Excessive Consumption of Soy Products Increases Women's Risk of Liver Cancer
Some studies have found that isoflavones in soy can reduce women's risk of breast cancer, but does that mean the more soy products you eat, the better? A large-scale survey by Japan's Ministry of Health, Labour and Welfare offers a negative answer: eating too many soy products increases women's risk of liver cancer.
According to a recent report in Japan's *Mainichi Shimbun*, a research group from the Ministry of Health, Labour and Welfare tracked the health status of approximately 20,000 people in Japan from 1993 to 2005. During this period, a total of 69 men and 32 women developed liver cancer. Researchers used questionnaires to understand the participants' consumption of soy products and analyzed the association between soy isoflavone intake and the incidence of liver cancer.
The results showed that only in women was there a link between the amount of isoflavone intake and the risk of liver cancer. The group of women with the highest isoflavone intake (equivalent to an average of more than 80 grams of tofu per day) had a 3.2 to 3.9 times higher risk of liver cancer than the group with the lowest intake (equivalent to less than 40 grams of tofu per day).
Researchers analyzed that the molecular structure of isoflavones is similar to that of estrogen in the female body. Estrogen increases the risk of breast cancer in women but has a protective effect against liver cancer. The increased risk of liver cancer from excessive isoflavone intake may be due to isoflavones interfering with the protective effect of estrogen against liver cancer.
Researchers recommend moderate intake of isoflavones in the diet. If a woman is confirmed to be infected with the hepatitis B or C virus, she should be careful not to consume too many soy products.