A new research presented in JAMA Oncology discovers that taking herring, mackerel and specific fish oils may raise the risk of cancer patients becoming resistant to chemotherapy.
With respect to the American Cancer Society, over 1.6 million individuals in the US will be diagnosed with cancer in 2015.
In add-on to receiving treatment for cancer, many sufferers with the condition will usually make lifestyle modifications with the aim of enhancing their health status.
For instance, study co-author Dr. Emilie E. Voest, of the Netherlands Cancer Institute in Amsterdam, and co-workers point to one research that recognized a threefold increase in food supplement use among sufferers who had obtained a cancer diagnosis.
“However,” the authors add, “there is a increasing issue that simultaneous use of supplements and anticancer medicines may adversely effect treatment result.”
The scientists notice that omega-3 fatty acids are generally used supplements among cancer sufferers, with about 20% of cancer sufferers using them in the US – most frequently in the form of fish oil.
Earlier study from the team identified that two fatty acids – 16:4(n-3) and 12S-HHT – induced chemotherapy resistance in mice who ingested the substances in small quantities.
For their research, Dr. Voest and co-workers set out to evaluate the fatty acid content in different fish oils, and examine how consumption of fish oil – through supplements or fresh fish – impacts the treatment result of sufferers with cancer.
Fish oil supplements, herring, mackerel raises 16:4(n-3) blood levels
From assessing a number of fish oils generally used for supplementation, the investigators identified that 16:4(n-3), but not 12S-HHT, was present in all of them.
The investigators enrolled healthy volunteers and calculated their blood levels of 16:4(n-3) after taking in the suggested daily amount of 10 milliliters (ml) of fish oil – either through three retail available fish oil supplements or via eating fresh fish, particularly salmon, tuna, smoked mackerel or cured herring.
The team identified that quickly after the volunteers had taken the fish oil supplements, their blood levels of 16:4(n-3) enhanced. These levels did not come back to regular till 8 hours after the supplements were consumed. After a 50-ml dose of fish oil supplements, blood levels of 16:4(n-3) took even longer to come back to normal.
The investigators also identified that taking 100 g of herring or mackerel was connected with an increase in 16:4(n-3) blood levels. Salmon intake led to small raise in 16:4(n-3) blood levels, while tuna consumption did not seem to affect blood levels.
The investigators also examined the outcomes of a survey finished by 118 sufferers getting cancer therapy at the University Medical Center Utrecht in the Netherlands, which collected details about their use of fish oil supplements.
They identified that 30% of these sufferers reported frequent use of fish oil supplements, while 11% revealed using supplements comprising omega-3 fatty acids.
Leaving comments on their results, the authors say:
“Herein we demonstrate that fish oil consists of substantial levels of 16:4(n-3), a fatty acid with potent chemotherapy-negating effects in preclinical models, and that ingestion of low doses of fish oil interferes with chemotherapy activity in mice.
Consumption of the suggested daily quantity of fish oil by healthy volunteers quickly enhanced 16:4(n-3) plasma levels. Since low levels of 16:4(n-3) were continue to active in mice, and since 11% of sufferers undergoing cancer treatment in our center used omega-3 supplements, these results may have essential clinical significances.”
Depending on these results, the investigators suggest that cancer sufferers going through chemotherapy avoid taking fish oil supplements from the day prior to their therapy until the day after.
“Although additional proof on the connection between fish intake and chemotherapy activity is preferred, we would presently also suggest to avoid herring and mackerel in the 48 hours surrounding chemotherapy exposure,” they add.