Intermittent fasting against breast cancer
Time-limited access to food has reduced the risk of developing and progressing breast cancer
Maria Azarova, Naked Science
Scientists have found that alternating periods of fasting with meals helps prevent the development of breast cancer, slow down tumor growth and avoid metastasis to the lungs. According to them, such a simple strategy can also become a practical way in the future to achieve a positive effect in the treatment of breast cancer in humans.
Breast cancer has long been considered the second most common type of cancer in the world – after lung cancer – and recently, according to the World Health Organization, it has begun to take a leading position. Approximately one million people are diagnosed with breast cancer every year. Many factors are responsible for the development, including smoking, early onset of menstruation, genetics, diabetes, excessive alcohol consumption, the use of exogenous hormones, late menopause and overweight.
In general, according to experts, obesity and related metabolic disorders, including hyperinsulinemia and aberrant circadian rhythms, increase the risk of developing various types of cancer, including breast cancer in the period after menopause (termination of menstrual cycles), which also knocks down circadian rhythms – apparently due to a decrease in steroid levels in the ovaries. Limiting the amount of calories consumed can neutralize the harmful metabolic effects of obesity and slow down the progression of cancer, but it is difficult, and sometimes impossible, for many of us to adhere to a certain diet.
But, probably, it is not necessary to go to extreme measures. According to a study by oncologists and endocrinologists from the University of California, San Diego (USA), published in the journal Nature Communications (Das et al., Time-restricted feeding normalizes hyperinsulinemia to inhibit breast cancer in these postmenopausal mouse models), time-limited meals are a kind of intermittent fasting, consistent with circadian rhythms – promote metabolic health and are able to slow the progression of postmenopausal breast cancer in obese mice.
"We managed to increase insulin sensitivity, reduce hyperinsulinemia, restore circadian rhythms by simply restricting access to food for mice. We have shown that this approach cancels obesity-enhanced breast tumor growth in the absence of calorie restriction or weight loss. They also learned to reduce metastasis (the spread of cells from the primary focus to other tissues. – Ed.) into the lungs," said senior author of the study Nicholas Webster, professor at the Medical School of the University of California at San Diego.
The experiment was carried out on obese female mice. Menopause was caused at the age of seven to eight weeks by either bilateral ovariectomy (removal of the ovaries) or follicle depletion and 4-vinylcyclohexenediepoxide. They were also injected with cancer cells.
After the preparatory period, the rodents were divided into three groups: the first had round–the–clock access to food, the second – only for eight hours at night (from 22:00 to 06:00), when the mice are most active; the third group - the control, without obesity - was put on an unlimited regular diet. The control mice remained thin throughout the study. The first group was gaining weight at this time, while the second showed stabilization of body weight.
Mammary glands of mice were evaluated weekly using ultrasound, and when tumors became palpable, their volumes were measured using a caliper. At the end of the experiment, the animals were sacrificed, plasma was collected, tumors, visceral adipose tissue, liver, spleen and lungs were cut out and weighed. The samples were treated with formalin or frozen for further analysis.
As the results showed, the antitumor effect of this type of intermittent fasting is associated with an improvement in metabolism and a decrease in insulin levels. "A time-limited approach to meals is likely to be effective in the prevention and treatment of breast cancer. It improved metabolic health in obese postmenopausal mice without changing the amount of nutrients consumed and led to a striking suppression of tumor development, its progression and metastasis compared to an unrestricted diet," the scientists write.
Thus, alternating periods of fasting and meals can become an inexpensive, simple, but effective strategy to reduce the risk of breast cancer or suppress its development without the need to follow a strict diet. Of course, all the data still need to be confirmed by clinical studies on humans. "Our results showed that it may be useful for a person to simply change the time of eating to prevent breast cancer, and not to change what he eats," the scientists concluded.
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