|KIM, HYUNSOOK - Konkuk University|
|Yokoyama, Wallace - Wally|
|DAVIS, PAUL - University Of California|
Submitted to: Journal of Medicinal Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2014
Publication Date: 12/5/2014
Citation: Kim, H., Yokoyama, W.H., Davis, P.A. 2014. Walnuts lower TRAMP prostate tumor growth by altering IGF-1, energy and cholesterol metabolism and is not due to their fatty acids. Journal of Medicinal Foods. 17(12):1281-1286.
Interpretive Summary: Mice that were genetically disposed to develop prostate cancer were fed high fat diets supplemented with walnuts or walnut oil. Tumors in mice fed the walnut and walnut oil diets grew at a slower rate than the mice fed high fat diets without walnuts. Expression of a tumor suppressor gene was higher in the walnut and walnut oil diets. Total cholesterol and insulin growth factor 1 (IGF1) was lower in the walnut and walnut oil diets. Lower tumor growth may be due to lower energy metabolism in mice fed walnut or walnut oil.
Technical Abstract: Dietary changes could potentially reduce prostate cancer morbidity and mortality. Prostate tumor size, gene expression, metabolite and plasma responses to a 100 g of fat/kg diet (whole walnuts, walnut oil and other oils; balanced for macronutrients, tocopherols (a-and ' ) for 18 weeks were assessed in mice genetically disposed to develop prostate cancer (TRAMP). Mice (N=25 per group) were fed diets with fat from either whole walnuts (diet group WW), walnut like fat (diet group WLF, oils blended to match walnut’s fatty acid profile) or as walnut oil (diet group WO, pressed from same walnuts as WW). Prostate tumor size and plasma IGF1, HDL and total cholesterol decreased in both WW and WO compared to WLF (p<0.05). WW and WO diet groups compared to WLF had 9 metabolites in common that changed in same direction from a total of 16 and 95 different altered metabolites. 17 mRNA species were in common and changed in same direction in WW and WO compared to WLF out of a total of 213 and 41 respectively. WW and WO both had increased MSMB, a tumor suppressor, mRNa but decreased COX2 mRNA. We concluded that walnuts reduced prostate tumor growth by affecting energy metabolism along with decreased plasma IGF-1 and cholesterol. This effect is not due to walnut’s N-3 fatty acids, tocopherols, or minerals (i.e. Zn, Mg or Se) and is due to component(s) found in walnut’s fat component.