Based on PubMed | Does eating fish reduce the risk of endometrial cancer?

Eating fish does not have a clear, consistent effect on endometrial (uterine) cancer risk based on current human studies. Some large prospective studies show no association, some suggest higher risk with higher fish or marine omega‑3 intake in certain groups, while others suggest possible lower risk in normal‑weight women; major clinical guidance focuses instead on maintaining a healthy weight, being physically active, and appropriate hormone balance as the key ways to lower risk. ^{[1] [2] [3] [4] [5]}

What the research shows

• Mixed findings across studies: A large U.S. prospective cohort found no link between total fish intake and endometrial cancer risk. ^[1] Another prospective cohort reported that women with the highest dietary EPA+DHA (the long‑chain omega‑3s in fatty fish) had a higher risk overall, especially among those with overweight or obesity, although normal‑weight women showed a trend toward lower risk. ^[2] A separate analysis from the Women’s Health Initiative observed linear reductions in risk with higher long‑chain omega‑3 intake, but this appeared limited to normal‑weight women. ^[3]

• Case‑control signals vs prospective data: One population‑based case‑control study suggested lower risk with higher EPA/DHA intake and with fish‑oil supplement use, but total fish intake itself was not associated; case‑control designs can be more prone to bias than prospective cohorts. ^[6]

• Overall take: When looking across better‑quality prospective cohorts, the evidence does not consistently support fish intake as a protective factor, and findings vary by body weight, suggesting that body mass and metabolic context may modify any effect. ^{[1] [2] [3]}

Practical guidance from clinical sources

Major clinical recommendations for lowering endometrial cancer risk emphasize weight management, physical activity, and balanced hormones rather than specific fish targets. ^[4] Keeping a healthy weight and staying active are consistently advised to reduce risk, and, when appropriate, combined oral contraceptives are known to reduce risk by counterbalancing estrogen with progestin. ^{[4] [5]}

How body weight may matter

• Obesity is the strongest modifiable risk factor for endometrial cancer because excess adipose tissue raises estrogen levels without enough opposing progesterone, stimulating the uterine lining. ^[4] In studies of fish and omega‑3s, any potential benefit appears most evident in normal‑weight women, whereas an increased risk signal has been seen in some cohorts among women with higher BMI. ^{[2] [3]}

Safety, nutrition, and a balanced approach

• Fish is still a nutritious choice for heart and brain health, supplying protein and omega‑3 fats, and it can help replace red and processed meats that have other health downsides, but current evidence does not justify eating fish specifically to prevent endometrial cancer. ^[1] Clinical advice prioritizes a generally healthy dietary pattern and weight control rather than fish intake per se for endometrial risk reduction. ^{[4] [5]}

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Summary table: What studies suggest about fish/omega‑3 and endometrial cancer

Evidence type	Exposure	Main finding	Notes
Prospective cohort (NIH‑AARP)	Fish intake	No association with risk	Large U.S. cohort with detailed diet data. [1]
Prospective cohort (VITAL)	Dietary EPA/DHA, fish	Higher overall risk at highest EPA/DHA; increase seen mainly in overweight/obese; possible lower risk in normal‑weight	Suggests effect modification by BMI. [2]
Prospective cohort (Women’s Health Initiative)	Long‑chain omega‑3s	Lower risk in normal‑weight; little effect in overweight/obese	BMI modifies association; reductions 15–23% per higher intake, mainly Type I cancers. [3]
Case‑control (population‑based)	EPA/DHA intake; fish oil supplements	Lower risk with higher EPA/DHA and fish oil use; no link with total fish	Susceptible to recall bias; supportive but not definitive. [6]
Clinical guidance	Lifestyle measures	Focus on healthy weight, activity, hormone balance; no fish‑specific recommendation for risk reduction	Emphasizes primary modifiable risks. [4] [5]

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What to do instead to lower risk

• Aim for a healthy weight with regular physical activity and a calorie‑aware, plant‑forward diet; this has the strongest support for lowering endometrial cancer risk. ^{[4] [5]}
• Discuss hormone‑related factors with your clinician; if you use estrogen therapy and still have a uterus, balancing with progesterone reduces risk. ^[5]
• Know symptoms and seek evaluation for abnormal vaginal bleeding, especially after menopause, for early detection. ^[4]

Bottom line

• It would be reasonable to include fish as part of a balanced diet for overall health, but there isn’t consistent evidence that eating fish by itself reduces endometrial cancer risk, and in some groups higher marine omega‑3 intake has been linked to higher risk. ^{[1] [2] [3]}
• For risk reduction, focus on weight control, physical activity, and appropriate hormone balance, which are the best‑supported strategies today. ^{[4] [5]}