Researchers in Iran studied 136 women with endometrial cancer (a type of cancer affecting the uterus) and compared them to 272 healthy women to understand how diet affects cancer risk. They found that women who ate the healthiest diets—with lots of vegetables, beans, and whole grains, while limiting sugary foods and unhealthy fats—had about 83% lower chances of developing this cancer compared to women who ate less healthy diets. This suggests that making better food choices might be an important way to protect yourself from this type of cancer.

The Quick Take

  • What they studied: Whether eating a high-quality diet (with lots of healthy foods and fewer unhealthy foods) could reduce the risk of developing endometrial cancer in Iranian women
  • Who participated: 408 women in Tehran, Iran: 136 women who had been diagnosed with endometrial cancer and 272 healthy women of similar age and weight for comparison
  • Key finding: Women who followed the healthiest eating patterns had 83% lower odds of having endometrial cancer compared to women who ate the least healthy diets. This difference was very unlikely to happen by chance (P < 0.001)
  • What it means for you: Eating more vegetables, beans, whole grains and less sugar, refined grains, and unhealthy fats may help reduce endometrial cancer risk. However, this study shows a connection but doesn’t prove diet causes the difference—more research is needed to confirm these findings

The Research Details

This was a case-control study, which is like looking backward in time. Researchers identified women who already had endometrial cancer (the cases) and compared them to similar women without cancer (the controls). They asked all the women detailed questions about what they ate using a food questionnaire with 168 different food items. The researchers then scored each woman’s diet quality using something called the Healthy Eating Index-2020, which rates diets based on how many healthy foods (like vegetables and whole grains) people eat and how much unhealthy stuff (like added sugars and saturated fats) they consume.

The researchers matched the cancer patients with healthy women who were similar in age and body weight, which helps make the comparison fairer. They also collected information about other factors that might affect cancer risk, like whether women had gone through menopause, their education level, physical activity, and any health conditions they had.

Case-control studies are useful for studying diseases that don’t happen very often, like endometrial cancer. By comparing women who have the disease to similar women who don’t, researchers can identify dietary patterns that might be protective. This approach is faster and less expensive than following healthy women forward in time to see who develops cancer. The detailed food questionnaire allowed researchers to understand not just what people ate, but the overall quality of their eating patterns.

This study has several strengths: the cancer cases were confirmed by looking at tissue samples under a microscope (histologically confirmed), the food questionnaire was validated (tested to make sure it works accurately), and researchers controlled for many other factors that could affect results. However, the study only included women in Iran, so results may not apply to all populations. Also, because people had to remember what they ate in the past, there could be some errors in their answers. The study was conducted in hospitals, which might mean the results don’t represent all women in the community.

What the Results Show

The main finding was striking: women in the top third of diet quality (highest Healthy Eating Index scores) had 83% lower odds of endometrial cancer compared to women in the bottom third. In simpler terms, if we imagine 100 women with the worst diets, about 17 women in the best diet group would have the same cancer risk. This relationship was very strong and consistent—the more healthy a woman’s diet was, the lower her cancer risk appeared to be.

The protective effect of a healthy diet held true regardless of whether women were overweight or normal weight, and whether they had gone through menopause or not. This suggests that diet quality matters for cancer prevention across different groups of women.

When researchers looked at specific foods, they found that the most important protective factors were eating more vegetables, legumes (beans and lentils), and plant-based proteins. At the same time, women who ate less saturated fat (the unhealthy kind found in meat and dairy), added sugars, and refined grains (like white bread and regular pasta) had lower cancer risk.

The study found that the benefits of healthy eating were independent of other factors. Even after accounting for reproductive history, education level, physical activity, and total calories eaten, the diet quality remained strongly associated with lower cancer risk. This suggests that diet quality itself—not just overall calorie intake—is what matters for cancer prevention.

This research adds important evidence from a non-Western population. Most previous studies on diet and endometrial cancer have been conducted in Western countries with different food cultures and eating patterns. This Iranian study shows that the protective effect of healthy eating appears to work across different populations and food traditions. The findings align with what we know about healthy diets reducing other cancer risks and chronic diseases.

Several limitations should be considered: First, this is a case-control study, which means it shows a connection between diet and cancer but cannot prove that diet causes the difference in cancer risk. Second, the study only included women in Tehran hospitals, so results may not apply to rural areas or other countries. Third, women had to remember what they ate, which can be inaccurate. Fourth, the study was relatively small with 408 women total, so larger studies would strengthen the findings. Finally, the researchers couldn’t measure all possible factors that might affect cancer risk, so some unmeasured factors could have influenced the results.

The Bottom Line

Based on this research, eating a high-quality diet rich in vegetables, beans, whole grains, and plant-based proteins while limiting sugary foods, refined grains, and unhealthy fats appears to be associated with lower endometrial cancer risk. However, this is moderate-strength evidence from one study in one population. Women, especially those at higher risk for endometrial cancer (overweight women, those with diabetes, or those with a family history), should consider adopting these healthy eating patterns as part of overall cancer prevention. These dietary changes also benefit heart health and overall wellness.

This research is most relevant for women concerned about endometrial cancer risk, particularly those who are overweight, have diabetes, or have a family history of cancer. Women of all ages can benefit from improving their diet quality, though the study focused on Iranian women and results may vary in other populations. Men should also note that similar healthy eating patterns are associated with reduced risk of many other cancers. People with specific health conditions should consult their doctor before making major dietary changes.

Changes in cancer risk from dietary improvements typically take months to years to develop, as cancer is a slow-growing disease. However, other health benefits from eating better—like improved energy, better digestion, and improved blood sugar control—may appear within weeks to months. Consistent healthy eating over years is what likely provides the strongest cancer prevention benefit.

Want to Apply This Research?

  • Track daily servings of vegetables (goal: 3+ servings), legumes/beans (goal: 2-3 times per week), and whole grains (goal: 3+ servings) while monitoring added sugars (goal: under 25g daily) and saturated fat intake (goal: under 10% of calories). Use the app to log these specific food categories and review weekly trends.
  • Start by adding one vegetable-based meal per week, replacing one refined grain product with a whole grain alternative, and incorporating beans or lentils into two meals weekly. Use the app to set reminders for these specific swaps and track completion. Gradually increase frequency as these become habits.
  • Use the app to calculate a weekly diet quality score based on the Healthy Eating Index principles: track vegetable and fruit intake, whole grain consumption, protein sources, added sugar intake, and saturated fat consumption. Review monthly trends to identify which areas need improvement and celebrate progress in healthier categories.

This research shows an association between diet quality and endometrial cancer risk but does not prove that diet changes will prevent cancer. Individual cancer risk depends on many factors including genetics, age, weight, hormones, and medical history. This information should not replace medical advice from your doctor. Women concerned about endometrial cancer risk should discuss screening and prevention strategies with their healthcare provider. If you have been diagnosed with cancer or have a family history of cancer, consult with your oncologist or healthcare team before making significant dietary changes.