May lower risk
Salmon, sardines and other oily fish
salmon, sardines, mackerel, herring, trout, anchovies. Protein.
- Verdict
- May lower riskSome studies point to lower risk, but it isn't confirmed.
- How sure
- Rung 2 · LimitedFew, small or conflicting human studies, or only indirect measures such as blood markers.
The rung shows how sure the science is, not how big the effect is. How to read these ratings
Cancers affected
Colorectal; prostate
What the evidence shows
Evidence that fish lowers colorectal cancer risk is rated limited. In men on prostate surveillance, a high omega-3, low omega-6 diet with fish oil lowered a tumor growth marker. Fish oil pills are a separate question: one analysis linked high blood omega-3 levels to more aggressive prostate cancer, though its methods were widely criticized.
What to do
Eat oily fish twice a week in place of red or processed meat. Ask before taking fish oil pills.
Sources
To take it to your doctor, print this page.
Step by step
For the whole picture, from prevention and screening to treatment and life after, see the colorectal cancer and prostate cancer pages.