A recent survey found out that many people suffering from various cancers take some counterintuitive medication during their chemotherapy sessions: fish oil supplements.
The researchers tested six different types of fish oil supplements, and all of them showed signs of making chemotherapy less effective. Why? Because according to the report in JAMA Oncology, they contained a specific fatty acid that decreased effectiveness of chemotherapy when tested on mice.
Lead author of the paper, Dr. Emile Voest from the Netherlands Cancer Institute in Amsterdam, said that people going through chemotherapy sessions should avoid any kind of fish oil supplements. Moreover, any supplements should be discussed with their doctors, as he urged patients to be honest about their intake of medication.
The most common source of fish oil, containing omega-3 fatty acids, come in the form of capsules sold for about $10 or $11 for 100 pills. The team’s survey showed that almost a fifth of Americans with cancer take them.
Voest explained that the mice experiments showed that even small amounts such fatty acids drastically reduced the chemotherapy’s effectiveness. Apparently, they act as enablers for cancer cells to start repairing themselves a lot faster after each chemotherapy session.
Back in November 2011, same researchers surveyed another 400 people undergoing treatment for cancer. Only 118 people answered the surveys, 35 percent of whom said they used nutritional supplements; at the same time, 11 percent reported taking omega-3 fatty acid supplements.
Part of the same study, the scientists asked 20 volunteers to eat mackerel or herring, and the results showed levels of 16:4(n-3) in their blood going up. On the other hand, salmon or tuna consumption did not have the same effect, but closer to none.
Further research is required for more solid data, but the investigators recommend that all patients undergoing chemotherapy should avoid fish oil – especially a day before and a day after they do the treatments.
Both the Dutch Cancer Society and the Dutch National Working Group for Oncologic Dieticians support this study, agreeing with their conclusions. Dr. Powel Brown, head of the Department of Clinical Cancer Prevention at the University of Texas, said that the results warrant more observations and experiments before making more strongly suggestions.
Even though Dr. Brown was not involved in the study, he discouraged patients’ use of additional supplements, as they are known to affect the natural course of chemotherapy.
Even though Voest admitted their study to have drawn some circumstantial conclusions, he added that ethics make it very difficult for researchers to confirm the findings. It is not allowed to randomly give chemotherapy patients fish oil capsules just to see the results.
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