clinical evidence regarding cancer is uncertain.
Here’s one reason they may take this position…
In 2006, researchers examined 38 studies on the effects of omega-3 fatty acids conducted over the past 40 years3. They considered studies that showed positive effects, negative effects, and even NO effects of omega-3 fatty acids on the development of cancer.
They concluded that these studies don’t provide enough evidence to suggest a significant link between omega-3 fatty acids and the cancer rate. They further determined that using omega-3 fatty acid supplements is unlikely to prevent cancer.
Although research may not prove conclusively that omega-3s are a silver bullet for cancer—preliminary study results suggest another benefit of fish oil supplements may be their ability to increase survival and the efficacy of chemotherapy in patients with non-small cell lung cancer4.
And a clinical study published in the journal Cancer concluded that omega-3 fatty acids seemed to prolong the survival of cancer patients who were also severely malnourished5.
Don’t forget heart health
The main reason for taking fish oil supplements is actually heart health — where the evidence is very strong — rather than cancer, where the evidence is mixed at best.
Studies have shown that the fatty acids in fish oil reduce risk factors for heart disease—such as high blood levels of triglycerides—and may even improve heart rhythm problems that can cause sudden death.
In my view, the evidence that omega-3 oils reduce inflammation is convincing. A great many people take the supplements to reduce arthritis pain — and they report good results. I wouldn’t call it a magic bullet for pain, but it helps. And if a person happens to be severely low on omega-3 fatty acids, he or she may enjoy an incredible reduction in pain after starting the supplements.
If you decide to boost your dietary intake of omega-3fats, you can easily find fish or plant oil supplements in capsule and liquid form in vitamin shops and through online retailers.
And if you choose to eat more fish to increase your intake of omega-3 fats, experts recommend varying the types of fish you consume. This can help minimize excessive exposure to any one type of toxin that may be in certain fish. As I said earlier, I don’t go this route because of the mercury contamination issue.
There’s more to this issue than you think
Fat metabolism is a super-complicated area. Scientists are just starting to sort it out. If you know something about the subject, this new prostate study isn’t as shocking as it seems at first glance. For example, omega-6 fatty acids aren’t bad for you. The issue is the BALANCE between omega-6 and omega-3 fatty acids.
In the typical American diet we eat almost NO omega-3’s and tons of omega-6’s. We need to redress the balance. It’s not as if omega-6 fatty acids are some kind of toxin. (Trans-fatty acids are something else: avoid at all costs!)
And it gets even more complicated: We need another fatty acid, called GLA, that I haven’t even mentioned till now. This one isn’t found in fish oil or in virtually any other food we eat. But it’s extremely valuable in reducing inflammation.
In fact, if you take fish oil without also taking another supplement that contains GLA, you may get very little relief from the fish oil. I get my GLA by taking an evening primrose oil supplement. GLA also occurs in borage oil.
According to the best information I have on this subject, you need at least 600 milligrams of GLA a day to have a significant effect on inflammation. That’s not 600 milligrams of the oil, it’s 600 milligrams of GLA. So you need to read the label to see how much GLA is actually in each capsule.
Everyone wants simple answers, and I’d love to give them to you, but dietary fats and oils and their role in good health is NOT a simple subject. That’s just the way it is.