Intensive diet and lifestyle changes slow the progression of low-grade prostate cancer, according to a landmark multi-institutional study.* While it is well known that a low-fat, plant-based diet is associated with a decreased risk of prostate cancer, this new research indicates that diet can influence the outcome of established prostate cancer.
At the onset of this 12-month study of men with biopsy-confirmed prostate cancer, all 93 participants had Gleason scores (a grading system for prostate cancer) of less than 7 and prostate-specific antigen (PSA) levels of between 4 and 10 ng/mL. Due to the low-risk nature of their prostate cancer, all the subjects had chosen a “watchful waiting” approach instead of conventional treatment such as surgery, chemotherapy, or radiation. The treatment group of 44 men consumed a vegan diet and supplemented daily with one serving of tofu, 58 grams of soy protein, 3 grams of fish oil, 400 IU of vitamin E, 200 mcg of selenium, and 2 grams of vitamin C. In addition, the treatment group walked 30 minutes six days per week, engaged in 60 minutes of stress management daily, and participated in a 60-minute support group once weekly. The 49 men who made up the control group followed the diet and lifestyle advice of their personal physicians.
At the end of one year, the treatment group demonstrated an average 4% decrease in PSA level, as compared with a 6% increase in the control group, representing a statistically significant difference. Increased PSA is considered a sign of disease progression and highly predictive of men who will require treatment, as opposed to continued watchful waiting.
Additionally, the researchers examined the effects of serums from the study and control patients on a line of androgen-dependent human prostate cancer cells in the laboratory. Serum from the men in the treatment group inhibited cancer cell growth by 70%, while serum from men in the control group decreased cancer cell growth by only 9%.
Diet and lifestyle factors appear to have a positive influence on men with untreated, low-grade prostate cancer. Further investigation is indicated to determine whether such changes may similarly benefit men undergoing conventional treatment for prostate cancer.
—Linda M. Smith, RN