# Nutrition and diets in metastatic breast cancer
Nutrition plays a supportive role in care for people with metastatic breast cancer. This tab describes which nutritional patterns and diets are mentioned in research and practice, and what is known about them.
Plant-based dietary pattern (whole food plant-based)
ResearchediPositive results in clinical studies, not yet standard treatment
A plant-based dietary pattern, where most of the diet consists of unprocessed plant-based sources (vegetables, fruits, whole grains, legumes, nuts, seeds), with little to no animal products, is being studied in metastatic breast cancer.
A pilot study from 2026 followed participants who adhered to a whole-food plant-based diet in the context of treatment for metastatic breast cancer. The findings suggest that long-term dietary changes may influence mortality, but the study was small in size and more research is needed to draw conclusions. Such studies provide insight into how nutrition may possibly contribute to quality of life and outcomes, but it is unclear whether this pattern is better than other patterns, and for whom it is most suitable.
Risks are mainly practical: a strict plant-based pattern requires good planning to obtain sufficient protein, vitamin B12, iron and calcium, especially when someone is already having difficulty eating due to treatment or illness. This should be discussed with the care provider or a dietitian.
Low-fat diet and prevention of advanced glycation
ResearchediPositive results in clinical studies, not yet standard treatment
Low-fat diet, where the fat percentage of total calories is reduced, has been studied for decades in relation to breast cancer protection and health. Studies also examine the role of advanced glycation end products (AGEs): substances that form when food is heated strongly or stored for long periods, and that may influence inflammatory processes.
The Women's Health Initiative study (large study from the United States) re-examined low-fat diet and AGE intake in relation to health in 2026. Although this study was not exclusively focused on metastatic cancer, such data provide starting points for dietary choices that may reduce inflammation risk. The results are mixed: low-fat diet shows protective effects in some studies, but not all.
For people with metastatic breast cancer, less intense heating of food (grilling, frying at high heat) and conscious choice of less processed products may be part of a broad approach, but this is not a standardized recommendation.
Protein enrichment (arginine)
ResearchediPositive results in clinical studies, not yet standard treatment
Studies examine supplemental amino acids such as arginine in relation to healing and recovery capacity after surgery. A study from 2026 examined arginine supplementation in breast cancer patients undergoing reconstructive surgery.
Arginine is an amino acid involved in immunity and wound healing. In certain situations (for example, after surgery), it is being examined whether extra arginine can help support body tissue. For metastatic cancer, such studies are not yet large in scope, and it is unclear whether this provides direct benefit outside the post-operative context.
More protein in general can help maintain muscle mass when someone is undergoing treatment, but this should be embedded in an overall nutritional plan guided by healthcare providers.
Physical activity and nutrition combined
ResearchediPositive results in clinical studies, not yet standard treatment
Studies increasingly show that nutrition and movement work together. A 2026 study among breast cancer survivors (including many women of Latin American descent) examined the effects of a combined diet and exercise program, and how the living environment plays a role in this. When nutrition and movement are addressed together, the effects on weight, energy level and well-being may be greater than each separately.
For people with metastatic breast cancer, this may mean that small, adapted movement (such as walking) and dietary choices can work together to support strength and quality of life.
Nutrition and immunity
ResearchediPositive results in clinical studies, not yet standard treatment
Research focuses on how nutrition can support the immune system, particularly in relation to cancer treatment. Recent studies examine the role of nutrients in immune modulators and how these can work alongside immunotherapy. This is still fairly theoretical and plays out mainly at research level.
Practically, this means that a dietary pattern rich in antioxidants, vitamins and minerals (from vegetables, fruit, whole grains) can be part of a supportive approach, but there is no specific diet that can replace or enhance immunotherapy.
---
Practical notes
Dietary choices for metastatic breast cancer are highly individualised. They depend on the specific treatment, side effects, body weight, energy level, and personal preference. Side effects of therapy — nausea, taste changes, reduced appetite — often determine what someone can and wants to eat.
Much of the research above is still relatively new or limited in scope. This does not mean nutrition is unimportant — quite the opposite. It means that good guidance from the treatment team and a specialised dietitian is crucial to tailor choices to the phase of illness, the treatment and the individual situation.
Many centres that treat metastatic breast cancer have dietitians on the team who have knowledge of how nutrition and cancer treatment go together. It is worth taking advantage of this offer.
_This information never replaces the judgment of a doctor. Always discuss your dietary choices with your own healthcare provider or dietitian._