Dietary omega-3 polyunsaturated fatty acids promote colon carcinoma metastasis

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I haven't seen this association before so I was taken aback by this!

" Rats were kept on either a low-fat diet or on a fish oil (omega-3

PUFAs) or safflower oil (omega-6 PUFAs) diet for 3 weeks before the

administration of colon cancer cells to the portal vein, until they

were sacrificed at 1 or 3 weeks after tumor transplantation. At 1 week

after transplantation, the fish oil diet had induced 7-fold more

metastases (in terms of number and size) than had the low-fat diet... "

What do you " fish advocates " make of this? I don't each much fish, now

i am glad i haven't, my diet is predominately plant-based. Prior to

this discovery, I have considered eating more, but not now.

Cancer Res. 1998 Aug 1;58(15):3312-9. Related Articles, Links

Dietary omega-3 polyunsaturated fatty acids promote colon

carcinoma metastasis in rat liver.

i P, Fehres O, Klieverik L, Vogels IM, Tigchelaar W,

Smorenburg SM, Van Noorden CJ.

Academic Medical Center, University of Amsterdam, Department of

Cell Biology and Histology, The Netherlands.

The effects of omega-3 polyunsaturated fatty acids (PUFAs) and

omega-6 PUFAs on the development of experimentally induced colon

carcinoma metastasis in rat liver were investigated quantitatively in

vivo. Rats were kept on either a low-fat diet or on a fish oil

(omega-3 PUFAs) or safflower oil (omega-6 PUFAs) diet for 3 weeks

before the administration of colon cancer cells to the portal vein,

until they were sacrificed at 1 or 3 weeks after tumor

transplantation. At 1 week after transplantation, the fish oil diet

had induced 7-fold more metastases (in terms of number and size) than

had the low-fat diet, whereas the safflower oil diet had not affected

the number and total volume of metastases. At 3 weeks after tumor

transplantation, the fish oil diet and the safflower oil diet had

induced, respectively, 10- and 4-fold more metastases (number) and

over 1000- and 500-fold more metastases (size) than were found in the

livers of rats on the low-fat diet. These differences were sex

independent. Immunohistochemical analysis revealed that the immune

system in the liver (Kupffer cells, pit cells, T cells, newly

recruited macrophages, and the activation state of macrophages) did

not play a significant role in this diet-dependent outgrowth of

tumors. In conclusion, omega-3 and omega-6 PUFAs promote colon cancer

metastasis in the liver without down-regulating the immune system.

This finding has serious implications for the treatment of cancer

patients with fish oil diet to fight cachexia.

PMID: 9699661