Fish and fish-derived products, such as fish oil or specific fatty acids, have been extensively studied for their effects on cancer risk and outcomes. This fact sheet focuses on fish consumption.
Multiple epidemiologic studies have compared the effect of high vs low fish consumption on various cancer types. Fish consumption has not, however, been associated with an increased risk of any cancer type — and may actually decrease the risk of cancer for some subtypes.
A meta-analysis that included 42 studies and over 232,000 patients demonstrated a modest association for combined gastrointestinal cancer with regular fish consumption (relative risk [RR], 0.93; 95% CI, 0.88-0.98) and high fish consumption (RR, 0.91; 95% CI, 0.84-0.97) compared with none or rare consumption.1 Fish consumption was associated with a significant reduction in risk for esophageal (RR, 0.91; 95% CI, 0.83-0.99), colorectal (CRC; RR, 0.93, 95% CI, 0.87-0.99), and hepatocellular (HCC; RR, 0.71; 95% CI, 0.48-0.95) cancers.
Several other meta-analyses evaluated the effect of fish consumption on esophageal cancer risk, and 3 of the 4 demonstrated a protective effect.2-5 The most recently published meta-analysis included 20 studies with 3990 cases of esophageal cancer.2 The risk of esophageal cancer was significantly lower with high fish consumption compared with the lowest consumption (summary relative risk [SRR], 0.69; 95% CI, 0.57-0.85), particularly for esophageal squamous cell carcinoma. There was no association between fish consumption and esophageal adenocarcinoma. Another meta-analysis, which included 7 cohort and 28 case-control studies, found no association between fish consumption and esophageal risk (RR, 0.95; 95% CI, 0.76-1.19).3
A meta-analysis of 17 studies found no association between fish consumption and gastric cancer (RR, 0.87; 95% CI, 0.71-1.07).6 A more recent study in Italy of 223 gastric cancer cases and 223 controls, however, demonstrated a significant protective effect of fish consumption (odds ratio [OR], 0.46; 95% CI, 0.24-0.90).7
Several meta-analyses demonstrated a protective effect against CRC with high fish consumption. An analysis of 19 studies found a modest decrease in the risk of CRC with high fish consumption compared with low consumption (RR, 0.88; 95% CI, 0.78-1.00).8 Each serving of fish per week conferred a modest protective benefit (RR, 0.96; 95% CI, 0.92-1.00). There was, however, no association between CRC-related mortality and fish consumption.
A more recent meta-analysis that included 21 studies found similar results, with an OR of 0.88 (95% CI, 0.80-0.95).9 An analysis of a Japanese population, however, found no association between fish consumption and CRC.10
Fish consumption also resulted in a protective effect against HCC in several meta-analyses, with the most recent including 11 studies.11,12 The highest level of fish consumption reduced the risk of HCC by 35% compared with the lowest level of consumption (SRR, 0.65; 95% CI, 0.51-0.79).11 For pancreatic cancer, a meta-analysis and a more recent cohort study found no association with fish consumption.13,14