Calorie restriction reduces the risk of breast cancer

Severe calorie restriction early in life appears to reduce the risk of breast cancer, especially in women who later have children, according to a study from researchers at Harvard University.

The study compared Swedish women who had been hospitalized for anorexia nervosa prior to age 40 years old—evidence that they had severely restricted calories—with the general population in Sweden.

WOMEN WITHOUT CHILDREN

Women who severely restricted caloires and had never given birth had 23 percent less breast cancer than women in the general Swedish population.

WOMEN WITH CHILDREN

Women who severely restricted caloires and later had given birth to one or more children had 76 percent less breast cancer than women in the general Swedish population.

These results are similar to those seen in animals.

SUBJECTS

The study included 7303 Swedish women who had been hospitalized for anorexia nervosa prior to age 40 years between 1965 and 1998, and compared to data from women the Swedish Inpatient Registry, the Swedish Cancer Registry, the Swedish Death Registry, and the Swedish Fertility Registry.

Thirty-one women who were diagnosed with breast cancer prior to their first discharge from the hospital for anorexia nervosa were excluded from the study.

COULD INTERMEDIATE FASTING—EATING EVERY OTHER DAY—HAVE SIMILAR BENEFITS?

Anorexia nervosa is a vey serious disease, can be life-threatening, and must be discouraged at all costs. There may be another way, however, to achieve similar benefits without the risks.

A 2003 study found that having rats eat only every other day—intermediate fasting—brought about a lot of the same benefits as calorie restriction (Anson et al, 2003).

Intermediate fasting did not lower body weight—the mice ate enough calories on the days they ate to maintain their body weight—but it did:

?????—lower blood sugar levels by roughly 30 percent,
?????—lower blood insulin levels by roughly 80 percent, and
?????—increased levels of insulin-like growth factor 1 (IGF-1) by roughly 16 percent, and
?????—increase resistance of neurons in the brain to excitotoxic stress.

Since elevated insulin levels are associated with an increased risk of cancer, it seems possible that intermediate fasting—eating every other day—might also reduce the risk of breast cancer without the life-threatening dangers of anorexia nervosa.

?The findings of this study suggest that [intermediate fasting] can enhance health and cellular resistance to disease even if the fasting period is followed by a period of overeating such that overall caloric intake is not decreased,? the authors of the study concluded. (Anson, p. 6220, col. 2)

REFERENCE

Michels KB, Ekbom A. Caloric restriction and incidence of breast cancer. JAMA. 2004 Mar 10, 291(10):1226-30.

Anson R, Guo Z, De Cabo R, Iyun T, Rios M, Hagepanos A, Ingram D, Lane M, Mattson M. Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. Proc Natl Acad Sci U S A. 2003 May 13, 100(10):6216-20.

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• Cancer, Breast