Omega-3 fatty acids and cancer
Some properties of Omega-3s make these fatty acids potential anticancer molecules.
Their biological and molecular characteristics, as well as their ability to interact with other nutrients such as omega-6 fatty acids and antioxidants, lead to speculation that they may significantly hinder the occurrence of some forms of cancer.
Not only that, these molecules also have all the credentials to succeed in enhancing the effect of some anticancer therapies.
In fact, it is known that Omega-3 competes withlinoleic acid, an Omega-6 fatty acid. The latter is a key nutrient in cancer.
Through this competition, Omega-3 would be able to reduce the amounts that the tumor mass takes from the bloodstream.
But the dispute between Omega-3 and Omega-6 is not limited only to this phenomenon. In fact, the 2 types of fatty acids also compete at the level of the activity of certain enzymes that promote the formation of molecules that promote the development of cancer.
In addition, Omega-3s make cancer cells more sensitive to the action of free radicals, highly reactive molecules that damage cellular structures. In fact, the membranes of cancer cells are richer in unsaturated fatty acids, a grouping to which Omega-3s also belong, and poorer in saturated fatty acids, which conversely make the membrane stiffer and less vulnerable.
Finally, while linoleic acid promotes the survival of neoplastic cells by activating a gene that prevents their death, Omega-3s promote theself-destruction of cancer cells, thus limiting the expansion of cancer
A budgetary issue
Studies have shown that the protective effect of Omega-3 on cancer depends on the balance between these fatty acids and Omega-6. Specifically, the higher the ratio of Omega-3 the lower the incidence of cancer.
In fact, it has long been known that if guinea pigs in whom tumor development has been artificially induced are fed a diet characterized by high levels of Omega-6, such as corn oil, their mortality rate increases significantly.
Conversely, in the same animals, survival levels increase if they are given high-dose fish oil, a source of high amounts of Omega-3. Not only that, a reduction in the size of the tumor mass can also be detected in these animals.
The anticancer properties of a diet rich in Omega-3s
These data obtained in animals lend support to the hypothesis that Omega-3s can delay or, even, reverse the development of various forms of cancer. But studies in humans also seem to confirm this theory.
As early as 1997, researchers at the University of Cape Town (South Africa) showed that a diet rich in fish, the main source of Omega-3, reduces the occurrence of cancer.
The authors of this study compared the incidence of colon cancer between Cape Town residents and fishermen residing in villages located on the coast. Although individuals who lived in the city also followed a healthy diet, characterized by high amounts of fruits, vegetables and nutrients known to have protective properties against colon cancer, such as fiber, calcium and antioxidants, the likelihood of developing this form of neoplasm was 6 times lower in coastal villagers.
Blood tests revealed that those who lived by the sea were characterized by blood levels of Omega-3 three times higher than Cape Town residents. The researchers justified this difference by the higher amount of fish in the diet of coastal dwellers.
These data have, therefore, shown that an adequate ratio of Omega-3 to Omega-6 protects against the occurrence of colon cancer.
Cancer therapies: omega-3s as adjuvants
These results do not mean that Omega-3s can be considered the ultimate remedy in the treatment of some forms of cancer. Data collected over years of trials suggest that these fatty acids can yield excellent results when used in combination with traditional treatments.
An example of this effectiveness was provided by researchers at Aston University in Birmingham, UK, who tested the potential of Omega-3s in treating cancer patients with cachexia.
The latter is a condition of extreme weight loss associated with weakness at the physical and psychological levels. Unfortunately, this disorder affects half of all individuals with cancer, coming to be the cause of death in 10-25% of cancer patients.
Not only that, comparing the survival of individuals with the same form of cancer, in those with cachexia, life expectancy is cut in half.
Nevertheless, British researchers have shown that the administration of eicosapentaenoic acid (EPA), one of the Omega-3s contained infish oil, is sufficient to significantly reduce weight loss in just three months.
Another significant example was provided by scientists at the University of Iowa (Iowa City, USA), who investigated the usefulness of Omega-3s in enhancing radiation and chemotherapy.
Both radiation and some chemotherapy drugs kill cancer cells by generating high amounts of free radicals, which damage membranes to such an extent that the cells are driven to self-destruction.
For their part, Omega-3s make cell membranes even more sensitive to the action of free radicals. This leads to an amplification of both the effects of radiotherapy, as well as those of chemo.
These results confirm earlier observations by researchers at the Allie M. Lee Laboratory for Cancer Research at the University of Nevada (Reno, U.S.), who compared the utility of corn oil and fish oil intake in rats in which tissue from human breast cancer had been implanted.
Again, treatment with a chemotherapeutic drug, myotomycin C, had been augmented by the combined intake of Omega-3s found in fish oil, which amplified the drug's efficacy 10-fold while reducing the rate of tumor growth.
In addition, the toxicity of cyclophosphamide, another well-known chemotherapy drug that killed 50 percent of animals fed corn oil after 60 days of treatment, was negated by simultaneous intake of fish oil.
More recently, the journal Nutition and Cancer published research from the same university in which supplementation with high doses of Omega-3, 15 grams of EPA and DHA (docosahexaenoic acid) , accompanied by a reduction to minimal levels of Omega-6 intake, cured a patient suffering a severe form of lung cancer.
Omega-3 and breast, colon, prostate cancers: proven efficacy
Since the first studies, several researches have confirmed the effectiveness of Omega-3 intake in the prevention and treatment of various types of cancer.
First, the usefulness of these fatty acids in colon cancer has been confirmed.
A study from the Catholic University of Rome has shown that daily treatment with Omega-3, specifically 4.1 grams of EPA and 3.6 grams of DHA, of patients with precancerous colon polyps is able to significantly decrease cell proliferation in just 2 weeks.
Not only that, the therapy was found to be well tolerated and free of significant side effects.
For these reasons, Italian researchers concluded that fish oil is a valuable aid for individuals at high risk of colon cancer.
These findings were later confirmed by a group of researchers from Harvard Medical School in Boston, USA. Their studies, too, have, in fact, shown that regular intake of fish oil prevents the appearance of new pre-cancerous polyps without side effects and being well tolerated by patients.
Other forms of cancer against which Omega-3s would be effective are prostate cancer and possibly breast cancer.
In the case of breast cancer some very interesting data have been obtained by Lillian Thompson and colleagues at the University of Toronto (Canada), who studied the effects of flaxseed intake by rats.
Researchers have shown that these seeds contain not only Omega-3 alpha-linolenic acid but also lignan, a molecule that is able to block the production of estrogen, female hormones.
Both of these molecules, the research authors explain, can reduce the size of breast tumors by 50 percent. But while the omega-3 fatty acid is most effective in already diagnosed forms of cancer, lignan exerts its anti-cancer action by blocking the formation of new neoplasms.
In contrast, a study from the Lombardi Cancer Center in Washington, U.S., has shown that Omega-3 intake by pregnant women characterized by significantly elevated estrogen levels reduces the likelihood that their daughters will develop breast cancer in adulthood.
Finally, a study conducted at the Hôpital Bretonneau in Tours, France, has shown that in breast cancer, levels of DHA present in adipose tissue is a predictor of sensitivity to chemotherapy.
Ihe treatment of metastases
Another interesting potential of omega-3 fatty acids in oncology concerns their ability to reduce the incidence of metastasis.
In fact, in order for a cancer cell to migrate away from the starting cancerous mass and colonize other areas of the body (thus originating a metastasis) it needs to adhere to the membranes that line both blood vessels and organs. The next step is the crossing of these membranes.
Omega-3s impair precisely the ability of cancer cells to adhere to membranes. This function is based on the inhibition of certain molecules that regulate cell adhesion processes.
And in case the cancer cells manage to attach to the membranes, Omega-3 fatty acids can interfere with the next step by blocking the production of the enzyme collagenase. This molecule, in fact, is needed to dissolve membranes and allow cancer cells to cross them.
Several studies have confirmed this potential. As early as 1994, a French study of 120 breast cancer patients showed that women in whom the adipose tissue associated with the breast was deficient in Omega-3 alpha-linolenic acid were 5 times more likely to develop metastases.
Subsequently, researchers at the American Health Foundation in Valhalla, New York, USA, showed that in rodents, a diet rich in the Omega-3 EPA and DHA prior to surgical removal of breast cancer reduced the likelihood of spread.
Not only that, the richer the diet is in these nutrients, the smaller the volume of any metastases that form in the animals.
Cancer patients who enrich their diets with EPA and DHA could benefit from the same effects. In fact, human cancer cells rich in these omega-3s that move away from the original cancer mass might grow more slowly and be less likely to colonize other parts of the body.
An aid to recovery
Finally, enriching yourdiet with Omega-3s can help you regain good health after surgery.
Evidence of this potential comes from a study conducted at Deaconess Hospital in Boston, United States. According to the data obtained in this research, cancer patients recover more readily after gastrointestinal surgery if they take Omega-3 with food than patients treated with standard postoperative procedures.
Specifically, intake of these Omega-3s is associated with reduced digestive problems, more regular kidney and liver function, lower triglyceride levels, and a 50% decrease in the number of postoperative infections.