Conclusions

Studies on PC cells support the conclusion that w-3 fatty acids, EPA and DHA, significantly inhibit cell proliferation more than other fatty acids.  The mammalian lignans at increasing concentrations up to 10-8 M significantly decreased the proliferation of all three PC cell lines.  The hormone-sensitive LNCaP cells were particularly inhibited by both lignans.  In the male TRAMP mice, a 5% flaxseed-supplemented diet as compared to the control diet significantly decreased the PC burden and increased the index of programmed cell death after 20 and 30 weeks of dietary treatment.  To date, our human pilot studies suggest that PC patients consuming a 30-g daily dose of flaxseed in combination with a low-fat (about 20% of total energy; w-3: w-6 ratio of approximately 1:4) diet as compared to the usual American diet had lower measures of cell proliferation and greater programmed cell death in their surgically-removed prostate tissues.  Additional isolated cell investigations are needed to clarify the relationships and mechanisms of various dietary factors to the inhibition of PC growth, promotion and possibly the initiation events.  Additional human studies using high ALA foods, supplements or food components are necessary to help identify the significant relationships associated with diminishing PC risk.  Future human and PC cell studies should help clarify the effects of flaxseed and its various components, such as ALA and the mammalian lignans.