Omega-3 fatty acids likely NOT associated with prostate cancer

A weakly constructed study was reported recently that purportedly associated higher levels of omega-3 fatty acid blood levels and prostate cancer. See this CBS News report, for instance.

Lipid and omega-3 fat expert, Dr. William Harris, posted this concise critique of the study, exposing some fundamental problems:

First, the reported EPA+DHA level in the plasma phospholipids in this study was 3.62% in the no-cancer control group, 3.66% in the total cancer group, 3.67% in the low grade cancer group, and 3.74% in the high-grade group. These differences between cases and controls are very small and would have no meaning clinically as they are within the normal variation. Based on experiments in our lab, the lowest quartile would correspond to an HS-Omega-3 Index of <3.16% and the highest to an Index of >4.77%). These values are obviously low, and virtually none of the subjects was in “danger” of having an HS-Omega-3 Index of >8%. So to conclude that regular consumption of 2 oily fish meals a week or taking fish oil supplements (both of which would result in an Index above the observed range) would increase risk for prostate cancer is extrapolating beyond the data.

This study did not test the question of whether giving fish oil supplements (or eating more oily fish) increased PC risk; it looked only a blood levels of omega-3 which are determined by intake, other dietary factors, metabolism and genetics.


The authors also failed to present the fuller story taught by the literature. The same team reported in 2010 that the use of fish oil supplements was not associated with any increased risk for prostate cancer. A 2010 meta-analysis of fish consumption and prostate cancer reported a reduction in late stage or fatal cancer among cohort studies, but no overall relationship between prostate cancer and fish intake. Terry et al. in 2001 reported higher fish intake was associated with lower risk for prostate cancer incidence and death, and Leitzmann et al. in 2004 reported similar findings. Higher intakes of canned, preserved fish were reported to be associated with reduced risk for prostate cancer. Epstein et al found that a higher omega-3 fatty acid intake predicted better survival for men who already had prostate cancer, and increased fish intake was associated with a 63% reduction in risk for aggressive prostate cancer in a case-control study by Fradet et al). So there is considerable evidence actually FAVORING an increase in fish intake for prostate cancer risk reduction.

Another piece of the picture is to compare prostate cancer rates in Japan vs the US. Here is a quote from the World Foundation of Urology:


"[Prostate cancer] incidence is really high in North America and Northern Europe (e.g., 63 X 100,000 white men and 102 X 100,000 Afro-Americans in the United States), but very low in Asia (e.g., 10 X 100,000 men in Japan).”

Since the Japanese typically eat about 8x more omega-3 fatty acids than Americans do and their
blood levels are twice as high, you’d think their prostate cancer risk would be much higher...
but the opposite is the case.


Omega-3 fatty acids are physiologically necessary, normalizing multiple metabolic phenomena including augmentation of parasympathetic tone, reductions of postprandial (after-meal) lipoprotein excursions, and endothelial function. It would indeed make no sense that nutrients that are necessary for life and health exert an adverse effect such as prostate cancer at such low blood levels. (Recall that an omega-3 RBC index of 6.0% or greater is associated with reduced potential for sudden cardiac death.)

I personally take 3600 mg per day of EPA + DHA in highly-purified, non-oxidized triglyceride form (Ascenta Nutrasea liquid) that yields an RBC omega-3 index of just over 10%, the level that I believe the overwhelming bulk of data suggest is the ideal level for humans.

Comments (6) -

  • Jeff

    7/23/2013 10:56:11 PM |

    Can you advise where you get the Nutrasea Liquid that you mention you personally use above?.  I'm not finding any in the 3600mg range.  I couldn't find any where 2 doses equals that amount either.  Looking for high quality Omega 3's that are not sourced from Krill due to shell fish allergy.  Currently taking fish oil gel caplets of dubious quality.  Thanks in advance.

  • pickinthefive

    7/29/2013 5:58:45 PM |

    Hi Dr. Davis,
    A question I would have.  If you are at a known risk for prostate cancer, i.e. father or uncle's already have it, or in my case a reletively high PSA and symptoms of BPH, would it be wise to avoid the Omega 3's ?
    Thank you,
    Monty

  • Edwin

    8/14/2013 9:27:43 AM |

    So my eating a canned salmon sandwich for lunch most days which has about 1g of Omega3 (I take no supplements) should be safe?

  • Stephen in Anaheim

    8/15/2013 5:29:38 AM |

    I have to say that this is a great thing to read! In most dietary articles that I stumble across nowadays, I can find at least a paragraph or more on why people should be adding more Omega-3 fatty acids to your diet. In fact, I have read that Omega-3 can be quite beneficial for a number of medical conditions ranging from childhood asthma to fibromyalgia. It is scary to think that it could associated with a higher risk of prostate cancer, even though the underlying study was not well constructed.

  • Edward

    8/16/2013 3:08:29 AM |

    Dr. Davis,
    I take fish oil from a brand called "Carlson fish oil" it contains omega 3 fish oil 1,600. What would be the highest safest amount a person can take in Omega 3 in your experience from your patients and practice? What are your thoughts on the Linus Pauling Heart therapy which calls for a person taking at least 10 grams of vitamin C and 3-5 grams of Lysine in order to reverse plaque and heart disease? I have read the two time Nobel prize winner's books and his writings on heart disease are compelling. I would love the insight from an actual cardiologist with a practice to confirm what works and doesn't work.

  • Edward

    8/16/2013 1:19:06 PM |

    Dr. Davis,
    How much fish oil would you consider the highest and safest dosage for a person to take for heart disease and would the dosage a person who is healthy or heart problems differ?

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Let's gamble with your health

Let's gamble with your health

Let's play a game.

I'm going to list some lipid patterns and you tell me whether or not the person with these values has heart disease.

Patient 1

Total cholesterol 150 mg/dl
LDL cholesterol 75 mg/dl
HDL 50 mg/dl
Triglycerides 125 mg/dl


Patient 2

Total cholesterol 300 mg/dl
LDL cholesterol 200 mg/dl
HDL cholesterol 35 mg/dl
Triglycerides 325


Patient 3

Total cholesterol 300 mg/dl
LDL cholesterol 100 mg/dl
HDL cholesterol 25 mg/dl
Triglycerides 875 mg/dl



Let's say that any one of these profiles is yours. Should you be getting your affairs in order, preparing for your cardiac catastrophe? Should you demand a stress test from your doctor, hoping that it will shed some light on your dilemma? Should you go ahead and go to the all-you-can-eat rib restaurant, content that you will be attending your granddaughger's wedding in 2020 in full health?

If you can tell, you're a lot better at this than I am.

I provide consultation to other physicians and patients on complex hyperlipidemias in my area. In other words, if someone has a difficulty to manage lipid disorder, the doctor sends the patient to me.

Managing these wildly variable values is the easy part. Deciding whether or not heart disease is concealed within the patient . . . well, that's the hard part.

Let's take it a step further: Suppose all three profiles also have 50% of all LDL particles as the abnormal small particles. And they all have a lipoprotein(a) level of 50 mg/dl, an abnormally high level.

How about now: Can you tell whether any or all of these people have hidden heart disease?

What if they are 20 years old? Does that make a difference?

What if they are all females over 65 years--how about now?

If the only tool you have to divine the presence of hidden heart disease is a lipid panel, or even a lipoprotein panel, then the best you can manage is to hazard a guess based on statistical probability. You also assume that this "snapshot" represents the sorts of values someone has had for their entire lives. You cannot factor in the fact that the first person gained 60 lbs in the last three years since completing menopause. You can't factor in that patient 2 smoked two packs of cigarettes a day for 25 years, but quit 10 years ago.

It's also foolhardy to believe that every known cause of heart disease is currently identifiable and revealed by modern-day blood testing.

A heart scan is simply a means to quantify the sum-total of risk factors--causes--that have exerted an effect up until the moment of your scan. It will reveal the quantity of coronary atherosclerotic plaque present, regardless of whether you stopped smoking 20 years ago or lost 30 lbs last year.

For these reasons, nothing can replace the value of quantifying plaque: not cholesterol, not the Framingham risk calculation, not measures of small LDL or lipoprotein(a), not the presence or absence of symptoms. In 2008, the method of choice for measuring plaque remains a CT heart scan. Perhaps in 10 years it will be some other method.

As always, let me remind Heart Scan Blog viewers that I make this point NOT to sell heart scans, which I have no reason whatsoever to do. I say this because we require a tool to track this potentially fatal disease. We require a yardstick for tracking progression or regression. The only tool that suits these purposes in 2008 is a CT heart scan.

Comments (4) -

  • Anonymous

    9/5/2008 4:31:00 PM |

    An EBT heart scan is also acceptabte, or equivalent to a CT scan?

  • lizzi

    9/6/2008 2:31:00 PM |

    So, Dr. Davis. Do you ever use carotid intimal medial thickness measurements in your practice? If so, how?  If not, why not?

  • Steve

    9/6/2008 8:43:00 PM |

    instead of having to be exposed to radiation of a heart scan why wouln't a carotid IMT study be enought to indicate CAD since a narrowing of the carotid would preesent a high probability of CAD?

  • Anonymous

    9/10/2008 3:37:00 AM |

    Well we are going to do the heart scan in Feb - thanks to your blog.
    Check this out, our local place that does it is offering a two for one price! So me and the hubby can both get it done. I am nervous a bit but ready to do it.

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