Processed meats and high-sugar 'inflammatory' diets could increase breast cancer risk, according to a study of over 300,000 women

• Diets full of meat, sugar, butter, and fried food may increase breast cancer risk as much as 12%.
• These foods are linked to inflammation, stress on the body that can increase risk of illness.
• Fruit, vegetables, coffee, and tea may reduce inflammation and lower cancer risk.

Diets full of processed meats, butter, fried foods, and sugary treats may increase your risk of breast cancer, new evidence suggests.

Women who ate more of these inflammatory foods had up to 12% higher risk of developing breast cancer, according to research being presented this month at the annual meeting of the American Society for Nutrition.

Fatty foods and sugar can cause inflammation, while plant foods can help reduce it

Researchers from the Catalan Institute of Oncology, World Health Organization, and Imperial College in London looked at data from 318,686 women who participated in a European study on nutrition and cancer risk over 14 years of follow up.

They found foods that cause inflammation, a stress response in the body, were linked to a higher risk of cancer. Diets including more whole foods and produce were linked to lower risk.

The researchers determined participants' typical diet by having them fill out food frequency surveys for a year. They then ranked how inflammatory the diet was based on how often it included certain foods.

Inflammatory foods cause stress on the body by triggering an immune system response to fight off potential cell damage, according to the Mayo Clinic. If this continues over time, it can lead to a condition known as chronic inflammation, which can cause stress to the body and increase risk of illness and symptoms.

Foods like red meat, processed meat, butter, margarine, frying oils, and sugary foods are on the "inflammatory" list.

Anti-inflammatory foods help prevent cell damage by providing nutrients the body can use to protect and repair itself. These include vitamins, minerals, and fiber, but also plant-based nutrients called polyphenols.

Fruits and vegetables, legumes, coffee, and tea are all rich sources of nutrients and considered anti-inflammatory. Evidence suggests that these foods help stress on the body and lower the risk of chronic illnesses like cancer.

Patterns of eating matter more than specific foods or nutrients

Previous research has looked at how specific foods or nutrients might influence cancer risk. This latest study adds to what we know, according to Carlota Castro-Espin, an author of the study and a predoctoral fellow at the Catalan Institute of Oncology and Bellvitge Biomedical Research Institute in Barcelona, Spain.

"People consume food not nutrients, thus examining overall dietary patterns, rather than single components of diets can lead to more accurate conclusions when analyzing associations with a health outcome such as breast cancer," Castro-Espin said in a press release.