Black women in the United States face higher breast cancer mortality than any other racial or ethnic group, a disparity researchers have long sought to better understand. A new study suggests that everyday eating patterns before diagnosis may be one factor worth closer attention.
In research published in eClinicalMedicine, scientists followed 1,733 Black women diagnosed with breast cancer in New Jersey and found that those who reported eating the highest amounts of ultraprocessed foods before their diagnosis had a higher risk of death during follow-up than those who ate the least. Women in the highest intake group were 36% more likely to die from any cause and about 40% more likely to die from breast cancer specifically.
“Black women have the highest mortality rate from breast cancer compared with other racial or ethnic groups in the U.S.,” said Tengteng Wang, PhD, lead author of the study and a member of the Cancer Prevention and Control Program at Rutgers Cancer Institute. “That’s why we wanted to see what factors might contribute to these differences.”
The women were part of the Women’s Circle of Health Follow-Up Study and were interviewed in their homes roughly 10 months after diagnosis. During those interviews, participants completed detailed food questionnaires describing what they had eaten in the year before their cancer was detected. Researchers then tracked health outcomes for a median of more than nine years.
Ultraprocessed foods are industrial formulations that typically contain ingredients not used in home cooking, such as preservatives, flavor enhancers and emulsifiers. In this study, women with the highest intake averaged more than eight servings per day, while those with the lowest intake averaged fewer than three. Common sources included processed meats, packaged snacks, sweets, sodas and ready-to-eat mixed dishes.
When researchers examined possible explanations for the association, they found that total calorie intake played an important role. After adjusting for calories, the link between ultraprocessed food consumption and mortality weakened, suggesting that overeating and metabolic strain may be part of the pathway. Still, the association did not disappear entirely.
“The total energy intake may be one of the mechanisms, but it’s not the only one because a positive association existed even after adjusting for caloric intake,” Wang said.
The team also looked more closely at different categories of ultraprocessed foods. Among the subgroups, processed meats showed the strongest association with breast cancer deaths, a finding that aligns with previous research linking processed meat to cancer risk and poorer outcomes.
“Maybe it’s too complicated for breast cancer patients to think about how to reduce consumption of ultraprocessed foods in general,” Wang said. “But we find processed meat is the top worst contributor among all UPF subgroups. So maybe a more detailed takeaway is to avoid this one thing.”
The findings echo earlier work from the United Kingdom. An analysis of the UK Biobank, which includes mostly white participants, found a higher risk of cancer-related death among cancer survivors who consumed the most ultraprocessed foods. The consistency across populations suggests that the underlying mechanisms may not be race-specific, even though the current study focused on an understudied group.
The researchers stress that the study does not prove ultraprocessed foods cause worse outcomes, nor does it suggest that diet alone determines survival. The dietary data reflect eating habits before diagnosis, and the study design cannot rule out other contributing factors such as access to care, stress, or broader social determinants of health.
Still, the authors note that diet is one of the few potentially modifiable factors available to people navigating life after cancer. Elisa Bandera, MD, PhD, a senior investigator on the study and chief of the Department of Medicine at Rutgers Robert Wood Johnson Medical School, emphasized that changes do not have to be all-or-nothing.
“Going back to cooking traditional meals can potentially save money and is generally better for your health,” she said.
The research adds to a growing body of evidence suggesting that how food is processed, not just what nutrients it contains, may matter for long-term health. For cancer survivors and those who support them, the findings point toward realistic, incremental shifts rather than strict dietary rules.
This work was supported by Cancer Research UK and by the World Cancer Research Fund UK as part of the World Cancer Research Fund International grant program. Additional funding was provided by The São Paulo Research Foundation. This research was conducted using the UK Biobank Resource.