Why fish oils may not always be adequate treatments for depression or other inflammatory illnesses: docosahexaenoic acid, an omega-3 polyunsaturated fatty acid, induces a Th-1-like immune response.
Maes M, Mihaylova I, Kubera M, Bosmans E.
Neuro Endocrinol Lett. 2007 Dec;28(6):875-80.
PMID: 18063921
Th1/Th2 balance: the hypothesis, its limitations, and implications for health and disease.
Kidd P.
Altern Med Rev. 2003 Aug;8(3):223-46. Review.
PMID: 12946237
Th1 pathways typically produce activation of cytotoxic T
lymphocytes (Tc), NK cells, macrophages, and monocytes, all of
which can attack cancer cells and generally defend against tumors.
55 IFN-gamma and other Th1 cytokines are typically lower in
advanced cancer patients, while the Th2 marker IL-4 can be higher
or unchanged.56 Nodules of non-small cell lung cancer freshly
removed from patients expressed a marked imbalance toward Th2, as
did biopsy samples from basal cell carcinoma.57 In prostate cancer
patients IL-2 was low (Th1) and IL-10 high.58 IL-10 is a confirmed
Th1-suppressive cytokine, and heightened IL-10 is a common factor
in cancer.55
IL-10 has a variety of suppressive effects that include inhibiting
Th1 cytokine production, down-regulating APC and NK cell function,
and lowering overall T-cell proliferation.57 Especially under the
influence of IL-4 (Th2), tumor cells apparently up-regulate IL-10
that suppresses nearby killer cells. Tumor-derived IL-10 has been
documented in lymphoma, ovarian carcinoma, melanoma, neuroblastoma,
and renal cell and colon carcinoma.57 IL-12 is another cytokine
that can be up-regulated by Th1 activity and inhibited by Th2.59 A
low IL-12/IL-10 ratio was found in cervical cancer patients.55
Recent clinical studies suggest elevated IL-10 is predictive of a
poor prognosis. 57 With both IL-4 and IL-10 being proven inhibitors
of Th1 and promoters of Th2 activity, the recognized capability of
cancerous tissue to suppress immunity is readily rationalized.
Prostaglandin E2 production and T cell function after fish-oil supplementation: response to antioxidant cosupplementation.
Trebble TM, Wootton SA, Miles EA, Mullee M, Arden NK, Ballinger AB, Stroud MA, Burdge GC, Calder PC.
Am J Clin Nutr. 2003 Sep;78(3):376-82.
PMID: 12936918
Lipoxin A4: anti-inflammatory and anti-angiogenic impact on endothelial cells.
Baker N, O'Meara SJ, Scannell M, Maderna P, Godson C.
J Immunol. 2009 Mar 15;182(6):3819-26.
PMID: 19265161
doi:10.4049/jimmunol.0803175
Impact of fish oil enriched total parenteral nutrition on DNA synthesis, cytokine release and receptor expression by lymphocytes in the postoperative period.
Schauder P, Röhn U, Schäfer G, Korff G, Schenk HD.
Br J Nutr. 2002 Jan;87 Suppl 1:S103-10.
PMID: 11895146
doi:10.1079/BJN2001463