Based on PubMed | Does regular coffee consumption lower the risk of endometrial cancer?

Regular coffee consumption is associated with a lower risk of endometrial (uterine) cancer in many observational studies, with evidence suggesting a dose–response pattern where higher intake is linked to greater risk reduction. ^[1] Multiple meta-analyses pooling cohort and case–control data report that each additional cup per day is associated with about an 8–10% lower relative risk, and the highest intake categories show roughly 30% lower risk versus the lowest. ^{[1] [2]}

What the research shows

• Meta-analyses of observational studies:

  • A large synthesis of 16 studies (6 cohort, 10 case–control; 6,628 cases) found a pooled relative risk (RR) of 0.71 for the highest versus lowest coffee intake, with a per–cup RR of 0.92, indicating lower risk with higher consumption. ^[1] This inverse association was consistent across study designs and showed stronger effects in some Asian cohorts. ^[1]
  • An earlier meta-analysis similarly reported an overall RR of 0.80 for drinkers vs. non‑drinkers, with RRs of 0.87 for low–moderate and 0.64 for heavy consumption, and a per–cup RR of 0.93. ^[2] These findings reinforce a likely protective association, though they cannot prove causation. ^[2]

• Prospective cohort signals:

  • In a Swedish cohort, each additional daily cup was associated with a 10% lower rate of endometrial cancer, and ≥4 cups/day was linked to a 25% lower risk compared with ≤1 cup/day. ^[3] Notably, the benefit appeared more pronounced in women with overweight or obesity, suggesting a link to metabolic pathways. ^[3]
  • A Japanese cohort reported multivariable-adjusted hazard ratios showing markedly lower risk with ≥1–2 cups/day and ≥3 cups/day, with a clear trend toward lower risk as intake increased. ^[4] Green tea did not show a similar association in that study. ^[4]

---

Possible biological reasons

• Coffee may improve insulin sensitivity and lower circulating insulin, which is relevant because insulin resistance and hyperinsulinemia are linked to endometrial cancer development. ^[3] This could help explain stronger associations among women with higher body mass index. ^[3]
• Coffee has been proposed to modulate estrogen and related sex hormones, potentially reducing estrogen-driven stimulation of the uterine lining. ^[4] These hormonal effects provide a biologically plausible pathway for reduced risk. ^[4]

---

How strong is the evidence?

• The evidence comes largely from observational studies (cohort and case–control), which can show associations but cannot definitively prove cause and effect because of potential confounding (for example, diet, weight, physical activity, or other lifestyle factors). ^[1] Consistency across many studies and dose–response trends strengthen confidence in a real association, but residual confounding remains possible. ^{[1] [2]}

• Major clinical guidance resources emphasize established risk factors for endometrial cancer such as obesity, estrogen–progesterone imbalance, age, certain medications like tamoxifen, and family syndromes and focus on weight control, physical activity, and oral contraceptive use for risk reduction, rather than recommending coffee as a preventive strategy. ^[5] These sources do not currently endorse coffee specifically to prevent endometrial cancer, reflecting the observational nature of the coffee evidence. ^[6]

---

Practical takeaways

• Based on current data, regular coffee consumption is associated with a lower risk of endometrial cancer, especially at higher intakes and possibly among women with higher BMI. ^{[1] [3]}
• Moderation is sensible: very high caffeine intake can cause side effects (e.g., palpitations, anxiety, sleep problems) and may not be appropriate for everyone (such as those who are pregnant or have certain heart conditions); the endometrial cancer literature shows benefits at intakes ranging from about 1–4+ cups/day. ^{[1] [3] [4]}
• Coffee should be seen as a complementary lifestyle factor, not a primary prevention tool; maintaining a healthy weight and addressing hormonal and metabolic health remain key strategies recognized by clinical resources. ^{[5] [6]}

---

Summary table: Coffee and endometrial cancer risk

Evidence type	Key finding	Estimated effect size
Meta-analysis (16 studies)	Highest vs. lowest intake associated with lower risk; dose–response present	RR 0.71 (95% CI 0.62–0.81); per cup RR 0.92
Meta-analysis (earlier)	Protective association; stronger at heavy intake; dose–response per cup	Overall RR 0.80; low–moderate RR 0.87; heavy RR 0.64; per cup RR 0.93
Swedish cohort	Each additional cup/day lowers risk; ≥4 cups/day vs. ≤1 cup/day lower risk; stronger in higher BMI	Per cup RR 0.90; ≥4 cups/day RR 0.75
Japanese cohort	Clear trend of decreasing risk with higher intake; green tea not associated	≥1–2 cups/day HR 0.61; ≥3 cups/day HR 0.38; p‑trend 0.007

---

Bottom line

It appears that drinking coffee is linked to a modestly lower risk of endometrial cancer, with a dose–response pattern and possible stronger benefit among women with insulin resistance or higher BMI, but this is based on observational data and should not replace proven lifestyle approaches like weight management and physical activity. ^{[1] [3] [4]} Healthcare guidance still focuses on established risk factors and general healthy lifestyle measures rather than recommending coffee specifically for prevention. ^{[5] [6]}