Overview:
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.
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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
â€Å“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.
