Breast cancer: Following a keto diet may have therapeutic benefits

Over the years, scientists have examined the different ways diet can affect breast cancer.

Previous research shows that unhealthy dietary practices may increase breast cancer risk. For example, a study published in September 2023 found a link between ultra-processed food consumption and increased breast cancer risk.

Increased sugar intake has also been associated with a higher risk for breast cancer, including drinking sugar-sweetened sodas.

Conversely, past studies also report that good nutritional habits may positively affect breast cancer prevention and treatment.

A study published in May 2021 found that eating more fruits, vegetables, cheese, and soy products. In addition, less red and processed meat was associated with a lower risk of breast cancer.

Research published in April 2023 reported that following the Mediterranean diet had a potentially protective effect against breast cancer.

Furthermore, a study published in November 2021 reported that the type of food a person with breast cancer consumes may be effective at easing cancer treatment-related toxicities and improving prognosis.

People following a ketogenic — or “keto” — diet obtain most of their daily calorie intake from protein and healthy fats and less from carbohydrates.

In the standard keto diet, a person would only obtain between 5–10% of their daily calories from carbohydrates.

Placing less focus on carbohydrates causes the body to burn fat for energy instead, thus entering a metabolic state called ketosis.

Previous research shows some potential benefits to following a keto diet, including promoting weight loss, suppressing appetite, and keeping the heart healthy.

Additionally, the keto diet has been shown to assist in the management of certain conditions such as type 2 diabetes, epilepsy, Alzheimer’s disease, polycystic ovary syndrome (PCOS), and cancer.

However, the keto diet also has some potential downsides. Many people starting the keto diet develop a “keto flu” as their body adjusts from burning carbs to fat.

The keto diet can also cause long-term side effects, such as kidney stones, vitamin deficiency, liver disease, and hypoproteinemia, where a person’s levels of protein in the blood are too low.

The keto diet is also not recommended for people with any conditions affecting their gallbladder, pancreas, liver, or thyroid, as well as pregnant people and people with eating disorders.

For the current review, researchers assessed the evidence so far about the potential link between the keto diet and breast cancer. They did this by performing a comprehensive literature search of preclinical and clinical studies examining this link.

After analyzing the data, the scientists reported that existing studies provide a diverse range of findings, with some suggesting that a keto diet may help with inhibiting tumor growth and improving treatment response in breast cancer.

However, the researchers cautioned that clinical trials are still needed in order to prove these possible positive effects, as the results are currently inconsistent, with limited human trial data.

Additionally, the scientists said there are also concerns regarding the safety and long-term effects of sustained ketosis in cancer patients.

While some of this study’s findings may be positive, experts caution that the keto diet cannot prevent or treat breast cancer.

“I would say that research is very preliminary at this point and I don’t recommend anyone diagnosed with cancer or wanting to prevent breast cancer to adopt a specific diet,” Dr. Parvin Peddi, a board-certified medical oncologist and director of Breast Medical Oncology for the Margie Petersen Breast Center at Providence Saint John’s Health Center in Santa Monica, CA, told Medical News Today.

“What is refreshing is that there are now multiple ongoing clinical trials that are carefully randomizing cancer patients to ketogenic [versus a] normal healthy diet, and hopefully they will provide answers as to the benefit and if so, degree of, this diet in conjunction with therapy for breast cancer,” she added. “We need clinical trials ongoing at this time to complete and be published before recommending this to patients.”

It is also important to note that the keto diet is not for everyone, and if going on a restricted diet burdens a person with breast cancer and adds stress resulting in a decline in quality of life, then this type of diet needs to be reevaluated, explained Anabelle Ahdoot, clinical nutrition manager and oncology nutrition specialist at Saint John’s Cancer Institute in Santa Monica, CA.

“Major weight loss and malnutrition must be avoided during cancer treatment and if putting limitations on what the patient can and can’t eat results in that, then the harm may outweigh the potential benefit,” she advised.

“Additionally, since like any extreme diet which severely limits or excludes certain foods, the keto diet may in turn lead to some other deficiencies and shortcomings in the long run leading to a proinflammatory environment which we were trying to avoid in the first place.”

– Anabelle Adhoot

Ahdoot also told MNT that any type of diet needs to be evaluated “in conjunction with” the existing medical modalities and treatments, such as chemotherapy, radiation, and other targeted therapies, under the supervision of a medical professional.

“When facing cancer, the main priority and focus must be on preserving the patient’s muscle mass, strength, and overall well-being while undergoing medical treatment,” she explained. “Patients are advised to consult their health care professionals before taking any extreme measures with anything, including their diet.”