November 12, 2026, 7:01 pm | Read time: 6 minutes
Many people prefer a sweet first meal of the day–such as bread with fruity spread, fresh fruit, or the classic: breakfast cereals. A South Korean study has now examined the link between such sugar-rich foods and breast cancer risk. The results suggest that it’s not just about how much sugar we consume, but also where it comes from. One food group stood out in particular.
It’s known that high sugar consumption can be detrimental to health. It’s also believed that a sugar-rich diet can indirectly promote the development of certain types of cancer. By “indirectly,” it is meant, for example, that it can affect body weight. It is assumed that weight gain (especially during certain life phases) can increase breast cancer risk.1
Not all sugar is the same.2 It has long been known that the health effects of sugar depend on the foods it comes from and the form in which it is consumed.
Study on the Influence of Sugar Types on Breast Cancer Risk
A research team from South Korea has now examined various sugar-rich foods for a possible link to breast cancer risk. The focus was on foods that many people enjoy for breakfast, as well as sweet snacks and popular desserts. They were particularly interested in the difference between naturally occurring sugar–such as from fruit–and sugar from highly processed foods with added sugar.
Most previous studies on this topic examined women from Western countries, the researchers explain. For Asian populations, the data has been limited. In their study, they specifically looked at Korean women. This means that the findings are likely not directly transferable to women in other countries (such as Germany).
Details of the Study
The study was conducted as a prospective cohort study. This means that the participants were observed over a longer period without interventions (such as controlled dietary changes) being made. The researchers wanted to find out which habits might be associated with diseases that occur later.
The data evaluated came from the Korean population study Health Examinees Study (HEXA).3 This was conducted from 2004 to 2013. After excluding various participants from the data pool (e.g., due to pre-existing cancer or missing dietary information), 71,264 women aged 40 to 69 were included in the final analysis.
Information on diet was collected using a questionnaire. Participants were asked to indicate how often and in what quantities they consumed a total of 106 selected foods. The scientists also developed a database on the sugar content of the recorded foods.
A total of seven food groups were examined separately:
- Breakfast cereals (with added sugar)
- Jam (and butter)
- Pastries, specifically: cakes and cookies
- Ice cream
- Candy
- Carbonated soft drinks
- Traditional Korean tea, sweetened
From the Korean cancer registry, the authors identified breast cancer diagnoses. The average follow-up period until December 31, 2018, was 9.2 years. Using statistical Cox regression models, the participants’ risk of disease was calculated, taking into account various possible influencing factors (e.g., age, BMI, alcohol consumption and smoking, level of physical activity, reproductive and fertility information).
Results
During the follow-up period, a total of 713 new breast cancer cases were identified. The average sugar intake of the 71,264 women was 44 grams per day, with fruit (about 42.89 percent) being by far the largest source of sugar in their diet. Sweetened tea was second (5.60 percent), and ice cream was third at 2.51 percent.
One of the key findings is that the link to breast cancer risk varied depending on the food source. Thus, the total sugar intake was not significantly associated with the risk of disease. No increased breast cancer risk was found for the overall high sugar consumption from fruit. However, it was different for other food groups.
The Breakfast Associated with the Highest Breast Cancer Risk
Women who consumed sweetened breakfast cereals more than once within two months had a 34 percent higher breast cancer risk compared to those who never did.
There was also a link with ice cream. Consuming it once a week was associated with a 26 percent higher risk compared to women who generally did not eat ice cream.
When considering all sugar-rich foods together, an increased risk was also noticeable. Consuming more than two servings per week resulted in a 28 percent higher breast cancer risk compared to consuming less than one serving per month.
Sugary Drinks Increase the Risk of 7 Cardiovascular Diseases
Women who incorporate this into their diet can reduce their risk of breast cancer.
Possible Significance of the Results
The observations suggest that the link between diet and breast cancer is not solely determined by the amount of sugar consumed. The source of the sugar seems to be particularly important. After all, fruit contributed the largest share to total sugar intake at 42.89 percent, and its consumption was not associated with an increased risk according to the analysis. For other groups, however–especially breakfast cereals–the link was statistically significant.
The authors cite biological mechanisms as a possible explanation. A high intake of added sugar can impair insulin sensitivity. This can result in increased insulin levels and concentrations of the hormone-like growth factor IGF-1 in the blood. IGF-1 influences cell growth and division and could therefore be relevant for tumor development.
What also speaks for fruit is its content of various beneficial nutrients that are often lacking in other sugar-rich foods. The researchers mention fiber, vitamins, carotenoids, and polyphenols.
However, the study did not investigate the possible mechanisms. It only shows statistical correlations so far. Concluding from the observations that the wrong breakfast (cornflakes or muesli) or ice cream causes breast cancer would be incorrect.
Also interesting: Study shows link between late eating and insulin resistance
Limitations
The dietary information was based on self-reports, which are inherently prone to error. Additionally, the information was only collected at the beginning of the study. It is therefore possible that the women’s eating habits changed over the following years.
The sugar database used also presents a limitation, as it does not distinguish between naturally occurring and added sugar. The researchers therefore used the sugar content of processed foods as an indicator of added sugar intake. However, an exact distinction was not possible.
Even though the researchers statistically accounted for various influencing factors, it cannot be ruled out that additional factors influenced the results. For example, possible hormone replacement therapies were not considered in the analysis, although a possible link to breast cancer risk is discussed. Information on the intake of calcium-rich and carotenoid-rich foods was also missing.
Finally, the data examined came from women in South Korea. As previously noted, the results are not directly transferable to women of other origins.