Calorie Restriction Might Reduce Breast Cancer Risk
Posted Feb 21 2011 10:09am
Calorie restriction without malnutrition has been linked to a variety of possible health benefits and a possible increased lifespan. These potential benefits appear to be mediated through a number of mechanisms, including obesity related hormones. However, the relationship between caloric restriction and breast cancer risk is not clearly understood.
A new breast cancer research study examined the potential relationships between caloric restriction, the obesity related hormones leptin and adiponectin, and breast cancer in mice. In this study, mice were assigned to be fed ad libitum (free access to food at any time) or to receive intermittent calorie restriction (3 weeks at 50% caloric restriction followed by 3 weeks free feeding), or to receive chronic calorie restriction (75% of free feeding group). Blood samples were collected and breast cancer incidence was measured in order to better understand the relationship between calorie restriction and breast cancer risk. The results of this study showed that
Blood levels of adiponectin did not change with either intermittent or chronic calorie restriction.
Blood levels of leptin decreased in both groups of mice subjected to caloric restriction, but rose in mice allowed to eat at will.
These changes in leptin levels resulted in an increase in the adiponectin:leptin ratio in mice subjected to intermittent calorie restriction.
Mammary fat pad tissue from mice subjected to intermittent caloric restriction and free of breast cancer had elevated levels of adiponectin compared to the two other groups of mice.
Breast cancer incidence was only 9.1% in mice receiving intermittent calorie restriction compared to about 35% in mice receiving chronic calorie restriction and 71% in mice allowed to eat freely.
Overall, these study results suggest that intermittent calorie restriction leads to a dramatic reduction in breast cancer risk in mice and that this reduction might be due to elevated breast tissue levels of adiponectin and an elevated ratio of adiponectin:leptin in the blood. This study appears to confirm earlier studies that suggested caloric restriction and adiponectin levels might be linked to breast cancer risk. Additionally, the results of this breast cancer research study imply that the hormone changes observed with calorie restriction might be part of the reason why some studies have reported a decrease in breast cancer risk with weight loss. While intermittent caloric restriction provided the greatest benefits in this study, both forms of calorie restriction reduced breast cancer risk compared to free feeding. This suggests that individuals unable to commit to one form of dieting might still obtain breast cancer fighting benefits through other forms of healthy weight loss.