Τhe importance of omega-3 in our diet
Sardinne fish
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Omega-3 fatty acids are considered essential fatty acids: They are necessary for human health but the body can’t make them -- you have to get them through food. Omega-3 fatty acids can be found in fish, such as salmon, tuna, and halibut, other seafood including algae and krill, some plants, and nut oils. Also known as polyunsaturated fatty acids (PUFAs), omega-3 fatty acids play a crucial role in brain function, as well as normal growth and development. They have also become popular because they may reduce the risk of heart disease. The American Heart Association recommends eating fish (particularly fatty fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon) at least 2 times a week.
Research shows that omega-3 fatty acids reduce inflammation and may help lower risk of chronic diseases such as heart disease, cancer, and arthritis. Omega-3 fatty acids are highly concentrated in the brain and appear to be important for cognitive (brain memory and performance) and behavioral function. In fact, infants who do not get enough omega-3 fatty acids from their mothers during pregnancy are at risk for developing vision and nerve problems. Symptoms of omega-3 fatty acid deficiency include fatigue, poor memory, dry skin, heart problems, mood swings or depression, and poor circulation.
It is important to have the proper ratio of omega-3 and omega-6 (another essential fatty acid) in the diet. Omega-3 fatty acids help reduce inflammation, and most omega-6 fatty acids tend to promote inflammation. The typical American diet tends to contain 14 - 25 times more omega-6 fatty acids than omega-3 fatty acids, which many nutritionally oriented physicians consider to be way too high on the omega-6 side.
The Mediterranean diet, on the other hand, has a healthier balance between omega-3 and omega-6 fatty acids. Many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet emphasizes foods rich in omega-3 fatty acids, including whole grains, fresh fruits and vegetables, fish, olive oil, garlic, as well as moderate wine consumption.
Uses
Clinical evidence is strongest for heart disease
and problems that contribute to heart disease, but omega-3 fatty acids
may also be used for:
High cholesterol
People who
follow a Mediterranean style diet tend to have higher HDL or “good”
cholesterol levels, which help promote heart health. Inuit Eskimos, who
get high amounts of omega-3 fatty acids from eating fatty fish, also
tend to have increased HDL cholesterol and decreased triglycerides (fats
in the blood). Several studies have shown that fish oil supplements
reduce triglyceride levels. Finally, walnuts (which are rich in alpha
linolenic acid or ANA, which converts to omega-3s in the body) have been
reported to lower total cholesterol and triglycerides in people with
high cholesterol levels.
High blood pressure
Several
clinical studies suggest that diets rich in omega-3 fatty acids lower
blood pressure in people with hypertension. An analysis of 17 clinical
studies using fish oil supplements found that taking 3 or more grams of
fish oil daily may reduce blood pressure in people with untreated
hypertension. Doses this high, however, should only be taken under the
direction of a physician.
Heart disease
The role of
omega-3 fatty acids in cardiovascular disease is well established. One
of the best ways to help prevent heart disease is to eat a diet low in
saturated fat and to eat foods that are rich in monounsaturated and
polyunsaturated fats (including omega-3 fatty acids). Clinical evidence
suggests that EPA and DHA (eicosapentaenoic acid and docosahexaenoic
acid, the 2 omega-3 fatty acids found in fish oil) help reduce risk
factors for heart disease, including high cholesterol and high blood
pressure. Fish oil has been shown to lower levels of triglycerides (fats
in the blood), and to lower the risk of death, heart attack, stroke,
and abnormal heart rhythms in people who have already had a heart
attack. Fish oil also appears to help prevent and treat atherosclerosis
(hardening of the arteries) by slowing the development of plaque and
blood clots, which can clog arteries.
Large population studies
suggest that getting omega-3 fatty acids in the diet, primarily from
fish, helps protect against stroke caused by plaque buildup and blood
clots in the arteries that lead to the brain. Eating at least 2 servings
of fish per week can reduce the risk of stroke by as much as 50%.
However, high doses of fish oil and omega-3 fatty acids may increase the
risk of bleeding. People who eat more than 3 grams of omega-3 fatty
acids per day (equivalent to 3 servings of fish per day) may have higher
risk for hemorrhagic stroke, a potentially fatal type of stroke in
which an artery in the brain leaks or ruptures.
Diabetes
People
with diabetes often have high triglyceride and low HDL levels. Omega-3
fatty acids from fish oil can help lower triglycerides and apoproteins
(markers of diabetes), and raise HDL, so eating foods or taking fish oil
supplements may help people with diabetes. Another type of omega-3
fatty acid, ALA (from flaxseed, for example) may not have the same
benefit as fish oil. Some people with diabetes can’t efficiently convert
ANA to a form of omega-3 fatty acids that the body can use. Also, some
people with type 2 diabetes may have slight increases in fasting blood
sugar when taking fish oil, so talk to your doctor to see if fish oil is
right for you.
Rheumatoid arthritis
Most clinical
studies examining omega-3 fatty acid supplements for arthritis have
focused on rheumatoid arthritis (RA), an autoimmune disease that causes
inflammation in the joints. A number of small studies have found that
fish oil helps reduce symptoms of RA, including joint pain and morning
stiffness. One study suggests that people with RA who take fish oil may
be able to lower their dose of non-steroidal anti-inflammatory drugs
(NSAIDs). However, unlike prescription medications, fish oil does not
appear to slow progression of RA, only to treat the symptoms. Joint
damage still occurs.
Laboratory studies suggest that diets rich in
omega-3 fatty acids (and low in the inflammatory omega-6 fatty acids)
may help people with osteoarthritis, although more study is needed. New
Zealand green lipped mussel (Perna canaliculus), another potential
source of omega-3 fatty acids, has been reported to reduce joint
stiffness and pain, increase grip strength, and improve walking pace in a
small group of people with osteoarthritis. For some people, symptoms
got worse before they improved.
An analysis of 17 randomized,
controlled clinical trials looked at the pain relieving effects of
omega-3 fatty acid supplements in people with RA or joint pain caused by
inflammatory bowel disease (IBS) and painful menstruation
(dysmenorrhea). The results suggest that omega-3 fatty acids, along with
conventional therapies such as NSAIDs, may help relieve joint pain
associated with these conditions.
Systemic lupus erythematosus (SLE)
Several
small studies suggest that EPA and fish oil may help reduce symptoms of
lupus, an autoimmune condition characterized by fatigue and joint pain.
However, 2 small studies found fish oil had no effect on lupus
nephritis (kidney disease caused by lupus, a frequent complication of
the disease).
Osteoporosis
Some studies suggest that
omega-3 fatty acids may help increase levels of calcium in the body and
improve bone strength, although not all results were positive. Some
studies also suggest that people who don’t get enough of some essential
fatty acids (particularly EPA and gamma-linolenic acid [GLA], an omega-6
fatty acid) are more likely to have bone loss than those with normal
levels of these fatty acids. In a study of women over 65 with
osteoporosis, those who took EPA and GLA supplements had less bone loss
over 3 years than those who took placebo. Many of these women also
experienced an increase in bone density.
Depression
Studies
have found mixed results as to whether taking omega-3 fatty acids can
help depression symptoms. Several studies have found that people who
took omega-3 fatty acids in addition to prescription antidepressants had
a greater improvement in symptoms than those who took antidepressants
alone. Other studies show that omega-3 fatty acid intake helps protect
against postpartom depression, among other benefits. However, other
studies have found no benefit.
Studies are also mixed on whether
omega-3 fatty acids alone have any effect on depression. Depression is a
serious illness and you should not try to treat it on your own. See a
doctor for help.
Bipolar disorder
In a clinical study
of 30 people with bipolar disorder, those who took fish oil in addition
to standard prescription treatments for bipolar disorder for 4 months
experienced fewer mood swings and relapse than those who received
placebo. But another 4 month long clinical study treating people with
bipolar depression and rapid cycling bipolar disorder did not find that
EPA helped reduce symptoms.
Schizophrenia
Preliminary
clinical evidence suggests that people with schizophrenia may have an
improvement in symptoms when given omega-3 fatty acids. However, a
recent well designed study concluded that EPA supplements are no better
than placebo in improving symptoms of this condition.
Attention deficit/hyperactivity disorder (ADHD)
Children
with attention deficit/hyperactivity disorder (ADHD) may have low
levels of certain essential fatty acids (including EPA and DHA). In a
clinical study of nearly 100 boys, those with lower levels of omega-3
fatty acids had more learning and behavioral problems (such as temper
tantrums and sleep disturbances) than boys with normal omega-3 fatty
acid levels.
However, studies examining whether omega-3 fatty
acids help improve symptoms of ADHD have found mixed results. A few
studies have found that omega-3 fatty acids helped improve behavioral
symptoms, but most were not well designed. One study that looked at DHA
in addition to stimulant therapy (standard therapy for ADHD) found no
effect. More research is needed, but eating foods that are high in
omega-3 fatty acids is a reasonable approach for someone with ADHD.
Cognitive decline
A
number of studies show that reduced intake of omega-3 fatty acids is
associated with increased risk of age related cognitive decline or
dementia, including Alzheimer's disease. Scientists believe the omega-3
fatty acid DHA is protective against Alzheimer's disease and dementia.
Skin disorders
In
one clinical study, 13 people with sun sensitivity known as photo
dermatitis showed less sensitivity to UV rays after taking fish oil
supplements. However, topical sunscreens are much better at protecting
the skin from damaging effects of the sun than omega-3 fatty acids. In
another study of 40 people with psoriasis, those who took EPA with their
prescription medications did better than those treated with the
medications alone. However, a larger study of people with psoriasis
found no benefit from fish oil.
Inflammatory bowel disease (IBD)
Results
are mixed as to whether omega-3 fatty acids can help reduce symptoms of
Crohn’s disease and ulcerative colitis, the 2 types of IBD. Some
studies suggest that omega-3 fatty acids may help when added to
medication, such as sulfasalazine (a standard medication for IBD).
Others find no effect. More studies are needed. Fish oil supplements can
cause side effects that are similar to symptoms of IBD (such as
flatulence, belching, bloating, and diarrhea).
Asthma
Studies
examining omega-3 fatty acids for asthma are mixed. In one small, well
designed clinical study of 29 children with asthma, those who took fish
oil supplements rich in EPA and DHA for 10 months reduced their symptoms
compared to children who took placebo. However, most studies have shown
no effect.
Macular Degeneration
A questionnaire
given to more than 3,000 people over the age of 49 found that those who
ate more fish were less likely to have macular degeneration (a serious
age related eye condition that can progress to blindness) than those who
ate less fish. Similarly, a clinical study comparing 350 people with
macular degeneration to 500 without the eye disease found that those
with a healthy dietary balance of omega-3 and omega-6 fatty acids and
more fish in their diets were less likely to have macular degeneration.
Menstrual pain
In one study of 42 women, they had less menstrual pain when they took fish oil supplements than when they took placebo.
Coloncancer
Eating
foods rich in omega-3 fatty acids seems to reduce the risk of
colorectal cancer. For example, Eskimos, who tend to have a high fat
diet, but eat significant amounts of fish rich in omega-3 fatty acids,
have a low rate of colorectal cancer. Animal studies and laboratory
studies have found that omega-3 fatty acids prevent worsening of colon
cancer. Preliminary studies suggest that taking fish oil daily may help
slow the progression of colon cancer in people with early stages of the
disease. If you have colorectal cancer, ask your doctor before taking
any supplements.
Breast cancer
Although not all
experts agree, women who eat foods rich in omega-3 fatty acids over many
years may be less likely to develop breast cancer. More research is
needed to understand the effect that omega-3 fatty acids may have on the
prevention of breast cancer.
Prostate cancer
Population
based studies of groups of men suggest that a low fat diet including
omega-3 fatty acids from fish or fish oil help prevent the development
of prostate cancer.
Dietary Sources
Fish,
plant, and nut oils are the primary dietary source of omega-3 fatty
acids. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are
found in cold water fish such as salmon, mackerel, halibut, sardines,
tuna, and herring. ALA is found in flaxseeds, flaxseed oil, canola
(rapeseed) oil, soybeans, soybean oil, pumpkin seeds, pumpkin seed oil,
purslane, perilla seed oil, walnuts, and walnut oil. The health effects
of omega-3 fatty acids come mostly from EPA and DHA. ALA from flax and
other vegetarian sources needs to be converted in the body to EPA and
DHA. Many people do not make these conversions very effectively,
however. This remains an ongoing debate in the nutrition community; fish
and sea vegetable sources of EPA and DHA versus vegetarian sources of
ALA. Other sources of omega-3 fatty acids include sea life such as krill
and algae.
Available Forms
Both EPA and DHA
can be taken in the form of fish oil capsules. Flaxseed, flaxseed oil,
fish, and krill oils should be kept refrigerated. Whole flaxseeds must
be ground within 24 hours of use, so the ingredients stay active.
Flaxseeds are also available in ground form in a special mylar package
so the components in the flaxseeds stay active.
Be sure to buy
omega-3 fatty acid supplements made by established companies who certify
that their products are free of heavy metals such as mercury, lead, and
cadmium.
How to Take It
Dosing for fish oil
supplements should be based on the amount of EPA and DHA, not on the
total amount of fish oil. Supplements vary in the amounts and ratios of
EPA and DHA. A common amount of omega-3 fatty acids in fish oil capsules
is 0.18 grams (180 mg) of EPA and 0.12 grams (120 mg) of DHA. Different
types of fish contain variable amounts of omega-3 fatty acids, and
different types of nuts or oil contain variable amounts of ALA. Fish
oils contain approximately 9 calories per gram of oil.
Children (18 years and younger)
There
is no established dose for children. Omega-3 fatty acids are used in
some infant formulas. Fish oil capsules should not be used in children
except under the direction of a health care provider. Children should
avoid eating fish that may be high in mercury, such as shark, swordfish,
king mackerel, and tilefish. (See Precautions section.)
Adults
Do
not take more than 3 grams daily of omega-3 fatty acids from capsules
without the supervision of a health care provider, due to an increased
risk of bleeding.
- For healthy adults with no history of heart
disease: The American Heart Association (AHA) recommends eating fish at
least 2 times per week.
- For adults with coronary heart disease:
The AHA recommends an omega-3 fatty acid supplement (as fish oils), 1
gram daily of EPA and DHA. It may take 2 - 3 weeks for benefits of fish
oil supplements to be seen. Supplements should be taken under the
direction of a physician.
- For adults with high cholesterol
levels: The AHA recommends an omega-3 fatty acid supplement (as fish
oils), 2 - 4 grams daily of EPA and DHA. It may take 2 - 3 weeks for
benefits of fish oil supplements to be seen. Supplements should be taken
under the direction of a physician.
- For adults with high blood
pressure, scientists generally recommend 3 - 4 grams per day, but you
should only take under the supervision of a health care provider.
Precautions
Because
of the potential for side effects and interactions with medications,
you should only take dietary supplements only under the supervision of a
knowledgeable health care provider.
Omega-3 fatty acids should be
used cautiously by people who bruise easily, have a bleeding disorder,
or take blood thinning medications including warfarin (Coumadin),
clopidogrel (Plavix), or aspirin. High doses of omega-3 fatty acids may
increase the risk of bleeding, even in people without a history of
bleeding disorders -- and even in those who are not taking other
medications.
Fish oil can cause gas, bloating, belching, and diarrhea. Time release preparations may reduce these side effects, however.
People
with either diabetes or schizophrenia may lack the ability to convert
alpha-linolenic acid (ALA) to eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA), the forms more readily used in the body.
People with these conditions should be sure to get enough EPA and DHA
from their diets. Also, people with type 2 diabetes may experience
increases in fasting blood sugar levels while taking fish oil
supplements. If you have type 2 diabetes, use fish oil supplements only
under the supervision of a health care provider.
Although studies
suggest that eating fish (which includes the omega-3 fatty acids EPA and
DHA) may reduce the risk of macular degeneration, a recent study
including 2 large groups of men and women found that diets rich in ALA
may increase the risk of this disease. Until more information becomes
available, people with macular degeneration should get omega-3 fatty
acids from sources of EPA and DHA, rather than ALA.
Fish and fish
oil may protect against prostate cancer, but some suggest that ALA may
be associated with increased risk of prostate cancer in men. More
research in this area is needed.
Some fish may contain potentially
harmful contaminants, such as heavy metals (including mercury),
dioxins, and polychlorinated biphenyls (PCBs). For sport caught fish,
the U.S. Environmental Protection Agency (EPA) recommends that pregnant
or nursing women eat no more than a single 6 ounce meal per week, and
young children less than 2 ounces per week. For farm raised, imported,
or marine fish, the U.S. Food and Drug Administration recommends that
pregnant or nursing women and young children avoid eating types with
higher levels of mercury (such as mackerel, shark, swordfish, or
tilefish), and eat up to 12 ounces per week of other fish types.
Buy fish oil from a reputable source that tests to make sure there is no mercury or pesticide residues in its products.
Possible Interactions
If
you are currently being treated with any of the following medications,
you should not use omega-3 fatty acid supplements, including
eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and
alpha-linolenic acid (ALA), without first talking to your health care
provider.
Blood thinning medications -- Omega-3
fatty acids may increase the effects of blood thinning medications,
including aspirin, warfarin (Coumadin), and clopedigrel (Plavix). Taking
aspirin and omega-3 fatty acids may be helpful in some circumstances
(such as in heart disease), but they should only be taken together under
the supervision of a health care provider.
Diabetes medications
-- Taking omega-3 fatty acid supplements may increase fasting blood
sugar levels. Use with caution if taking medications to lower blood
sugar, such as glipizide (Glucotrol and Glucotrol XL), glyburide
(Micronase or Diabeta), glucophage (Metformin), or insulin. Your doctor
may need to increase your medication dose. These drugs include:
Cyclosporine
-- Cyclosporine is a medication given to people with organ transplants.
Taking omega-3 fatty acids during cyclosporine (Sandimmune) therapy may
reduce toxic side effects, such as high blood pressure and kidney
damage, associated with this medication.
Etretinate and topical steroids
-- Adding omega-3 fatty acids (specifically EPA) to the drug therapy
etretinate (Tegison) and topical corticosteroids may improve symptoms of
psoriasis.
Cholesterol-lowering medications --
Following dietary guidelines, including increasing the amount of omega-3
fatty acids in your diet and reducing the omega-6 to omega-3 ratio, may
help a group of cholesterol lowering medications known as statins to
work more effectively. These medications include:
Atorvastatin (Liptor)
Lovastatin (Mevacor)
Simvastatin (Zocor)
Nonsteroidal anti-inflammatory drugs (NSAIDs)
-- In an animal study, treatment with omega-3 fatty acids reduced the
risk of ulcers from nonsteroidal anti-inflammatory drugs (NSAIDs).
NSAIDs include ibuprofen (Motrin or Advil) and naproxen (Aleve or
Naprosyn). More research is needed to see whether omega-3 fatty acids
would have the same effects in people.
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