Fish Oil Omega-3 Fatty Acids Offer the First Line of Defense Against Prostate Cancer
In contrast to this attack on omega-3s, the scientific literature identifies diets high in omega-6 fats, trans-fatty acids, and saturated fats as associated with greater prostate cancer risk, whereas increased intake of long-chain omega-3 fats from fish has been shown to reduce risk. Based on consistent findings across a wide range of human populations, scientific research has identified why eating the wrong kinds of fatty acids provokes a stimulatory effect on prostate cancer.29,30
To ascertain what occurs after dietary fatty acids are consumed, the biochemical pathways shown on the chart below provides the answers. For example, let us assume that for dinner, you eat a steak (a source of saturated fat, as well as arachidonic acid) and a salad, along with a typical dressing rich in an omega-6 fat such as soybean or safflower oil.
Omega-6 fat readily converts to arachidonic acid in the body. As shown on the chart below, the body attempts to compensate for excess arachidonic acid through the 5-lipoxygenase (5-LOX) pathway. Multiple studies strongly show that 5-LOX enzymatic by-products like leukotriene B4 and 5-HETE directly stimulate prostate cancer cell proliferation through several well-defined mechanisms.31-36
For example, arachidonic acid is metabolized by 5-LOX to 5-hydroxyeicosatetraenoic acid (5-HETE), a potent survival factor that prostate cancer cells use to escape destruction.37,38 Consuming a diet of foods rich in arachidonic acid, or precursors to arachidonic acid like the omega-6 fat linoleic acid, directly provokes the production of dangerous 5-LOX metabolic by-products, which can promote the progression of prostate cancer. In addition to 5-HETE, 5-LOX also metabolizes arachidonic acid into leukotriene B4, a potent pro-inflammatory agent that causes destructive reactions throughout the body and inflicts severe damage to the arterial wall.39-41
If arachidonic acid levels are reduced, a corresponding suppression of the 5-LOX products 5-HETE and leukotriene B4 will occur. A wealth of scientific research clearly demonstrates that supplementation with long-chain fatty acids like EPA and DHA from fish oil can help reduce the production of arachidonic acid-derived eicosanoids in the body.42
In contrast with the misinterpreted results presented in this report of men who were not consuming significant amounts of omega-3s, many other clinical studies indicate substantial benefit with omega-3 fatty acid intake in prostate cancer.
Additional Studies Indicate Substantial Benefit with Increased Intake of Omega-3 Fatty Acids
The report attacking omega-3s conflicts with prior studies demonstrating that increased intake of omega-3 fats has been shown to reduce prostate cancer risk and diets high in omega-6 fats are associated with greater risk. This flawed analysis suggests a relationship between increased omega-6 fatty acid levels and decreased risk of prostate cancer, which is, again, utterly inconsistent with the known pro-inflammatory effects of omega-6 fatty acids. The following studies, overlooked by the headline hungry media, show a reduction in prostate cancer in response to higher omega-3 status:
- A 2010 meta-analysis found a 63% reduction in prostate cancer death rates in those with higher fish consumption.2
- A 2004 study of 47,866 men found a trend toward decreased risk of prostate cancer with increasing levels of EPA and DHA.3
- A 2007 Harvard study of 14,916 men found lower incidence of prostate cancer in men who had higher levels of long chain omega-3 fatty acids.4
- A 2013 Harvard study of 293,464 men found increased omega-3 fatty acid intake was associated with significantly lower rate of fatal prostate cancer. 5
- A 2012 Harvard study of 525 men found a 40% lower prostate cancer death rate among men with the highest intake of marine fatty acids. 6
- A 2011 Duke University study found an increased omega-6:omega-3 ratio (i.e., more omega-6 and less omega-3) was associated with a significantly elevated risk of high grade prostate cancer.7
- A 1999 New Zealand study found significantly lower rates of prostate cancer with higher blood levels of EPA and DHA.8
- A 1999 Korean study found increased blood levels of omega-3 fatty acids associated with lower rates of prostate cancer and benign prostatic hyperplasia. 9
- A 2003 prospective study reported “that men with high consumption of fish had a lower risk of prostate cancer, especially for metastatic cancer.” 11
- A 2010 study that evaluated nutrient intake and prostate cancer risk concluded “High intake of omega-6 fatty acids, through their effects on inflammation and oxidative stress, may increase prostate cancer risk.”43
- The University of Chicago conducted a study published in 2004 that showed PSA levels rose in tandem with the omega-6 to omega-3 ratio in Jamaican men whose PSA was >10 ng/mL. The researchers noted, “Increased levels of Omega-6 PUFAs and the ratio of Omega-6/Omega-3 PUFAs in Jamaican men are associated with an increased mean PSA level and risk of prostate cancer.”44
- In addition to the clinical trial literature indicating consistent benefits with omega-3 fatty acid intake, traditional Japanese and Mediterranean diets rich in omega-3 fatty acids show a strong, consistent risk reduction in prostate cancer vs. Western diets rich in omega-6 and saturated fat.
Traditional Diets in Japan and The Mediterranean Region High in Fish are Protective Against Prostate Cancer
The results set forth by authors of the negative report on fish oil that omega-3 intake may be linked to prostate cancer are inconsistent, and in abject contrast, to longstanding evidence that diets high in marine lipids, such as the traditional Japanese diet and the Mediterranean diet, are protective against prostate cancer.
For example, the traditional Japanese diet, rich in omega-3 fatty acids from fish, confers protection against prostate cancer, as does the relatively high intake of fermented soy products and relatively low levels of saturated fat.45 The characteristics of the traditional Japanese diet high in soybean products, high in fish, and low in red meat are highly relevant in prostate cancer biology. In all likelihood, the traditional Japanese diet reduces the risk of prostate cancer through a combination of characteristics that generate a synergistic, anti-cancer effect (on prostate cancer.)
Likewise, the protective properties of the Mediterranean diet in relation to heart disease and prostate cancer risk are well-established. Several aspects of this dietary pattern are protective, including regular consumption of small fish (smaller fish are less likely to contain contaminants than larger predatory fish such as tuna), high olive oil intake (there is synergy between olive polyphenols and fish oil), high daily ingestion of fresh vegetables, whole fruits (not pasteurized fruit juice rich in concentrated fructose), high-fiber cereals and legumes, and low intake of saturated animal fats and red meat.46
Benefit Clearly Outweighs Risk for Fish Oil Supplementation Among Men
Overwhelming evidence currently available strongly favors fish oil supplementation for most aging humans.
Fish oil and greater marine omega-3 intake have repeatedly and consistently been shown to reduce cardiovascular risk across multiple types of studies. For example:
- A randomized, placebo-controlled trial found 1,800 mg of combined EPA plus DHA was associated with a 10% lower rate of cardiac events, 12% lower rate of non-fatal infarctions, and an almost 11% lower rate of cardiac deaths.47
- In a large intervention study, 18,000 patients were randomized to receive either a statin medication alone or a statin plus1,800 mg of EPA-fish oil daily. After five years, those with a history of coronary artery disease had a 19% lower rate of major coronary events in the statin-plus EPA-fish oil group compared to the statin-only group.48
- A randomized, double-blind, placebo-controlled trial with chronic hemodialysis patients found that 1,700 mg of omega-3 fatty acids daily was associated with a 70% reduction in the relative risk of myocardial infarction.49
- A randomized, controlled trial using 3,300 mg of EPA and DHA (and then a decreased dosage) found a trend toward lower cardiovascular event occurrence with fish oil supplementation. Seven cardiovascular events occurred in the placebo group (not given fish oil) while only two cardiovascular events occurred in the fish oil-supplemented group during the study.50
- A meta-analysis with an average fish oil dose of 3,700 mg found lowered systolic blood pressure by an average 2.1 mmHg and diastolic by 1.6 mmHg.51
- In a randomized trial with peripheral arterial disease patients, 2,000 mg of omega-3 fatty acids daily resulted in a 49% improvement in flow-mediated dilation, a marker of endothelial cell health.52
- The GISSI-Prevenzione study (a large, randomized, controlled trial) found that 1,000 mg/day of EPA and DHA in 11,323 patients with a history of recent myocardial infarction reduced the risk of total mortality by 20% and sudden death by 45%.53,54
- The DART study — a randomized, controlled trial that examined the effects of advising 2,033 subjects to increase dietary fatty fish — revealed a 29% reduction in all-cause mortality compared with those not advised.55
- A 2009 meta-analysis of randomized, controlled trials found that dietary supplementation with omega-3 fatty acids reduced the incidence of sudden cardiac death in subjects with prior myocardial infarction.56
- Another 2009 meta-analysis of randomized, controlled trials found that dietary supplementation with omega-3 fatty acids reduced the risk of cardiovascular death, sudden cardiac death, all-cause mortality, and non-fatal cardiovascular events in patients with a history of certain cardiovascular events or risk factors.57
- A 2008 meta-analysis found a significant reduction in death from cardiac causes with fish oil supplementation.58
- A 2002 meta-analysis of randomized, controlled trials concluded that omega-3 fatty acids reduced overall mortality, mortality due to myocardial infarction, and sudden death in patients with coronary heart disease.59