Cancer
Soy’s relationship to cancer has been studied extensively over the past 20 years. Epidemiological studies show lower cancer rates in populations that regularly consume soy1, and the data suggest that soy intake may have particular benefits for reducing the risk of breast and prostate cancers.2-5
Soyfoods can also be encouraged as an important protein source in the plant-based diets frequently recommended to help reduce the risk of cancer and cancer recurrence.
References: 1. Pisani P, Bray F, Parkin DM. Estimates of the world-wide prevalence of cancer for 25 sites in the adult population. Int J Cancer. 2002;97:72-81.
2. Korde LA et al. Childhood soy intake and breast cancer risk in Asian American women. Cancer Epidemiol Biomarkers Prev. 2009; Apr 18(4): 1050-9.
3. Shu X et al. Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women. Cancer Epidemiol Biomarkers Prev. 2001; 10:483-8.
4. Shu XO et al. Soyfood intake and breast cancer survival. JAMA. 2009; 302(22): 2437-2443.
5. Yan L, Spitznagel EL. Soy consumption and prostate cancer risk in men: a revisit of the meta-analysis. Am J Clin Nut. 2009; 89: 1155-63.
Soy & the American Cancer Society
According to the American Cancer Society, soy may reduce the risk of certain cancers: “As with other beans or legumes, soy and foods derived from soy are an excellent source of protein and thus provide a good alternative to meat. Soy contains several phytochemicals, and is a rich source of isoflavone phytochemicals, which have weak estrogenic activity and may protect against hormone-dependent cancers. There is growing evidence from epidemiologic studies that the consumption of traditional soy foods such as tofu may decrease the risk of cancers of the breast, prostate, or endometrium, and there is selected evidence for a risk reduction of some other cancers.”
Link to abstract
Kushi LH, Doyle C, McCullough M, et al. (2012) American Cancer Society guidelines on nutrition and physical activity for cancer prevention: Reducing the risk of cancer with healthy food choices and physical activity. CA Cancer J Clin 62:30-67.
Study suggests soy may lower risk for lung cancer
A review of 11 studies found a 23% lower risk of lung cancer in those who consumed a higher amount of soy, such as tofu and soymilk, than those who consumed less soy. The authors cautioned the strongest link was in people who never smoked, women, and in Asian populations, and more studies need to be conducted to fully understand the connection between soy and lung cancer.1
Link to study
1. Yang WS, Va P, Wong MY, et al. Soy intake is associated with lower lung cancer risk: results from a meta-analysis of epidemiologic studies. Am J Clin Nutr. 2011 Nov. 9 [Epub ahead of print]
Evidence suggests soy consumption is not associated with increased risk of breast cancer recurrence.
A large meta-analysis of over 16,000 breast cancer survivors showed that eating soyfoods such as soymilk and tofu did not increase the risk of cancer recurrence. While not statistically signficant, a trend was observed toward benefits of soy consumption – women who consumed the most isoflavones (more than 23 mg isoflavones/day, about 1 serving of soymilk), had a 9% reduced risk of mortality and a 15% reduced risk for cancer recurrence.1
Link to study
References:
1.Xiao S et al. Presented at the 102nd Annual Meeting of the American Association for Cancer Research, Orlando, FL, April 2-6, 2011.
Early soy consumption may help to decrease the risk of breast cancer later in life.
A study by researchers at the National Cancer Institute found that Asian-American women who consumed the most soy between the ages of 5 and 11 were 58% less likely to develop breast cancer in comparison to women who consumed little soy during childhood.1
Link to study
References:
1. Korde LA et al. Childhood soy intake and breast cancer risk in Asian American women. Cancer Epidemiol Biomarkers Prev. 2009; Apr 18(4): 1050-9.
Epidemiological evidence suggests soy intake is associated with decreased breast cancer risk.
A recent meta-analysis found that in Asian populations, higher soy intake was associated with a 29% decreased risk of breast cancer.1 However, evidence suggests that this benefit depends on soy consumption early in life.
Link to study
References:
1.Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 2008 Jan 15; 98: 9-14.
Soy may help reduce the risk of cancer recurrence
In a recent epidemiological study of nearly 2,000 American breast cancer patients, researchers found that soy isoflavone consumption was associated with an improved prognosis and a reduced risk of cancer recurrence over the six-year follow up period.1
Link to study
References: 1. Guha N et al. Soy isoflavones and risk of cancer recurrence in a cohort of breast cancer survivors: the Life After Cancer Epidemiology Study. Breast Cancer Res Treat 2009; 118: 395-405.
