According to the study conducted by Dr. Larissa Korde of the National Cancer Institute, women who ate soy products on a regular basis during childhood had a 58% reduced risk of acquiring breast cancer. The study was published in the journal Cancer Epidemiology Biomakers and Prevention.
Asian-American women who ate a lot of soy as children had a 58 percent reduced risk of developing breast cancer, US research said in a finding that suggests soy may have a protective effect. It was also mentioned that childhood soy intake was significantly associated with reduced breast cancer risk.
Historically, breast cancer rates among white women in the United States are four to seven times higher than women in China or Japan, Regina Ziegler of the National Cancer Institute said in a statement.
But when Asian women immigrate to the United States, their risk for breast cancer rises over several generations, suggesting something other than genetics was at play. Korde and colleagues checked to see if diet or other lifestyle factors could explain the difference.
They interviewed nearly 1,600 women of Chinese, Japanese and Filipino descent who were living in San Francisco, Oakland, or Los Angeles, California, or Hawaii. Some 600 had breast cancer and the rest were healthy.
If the women had mothers living in the United States, they asked the mothers about their daughter’s soy consumption in childhood.
Women who consumed the highest amounts of soy in childhood had 58 percent less risk of breast cancer.
The effect was weaker when adolescents or adults ate or drank a lot of soy, but the study still found a 20 to 25 percent reduction in risk.
The relationship between childhood soy consumption and reduced cancer risk held for all women in the study, regardless of family history of breast cancer.
The findings about childhood soy consumption suggest the timing of soy intake may be especially critical Korde said.
Why soy may protect is not known, but early soy consumption may interfere with the biology of breast cancer. Soy contains isoflavones with properties similar to the females’ sex hormones estrogen, which may alter breast tissue, she said in a statement.