Pro-inflammatory diets may increase breast cancer risk

Diets that promote inflammation may increase the risk for breast cancer, according to a recent study.

Another study suggests that adults in the United States, particularly women, are less often eating foods with anti-inflammatory properties, such as vegetables, amid the COVID-19 pandemic.

Both studies were presented during the annual meeting of the American Society for Nutrition, held virtually.

Pro- vs. anti-inflammatory diet

Inflammation is a “hallmark” of carcinogenesis, and previous research has demonstrated an association between low-grade chronic inflammation and several cancers, according to Carlota Castro-Espin, BSc, MS, a PhD student from the Catalan Institute of Oncology at Hospitalet de Llobregat in Catalonia, Spain.

“Regarding breast cancer, the specific inflammatory pathways for its development are still unclear,” Castro-Espin said during a presentation. “The impact of inflammation on breast cancer risk is often assumed to have an indirect effect, mainly mediated through obesity and decreased physical activity.”

Although diet contributes to low-grade chronic inflammation, no dietary components other than alcohol have been linked to breast cancer “with a convincing degree of evidence,” Castro-Espin said.

Castro-Espin and colleagues analyzed data from the EPIC study to evaluate the inflammatory potential of diets and their impact on breast cancer risk. The trial enrolled more than 500,000 participants across 10 European countries from 1992 to 2000. The participants were followed for nearly 15 years.

The current analysis included 318,686 EPIC participants who had information on diet and lifestyle behaviors. Among them, 13,246 had breast cancer.

The researchers used food frequency or diet history questionnaires to calculate each participant’s inflammatory score of diet (ISD).

Castro-Espin reported that women with the highest ISD values — indicating the most pro-inflammatory diets — had a 12% increased risk for breast cancer compared with women who had the most anti-inflammatory diets (HR = 1.12; 95% CI, 1.04-1.21).

Each standard deviation increase in ISD was associated with a 4% increased risk for breast cancer among all participants. The association appeared to be stronger in premenopausal women, who had an 8% increased risk for breast cancer with each standard deviation increase in ISD.

Based on the findings, Castro-Espin hypothesized that “the potential effects of a pro- or anti-inflammatory diet could be stronger among women for whom hormonal pathways are less relevant, such as premenopausal women.”

“This is very exciting research, especially since premenopausal breast cancer is often more aggressive and does not have the same relationship to obesity as post-menopausal breast cancer,” Melina B. Jampolis, MD, past president of the National Board of Physician Nutrition Specialists who is not affiliated with the study, told Healio Primary Care. “The notion that a diet that produces less inflammation — such as a Mediterranean diet, which is easy for a primary care physician to recommend — can decrease a women’s risk of breast cancer is very encouraging and actionable! Especially since women fear more than heart disease, even though heart disease is much more common.”

Survey shows decline in healthy food consumption

In another presentation, Caroline Y. Um, PhD, MPH, RD, a postdoctoral fellow of population science with the American Cancer Society, reported that adults in the U.S. are cutting back on healthy foods, including those with potentially anti-inflammatory properties.

The findings are based on an analysis of the Cancer Prevention Study-3 (CPS-3). Since 2015, CPS-3 participants completed food frequency or food group questionnaires every 3 years. In July and August 2020, Um and colleagues administered a COVID-19 survey to 2,335 CPS-3 participants. The researchers compared the responses to food-related questions with responses from the 2018 food questionnaire.

Um said that, overall, diet quality improved among participants who were men, white and those who lost weight between 2018 and 2020. Meanwhile, participants who were women, Black, Latino and those who gained weight reported eating less vegetables and whole grains.

“This study is not at all surprising, as many people turned to comfort food during the pandemic and were not able to shop as much in the early days due to fear of going out,” Jampolis said. “It is unfortunate as a nutrient-rich diet loaded with fruits and vegetables can support healthy immune function while sugar and highly processed foods can impair it.”

References:

Castro-Espin C, et al. Inflammatory potential of the diet and risk of breast cancer in the European Investigation Into Cancer and Nutrition (EPIC) study. Presented at: Nutrition Live Online 2021. June 7-10, 2021 (virtual meeting).

Um CY, et al. Change in diet quality and meal sources during the COVID-19 pandemic in a subset of men and women in the Cancer Prevention Study-3. Presented at: Nutrition Live Online 2021. June 7-10, 2021 (virtual meeting).