BOGUS CLAIM by the Researcher??
Dr. MICHAEL MURRAY from GREEN MED INFO Refuted:
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. 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% increased risk of high-grade prostate cancer; a 44% increase in the risk of low-grade prostate cancer and an overall 43% 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:
1. This study is NOT consistent with other studies (discussed below).
2. 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.
3. There is NO evidence that anybody in this study took fish oil supplements or even ate fish.
4. 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.
5. Patients with prostate cancer may have only recently increased their fish and/or fish oil consumption.
6. 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.
7. 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)*
That 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)
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 studiesshow 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 mortalitydue 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 2-3 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 (≥5x per week) reduced the risk of dying from prostate cancer by 36% -specific death.
A study conducted by the Harvard School of Public Health that involved 47,882 men over 12 years found that eating fish more than 3x 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 yearsEPA+DHA intake at the highest levels was associated with a 26% reduced riskof developing prostate cancer.
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. 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. These are important considerations.
Dr. Murray reckons that men should be consuming 1000mg of EPA & DHA DAILY for general well-being and increase to 3000mg DAILY if suffering from any of the more than 60 different heart conditions proven to have benefitted from FISH OIL supplements than to forego based on the extensive positive clinical data available.
Dr. JOSEPH MERCOLA wrote extensively in response to this featured study:
“Omega-3 rich fish oil is one of the most well-researched substances on the market. Its wide ranging health benefits have been repeatedly proven, and animal-based omega-3 is one of the few supplements I recommend for virtually everyone to improve overall health.”
- “These headlines are perfect examples of gross misreporting of science by the media, and it is instances like this that demonstrate why you cannot trust the conventional press to keep you informed about health”.
- “I couldn’t agree more” with Dr Jonny Bowden (Huffington Post) who reported that this featured study to be “disgraceful, incompetent, and scientifically illiterate.”
- Researchers had equated higher DHA (omega-3 fat) blood levels to: i) the higher risk of prostate cancer, and ii) 71% higher risk to develop high-grade (abnormality level of cancer cells) prostate cancer, and concluded that omega-3 fatty acids caused “Prostate Tumorigenesis” despite the ABSENCE of correlation for EPA and ALA.
- “Most absurd advice I have seen in a long time”:
– especially to conclude that omega-3 supplements are ‘dangerous’, based on the featured study where Theodore Brasky(lead author) warned, “men with a family history of prostate cancer should discuss with their doctor whether fish oil supplements are safe for them” in view of fish oil Supplements leaning towards a concentrated composition of omega-3 fats
-Basky recommended that men taking supplements should reduce their Fatty Fish consumption though not completely “eliminate”, otherwise they would have too much of DAILY fish oil on the grounds that the supplement are made up of approximately 30-60% of ONE Serving of fish.
- “Another immediate tip-off that something’s awry is the finding that participants who had the highest levels of trans fats in their blood had the lowest risk for prostate cancer…”
- DHA levels reported may be “meaningless” as levels were “based on percentage of total fatty acids rather than the absolute value, which in and of itself can be quite misleading, as it actually obscures any real differences”.
“A cohort study…found that men who were overweight or obese increased their risk of prostate cancer by 57%– a percentage that falls right smack in the middle of that 44-71% range attributed to high DHA serum levels in the featured study. And this association between obesity and prostate cancer held for all cases- low-grade and high-grade, early stage and late, nonaggressive and aggressive prostate cancer.”
Dr. ROBERT ROUNTREE (MD; Chief Medical Officer, Thorne Research) commented:
- “A number of confounding risk factors might have influenced the purported outcomes in the study, despite attempts by the investigators to account for them:
*53% of the subjects with prostate cancer were smokers.
*64% of the cancer subjects regularly consumed alcohol.
*30% of the cancer subjects had at least one first-degree relative with prostate cancer.
*80% of the cancer subjects were overweight or obese.”
- “Considering the extensive body of literature that supports the anti-inflammatory effects of omega-3 fatty acids, there is NO credible biological mechanism, NOR is one suggested in the article, that would explain WHY these essential fatty acids might increase tumorigenesis.”
- “Given the inconsistent data attributable to omega-3 fatty acids and prostate cancer, and acknowledging the broad range of health benefits that are almost universally accorded to omega-3 fatty acid consumption, it would be premature to stop eating fish or to discontinue taking omega-3 nutritional supplements on the basis of this study.”
Time Magazine (11 July 2013):
“The study …did NOT include information on the volunteers’ eating habits, so researchers could NOT differentiate between the effects of fatty acids from fish from those of supplements. …overwhelming majority of the participants did NOT take fish oil supplements.”
DR. JOHNNY BOWDEN (PhD, CNS; Huffington Post) argued:
“NO fish oil supplements — or any other kind of supplements, for that matter — were given in this study. …Supplements weren’t a part of the study and weren’t given to the participants. Period”
“If blood levels of omega-3s are the problem, fish should be just as “dangerous” as fish oil supplements.”
“How do you explain the fact that reporter after reporter and news outlet after news outlet conveniently equated higher blood levels of DHA with “fish oil supplement taking”? There’s almost no other explanation other than a strong anti-supplement bias and a desire for shocking headlines. And any doubt about the objectivity of the researchers should have been abandoned after one of them — Dr. Alan Kristy — told reporters, “We’ve shown once again that use of nutritional supplements may be harmful.””
“Want to know what else the researchers found? Participants who had the highest levels of trans fats in their blood also had the least risk for prostate cancer.”(??!!)
DENISE MINGER in her Blog, Raw Foods SOS, reasoned:
“Serum fatty acids aren’t a perfect mirror of diet—and the men with higher levels of DHA weren’t necessarily eating more fish. In fact, it seems low-fat diets can actually increase DHA status in the blood the same way omega-3 supplementation can.”
Minger supported her statement through the study published in The Journal of Nutrition (1 February 2001) 131(2):231-234:
“Free fatty acid compositions are responsive to total dietary fat content. Specifically, the consumption of a low fat diet promotes an increase in the level of total and highly unsaturated long-chain (n-3) fatty acids and a decrease in the total (n-6) content of plasma phospholipid and cholesteryl ester fatty acids. The observed modifications in phospholipid and cholesteryl ester fatty acids in response to a low fat diet are similar to those observed when (n-3) fatty acids of plant or animal origin are fed.”
DONNIE YANCE (Cert.Nutritionist; Reg.Herbalist, American Herbalist Guild) insisted:
“..at least 20 clinical studies from major medical journals … have found only positive effects of omega-3 fatty acids (in the form of dietary fish or fish oil) on inhibiting and/or suppressing prostate cancer.”
OTHER PREVIOUS PUBLICATIONS taking on Omega-3/Fish oil and/or Prostate Cancer contested:
- British Journal of Cancer (2006) 94:842–853:
Omega-6 fats (found in most vegetable oils) increased prostatic tumor cells’ spread into the bone marrow where on the other hand, omega-3 fats blocked cancer cells’ spread therefore implicating the potential prohibition of “early stage prostate cancer” by omega-3 fats.
- American Journal of Clinical Nutrition (2009):
“Expressing plasma phospholipid fatty acid composition as a percentage of the total is meaningful only when the total fatty acid content is identical for all subjects. …
…evaluation of the association between the risk of prostate cancer and plasma phospholipid fatty acid composition on the basis of actual content is more appropriate than that based on a percentage of the total.”
- American Journal of Clinical Nutrition (2010 Nov) 92(5):1223-33:
A more recent meta-analysis of available research tied fish consumption to a 63% reduction in prostate cancer-specific mortality, even though there was NO association between fish consumption and significant reduction in prostate cancer incidence.
- Public Library of Science, PLoS One (2011):
“Obese RP patients were more likely to have lower PFP values than non-obese patients, suggesting a higher risk of experiencing prostate cancer progression. Identifying men with potentially higher risks due to obesity may improve disease prognosis and treatment decision-making.”
- Cancer Epidemiology, Biomarkers & Prevention (22 April 2013):
“Obesity is associated with the presence of PIN in benign specimens and with future prostate cancer risk after an initial benign finding. …
Obesity may be a factor to consider when planning clinical follow-up after a benign biopsy.”
- Public Library of Science, PLoS One (17 April 2013)
The study of 2268 men demonstrated “salted or smoked fish may increase risk of advanced prostate cancer, whereas fish oil consumption may be protective against progression of prostate cancer in elderly men. In a setting with very high fish consumption, no association was found between overall fish consumption in early or midlife and prostate cancer risk.”
Surely, this featured study has gotten what they may have intended in the first place, ATTENTION, and lots, but unfortunately, in a negative mode!!______________________________________________________________________________________________________________
SOURCE REFERENCES & FURTHER READING:
A BOGUS REPORT? -Fish Oils may raise Prostate Cancer Risks…