Franziska Spritzler, RD, CDEBreast cancer remains one of the most prevalent cancers worldwide, with millions of new cases diagnosed annually. Early detection, particularly through regular screening, has greatly improved survival rates. Standard treatments–– including surgery, chemotherapy, radiation therapy, and hormonal therapy––can be effective in many cases, although they often come with severe side effects. The journey through breast cancer treatment can be extremely demanding, both physically and emotionally.
One area of growing interest is the potential role of diet, particularly the ketogenic diet, in managing breast cancer. The science behind this is compelling: cancer cells typically rely on glucose (sugar) for energy. By drastically reducing carbohydrate intake, the body enters a state of ketosis, where it uses fat, instead of glucose, as its primary energy source. This metabolic shift can theoretically starve cancer cells, while healthy cells adapt to using ketones for energy. (1)
Recent research has investigated whether this dietary approach could help slow tumor growth, reduce inflammation, and improve outcomes, particularly in cancers like breast cancer that are influenced by metabolic factors such as insulin resistance.
Below are four clinical trials published within the past five years that explore the potential of ketogenic diets in treating breast cancer.
Study 1. A study published in 2020 aimed to assess the safety, tolerability, and potential benefits of a medium-chain triglyceride (MCT) ketogenic diet on body composition, blood parameters, and survival in breast cancer patients.(2) 60 patients with locally advanced or metastatic breast cancer were randomly assigned to either a ketogenic diet or a control diet for 3 months. Blood sugar levels, beta-hydroxbutyrate (BHB) levels, body composition, and overall survival were measured throughout the study. Weekly checks ensured compliance and monitored safety.
Key findings:
Fasting blood sugar significantly decreased in the ketogenic diet group.
BHB levels increased significantly in the ketogenic diet group, averaging 0.9 mmol/L.
Body fat percentage significantly decreased in the ketogenic diet group compared to the control group.
No severe adverse effects were observed regarding lipid profiles or kidney/liver function.
Overall survival was higher in the ketogenic diet group in people who received chemotherapy or radiation prior to surgery.
Study 2. In a study published in 2021 involving 80 breast cancer patients receiving chemotherapy, half followed a ketogenic diet for 12 weeks. (3) Blood samples were taken at the start, at six weeks, and at 12 weeks to measure various biomarkers, including insulin and inflammation. Scans were also done to track tumor changes, and surgery was performed for those with advanced cancer after chemotherapy.
Key findings:
- Patients on the ketogenic diet had lower levels of TNF-α, a marker of inflammation, and higher levels of the anti-inflammatory marker IL-10.
The ketogenic diet group experienced a reduction in insulin levels.
89% of patients who completed the ketogenic diet were considered compliant based on maintaining BHB levels >0.3 mmol/L.
Tumor size decreased by 27 mm in the ketogenic diet group vs. 6 mm in the control group.
Cancer stage decreased in patients with advanced disease on the ketogenic diet. However, no significant impact was seen on the response in patients with metastatic cancer.
Study 3. A study published in 2021 compared 29 breast cancer patients following a ketogenic diet with 30 patients consuming their standard diet during radiation therapy. (4) Patients were evaluated using a quality-of-life questionnaire and various blood tests to assess metabolic and hormonal health before, during, and after radiotherapy.
Key findings:
Women on the KD experienced significant improvements in emotional functioning, social functioning, and sleep quality.
Breast symptoms increased in both groups but were less severe in the ketogenic diet group.
BHB levels in the ketogenic group rose significantly during the first two weeks, remained stable through week six, and then gradually declined to an average of 0.5 mmol/L by the end of the study.
Significant improvements in metabolic health markers (gamma-glutamyl-transpeptidase, creatinine, triglycerides, IGF-1, and free T3) were observed in the ketogenic diet group but not in the standard diet group.
No negative effects on liver or kidney function were found in the ketogenic diet group.
Study 4. The Keto-CARE trial, published in 2024, evaluated the feasibility and metabolic outcomes of a six-month, well-formulated, non-calorie-restricted ketogenic diet in women with stage IV metastatic breast cancer undergoing chemotherapy.
Key findings:
The women maintained average blood ketone levels of 0.8 mmol/L in the first three months and 0.7 mmol in the second three months, indicating dietary adherence.
There were significant reductions in blood glucose levels, fasting insulin levels, and insulin resistance throughout the trial.
The women experienced a loss of 10% of body weight, on average, with 78% of the loss coming from body fat rather than lean mass.
Although all of these results are very encouraging, it’s important to acknowledge the complexity of cancer metabolism. Indeed, metabolic reprogramming has been identified as a critical element in cancer biology. Recent studies highlighted the critical role of fatty acid metabolism in supporting the proliferation of certain cancers, including HER2+ breast cancer, which could potentially be targeted with a strategic combination of the ketogenic diet and pharmacological intervention.(6)
Further research is needed to fully understand the role of the ketogenic diet in cancer treatment, and breast cancer patients should consult with their healthcare team before making any dietary changes. A ketogenic diet can have significant effects on metabolism, and it may not be suitable for everyone, especially during active cancer treatment.
For those battling breast cancer, the combination of traditional therapies and emerging dietary approaches like the ketogenic diet offers new hope. With advancements in both medical and nutritional science, the outlook for breast cancer patients is more optimistic than ever.
REFERENCES
Revisiting the Warburg Effect: Diet-Based Strategies for Cancer Prevention, Biomed Research International 2020
Feasibility, Safety, and Beneficial Effects of MCT-Based Ketogenic Diet for Breast Cancer Treatment: A Randomized Controlled Trial Study, Nutrition and Cancer 2020
Effects of ketogenic metabolic therapy on patients with breast cancer: A randomized controlled clinical trial, Clinical Nutrition 2021
