Eating sugary foods more than twice a week was linked to 28% higher breast cancer risk

Does breast cancer risk depend on how much sugar women eat or where that sugar comes from? A study following more than 71,000 Korean women examines how everyday food choices relate to cancer incidence.

Relative contribution of each food group to total sugar intake (%). Study: High-sugar foods and breast cancer risk from the Health Examinees study

Want to read later? Download your clean, ad-free, print-friendly PDF copy by clicking here.

Breast cancer is the most frequently diagnosed cancer among women worldwide. In a recent study published in the European Journal of Nutrition, researchers at Seoul National University, Korea, examined whether eating high-sugar foods often is linked to breast cancer.

Breast cancer and diet

The World Health Organization (WHO) advises limiting free sugars to below 10% of total daily energy intake, yet sugar intake remains high worldwide. In the United States, added sugars provide about 12.7% of energy intake. The paper also notes high sugar consumption in Korea, but the reported measures are not directly comparable with WHO guidance on free sugars.

Identifying modifiable dietary risk factors for breast cancer remains an important research priority. Genetics, lifetime estrogen exposure, alcohol use, and physical activity are established contributors, and researchers are increasingly examining the contribution of diet to breast cancer risk. Studies suggest that higher intake of vegetables, fruits, and calcium- and carotenoid-rich foods may relate to lower risk, but the evidence for whole grains, dietary fat, and processed meat remains mixed. Research on the relationship between dietary sugar and breast cancer risk remains limited and inconsistent.

About the study

In the present study, the researchers used data from the Health Examinees (HEXA) study, a community-based cohort in Korea that recruited 169,718 adults aged 40 to 69 years at 38 centers between 2004 and 2013. The analysis used the HEXA-G subset.

The HEXA-G subset included 92,314 women before study-specific exclusions. Women were excluded if they lacked consent for registry linkage, had incomplete dietary questionnaires, reported implausible energy intake, or had any cancer before enrollment. Women diagnosed with breast cancer within two years of enrollment were also removed to reduce the chance that undiagnosed disease at baseline affected the findings. The final sample included 71,264 women.

A semi-quantitative food frequency questionnaire covering 106 food items was used to determine average daily intake. Participants reported how often they ate each item over the past one year and the portion size, which were converted into average daily intake.

The team built a sugar content database for all 106 items from national and international food composition tables and nutrition labels. They then identified seven high-sugar food groups: carbonated drinks, Korean traditional sugar-based tea, cakes and cookies, sweets, sugary cereals, ice cream, and jam and butter (a questionnaire category also including honey and margarine). Servings were summed to estimate total high-sugar food intake.

Breast cancer cases through December 31, 2018, were identified by linkage to the Korea Central Cancer Registry, using code C50 of the International Classification of Diseases, 10th revision (ICD-10). Questionnaires and examinations provided data on smoking, alcohol use, education, exercise, reproductive history, family history, and body mass index (BMI). Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs), using age as the time scale and adjusting for these factors and energy intake. Subgroup analyses also examined age, BMI, alcohol use, and physical activity.

Major findings

The study found that women who ate high-sugar foods more often had a higher risk of breast cancer, while neither total dietary sugar nor fruit consumption showed a statistically significant association. Over an average follow-up of 9.2 years, the researchers identified 713 new breast cancer cases among 71,264 women.

Fruit accounted for about 43% of total dietary sugar, and mean sugar intake was 44 grams per day. Women who consumed more than two servings of high-sugar foods per week had a 28% higher risk than those who ate one serving per month or less.

Sugar intake from these foods followed a similar pattern, with the top quarter of consumers showing a 28% higher risk than the bottom quarter. Women who ate ice cream at least once a week had a 26% higher risk than those who did not, and eating sugary cereal at least once every two months was associated with a 34% higher risk than never eating it. The ice cream estimate was borderline statistically, and the authors noted that sugary cereal consumption was relatively low.

No significant associations were found for carbonated drinks, cakes and cookies, sweets, jam and butter, or traditional sugar-based Korean tea. The same applied to total sugar, sugar from fruit, fruit servings, carbohydrates, and fat.

The association was statistically significant among women younger than 50 in the highest versus lowest consumption group, but the overall trend across categories was not significant. A significant association was also observed among women who had consumed alcohol. The age interaction was not significant, so the study did not establish a difference between age groups. Interaction tests suggested possible differences by alcohol use, BMI, and physical activity that warrant further investigation.

These results suggested that the source and context of dietary sugar may be relevant to breast cancer risk. Fruit contributed the most to total sugar intake but showed no significant association with risk, pointing to processed, sugar-rich foods as a possible focus for public health strategies. Because the study did not separate added from naturally occurring sugars, it could not determine whether sugar itself or other food components explained the associations.

Limitations to the study included a single baseline diet assessment, no distinction between natural and added sugars, no detailed cancer subtype or stage data, no menopausal status at diagnosis, and possible residual confounding. Missing family history data and the exclusion of early diagnoses may also have introduced bias. The observational design prevented causal conclusions, and the proposed biological mechanisms were not directly tested.

Conclusion

Overall, the findings indicated that among Korean women, frequent consumption of high-sugar foods, particularly sugary cereals and ice cream, was associated with a higher risk of breast cancer, whereas fruit intake and total sugar intake were not significantly associated with risk. The authors concluded that the source and context of sugar should be evaluated along with the amount consumed. They also recommended that future studies examine this association using repeated dietary measures, breast cancer subtype data, and menopausal status at diagnosis.

Source:

Journal reference:

• Shin, W.-K., Lee, H., Huang, D., De la Torre, K., Min, S., Choi, J.-Y., Shin, A., Han, W., Lee, J. E., & Kang, D. (2026). High-sugar foods and breast cancer risk from the Health Examinees study. European Journal of Nutrition, 65(8), Article 291. DOI:10.1007/s00394-026-04134-0, https://link.springer.com/article/10.1007/s00394-026-04134-0