Eating more plant-based foods may lower breast cancer risk, major international study indicates

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Feb 15 2026

Large international cohort data suggest plant-forward eating patterns and certain micronutrients may be linked to lower breast cancer risk and improved survival, highlighting diet as a potentially modifiable factor worth further investigation.

Study: Plant-based dietary patterns, micronutrient status and breast cancer outcomes: a joint analysis of UK Biobank and Chinese longitudinal healthy longevity survey. Image Credit: Pixel-Shot / Shutterstock

In a recent study published in the journal Frontiers in Nutrition, researchers examined whether adherence to healthful plant-based diets and intake of specific micronutrients were associated with the risk of breast cancer and mortality among breast cancer patients.

Their findings suggest that higher adherence to a healthful, plant-based diet is linked to a decreased risk of breast cancer and reduced mortality after diagnosis. Greater intake of calcium, vitamins B2 and C, magnesium, and phosphorus, rather than breast cancer incidence, was associated with a lower risk of mortality, whereas higher sodium intake increased the risk of mortality. These associations were observational and do not establish causation.

Background: Diet as a Modifiable Risk Factor in Breast Cancer

Despite improvements in screening and treatment, the global burden of breast cancer continues to rise, underscoring the importance of identifying modifiable risk factors.

Diet is increasingly recognized as a potentially important determinant of both cancer development and prognosis. Plant-based dietary patterns, such as the Alternate Mediterranean Diet (AMED) and the Healthful Plant-Based Diet Index (HPDI), emphasize whole grains, vegetables, fruits, legumes, and other nutrient-dense plant foods while avoiding processed foods and red meat.

Plant-based diets are rich in antioxidants, fiber, and bioactive compounds that may exert anti-inflammatory and anticancer effects. However, these biological mechanisms remain plausible hypotheses rather than proven causal pathways in this study. Although prior studies suggest that these diets are associated with lower breast cancer risk, evidence regarding their impact on survival after diagnosis remains limited and inconsistent.

Moreover, most research focuses on overall dietary patterns without disentangling the independent roles of specific micronutrients. The long-term predictive value of diet for breast cancer outcomes has also been insufficiently explored using advanced statistical and machine learning approaches. In this study, AMED associations were generally directionally protective but not statistically significant.

Cohort Design, Dietary Assessment, and Statistical Modelling

Researchers analyzed data from two prospective cohorts, the UK Biobank and the Chinese Longitudinal Healthy Longevity Survey (CLHLS). The UK Biobank sample included 67,045 individuals who did not have breast cancer and 3,397 women with breast cancer at baseline.

The CLHLS analysis included 7,431 cancer-free participants followed for incident overall cancer rather than breast cancer specifically. Dietary intake in the UK Biobank was assessed using a validated 24-hour recall, whereas CLHLS used a food frequency questionnaire. The cohorts differed substantially in age structure, ethnicity, and dietary assessment approaches, which may affect comparability.

Plant-based dietary adherence was measured using the HPDI and AMED scores. The HPDI incorporated 17 food groups, assigning positive scores to healthy plant foods and negative scores to animal foods and less healthy plant foods. Micronutrient intakes were calculated by linking reported food consumption to nutrient composition databases. Outcomes included incident breast cancer and all-cause mortality, identified through the respective national registries in UK Biobank, while CLHLS cancer outcomes were self-reported during follow-up surveys.

Associations were evaluated using multivariable proportional hazards modeling with progressive adjustment for demographic, socioeconomic, lifestyle, and clinical factors. Restricted cubic spline models were used to assess potential nonlinear dose-response relationships.

Predictive performance was evaluated using concordance indices, Random Forest models, and time-dependent receiver operating characteristic curves at 3, 5, and 10 years.

Key Findings: Dietary Patterns, Micronutrients, and Mortality

Among UK Biobank participants, higher adherence to the HPDI was correlated with reduced breast cancer incidence and improved survival. Women in the highest HPDI tertile were 11% less likely to develop breast cancer compared to those in the lowest tertile. Each standard deviation increase in HPDI corresponded to a 4% reduction in risk.

Among women with breast cancer, those in the highest HPDI tertile experienced a 28% lower risk of all-cause mortality, and each standard deviation increase in HPDI was associated with an 11% reduction in mortality risk. No significant nonlinear associations were observed.

In the CLHLS cohort, higher Plant-Based Diet Index (PDI) scores were significantly associated with lower overall cancer incidence, with a 39% reduction in risk in the highest versus the lowest group.

Micronutrient analyses revealed that higher intakes of calcium, magnesium, copper, and vitamin C were correlated with lower breast cancer risk. Among patients, higher intakes of calcium, phosphorus, magnesium, and vitamin B2 were linked to lower mortality. These micronutrient associations differed by outcome, with some linked primarily to incidence and others to mortality. In contrast, each standard deviation increase in sodium intake increased mortality risk by 15%.

Predictive models showed modest discrimination overall. Micronutrients alone performed best in predicting breast cancer incidence, whereas HPDI showed the strongest performance in predicting five-year mortality. Combined models performed best at 10 years. Overall predictive accuracy was modest, suggesting limited immediate clinical predictive utility.

Interpretation, Strengths, and Limitations

This large prospective study found that stronger observance of healthful plant-based diets was correlated with lower breast cancer incidence and improved survival after diagnosis.

Several micronutrients, particularly calcium, vitamin B2, vitamin C for incidence rather than mortality, magnesium, and phosphorus, showed independent protective associations, while sodium intake was linked to increased mortality. These findings align with prior research suggesting that plant-forward dietary patterns and nutrient-rich diets may reduce inflammation, oxidative stress, and cancer progression, although causal mechanisms remain uncertain.

Key strengths include the large sample size, prospective design, use of two international cohorts, and application of multiple analytical approaches, including spline models and machine learning. The simultaneous assessment of dietary patterns as well as individual micronutrients enhances interpretability.

However, limitations of the analysis include its observational design, precluding causal inference; confounding factors could not be excluded. Important risk factors for breast cancer, including hormone therapy and parity, were unavailable. Limited ethnic diversity in the UK Biobank and self-reported cancer data in CLHLS may affect generalizability. Dietary intake was assessed only at baseline, limiting the ability to assess dietary changes over time, and additional factors such as family history and detailed menopausal hormone data were incompletely captured.