Omega-3 fatty acids have been linked with everything from improving memory to helping reduce chronic inflammation. This essential part of our diet, according to new research, may even benefit people who have been diagnosed with bowel cancer.
The research team found that a high dietary intake of omega 3 fatty acids, derived from oily fish, may help to lower the risk of death from bowel cancer in patients diagnosed with the disease. Does this mean patients with bowel cancer can potentially prolong their survival?
Previous experimental research has shown that omega 3 polyunsaturated fatty acids (PUFAs) —namely, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) — can suppress tumor growth and curb blood supply to malignant cells (angiogenesis).
The researchers base their findings on the participants of two large long term studies
All participants filled in a detailed questionnaire about their medical history and lifestyle factors when they joined the studies, and continued doing so every two years.
Participants were asked to report any diagnosis of bowel cancer as well as other potentially influential factors, such as height, weight, smoking status, regular use of aspirin and non-steroidal inflammatory drugs and exercise.
Data on what they ate was collected and updated every four years, using Food Frequency Questionnaires, with categories for each nutrient ranging from "never or less than once a month," to "6 or more times a day."
The completeness of the data was above 95% for each of the questionnaires in both studies all the way through 2010.
Among 1,659 participants who developed bowel cancer:
Other major causes of death included cardiovascular disease (153) and other cancers (113).
Participants with a higher dietary intake of omega 3 from oily fish were more likely to be physically active, to take multivitamins, to drink alcohol and to consume more vitamin D and fiber. They were also less likely to smoke — all factors associated with a lower risk of bowel cancer.
Those who were diagnosed with bowel cancer and whose diets contained higher levels of marine omega 3 had a lower risk of dying from the disease. Omega 3 intake, however, was not linked to a lower risk of death, overall.
The extent of the reduced risk seems to be linked to dose, the researchers explain, with higher doses associated with lower risk. This held true even after researchers took account of intake prior to the diagnosis, as well as other potentially influential factors.
Compared with patients who consumed under 0.1 g of omega 3 fatty acids daily, patients who consumed at least 0.3 g daily after their diagnosis had a 41% lower risk of dying from their disease.
This reduced risk applied to food sources and supplements, although few people used omega 3 fish oil supplements, the researchers point out.
The association between marine omega 3 intake and lowered risk of death seemed to be particularly evident among those who were tall, had a BMI below 25 or who didn't take regular aspirin.
And increasing intake of marine omega 3 by at least 0.15 g daily after diagnosis was associated with a 70% lower risk of dying from bowel cancer; while a reduction in daily intake was associated with a 10% heightened risk of death from the disease.
Similar patterns were evident for death from all causes (13% lower and 21% higher, respectively) in those who either increased or decreased their intake after diagnosis.
This is an observational study so no firm conclusions can be drawn about cause and effect, but the researchers say that their findings provide the first line of population-based evidence for the potentially positive impact of oily fish omega 3 fatty acids on bowel cancer survival.
"If replicated by other studies, our results support the clinical recommendation of increasing marine omega 3 PUFAs among patients with bowel cancer," they conclude.
While we wait for more conclusive results, however, we all should strive to include omega-3 fatty acids in our diets, regardless of whether we are sick or not.
The team's research was published online in the journal Gut.