What is the connection between fish oil, or EPA and DHA, to cancer?
According to most experts, a high intake of fish, fish oil, or supplements containing the omega-3 oils EPA and DHA , would be expected to reduce the incidence of cancer and perhaps play a role in treatment. Studies support this, especially for breast cancer and colon cancer.
“. . .there is increasing support for an anti-cancer effect of EPA and DHA. Additionally, there are data showing that if cancer has developed, EPA and DHA supplementation may ease the way by decreasing inflammation, and . . . decrease physical aspects of fatigue.” (Jorn Dyerberg, M.D., DMSc. & Richard Passwater, Ph.D. The Missing Wellness Factors–EPA and DHA. Basic Health Publications Inc, 2012)
It only makes sense. Various observations stimulated scientific curiosity. Scientists noticed, for example, that Japanese women who switched from their traditional high-fish diet to a Westernized diet experienced an increased incidence of breast cancer. These clues led to in-depth research that provided numerous biochemical explanations as to why EPA and DHA would exert anti-cancer action. These various mechanisms are explained nicely in the book by Dyerberg & Passwater, referenced above.
So every indication, until recently, led to the conclusion that a high omega-3 oil intake would, if anything, have a beneficial effect on cancer risk. It was quite a surprise, therefore, when the recent headlines proclaimed "Too Much Fish Oil Might Boost Prostate Cancer Risk."
What about prostate cancer? Is there any reason to expect the relationship between EPA and DHA to prostate cancer would be different from other cancers? Apparently not.
In fact, there have been studies dealing with omega-3 oils and prostate cancer.
Studies on humans suggest that decreasing the ratio of omega-6 to omega-3 fatty acids, i.e. increasing the amount of omega-3's, decreases the risk of prostate cancer from developing and progressing. This was investigated in men undergoing radical prostatectomy who were randomly assigned to receive a low-fat diet with 500 mg of fish oil daily (higher omega-3 ratio) or a controlled Western diet (higher omega-3 ratio) for four to six weeks prior to surgery. After the surgery, men in the low-fat fish-oil group were found to have fewer tumors (both less benign and cancerous tissue) and slower cancer cell growth than men consuming the West- ernized diet (Aronson, WJ et al. Cancer Prev Res 2011 Dec;4(12):2062-2071).
Dr. Michael Murray, in his excellent newsletter, doctormurray.com, presents a comprehensive list of studies dealing with fish oil and prostate cancer:
“What do other Studies Show?
“In addition to population-based studies, several studies have been conducted that were actually designed to determine the effects of fish and fish oil consumption in prostate cancer. In a detailed meta-analysis conducted in 2010, while fish consumption did not affect prostate cancer incidence, it was associated with a 63% reduced mortality due to prostate cancer.
“A meta-analysis examines all previously conducted studies. Here are some of the results from some of these studies:
?Researchers investigated the effect of dietary fatty fish intake among 6,272 Swedish men who were followed for 30 years. Results showed that men who ate no fish had a two- to three-fold increase in the risk of developing prostate cancer compared with those who consumed large amounts of fish in their diet.
?Data from the Physician's Health Study, a study spanning 22 years, found that fish consumption (=5 times per week) reduced the risk of dying from prostate cancer by 36%..
?A study conducted by the Harvard School of Public Health that involved 47,882 men over twelve years found that eating fish more than three times a week reduced the risk of prostate cancer but had an even greater impact on the risk of metastatic prostate cancer. For each additional 500 mg of marine fat consumed, the risk of metastatic disease decreased by 24%.
?In one of the best-designed studies, researchers in New Zealand examined the relationship between prostate cancer risk and EPA+ DHA in red blood cells (a more reflective marker for long-term omega-3 fatty acid intake). Higher levels of EPA+DHA were associated with a 40% reduced risk of prostate cancer.
?In a study of 47,866 US men aged 40-75 years with no cancer history in 1986 who were followed for 14 years EPA+DHA intake at the highest levels was associated with a 26% reduced risk of developing prostate cancer.”
(A link to Doctor Murrays website and newsletter will be provided below)
It is not surprising, then, that the recent headline was greeted with a great deal of skepticism by those who are experts in the field. The study itself was published in the Journal of the National Cancer Institute. ("Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial", by Theodore M. Brasky, Amy K. Darke, Xiaoling Song, et al)
They looked at data and specimens collected from men who participated in an earlier study, the Selenium and Vitamin E Cancer Prevention Trial (SELECT), a large randomised, placebo-controlled trial in Europe which aimed to test whether selenium and vitamin E reduced prostate cancer risk. The measured blood levels of omega-3 fatty acids in men with prostate cancer, and a group selected randomly. What they found was that the men with the highest blood levels of omega-3 fatty acids had the highest risk for prostate cancer.
What does this mean? Numerous experts have pointed out the various limitations of this study, and the fact that few valid conclusions can be drawn. Those responses will be presented shortly. First, let’s look at some key considerations:
?This was an “observational” study. It is inappropriate to attempt to draw “cause and effect” conclusions from observational studies. Here is an example. Suppose we are back in the 1600's and we are trying to figure out what causes gout. We analyze the data, and observe that people who live in big houses, wear wigs, and ride in fancy carriages are at much higher risk of gout than people who live in shacks and can’t afford a horse. So we call gout a “rich man’s disease,” and conclude it is caused by large houses! . . . or wearing wigs! We now know, of course, that it was the high intake of meat and alcohol, not the large house. This is the problem with drawing conclusions about cause and effect from “observational” studies.
?The study looked at omega-3 blood levels. It did not look at fish, fish oil, or fish oil supplement intake. And the differences between “high” and “low” blood levels were relatively small–about 0.2%! All within the “normal” range! These are pretty big conclusions to base on such a small difference. We do not even know if the men took supplements. So is it really appropriate for the lead author to make the statement "We've shown once again that use of nutritional supplements may be harmful." This implies a strong anti-supplement bias, and raises questions about the authors objectivity.
?A dose of common sense: If it was true that higher blood levels of EPA and DHA led to increased risk of prostate cancer, you would naturally expect to see high incidence of prostate cancer in men living in those countries where seafood represents a large portion of the diet. In Japan, studies have shown the opposite.
For those of you who would like a more detailed critique of this recent study, here are several detailed and informative responses:
CRN Says New Study On Omega-3 Conclusions Are Overblown
WASHINGTON, D.C., July 11, 2013—In response to a new study, “Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial,” published yesterday online in the Journal of the National Cancer Institute, the Council for Responsible Nutrition (CRN), the leading trade association representing the dietary supplement industry, today issued the following statement:
Statement by Duffy MacKay, N.D., vice president, scientific and regulatory affairs, CRN:
“The numerous benefits of omega-3 fatty acids from foods (like salmon and sardines) and dietary supplements are well-established for men and women in all stages of life—and this new study does not change those recommendations about the importance of this nutrient. Hundreds of studies over the past two decades have shown omega-3 fatty acids to have positive effects associated with cardiovascular health, perinatal health, inflammation, cognitive function, or cancer. Collectively, this body of research serves as the basis for numerous recommendations from respected organizations, scientific boards and healthcare practitioners that Americans get omega-3 fatty acids in their diets.
While we encourage researchers to continue to study omega-3 fatty acids with an open mind, it is counterproductive when studying nutrition for researchers to promote their study as if it were the only piece of research that counts. In this case in particular, it is especially disingenuous for the researchers to make the kinds of assertions we’ve seen in the press, given their results are in stark contrast to previous epidemiologic studies1 that not only demonstrate no correlation between omega-3 consumption through fish and/or supplementation and the risk of prostate cancer, but in many cases also showed a protective effect against prostate cancer.
Further, the researchers were quick to blame dietary supplements even though there is no evidence that anybody in this study took fish oil dietary supplements. In fact, the study demonstrates no cause and effect; it can only purport to show an association between higher plasma levels of omega-3 fatty acids and those whom the researchers advise had an increased rate of prostate cancer.
One should also consider whether this study could have simply been measuring a biomarker reflecting recent intake of fish or fish oil supplements in a group of high risk cancer patients that had been told to increase their EPA and DHA levels, as compared to a group of non-cancer patients that had not been told to consume more EPA and DHA. Plasma levels of EPA and DHA reflect very recent intake and are considered a poor biomarker of long term omega-3 intake especially when compared to red blood cell levels, which reflect medium term intake. A single fish oil dose (or hearty serving of fish at lunch) results in >100 percent increase in plasma omega-3 levels. So looking at plasma levels in healthy and sick people may only provide insight into the recent habits of these individuals.
Additionally, the study’s conclusions are also limited by the fact that the study was not designed to evaluate the question the researchers sought to confirm.
The American Heart Association, the World Health Organization (WHO), the U.S. Institute of Medicine’s Food Nutrition Board (IOM FNB) and the 2010 Dietary Guidelines all have current policies advising Americans to eat more fatty fish to get the benefits of omega-3 fish oils. It is highly unlikely this one study will change that advice. Omega-3s can also be obtained by taking one of the many supplement products on the market. For those consumers who have concerns about prostate cancer or other questions about omega-3 fatty acids, we recommend speaking with your doctor or other healthcare practitioner.”
Berquin IM, Min Y, Wu R et al. Modulation of prostate cancer genetic risk by omega-3 and omega-6 fatty acids. J Clin Invest 2007; 117: 1866–75
Wang MT, Honn KV, Nie D. Cyclooxygenases, prostanoids, and tumor progression. Cancer Metastasis Rev 2007; 26: 525–34
Terry P, Lichtenstein P, Feychting M, Ahlbom A, Wolk A. Fatty fish consumption and risk of prostate cancer. Lancet 2001; 357: 1764–6
Chavarro JE et al. A 22-y prospective study of fish intake in relation to prostate cancer incidence and mortality. Am J Clin Nutr 2008; 88: 1297–303.
Augustsson, K., et al., A prospective study of intake of fish and marine fatty acids and prostate cancer. Cancer Epidemiol Biomarkers Prev, 12(1): p. 64-7, 2003.
Szymanski KM, Wheeler DC, Mucci LA. Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr. 2010 Nov;92(5):1223-33.
Leitzmann MF, Stampfer MJ, Michaud DS, et al. Dietary intake of n-3 and n-6 fatty acids and the risk of prostate cancer. Am J Clin Nutr. 2004 Jul;80(1):204-16.
Ritchie JM, Vial SL, Fuortes LJ, Robertson LW, Guo H, Reedy VE, Smith EM.Comparison of proposed frameworks for grouping polychlorinated biphenyl congener data applied to a case-control pilot study of prostate cancer. Environ Res. 2005 May;98(1):104-13.
How a SELECTed Bad Study Became Big News
by Dr. Michael Murray
On July 10, 2013, major media headlines and news stories claimed "Too Much Fish Oil Might Boost Prostate Cancer Risk." Wow, that sure seems fishy given all of the positive health benefits linked to fish oil intake. In examining the study, there are numerous issues that clearly indicate that perhaps the conclusion is wrong, but really a study's conclusion is only as good as the study itself.
Data Used was From the SELECT Study
The pedigree of the study source is impressive. It was published in the Journal of the National Cancer Institute and was conducted by researchers from the Fred Hutchinson Cancer Center in Seattle, WA.1 Yet, the data they used is from the much maligned Selenium and Vitamin E Cancer Prevention Trial (SELECT). That is the real problem.
The SELECT study was a very large clinical study that attempted to determine whether vitamin E could prevent prostate cancer. Previous studies had shown 50 IU of vitamin E was protective against prostate cancer, but the SELECT study chose to use 400 IU of synthetic vitamin E (dl-alpha-tocopherol) at a dosage of 400 IU. Results showed that the subjects taking vitamin E alone had a 17% higher risk of prostate cancer compared to the control group.
In the new analysis, researchers measured the levels of fats in the blood (plasma phospholipids) and concluded that men with the highest concentrations of EPA, DPA and DHA-three fatty acids derived from fish and fish-oil supplements-had an increased risk of prostate cancer. Specifically, they reported a 71 percent increased risk of high-grade prostate cancer; a 44 percent increase in the risk of low-grade prostate cancer and an overall 43 percent increase in risk for total prostate cancer in a subset of patients with the highest level of these omega-3 fatty acids.
Important considerations of this data are the following:
- This study is not consistent with other studies (discussed below)
- The study did NOT include information or documentation of fish or fish oil intake in the study group. It was NOT set up initially to evaluate these factors, hence its relevance is not as significant as studies designed to specifically determine the impact of omega-3 fatty acids on prostate cancer risk.
- There is no evidence that anybody in this study took fish oil supplements or even ate fish.
In usual circumstances, plasma levels of EPA and DHA reflect very recent intake and are considered a poor biomarker of long-term omega-3 intake.
- Patients with prostate cancer may have only recently increased their fish and/or fish oil consumption.
- Fish and fish oil ingestion produces a big rise in plasma omega-3 levels in about 4.5 hours and washes out around 48 hours.
- The data may reflect cancer activity rather than a causative association. Without dietary history or documentation of fish oil use there is no way of knowing.
Lastly, the following statement by the authors suggests that they may have significant bias: "There is really no evidence that taking dietary supplements is beneficial to health, and there is increasing evidence that taking high doses is harmful." Such a statement shows a clear axe to grind in light of a great deal of scientific evidence on the value of dietary supplementation.
A Closer Look at the Reported Results
Let's take a closer look at the reported results to see if things add up. The bottom line is that they do not. Let's first take a look at the blood levels of EPA+DHA - the major forms of long-chain omega-3 fatty acids found in fish oil supplements. As Table 1 shows the levels are quite similar among the groups. These blood levels of EPA+DHA are actually quite modest and do not reflect huge levels of fish or fish supplements being consumed. The average EPA+DHA plasma level for men is generally approximately 4%. So, the levels reported here are typical, but a little lower than normal and the ratio of EPA to DHA is also a little lower as well.
Table 1. Distribution of EPA and DHA among SELECT participants by prostate cancer grade (n=2273)*
(See original article for table http://doctormurray.com/how-a-selected-bad-study-became-big-news/)
What the researchers did next was divide cancer patients up by their blood levels of fatty acids and look at the hazard ratio - the relative risk over time - associated with different levels of the various fatty acids (see Table 2). As it relates to EPA, statistical significance was not achieved for total cancer or high-grade cancer (the P value has to be less than 0.05 to be deemed anything more than random chance). For DHA, there was statistical significance. But, again, the levels of DHA are typical of what is found in men consuming modest amounts of fish. However, the level of EPA was lower than that typically found and the ratio of EPA to DHA was also lower. What this may mean is that there may be increased conversion of EPA to DHA in prostate cancer. Though one interesting observation is that the hazard ratio (HR) actually went down in high-grade prostate cancer in the group with the highest level of DHA compared to the next highest group. This suggests that it is not that significant of a factor as one would expect if it was that the higher the level the higher the HR. But, this finding has a P value of 0.09 so no real conclusions can be made as it was probably a random finding.
Table 2. Associations between EPA and DHA among SELECT participants by prostate cancer grade (n=2273)
(See original article for table http://doctormurray.com/how-a-selected-bad-study-became-big-news/)
The authors conclude that men are at higher risk of aggressive prostate cancer if the total plasma level of long-chain omega-3 fatty acids (EPA+DPA+DHA) is greater than 3.68%. If that were true, then aggressive prostate cancer would be a major health concern and the leading cause of death in any country with even moderate fish consumption. The facts are that population-based studies show just the opposite effect. For example, prostate cancer incidence and death rates are among the lowest known in populations consuming the traditional Japanese or Mediterranean diets, two diets with a relatively high content of EPA+DHA.
What do other Studies Show?
In addition to population-based studies, several studies have been conducted that were actually designed to determine the effects of fish and fish oil consumption in prostate cancer. In a detailed meta-analysis conducted in 2010, while fish consumption did not affect prostate cancer incidence, it was associated with a 63% reduced mortality due to prostate cancer.2 A meta-analysis examines all previously conducted studies. Here are some of the results from some of these studies:
Researchers investigated the effect of dietary fatty fish intake among 6,272 Swedish men who were followed for 30 years. Results showed that men who ate no fish had a two- to three-fold increase in the risk of developing prostate cancer compared with those who consumed large amounts of fish in their diet.3
Data from the Physician's Health Study, a study spanning 22 years, found that fish consumption (=5 times per week) reduced the risk of dying from prostate cancer by 36%.4 -specific death.
A study conducted by the Harvard School of Public Health that involved 47,882 men over twelve years found that eating fish more than three times a week reduced the risk of prostate cancer but had an even greater impact on the risk of metastatic prostate cancer. For each additional 500 mg of marine fat consumed, the risk of metastatic disease decreased by 24%.5
In one of the best-designed studies, researchers in New Zealand examined the relationship between prostate cancer risk and EPA+ DHA in red blood cells (a more reflective marker for long-term omega-3 fatty acid intake). Higher levels of EPA+DHA were associated with a 40% reduced risk of prostate cancer.6
In a study of 47,866 US men aged 40-75 years with no cancer history in 1986 who were followed for 14 years EPA+DHA intake at the highest levels was associated with a 26% reduced risk of developing prostate cancer.7
While some studies make an important distinction, others do not. When ascertaining the benefits of fish consumption it is important to find out how the fish is being prepared. For example, regular ingestion of fried fish was associated with a 32% increased risk for prostate cancer.8 In addition, many studies do not control for the quality of fish or fish oil. Some fish (and fish oil supplements) can contain environmental chemicals that can contribute to prostate cancer such as PCBs, heavy metals, and other toxic chemicals.9, 10 These are important considerations.
The best thing about this study is that it will stimulate more research into the role of omega-3 fatty acids in prostate health. The worst thing about this study is that it may lead to many men abandoning the use of fish oil supplements. Based upon a large amount of clinical data it makes sense for men to be consuming 1,000 mg of EPA+DHA daily for general health. And, if they are suffering from one of the over 60 different health conditions shown to be benefitted by fish oil supplementation the dosage should be increased to 3,000 mg of EPA+DHA daily.
1. Brasky TM, Darke AK, Song X, et al. Plasma phospholipid fatty acids and prostate cancer risk in the SELECT Trial. J National Cancer Inst Online. July 10, 2013 doi: 10.1093/jnci/djt174
2. Szymanski KM, Wheeler DC, Mucci LA. Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr. 2010 Nov;92(5):1223-33.
3. Terry P, Lichtenstein P, Feychting M, Ahlbom A, Wolk A. Fatty fish consumption and risk of prostate cancer. Lancet 2001; 357: 1764-6
4. Chavarro JE et al. A 22-y prospective study of fish intake in relation to prostate cancer incidence and mortality. Am J Clin Nutr 2008; 88: 1297-303.
5. Augustsson, K., et al., A prospective study of intake of fish and marine fatty acids and prostate cancer. Cancer Epidemiol Biomarkers Prev, 12(1): p. 64-7, 2003.
6. Norrish AE, Skeaff CM, Arribas GL, Sharpe SJ, Jackson RT. Prostate cancer risk and consumption of fish oils: a dietary biomarker-based case-control study. Br J Cancer 1999;81:1238-42.
7. Leitzmann MF, Stampfer MJ, Michaud DS, et al. Dietary intake of n-3 and n-6 fatty acids and the risk of prostate cancer. Am J Clin Nutr. 2004 Jul;80(1):204-16.
8. Stott-Miller M, Neuhouser ML, Stanford JL. Consumption of deep-fried foods and risk of prostate cancer. Prostate. 2013 Jun;73(9):960-9.
9. Ritchie JM, Vial SL, Fuortes LJ, Robertson LW, Guo H, Reedy VE, Smith EM.Comparison of proposed frameworks for grouping polychlorinated biphenyl congener data applied to a case-control pilot study of prostate cancer. Environ Res. 2005;98(1):104-13.
10. Mullins JK, Loeb S. Environmental exposures and prostate cancer. Urol Oncol. 2012 Mar-Apr;30(2):216-9.
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Fatty Acids and Risk of Prostate Cancer: Response to a Study Currently in the News
Dr Jeffrey Bland
News of a just-published study titled "Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial" has been covered in the mainstream media over the last several days, leading to many online discussions and quite a bit of confusion. In this video, Deanna Minich, Ph.D., vice president of education for the Personalized Lifestyle Medicine Institute, and I discuss what is known about this research by Fred Hutchinson Cancer Research Center, and also how the information should be put into context when considering the broad spectrum of information that is available about essential fatty acids.
Michael Savage Interviews Dr. D’Amico
In reaction to the recent study linking omega-3 with prostate cancer, the syndicated radio talk show host Michael Savage interviewed Professor D’Amico on his show, The Savage Nation.
Anthony D'Amico, professor of Radiation Oncology at Harvard Medical School and chief of Genitourinary Radiation Oncology at the Brigham and Women's Hospital and Dana-Farber Cancer Institute, has gained international notoriety for his work in detection and treatment of prostate cancer in more than 140 peer-reviewed publications, and he has co-edited four textbooks in Urologic Oncology.
Michael Savage is an expert in this field as well. He holds master’s degrees in Medical Botany and Medical Anthropology, and a PhD in Nutritional Ethnomedicine. As Michael Weiner (his birth name), he has written books on herbal medicine and homeopathy.
Before interviewing Professor D’Amico, Savage began by stating: “There is a very, very dangerous report out there, that many of you have panicked over, about fish oils and what happened was, the idiots in the media immediately jumped on this assistant professor’s opinion that fish oil is somehow related to prostate cancer risk, which nothing could be further from the truth."
"It’s a completely, let’s put it to you this way; it’s junk science. It was picked up by every media outlet in the country, hook line and sinker, just like the fish that they are.”
“You are going to say my opinion isn’t good enough. First of all I have a PhD in Epidemiology and Nutrition. This is right up my alley. I read the original publication ....... it’s a bogus study.”
“If my expertise isn’t sufficient for you ........we are going to have an expert with an MD, PhD whose speciality happens to be prostate cancer ........with a great Harvard degree and he will tell you what he thinks.”
During the course of the interview, Michael Savage asked Professor D’Amico what his position is on the “so called study on fish oil and prostate cancer?” He also asked him a number of other pertinent questions. In responding Professor D’Amico’s comments included the following:
Harvard professor Anthony D'Amico: “The study really cannot make the conclusion that it’s trying to..."
“The study really cannot make the conclusion that it’s trying to, because these types of studies are not cause and effect; that is, if you take the fish oil you’re going to get an aggressive or some kind of prostate cancer."
"These studies are simply association and when you have an association type study, the way you strengthen it... is that you try to adjust for that association, for all the things you know can cause prostate cancer."
"And this is the main issue with the study. They tried this, but they didn’t do it properly...they left out some very important risk factors for prostate cancer...”
“So what you’re left with at the end of the day is an association that at best is very weak and further weakened by the fact that they didn’t account for the known predictors of prostate cancer, when they were making this calculation.”
Dr D'Amico continued: “The thing that concerns me the most is that you can find almost anything associated with aggressive prostate cancer. You can find that driving a Cadillac [could be linked to it] ...if you don’t adjust for the factors that are known to be associated with it, and you know, from a truly scientific standpoint that’s what makes this association extremely weak and possibly false.”
Savage was very dismissive of the lead researcher and author of the study, Theodore Brasky PhD). He commented: “I don’t want to knock the guy that wrote it but he is really a kind of lowly assistant professor who I think was looking for some media attention.”
Savage followed up by asking “But how do we know when the men with prostate cancer started taking fish oils? Did they start taking the fish oils after they were diagnosed with prostate cancer or before?” [DG: There was no information as to whether the men were taking fish oil supplements. There was no information on their dietary fish intake. ]
Professor D’Amico replied: “It’s not discussed, it’s a good point.”
Savage then made the point that many men, when they get sick, suddenly look for anything to help them and start taking fish oils. He then said, “Does that mean it caused it? Of course not.”
Savage added, “So the study is really valueless as far as I can tell.”
Professor D’Amico concluded, “The scientific strength of it is weak, at best.”
Latest Omega-3 Prostate Cancer Study – Don’t Believe All You Read
Omega-3 and prostate cancer are making headlines after the latest study. There is good and bad about getting your health information off the Internet. The good is that you have all the latest studies at your fingertips. And the bad is that you have all the latest studies at your fingertips. The media loves to jump on the latest story that goes against all the other evidence. How does this relate to omega-3 fatty acids from fish oil and your prostate you ask? Well there are countless studies on the benefits of taking omega-3 fatty acids for prostate health, but then one recent study on omega-3 and prostate cancer was published stating the opposite, that omega-3 fatty acids can cause prostate cancer. That leaves people like us who don’t know whether to keep heading up stream or turn around and forget everything we have ever known about these healthy oils.
What Is Omega-3?
Omega-3 fatty acids are considered essential because they are not made by the body and must be consumed through food or supplements. Common sources are fish oil and flaxseed oil. Omega-3 fatty acids are a type of polyunsaturated fat that has many health benefits in the body including lowering cholesterol and triglycerides, being good for blood pressure and cardiovascular health, helping the body with responding to insulin, and by preventing cancer cell growth including prostate cancer.
What Are the Studies on Omega-3 Preventing Prostate Cancer?
Researchers conducted a study at UC San Francisco that was published in 2009 on omega-3 and prostate cancer. They studied 466 men with an aggressive form of prostate cancer and 478 healthy men. They screened the men for a gene known to increase risk of prostate cancer and had them men fill out questionnaires about diet.
After compiling the data, researchers saw that men who ate dark fatty fish like salmon at least once per week had a 63% reduced risk of developing prostate cancer. Men who consumed little to no fish and had the gene variation were 5 times more likely to develop advanced prostate cancer. The researchers concluded that omega-3 might decrease inflammation in the prostate and the progression of cancer by having an effect on the gene.
Cancer Prostate in Sweden
A large Swedish study also looked at men who had this same gene and fish consumption. Researchers found that the risk of prostate cancer was 43% lower in men who consumed salmon and similar fish more than one time per week when compared with men who never ate fatty fish.
Researchers conducted a large Physician’s Health Study at Harvard School of Public Health of over 20,000 men. They found that of the men diagnosed with prostate cancer, the men who ate fish at least 5 times per week had a 48% lower risk of dying from prostate cancer.
What About the Latest Study?
Keep in mind that this is one study, and it may not be the best study. It is a retrospective study as described by Dr. Geo, which means it looks back over time at a different trial and it does not show cause and effect. This study was conducted by Theodore Brasky and his team. The abstract can be found here.
The researchers looked at specimens from the SELECT trial. These findings indicate that high concentrations of EPA, DPA, DHA (which are anti-inflammatory fatty acids that come from fatty acids and fish oil supplements) are connected to a 71% increase in the risk for high-grade prostate cancer. Additionally, the study found a 44% increase in the risk of low-grade prostate cancer, and a 43% increase in risk for all kinds of prostate cancers. But what the researchers did not account for is the known risk factors of prostate cancer:
- PSA level
- DRE (digital rectal exam)
- Body Mass Index (BMI)
These known risk factors were not considerations in the study, which could heavily affect the findings. Also, the study did not say when the men started taking fish oils, before or after they were diagnosed with prostate cancer.
An interesting aspect of this study is that is found that omega-6 fatty acids were associated with a lower risk of prostate cancer, which is in conflict with most other studies. Most other research has found excessive omega-6 fatty acids to contribute to the risk of prostate cancer. Also interesting is that the study group published a paper in 2011 stating that unhealthy trans fatty acids (found in margarine and known to increase risk of heart disease) were associated with decreasing the risk of aggressive prostate cancer. These researchers are going against mountains of well-researched evidence against trans fat, omega-6 and omega-3.
- See more at: http://www.prostate.net/2013/prostate-cancer/omega-3-prostate-cancer-study/#sthash.EQDbGWuy.dpuf