A friend reached out to me recently to share that she had received a breast cancer diagnosis and would be undergoing chemotherapy. She asked if I had any advice on nutrition to improve her chances of a successful outcome. While it’s a difficult question to answer, as some evidence supports the benefits of nutrition in cancer treatment, such as the Mediterranean-style diet, other approaches like intermittent fasting are more controversial.
However, new research suggests that intermittent fasting can be helpful in certain patients. There are different types of intermittent fasting, including time-restricted eating and the 5:2 diet. A study conducted by Manchester University in 2013 found that intermittent fasting, specifically the 5:2 diet, showed potential benefits in preventing breast cancer in women with a family history of the disease.
The study randomly assigned 115 middle-aged women to either a standard low-calorie diet or the 5:2 diet. After eight weeks, the intermittent fasting group lost an average of 6kg, nearly twice as much as the daily dieters. Additionally, they experienced greater improvements in insulin sensitivity, which is important as high insulin levels are believed to promote cancer growth. Another study by the same researchers in 2016 revealed that intermittent fasting led to weight loss and changes in gene activity in breast tissue, suggesting a reduced risk of cancer.
Intermittent fasting may not only impact insulin levels but also enhance the effectiveness of T cells, a crucial part of the immune system. A study by Van Andel Research Institute in Michigan found that ketones produced during intermittent fasting can supercharge T cells, making them more effective in fighting cancer. This evidence suggests that intermittent fasting can boost the immune system and potentially reduce the risk of certain cancers, including breast cancer.
While there have been limited human studies, recent research presented at the European Society for Medical Oncology conference by Charité University Medicine Berlin caught my attention. The study involved 106 women with early breast cancer who were about to undergo chemotherapy. Half of them followed a low-calorie diet consisting mainly of vegetable juices and broths for two days before and 24 hours after chemotherapy. Surprisingly, these women reported less fatigue and a greater sense of well-being compared to the control group, with no reported side effects.
Short-term fasting not only increases ketone levels but also reduces blood glucose levels, making it harder for cancers to grow. However, the study was too short to determine the impact of short-term fasting on long-term survival. Therefore, outside of a proper clinical trial, intermittent fasting is not recommended for chemotherapy patients.
Instead, I advised my friend to adopt a Mediterranean-style diet, which includes oily fish, olive oil, nuts, fruits, vegetables, and legumes. This diet has been shown to reduce the risk of cancer and may also improve tolerance to chemotherapy. A study by the University of Rochester Medical Center found that cancer patients who followed a Mediterranean-style diet reported less fatigue after chemotherapy compared to those who followed a usual care program. Interestingly, the diet seemed to boost the patients’ mitochondria, the powerhouses of cells, particularly those supplying T cells.
Currently, the Mediterranean-style diet is not routinely recommended for individuals undergoing chemotherapy, but I personally recommend it as a safer approach.
