Dr. Taichi Shimazu, from the National Cancer Center, in Tokyo, Japan, and fellow Japanese colleagues performed a study of 36,177 men and 40,484 women in Japan who were 45 to 74 years of age.
At the beginning of the study, none of the subject had any signs of cancer. The baseline years were from 1995 to 1999.
Their research was published online on January 13, 2010, in the American Journal of Clinical Nutrition.
Their paper, entitled 'Isoflavone intake and risk of lung cancer: a prospective cohort study in Japan (doi: 10.3945/ajcn.2009.28161), was authored by Taichi Shimazu, Manami Inoue, Shizuka Sasazuki, Motoki Iwasaki, Norie Sawada, Taiki Yamaji, and Shoichiro Tsugane.
They said in the paper that summarized their research: 'Although case-control studies support the idea that soy foods or isoflavone intake is associated with a decreased risk of lung cancer, little evidence is available from prospective cohort studies."
And, "Moreover, no prospective study has addressed this association in men.'
Page two continues with additional information on isoflavones, along with results from the study.
Isoflavones are naturally occurring organic compounds that are antioxidants. They are produced by members of the bean family Fabaceae, or Leguminosae.
Less then 23,000 of the men were smokers. The Japanese participants were studied for about eleven years.
The men ate between 34 grams and 162 grams of soy each day, on average.
For additional on soy, please go to U.S. Soyfoods.
Over this period of eleven years, which the researchers called '671,864 person-years,' 481 men (1.3%) and 178 women (0.04%) were diagnosed with cancer.
Of the 13,051 men (36.1%) that had never smoked and ate the least amount of soy, 22 of them were diagnosed with lung cancer during the study.
Page three continues with further results from the Japanese study.
Of these same number of never-smoking men, the ones that ate the most soy, only 13 cases of lung cancer were diagnosed.
Consequently, the researchers could not make any conclusions on the relationship of eating soy and not smoking, and lung cancer.
The Japanese researchers found that soy, which contains isoflavones, may help to reduce the risk of lung cancer in men who don't smoke and eat large amounts of soy.
Isofavones are already thought by scientists to have characteristics that help to reduce the risk of some cancers, particularly breast cancer and prostate cancer.
Based partially on this study, soy is thought to also reduce the risk of lung cancer because cells in and around the lung are thought to respond favorably to isoflavones.
Page four provides a conclusion made by the researchers.
The Japanese researchers concluded, 'In a large-scale, population-based, prospective study in Japan, isoflavone intake was associated with a decreased risk of lung cancer in never smokers.' [Abstract to their paper]
Additional information on soy and healthy living in women is provided in the HealthfulLife.com article "Soy products may reduce risk of lung cancer and bone fracture in postmenopausal women."
Such scientific studies show that soy products may help to reduce health problems in humans.
These studies are not conclusive yet, but they are a beginning to possibly proving that soy foods and products are a healthy choice for both men and women.
The HealthfulLife.com article states, "Soy foods and soy products have been shown in some studies to reduce the risk of cardiovascular disease (heart attack, stroke) and certain cancers, notably cancers of the uterus (endometrium) and breast; but the studies are not consistent so the role of soy as a preventive in these diseases is not established."