IGF-1 is a hormone important to the growth and function of many organs. Higher levels of IGF-1 have been associated independently with an increased risk of a number of cancers, including prostate, colon, lung and breast cancer. Two studies examined the relationship between modifiable lifestyle factors and circulation levels of IGF-1 to potentially define new methods of cancer prevention. Women with four or more pregnancies had IGF-1 levels that were on average 15 percent lower than in women who had no history of pregnancy. “Our most important new finding is that there is an inverse association of circulating IGF-1 levels with increasing parity in healthy women,” said researcher Michelle Holmes. “This association may define one way in which pregnancy exerts a protective influence on cancer, reducing risk in women.” A second related study examined how diet affects IGF levels in well-nourished individuals. The most consistent finding was a positive association between protein with circulating IGF-1 concentrations, largely attributable to milk intake. “We concluded that greater milk consumption was associated with higher levels of IGF-1,” said Holmes.