Association between soy and isoflavone consumption, gastrointestinal (GI) cancer risk

the Oncology Nurse Advisor take:

According to a new study published in the European Journal of Nutrition, soy consumption is only associated with a small decrease in gastrointestinal cancer risk, while isoflavone consumption is significantly associated with a reduction in gastrointestinal cancer risk.

For the study, researchers sought to investigate the association between soy and isoflavone consumption and gastrointestinal cancer risk. Isoflavone is an active soy constituent but can be consumed as a dietary supplement.

Researchers identified 22 case-control and 18 cohort studies with a total participation of 633,476 patients and 13,639 cases of gastrointestinal cancer. Of the 40 studies, 10 were used for a subgroup analysis for isoflavone consumption.

Results showed that there was only a small reduction in gastrointestinal cancer risk due to soy intake (combined odds ratio = 0.93; 95% CI: 0.87 - 0.99; P = 0.01).

Particularly, the association was stronger for colon and colorectal cancers. In contrast, the subgroup analysis for isoflavone showed a significant reduction in gastrointestinal cancer risk, especially colorectal cancer risk, due to isoflavone consumption (OR = 0.73; 95% CI: 0.59 - 0.92; P = 0).