Flaxseed Supplementation (Not Dietary Fat Restriction) Reduces Prostate Cancer Proliferation Rates in Men Presurgery
What this study found
Flaxseed supplementation was associated with lower prostate tumor cell proliferation before surgery, whereas low-fat diet alone did not show a clear antitumor effect. Median Ki-67 proliferating cells per total nuclei x100 was 1.66 in the flaxseed group and 1.50 in the flaxseed plus low-fat group, compared with 2.56 in the low-fat group and 3.23 in controls; flaxseed arms showed lower proliferation with P < 0.002, and reported flaxseed-effect P values ranged from 0.0007 to 0.02. There were no consistent between-arm differences in apoptosis or most serologic endpoints. The low-fat arm…
- Study & population
- Randomized presurgical controlled trial in men with biopsy-confirmed prostate cancer scheduled for prostatectomy.
- Intervention
- Men in the flaxseed arm received 30 g/day of ground flaxseed orally, stepped up over 7 days (10 g on days 1–3, 20 g on days 4–6, 30 g/day from day 7 onward) with at least 64 oz/day of fluids.
- Key limitation
- The intervention period was short, averaging 30.7 days and ending within 3 days of surgery, so long-term clinical relevance is uncertain.
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Open PDFOriginal abstract
Background: Prostate cancer affects one of six men during their lifetime. Dietary factors are postulated to influence the development and progression of prostate cancer. Low-fat diets and flaxseed supplementation may offer potentially protective strategies. Methods: We undertook a multisite, randomized controlled trial to test the effects of low-fat and/or flaxseed-supplemented diets on the biology of the prostate and other biomarkers. Prostate cancer patients (n = 161) scheduled at least 21 days before prostatectomy were randomly assigned to one of the following arms: (a) control (usual diet), (b) flaxseed-supplemented diet (30 g/d), (c) low-fat diet (<20% total energy), or (d) flaxseed-supplemented, low-fat diet. Blood was drawn at baseline and before surgery and analyzed for prostate-specific antigen, sex hormone-binding globulin, testosterone, insulin-like growth factor-I and binding protein-3, C-reactive protein, and total and low-density lipoprotein cholesterol. Tumors were assessed for proliferation (Ki-67, the primary endpoint) and apoptosis. Results: Men were on protocol an average of 30 days. Proliferation rates were significantly lower (P < 0.002) among men assigned to the flaxseed arms. Median Ki-67-positive cells/total nuclei ratios (×100) were 1.66 (flaxseed-supplemented diet) and 1.50 (flaxseed-supplemented, low-fat diet) versus 3.23 (control) and 2.56 (low-fat diet). No differences were observed between arms with regard to side effects, apoptosis, and most serologic endpoints; however, men on low-fat diets experienced significant decreases in serum cholesterol (P = 0.048). Conclusions: Findings suggest that flaxseed is safe and associated with biological alterations that may be protective for prostate cancer. Data also further support low-fat diets to manage serum cholesterol. (Cancer Epidemiol Biomarkers Prev 2008;17(12):3577–87)