Two new lab studies reinforce serious cancer risks of common dietary imbalance 
by Craig Weatherby 

Echoing the results other cancer-cell studies, two scientific teams now report that omega-3 fatty acids from fish may help to prevent the growth of prostate cancer, while the omega-6 fats that predominate in common vegetable oils may speed its spread.


Prostate cancer is the third most common cancer in men worldwide with 543,000 new cases each year, and it is both is more treatable and has a better survival rate if it is diagnosed and treated in its earliest stages.


Omega-3s seen to curb prostate cancer growth

Lead researcher Mick Brown, Ph.D. of Christie Hospital in Manchester, England said the results of his research suggest that diets rich in omega-3 fatty acids might help to inhibit the spread of the disease in men with early prostate cancer.

Dr. Brown's team found that prostaglandin E2, a metabolite (breakdown product) of the essential omega-6 fat called arachidonic acid, accelerated the spread of prostate cancer cells to bone marrow cells.


However, when the fish-derived omega-3 fats called EPA and DHA were present at just half the concentration of the omega-6 fatty acid, spread of the prostate cancer cells came to a halt.


As Dr. Brown said in a press release, "Omega-6 fats, found in vegetable oils, nuts and seeds, increased the spread of tumor cells into bone marrow. This invasion was blocked by omega 3 fats: the ones found in oily fish. It is possible to have a healthy balance of these two types of fat—we only need about half as much omega-3 as omega-6—that will still stop cancer cells from spreading".


Researchers have found omega-3 fatty acids interfere with functions of omega-6, which cancer cells may use as a source of energy, and prevent them from spreading beyond the prostate gland.


Study co-author Noel Clarke echoed Dr. Brown's comments, saying, "Eating a diet with the right balance of omega 3 and omega 6 fats may well help to keep prostate cancer within the prostate gland where it may be monitored safely or more easily treated with surgery or radiotherapy."


Omega-6s seen to speed prostate cancer growth

Conversely, the results of another new study support earlier findings that omega-6 fats promote the growth of cancer.


In a previous study, Dr Millie Hughes-Fulford of the San Francisco VA Medical Center introduced the omega-6 fatty acid called arachidonic acid into human prostate tumor cells in culture. They found that the arachidonic acid promoted production of the enzyme cPLA2, which in turn caused a chain of biochemical reactions that led to tumor growth.


When her team added omega-6 fatty acids to a growth medium feeding cancer cells, they observed that tumors grew twice as fast as those without omega-6.


And her team uncovered a possible reason for this undesirable effect: "Investigating the reasons for this rapid growth, we discovered that the omega-6 was turning on a dozen inflammatory genes that are known to be important in cancer. We then asked what was turning on those genes, and found that omega-6 fatty acids actually turn on a signal pathway called PI3-kinase that is known to be a key player in cancer."


In 2004, a Spanish team reported that omega-6 fats enhanced expression of certain genes that accelerate breast cancer.


The results of these studies define specific dangers linked to the increased levels of omega-6 fatty acids in the modern American diet.


In 1945, the dietary ratio of omega-6 to omega-3 in the US was about three or four to one. Today, the ratio is as high as 15 or 20 to one. During the intervening decades, the rate of prostate cancer here has increased steadily.




  • Brown MD, Hart CA, Gazi E, Bagley S, Clarke NW. Promotion of prostatic metastatic migration towards human bone marrow stoma by Omega 6 and its inhibition by Omega 3 PUFAs. Br J Cancer (2006) 94, 842-853. doi:10.1038/sj.bjc.6603030 Published online 7 March 2006
  • Hughes-Fulford M, Li CF, Boonyaratanakornkit J, Sayya S. Arachidonic Acid Activates Phosphatidylinositol 3-Kinase Signaling and Induces Gene Expression in Prostate Cancer. Cancer Res 66, 1427-1433, February 1, 2006.