Flaxseed, Soy Protein Offer Varying Results in the Treatment of Breast Cancer
by Somlynn Rorie 11/09/2007
TORONTO—Researchers at the University of Toronto continue to investigate the role of flaxseed and soy protein isolate in the treatment of breast cancer (Journal of Toxicology and Environmental Health 2007; 70.22:1888-96).
Researchers found that flaxseed (FS) reduced breast tumor growth in ovariectomized mice; while soy protein isolate (SPI) stimulated growth. Consequently, combining both SPI and FS resulted in the negation of SPI-induced tumor growth. The effect of SPI, FS and their combination were also examined on mouse bone and uterus to ensure overall safety of breast cancer treatment.
The mice in the study had MCF-7 xeonografts and were fed either a controlled diet or one supplemented with 10 percent FS, 20 percent SPI or a combination of SPI and FS for 25 weeks. Their bones were analyzed for mineral density and biomechanical strength, such as yield load, stiffness and peak load.
The SPI group possessed a higher femur bone mineral density and more strength, while the FS group possessed increased femur stiffness and peak load.
Femur mineral density was not affected in the mice who consumed a combination of SPI and FS; however, the femur size was significantly reduced but the biomechanical parameters increased.
Additionally, uterus weight was significantly increased by the combined SPI and FS diet, while the SPI diet induced an intermediate effect.
Researchers concluded that while these treatments had beneficial effects on bone of postmenopausal cancer, other factors and parameters must be measured to determine the overall safety of FS, SPI and the combination of both as a treatment to breast cancer.
We conducted a case-control study to examine the relationship between fruit, vegetable, and soy food intake and breast cancer risk in Korean women.
Incident cases (n=359) were identified through cancer biopsies between March 1999 and August 2003 at two university hospitals in Seoul, Korea. Hospital-based controls (n=708) were selected from patients in the same hospitals during the same period.
Subjects were asked by personal interview to indicate their average fruit, vegetable, and soy food intake for a 12-mo period 3 yr prior to the baseline phase.
A food intake-frequency questionnaire (98 items) was given by a trained dietitian. Odds ratio (OR) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression after adjustment for confounding factors and total energy intake.
There was no association between the intake of total fruits, vegetables, or soy food and breast cancer risk.
Increasing consumption of grapes was linked to a significant protective effect against risk of breast cancer (OR=0.66; 95% CI=0.41-0.86; P<0.01).
Among the vegetables, reduced risk was observed with high tomato intake (OR=0.62; 95% CI=0.38-0.81; P<0.01). Among soy foods, high consumption of cooked soybeans, including yellow and black soybeans, had an association with reduced breast cancer (OR=0.67; 95% CI=0.45-0.91; P<0.02).
Our data suggest that increased intake of some fruits, vegetables, and soy foods may be associated with breast cancer risk reduction in Korean women.