2012年3月14日 星期三

User Guide to Omega-3 Fatty Acids


Let me start by saying that Omega-3 is probably the one nutrition supplement you should take. Over the years numerous clinical trials has been made to assess the health benefits of Omega-3 fatty acids. The bottom line of the majority of these trails is that taking Omega-3 will be beneficial to your health whether you are healthy or suffering from various health conditions.

The origin of our dependency in Omega-3 fatty acids is still unknown but the fact is that Omega-3 fatty acids are one of the major building blocks of our body.

Back to the basics - what is Omega-3?

Omega-3 fatty acids are essential fatty acids: They are necessary for human health but the body can't make them which means you have to get them through food. Omega-3 fatty acids usually refer to 3 forms of fatty acids: ALA (alpha-Linolenic acid), EPA (Eicosapentaenoic acid), DHA (Docosahexaenoic acid). 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. 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.

Omega-3 in Childhood Brain Development

During the last trimester of fetal life and the first two years of childhood, the brain undergoes a period of rapid growth - the "brain growth spurt." Nutrient insufficiency during this period can compromise brain function. DHA is one nutrient absolutely required for the development of the sensory, perceptual, cognitive, and motor neural systems during the brain growth spurt. The fundamental importance of DHA for brain development is beyond dispute. The neurons are continually forming axons and dendritic extensions with accompanying cell membranes. Growing membrane must be relatively fluid, and DHA is the most fluidizing element in cell membranes. Even the synapses that are the primary functional units of brain circuits are made from membranes preferentially enriched in DHA. The retina, functionally an extension of the brain, contains rods and cones with the most fluid membranes of all the body's cell types; they are also highly enriched in DHA. Laboratory animals (rodents, primates) with experimentally induced omega-3 deficiencies show deficits in retinal structure, visual acuity development, and cognitive performance.

Perinatal Importance of DHA and EPA

Demand for DHA rises exponentially as the brain rapidly expands in the third trimester, and continues after birth as the baby interfaces with environmental stimuli. Infants born prematurely are at special risk for omega-3 insufficiency because they may not have benefited from a full trimester of the mother's lipid stores. Preterm infants have very limited ability to Synthesize DHA from the shorter chain alpha-linolenic acid (ALA). After birth, omega-3 status depends on the infant's innate lipid metabolism and dietary intake of breast milk or formula. Although DHA and EPA are prominent ingredients of breast milk, many infant formulas do not contain these nutrients. Supplementing the mother's diet with ALA is not a reliable means for obtaining DHA. In one study, lactating mothers received 10.7 g/day of ALA from flaxseed oil for four weeks. Breast milk levels of ALA, EPA, and DPA (docosapentaenoic acid) increased, but not that of DHA. All infants, whether preterm or full term, seem to require dietary DHA for retinal development and normal visual function.

Treating Developmental Coordination Disorder/Dyspraxia

The importance of DHA/EPA for overall brain and motor development after birth is illustrated by dyspraxia, also known as developmental coordination disorder (DCD). DCD/dyspraxia involves specific impairments of motor function and seriously affects about five percent of school-aged children. DCD's core motor deficits are often accompanied by difficulties with learning, behavior, and psychosocial adjustment that overlap with dyslexia and attention deficit/hyperactivity disorder (AD/HD) and often persist into adulthood.

Managing Attention Deficit/Hyperactivity Disorder

AD/HD is the most common childhood developmental disorder, with prevalence estimates ranging from 4-15 percent for school-age children in the United States and elsewhere. Often AD/HD persists into adulthood. Considerable damage to the individual, family, and society can be exacerbated by co-morbidity with many other disorders of behavior, learning, or mood. AD/HD children consistently exhibit abnormal fatty acid status. Typically, reductions have been found in DHA and total omega-3 some of which may persist into adulthood. Low omega-3 levels are associated with a range of behavioral and learning problems. Omega-3 deficiencies correlate with behavioral problems (conduct disorder, hyperactivity-impulsivity, anxiety, temper tantrums, sleep difficulties) and learning difficulties in children. Omega-3 status is likely to be more relevant to AD/HD and related behavioral disorders.

Clinical Experience with Autism

The emergent rationale for employing DHA/EPA for autistic spectrum disorder (ASD) and other pervasive developmental disorders (PDD) dates to 2001, with case histories provided independently by two research groups. Vancassel reported low DHA (measured in plasma phospholipids), 20-percent lower-than-normal total omega-3 in ASD children. Bradstreet and Kartzinel reported finding omega-3 fatty acid deficiencies in nearly 100 percent of ASD cases. Then in 2002, Hardy and Hardy claimed that, of 50 children diagnosed with PDD, 90 percent were deficient in red blood cell membrane DHA/EPA. Various integrative physicians working with ASD and PDD patients have integrated DHA and EPA into their comprehensive regimens. A group in Austria conducted a six-week trial with 13 children, ages 5-17 years, diagnosed with ASD and displaying severe tantrums, aggression, and self-injurious behavior. Intervention was 1.5 g/day DHA/EPA (700 mg DHA and 840 mg EPA) or placebo. The DHA/EPA was well tolerated and there was a trend toward significant improvement over placebo for hyperactivity

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 rich in omega-3 fatty acids reduce triglyceride levels.

High blood pressure

Several clinical studies suggest that diets or fish oil supplements 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.

Heart disease

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 two 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 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.

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 rich in omega-3 fatty acids 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 ALA to a form of omega-3 fatty acids that the body can use.

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 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). 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. 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 group of people with osteoarthritis. An analysis of 17 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 studies suggest that EPA and fish oil may help reduce symptoms of lupus, an autoimmune condition characterized by fatigue and joint pain.

Osteoporosis

Some studies suggest that omega-3 fatty acids may help increase levels of calcium in the body and improve bone strength. Some studies also suggest that people who don' t get enough of some essential fatty acids 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 omega 3 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

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. Studies are mixed on whether omega-3 fatty acids alone have any effect on depression.

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.

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. 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.

Inflammatory bowel disease (IBD)

omega-3 fatty acids can help reduce symptoms of Crohn' s disease and ulcerative colitis, the two 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).

Asthma

Omega 3 may be beneficial to asthma patients. In a 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.

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.

Colon cancer

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.

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 of omega-3

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. Other sources of omega-3 fatty acids include sea life such as krill and algae. Although ALA is a form of omega-3 it is less effective form since it has to be converted to EPA and DHA. Studies show that conversion rate of ALA to DHA (most essential form of omega-3) are between 0.2% (in men) -10% (in women) only.

Available Forms of omega-3

Both EPA and DHA can be taken in the form of fish oil capsules. Be sure to buy omega-3 fatty acid supplements made by established companies. Do not rely on companies that state that their products are free of heavy metals such as mercury, lead, and cadmium. Look only for companies who publish a COA (certificate of analysis) for their product. Most companies that do not publish their COA do so because their product does not comply with the industry standards such as IFOS (international fish oil standard) and CRN (council for responsible nutrition).

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. Five grams of fish oil contains approximately 0.17 - 0.56 grams (170 -560 mg) of EPA and 0.072 - 0.31 grams (72 - 310 mg) of DHA. Different types of fish contain variable amounts of omega-3 fatty acids.

Children

There is no established dose for children. Omega-3 fatty acids are used in some infant formulas. Children should avoid eating fish that may be high in mercury, such as shark, swordfish, king mackerel, and tilefish.

Adults

Do not take more than 3 grams daily of omega-3 fatty acids from capsules without the supervision of a health care provider.


For healthy adults with no history of heart disease: The American Heart Association recommends 0.5 gram daily of EPA and DHA.
For adults with coronary heart disease: The American Heart Association 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.
For adults with high cholesterol levels: The American Heart Association 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.

Author choice product

There are many high grade omega-3 supplements out there, my choice is based on the following guide lines:


Product grade - high grade omega-3 supplement
COA - published certificate of analysis
Industry standards - product specifications comply with IFOS and CRN demands
Omega-3 content - high amount of Omega-3 fatty acids rich in DHA
Price - truly affordable high grade omega-3




My choice comes from a New Zealand based company who to this author opinion produce one of the best omega-3 supplements out there.





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