Omega-3 Fatty Acids and Cancer Prevention
Homer S Black *
Department of Dermatology, Baylor College of Medicine, Houston, Texas 77030, USA
- *Corresponding Author:
- Homer S Black
Department of Dermatology
Baylor College of Medicine, Houston
T exas 77030, USA
T el: 832-741-1052
Received date: January 27, 2017; Accepted date: February 09, 2017; Published date: February 16, 2017
Citation: Black HS (2017) Omega-3 Fatty Acids and Cancer Prevention. J Integr Oncol 6:e112. doi: 10.4172/2329-6771.1000e112
Copyright: © 2017, Black HS. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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A recent review has summarized the evidence that omega-3 fatty
acids (FA) have potential in reducing the risk for a common form of
cancer . This editorial is a synopsis of that review covering the
historical interest in the potential health benefits of omega-3 FA; the
mechanistic rationale for such beneficial effect; and the experimental
and clinical evidence that omega-3 supplementation could play an
important role in cancer prevention.
Omega-3 fatty acids (FA) are one of two classes (Omega-3 and
Omega-6) of essential fatty acids (EFA). They are both considered
essential as they cannot be interconverted by the human body and the
precursors, linoleic acid and linolenic acid for omega-6 and omega-3
FA respectively, must be provided in the diet . Interest in the health
benefits of omega-3 FA arose from earlier observations that
Greenlandic West Coast Eskimos, whose lipid diet consisted mainly of
marine oils, rich in omega-3 FA, exhibited low incidence of ischemic
heart disease and general inflammatory symptoms [3-5]. Results from
randomized clinical trials regarding the relation of omega-3 FA on
cardiovascular disease (CVD) have remained controversial although
observational studies have generally shown that higher levels of
omega-3 FA intake was associated with lower risk for CVD outcomes
[6-9]. Whereas the primary interest has been on cardiovascular
disease, studies of other inflammatory diseases have included diabetes,
inflammatory bowel disease, arthritis, and asthma [10,11]. A recent
study reports that supplementation of omega-3 FA in the third
trimester of pregnancy reduced the absolute risk of wheeze and asthma
in offspring by about one-third .
Inflammatory mechanisms appear to be common to the above
noted diseases as well as to carcinogenesis. Indeed, inflammatory
processes are involved in initiation, promotion, and progression stages
of cancer . Herein, lays a rationale for potential involvement of
omega-3 FA in reduction of cancer risk. These two series of FA,
omega-6 and omega-3, compete for active enzyme sites in the
cyclooxygenase (COX) and lipoxygenase (LOX) pathways and thus
influence the oxidative metabolites passing through these pathways
. The omega-6 FA metabolites are of greater hormonal potency than
those of the omega-3 FA. Some of these metabolites are known to
influence tumor biology. As an example, prostaglandin E2 (PGE2),
derived from the omega-6 FA metabolism through the COX pathway,
acts as a tumor promoter and has been associated with aggressive
growth patterns in both basal cell carcinoma (BCC) and squamous cell
carcinoma (SCC) in humans . Contrarily, omega-3 FA, competing
with omega-6 FA, inhibit the production of PGE2 and results in
formation of the less potent PGE3. Omega-3 FA may also shunt
potential prostaglandin precursors through the LOX pathway resulting
in intermediates that inhibit tumor growth and that are involved in
immune surveillance . Based upon the influence of dietary lipids
on the COX and LOX pathways, and their differential bioactive intermediates, a strong rationale is provided for the potential of
omega-3 FA in cancer prevention. Consequently, this potential has
been examined in several types of cancers. Although studies on the
effects of omega-3 FA on CVD have generally been positive, the studies
on human cancers have been equivocal. Some cohort and case control
studies, but not all, have shown that women that have a higher intake
of omega-3 FA intake, compared to omega-6 FA, have a lower
incidence of breast cancer. However, among 43 risk ratios calculated
across 19 cohorts for 11 different types of cancer and five different
ways to assess omega-3 FA consumption, only four were significant
and it was concluded that omega-3 FA did not reduce overall cancer
risk [16-19]. Similar ambiguities occur with respect to prostate cancer
The American Cancer Society estimates that over 3.5 million new
cases of skin cancer will occur this year in the U.S. . In regard to
this most common cancer, a considerable body of experimental and
clinical evidence, albeit circumstantial at this point, exists that omega-3
FA supplementation could reduce the incidence of this most frequently
occurring cancer. This evidence has been reviewed  and is herein
Experimental animal studies
• Increasing dietary levels of omega-6 FA exacerbates ultraviolet
radiation (UVR)–induced carcinogenic expression whereas
omega-3 FA dramatically inhibits UVR carcinogenic expression
with regard to both tumor latency and multiplicity [23, 24].
• Pro-inflammatory and immunosuppressive PGE2 levels are
increased linearly as dietary omega-6 FA levels are increased
whereas PGE2 levels are dramatically reduced by dietary omega-3
FA consumption .
• Dietary omega-6 FA suppresses the immunologic responses
involved in tumor transplant rejection and the immunologic
pathways involved in delayed type hypersensitivity (DTH) and
contact hypersensitivity (CHS), whereas omega-3 FA inhibits the
UVR induced suppression of DTH and CHS [25-27].
Human clinical and cell culture studies
• Omega-3 FA supplementation significantly increases the erythema
(an inflammatory response) threshold to UVR [28, 29].
• Omega-3 FA modulate a number of cytokines and eicosanoids,
including PGE2, that mediate immune and inflammatory
• Omega-3 FA inhibit specific genotoxic markers of UVR-induced
DNA damage, including UVR-induced cutaneous p53 .
• Omega-3 FA abrogate UVR-induced immunosuppression of cell
mediated immunity assessed as nickel CHS .
Indeed, these data are overwhelming suggestive that omega-3 FA
supplementation could result in a significant reduction in human skin
cancer incidence. It has been suggested that the most direct evidence
for the positive potential of omega-3 FA in this preventive role is
through intervention trials in populations with high, and known risk
for non-melanoma skin cancer with a study design similar to that in
which reduction of total dietary fat intake was shown to reduce cancer
risk [36-38]. It is probable that omega-3 FA supplementation could
have beneficial effects on a range of other inflammatory diseases.
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- Black HS (2012) Omega-3 fatty acids and nonmel;anoma skin cancer. In Handbook of diet, nutrition and the skin. Wageningen Academic Publishers, The Netherlands.
- Bang HO. Dyerberg J (1971) Plasma lipid and lipoprotein pattern in Greenlandic West Coast Eskimos. Lancet 1: 1143-1145.
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