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Intake of fish and marine n-3 polyunsaturated fatty acids and risk of breast cancer: meta-analysis of data from 21 independent prospective cohort studies

BMJ 2013; 346 doi: https://doi.org/10.1136/bmj.f3706 (Published 27 June 2013) Cite this as: BMJ 2013;346:f3706

Re: Intake of fish and marine n-3 polyunsaturated fatty acids and risk of breast cancer: meta-analysis of data from 21 independent prospective cohort studies

Dear Ju-Sheng Zheng and Professor Duo Li,

Thank you very much for your answer. But your "Conclusions - Higher consumption of dietary marine n-3 PUFA is associated with a lower risk of breast cancer" is still questionable. Women with the lowest incidental outcome of breast cancer are not those with higher consumption of dietary marine n-3 PUFA (16  178 breast cancer events and 527 392 participants).

Only those with "15 g/day increment of fish intake" consumption had the lowest incidental outcome of breast cancer (13 323 breast cancer events and 687 770 participants).

Your discussion that "dose-response analyses indicated a 5% lower risk of breast cancer per 0.1g/day or 0.1% energy/day increment of dietary marine n-3 PUFA" is also doubtful. Because it might suggest that daily intake of 2.0 gram of marine n-3 PUFA could reduce the risk of breast cancer by 100 percent?

Yours sincerely
Dr. med. Thomas G. Schätzler
Family Medicine Unit
24 Kleppingstr.
D 44135 Dortmund/Germany
th.g.schaetzler@gmx.de

Competing interests: No competing interests

12 August 2013
Thomas Georg Schaetzler
Family Medicine
Medical Office
24 Kleppingstreet D Dortmund