Omega-3 Fatty Acids
Omega-3 fatty acids-eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA)-are derived from fish oils of
cold water fish (salmon, trout, or most commonly menhaden
fish) and flaxseed. Omega-6 fatty acids-linoleic acid (LA) and
gamma-linolenic acid (GLA)-are derived from the oils of seeds
such as evening primrose, black currant, and borage. Often,
fatty acids are added to the diet with other supplements to
attain an additive effect.
In transplanted tumor models, omega-3 fatty acids
reduced tumor development while omega-6 fatty acids
stimulated tumor development. Omega-3 fatty acids have
been shown to inhibit tumor growth as well as the spread of
cancer. Reduced radiation damage in the skin was also seen
following supplementation with omega-3 fatty acids.
The use of omega-3 fatty acids can promote weight
gain and may have anticancer effects, and warrants
special mention. In people, the use of omega-3 fatty acids,
such as those found in fish oils, improves the immune
status, metabolic status, and clinical outcomes of cancer
patients. These supplements also decrease the duration
of hospitalization and complication rates in people with
gastrointestinal cancer. In animal models, the omega-3s
inhibit the formation of tumors and metastasis. Finally,
omega-3 supplementation shows anticachetic (anti-wasting)
Note: Flaxseed oil is a popular source of alpha-linoleic acid
(ALA), and omega-3 that is ultimately converted to EPA and
DHA. However, many species of pets (probably including dogs)
cannot convert ALA to these other more active non-inflammatory
omega-3s. Also, flaxseed oil contains omega-6, which are not
recommended in pets with cancer. In one study in people,
flaxseed oil was ineffective in reducing symptoms or raising levels
of EPA and DHA. While flaxseed oil has been suggested as a
less smelly substitute for fish oil, there is no evidence that it is
effective when used for the same therapeutic purposes as fish oil.
Therefore, supplementation with EPA and DHA is important,
and this is the reason flaxseed oil is not recommended as the sole
fatty acid supplement for pets.
While many doctors use fatty acids for a variety of medical
problems, there is considerable debate about the use of fatty
acids. The debate concerns several areas.
What is the "best" dose to use in the treatment of pets?
Most doctors use anywhere from two to ten times the label
dose. The recommended dosage for pets with cancer is
approximately 1500 mg/100 kcal of food. In order to get this
dose, depending upon the product selected, you would need
to feed your dog about five capsules per 100 kcal of diet. This
is a LOT of fatty acid capsules!
Is supplementation with fatty acid capsules or liquids
the best approach, or is dietary manipulation preferred for
treatment of cancer? There is one diet, Prescription Diet n/d,
made for dogs with cancer. This diet contains the "proper"
amount of omega-3 fatty acids, and it is impossible to add
enough fatty acids in the form of supplements to equal the
amount found in this diet. However, the protein source, beef
lung, is not the most wholesome protein source, which is a
concern for holistic pet owners. Many owners use some of
the n/d with a homemade diet plus additional fatty acids to
achieve a compromise.
Studies done in dogs with lymphoma and nasal tumors
have shown that dogs eating the n/d showed increased
disease-free intervals and survival times when compared
with similarly treated dogs not eating this diet. While
research has not been reported in dogs with other cancers
or in cats with cancers, it is recommended to use fatty acid
supplementation in pets with any kind of cancer due to the
Fish Oils For Pets
Since fish oils can easily oxidize and become rancid, some
manufacturers add vitamin E to fish oil capsules and liquid
products to keep the oil from spoiling. (Others remove
oxygen from the capsule.)
The bottom line is there are many questions regarding
the use of fatty acid therapy. More research is needed, as
well as the proper dosage needed to achieve clinical results.
Until definitive answers are obtained, you will need to work
with your doctors to determine the use of these supplements
for your pet.
Fish oil appears to be safe. The most common side effect
is a fish odor to the breath or the skin.
Because fish oil has a mild "blood-thinning" effect,
it should not be combined with powerful blood-thinning
medications, such as Coumadin (warfarin) or Heparin, except
on a veterinarian's advice. Fish oil does not seem to cause
bleeding problems when it is taken by itself at commonly
recommended dosages. Also, it does not appear to raise
blood sugar levels in people or pets with diabetes.
Flaxseed Oil For Pets
Flaxseed oil is derived from the seeds of the flax plant and
has been proposed as a less smelling alternative to fish oil.
Flaxseed oil contains alpha-linolenic acid (ALA), an omega-3
fatty acid that is ultimately converted to EPA and DHA. In
fact, flaxseed oil contains higher levels of omega-3 fatty acids
(ALA) than fish oil. It also contains omega-6 fatty acids.
As mentioned, many species of pets (probably including
dogs and cats) cannot convert ALA to these other more
active non-inflammatory omega-3 fatty acids. In one study
in people, flaxseed oil was ineffective in reducing symptoms
or raising levels of EPA and DHA. While flaxseed oil has been suggested as a substitute for fish oil, there
is no evidence that it is effective when used for the same
therapeutic purposes as fish oil. Unlike the case for fish oil,
there is little evidence that flaxseed oil is effective for any
specific therapeutic purpose.
Therefore, supplementation with EPA and DHA
is important, and this is the reason flaxseed oil is not
recommended as the sole fatty acid supplement for pets.
Flaxseed oil can be used to provide ALA and as a coat
Flaxseed oil also contains lignans, which are currently
being studied for use in preventing cancer in people. To date,
we have no information to recommend their use in pets with
The essential fatty acids in flax can be damaged by
exposure to heat, light, and oxygen. For this reason, you
shouldn't cook with flaxseed oil. A good product should be
sold in an opaque container, and the manufacturing process
should keep the temperature under 100 degrees F. Some
manufacturers combine the product with vitamin E because
it helps prevent rancidity.
The best use of flaxseed oil is as a general nutritional
supplement to provide essential fatty acids. It appears to be
a safe nutritional supplement when used as recommended.
Glycoproteins are protein molecules bound to carbohydrate
molecules. Glycoprotein molecules coat the surface of
every cell with a nucleus in the human body. The body
uses the glycoproteins on cell surface glycoconjugates
as communication or recognition molecules. These
communications may then result in other cellular events,
including secretion of bioactive substances (interferon,
interleukin-1, complement), ingestion of bacteria and cell debris, inhibition of adherence necessary for bacterial
infection, and the spread of cancer cell metastasis.
Scientists have identified eight sugars, glycoforms,
found on human cell surfaces that are involved in cellular
recognition processes. Of the 200 such sugars occurring
naturally in plants, to date only these eight have been
identified as components of cellular glycoproteins. These
eight sugars that are essential for glycoconjugate synthesis
(mannose, galactose, fucose, xylose, glucose, sialic acid,
N-acetylglucosamine, N-acetylgalactosamine) can be readily
absorbed and directly incorporated into glycoproteins and
Research has found specific cell surface glycoforms to be
characteristic of many disease conditions. In some people
with rheumatoid arthritis, some of these patients' defense
cells (IgG antibody) bear malformed glycoproteins. These
cells are missing required galactose molecules; the extent to
which the galactose molecules are missing correlates with
disease severity and reverses in disease remission. In people
with cancer, more than 20 different malignancies are known
to be associated with characteristic glycoproteins.
Glyconutritional supplements are designed to provide
substrates for the body to use in building part of the
glycoconjugates on cell surfaces. These supplements, most
commonly acemannan and mannose, are designed to make
the necessary sugars available to the cells quicker and in
Acemannan is a glycoprotein (a long chain of mannan
polymers with random o-acetyl groups) derived from the
aloe vera plant that has been shown to increase the body's
production of immune-modulating chemicals, including
interleukins 1 and 6, and Prostaglandin E2 and tumor necrosis
factor alpha by macrophages. Acemannan also enhances
macrophage phagocytosis and nonspecific cytotoxicity, which
increases the ability of white blood cells (macrophages)
to destroy infectious organisms. Glycoproteins such as
acemannan also offer antiviral activity as well as bone
marrow stimulating activity.
Acemannan has been approved as an adjunct therapy for
solid tumors called fibrosarcomas. Intralesional injection
into the tumor (2 mg weekly for up to six weeks), combined
with intraperitoneal injections (1 mg/kg of body weight given
weekly for six weeks, followed by monthly injections for one
year), has been shown to be effective in shrinking tumors
(via necrosis and inflammation).
All eight of the glycoconjugate sugars are readily absorbed
from the intestines when taken orally. Studies has shown
intact mannose molecules are rapidly absorbed from the
intestine of rats into the blood, elevate the blood mannose
levels by 3-to 10-fold, and is cleared from the blood within
hours. The conclusion reached was that mannose was
absorbed from the intestinal tract into the blood and from
the blood into the cells. These studies suggest that dietary
mannose may make a significant contribution to glycoforms
synthesis in mammals.
Other human and animal ingestion studies show
mannose is readily absorbed, and is cleared from the blood
over several hours; some of the mannose was incorporated
into glycoproteins. After absorption into the blood,
glycoconjugate sugars generally become distributed (usually
as glycoproteins and glycolipids) into body fluids, organs,
and various body tissues.
In one study, healthy humans were given radiolabeled
galactose, mannose, or glucose. This study showed galactose
and mannose were directly incorporated into human
glycoproteins without first being broken down into glucose.
The conclusion was specific dietary sugars could represent a
new class of nutrients and the use of these nutrients could
have important consequences. Therapy with mannose offers
a treatment that is easy to administer and is nontoxic.
Most of the essential glycoconjugate sugars have
demonstrated an ability to inhibit cancer growth and the
spread of tumor cells both in vitro and in vivo (in experiments
in pets and people). The ability of the glycoproteins to
inhibit tumor growth may be related to their ability to alter
the activities of the immune system. Glycoconjugate sugars
stimulate white blood cells (macrophages), which secrete
interferons. The interferons activate natural killer cells
that help eliminate cancer cells. The glycoproteins may
inhibit the spread of tumor cells by preventing them from
adhering to each other as a result of competitive inhibition
of glycoconjugate receptor binding.
Adverse effects caused by glycoconjugate sugars are
rare and usually occur when they are injected or when doses
greatly exceed levels that would be expected in normal
diets. For pets being treated with the most commonly used
glycoproteins (acemannan and mannose), side effects would
not be expected.
The final part of our cancer in pets series concludes
next month. We will discuss the use of antioxidants, and
conventional therapies such as surgery, radiation and