Soy protein and breast cancer:
Research suggests that soy lowers the risk of breast cancer recurrence and increases the chances for survival in women. Findings from the Shanghai Breast Cancer Survival Study of 5,033 Chinese women diagnosed with breast cancer found a high soy diet (compared to a diet with little or no soy) lowered the risk of breast cancer death and recurrence by 29% and 32%, respectively. Among women with high soy intake (top 25%) 4-year mortality was 7.4% compared to 10.3% for low soy intake (bottom 25%). Recurrence rates were 8.0% for high soy intake and 11.2% for low soy intake. (5)
Assessment and Plan: Soy Protein
- Benefits of soy protein include improved cardiovascular status, potentially improved survival for breast cancer, reduction of total cholesterol/LDL, and enhancement of lean muscle mass with training.
- Soy protein and cholesterol: The Food and Drug Administration (FDA) has approved a statement on food labels that soy protein may reduce the risk of coronary artery disease by lowering cholesterol levels when included in a diet low in saturated fat and cholesterol (1).
- Subjects on a National Cholesterol Education Program Step I diet plus taking isolated soy protein with 62 mg isoflavones per 25 grams for 9 weeks lowered total cholesterol by about 4% and LDL cholesterol by about 6% compared to casein. A greater benefit was seen in subjects with higher LDL levels. The soy protein did not affect plasma concentrations of triglycerides or HDL cholesterol. (2)
- Soy protein, whey protein, resistance training, and cholesterol: Whey protein may have a greater benefit than soy protein in controlling cholesterol. A study showed that overweight men with hyperlipidemia performing resistance training for 12 weeks showed total cholesterol reductions of 10.4 mg/dL for placebo, 11.2 mg/dL for soy protein, and 15.9 mg/dL for whey protein (3).
- Soy protein and resistance training: Researchers found that both soy and whey protein supplementation during resistance training increased lean tissue mass and strength over placebo with equal calorie diet and resistance training (4).
- Soy protein and breast cancer: Findings from the Shanghai Breast Cancer Survival Study of 5,033 Chinese women diagnosed with breast cancer found (5):
- High soy diet compared to a diet with little or no soy lowered the risk of breast cancer death and recurrence by 29% and 32%, respectively.
- 4-year mortality was 7.4% for high soy intake vs. 10.3% for low soy intake.
- Recurrence rates of breast cancer were 8.0% for high soy intake and 11.2% for low soy intake.
