Does Lower Energy Intake Lessen the Risk of Cancer in AN Patients?

Scientists have shown that restricting energy intake (without producing malnutrition) is a potent way to prevent cancer in animals. Humans are another matter, and it is not clear whether this principle applies to us. Furthermore, in one Danish study of 2000 female patients with anorexia nervosa (AN), there was a slight but not significant reduced rate of cancer compared to the general Danish female population (Cancer Causes Control. 2001; 12:123). In contrast, Israeli Jewish survivors of World War II, who had extremely low energy intake, had an increased risk of cancer (Natl Cancer Inst. 2009; 101:1489).

Scandinavian researchers recently designed a register-based matched cohort study of patients with AN in Sweden, Denmark, and Finland to test the cancer-energy intake connection (PLOS ONE. DOI:10.1371/journmal.pone.p128018. May 22, 2015). The retrospective study examined the cases of 22,654 women and 1,678 men 10 to 50 years of age who were diagnosed with AN between 1968 and 2010. A comparison group matched for age, gender, and place of residence, was randomly selected from population registers. The next step was to link the cases of the AN patients and comparison group to the cancer registries in each of the three countries.

Cancer was not linked to energy restriction

The overall incidence of cancer among patients with AN was very similar to that of the general population. One interesting finding was a markedly decreased incidence of breast cancer among anorexic women (a decreased incidence of roughly 40%), which the authors suggested could be traced to low estrogen levels, higher levels of physical activity, or lower amounts of adipose tissue. There was also increased risk of cancer of the esophagus, lung, and liver among women with AN compared to controls. Among men with AN, no significant decreases for any of the cancer sites investigated were found. The authors concluded that they could find no evidence that energy restriction reduces cancer incidence among humans, but it appears there may be reduced risk for specific cancer types.