Omega-3 fatty acids are essential fatty acids, which means that they are essential to human health but cannot be manufactured by the body. For this reason, omega-3 fatty acids must be obtained from food. Omega-3 fatty acids can be found in fish and certain plant oils. It is important to maintain an appropriate balance of omega-3 and omega-6 (another essential fatty acid) in the diet as these two substances work together to promote health. Also known as polyunsaturated fatty acids (PUFAs), omega-3 and omega-6 fatty acids play a crucial role in brain function as well as normal growth and development.

There are three major types of omega 3 fatty acids that are ingested in foods and used by the body: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3 fatty acids more readily used by the body. Extensive research indicates that omega-3 fatty acids reduce inflammation and help prevent certain chronic diseases such as heart disease and arthritis. These essential fatty acids are highly concentrated in the brain and appear to be particularly important for cognitive 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.

Omega 3 – Omega 6 balance

It is very important to maintain a balance between omega-3 and omega-6 fatty acids in the diet. Omega-3 fatty acids help reduce inflammation and most omega-6 fatty acids tend to promote inflammation. An inappropriate balance of these essential fatty acids contributes to the development of disease while a proper balance helps maintain and even improve health. A healthy diet should consist of roughly one to four times more omega-6 fatty acids than omega-3 fatty acids. The typical American diet tends to contain 11 to 30 times more omega-6 fatty acids than omega-3 fatty acids and many researchers believe this imbalance is a significant factor in the rising rate of inflammatory disorders in the United States.

In contrast, however, the Mediterranean diet consists of a healthier balance between omega-3 and omega-6 fatty acids and many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet does not include much meat (which is high in omega-6 fatty acids) and 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.

Health Benefits

Cardiovascular health

On September 8, 2004, the U.S. Food and Drug Administration gave “qualified health claim” status to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) omega-3 fatty acids, stating that “supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.”

A 2006 report in the Journal of the American Medical Association concluded that their review of literature covering cohorts from many countries with a wide variety of demographic characteristics failed to demonstrate a link between omega-3 fatty acids and cancer prevention. This is similar to the findings of a review by the British Medical Journal of studies up to February 2002 that failed to find clear effects of long and shorter chain omega-3 fats on total mortality, combined cardiovascular events and cancer.

In April 2006, a team led by Lee Hooper at the University of East Anglia in Norwich, UK, published a review of almost 100 separate studies into omega-3 fatty acids, found in abundance in oily fish. It concluded that they do not have a significant protective effect against cardiovascular disease.

The above stands in stark contrast with two different reviews also performed in 2006 by the American Journal of Clinical Nutrition and a second JAMA review that both indicated decreases in total mortality and cardiovascular incidents (i.e. myocardial infarctions) associated with the regular consumption of fish and fish oil supplements. Of particular importance is that no or very few complications were documented.

Research in 2005-06 has suggested that the in-vitro anti-inflammatory activity of omega-3 acids translates into clinical benefits. Cohorts of neck pain patients and of rheumatoid arthritis sufferers have demonstrated benefits comparable to those receiving standard NSAIDs.[citation needed]

Those who follow a Mediterranean-style diet tend to have higher HDL (“good”) cholesterol levels. Similar to those who follow a Mediterranean diet, Arctic-dwelling Inuit – who consume high amounts of omega-3 fatty acids from fatty fish – also tend to have increased HDL cholesterol and decreased triglycerides (fatty material that circulates in the blood). In addition, fish oil supplements containing EPA and DHA have been shown to reduce LDL (“bad”) cholesterol and triglycerides. Finally, walnuts (which are rich in ALA) have been shown to lower total cholesterol and triglycerides in people with high cholesterol.

Diabetes

People with diabetes tend to have high triglyceride and low HDL levels. Omega-3 fatty acids from fish oil can help lower triglycerides and raise HDL, so people with diabetes may benefit from eating foods or taking supplements that contain DHA and EPA. ALA (from flaxseed, for example) may not have the same benefit as DHA and EPA because some people with diabetes lack the ability to efficiently convert ALA to a form of omega-3 fatty acids that the body can use readily.

Arthritis

Most clinical studies investigating the use of omega-3 fatty acid supplements for inflammatory joint conditions have focused almost entirely on rheumatoid arthritis. Several articles reviewing the research in this area conclude that omega-3 fatty acid supplements reduce tenderness in joints, decrease morning stiffness, and allow for a reduction in the amount of medication needed for people with rheumatoid arthritis.

In addition, laboratory studies suggest that diets rich in omega-3 fatty acids (and low in omega-6 fatty acids) may benefit people with other inflammatory disorders, such as osteoarthritis. In fact, several test tube studies of cartilage-containing cells have found that omega-3 fatty acids decrease inflammation and reduce the activity of enzymes that destroy cartilage. Similarly, New Zealand green lipped mussel (Perna canaliculus), another potential source of omega-3 fatty acids, has been shown to reduce joint stiffness and pain, increase grip strength, and enhance walking pace in a small group of people with osteoarthritis. In some participants, symptoms worsened before they improved.

Osteoporosis

Studies suggest that omega-3 fatty acids such as EPA help increase levels of calcium in the body, deposit calcium in the bones, and improve bone strength. In addition, studies also suggest that people who are deficient in certain essential fatty acids (particularly EPA and gamma-linolenic acid [GLA], an omega-6 fatty acid) are more likely to suffer from bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those given EPA and GLA supplements experienced significantly less bone loss over three years than those who were given a placebo. Many of these women also experienced an increase in bone density.

Asthma

Preliminary research suggests that omega-3 fatty acid supplements (in the form of perilla seed oil, which is rich in ALA) may decrease inflammation and improve lung function in adults with asthma. Omega-6 fatty acids have the opposite effect: they tend to increase inflammation and worsen respiratory function. In a small, well-designed study of 29 children with asthma, those who took fish oil supplements rich in EPA and DHA for 10 months had improvement in their symptoms compared to children who took a placebo pill.

Dietary Sources

Daily values

As macronutrients, fats are not assigned recommended daily allowances. Macronutrients have AI (Acceptable Intake) and AMDR (Acceptable Macronutrient Distribution Range) instead of RDAs. The AI for n-3 is 1.6 grams/day for men and 1.1 grams/day for women while the AMDR is 0.6% to 1.2% of total energy.

“A growing body of literature suggests that higher intakes of a-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) may afford some degree of protection against coronary heart disease. Because the physiological potency of EPA and DHA is much greater than that for a-linolenic acid, it is not possible to estimate one AMDR for all n-3 fatty acids. Approximately 10 percent of the AMDR can be consumed as EPA and/or DHA.”

There was insufficient evidence as of 2005 to set a UL (upper tolerable limit) for n-3 fatty acids.

Researchers believe the ideal omega-6 intake should be no more than 4-5 times that of our omega-3 intake. The National Institutes of Health recently published recommended daily intakes of fatty acids, specific recommendations include 650 mg of EPA and DHA, 2.22 g/day of alpha-linolenic acid and 4.44 g/day of linoleic acid.

The greatest risk of fish oil omega-3 supplementation is heavy metal poisoning by the body’s accumulation of traces of heavy metals, in particular mercury, lead, nickel, arsenic and cadmium as well as other contaminants (PCBs, furans, dioxins), which may be found especially in less refined fish oil supplements.[citation needed] For these reasons, the FDA recommends that total dietary intake of omega-3 fatty acids from fish be limited to 3 grams per day, of which no more than 2 grams per day are from nutritional supplements.

Historically, the Council for Responsible Nutrition (CRN) and the World Health Organization (WHO) have published acceptable standards regarding contaminants in fish oil. The most stringent current standard is the International Fish Oils Standard (IFOS). Fish oils that typically make this highest grade are those that are molecularly distilled under vacuum, and have virtually no measurable level of contaminants (measured parts per billion and parts per trillion).

Fish

Oily fish such as mackerel are indeed a source of omega-3s, but others are just as good and more sustainable. Early humans evolved eating inter-tidal shellfish, while living a shoreline existence in Africa. Now, as then, inter-tidal herbivorous shellfish such as mussels and clams can help people reach a healthy 1:1 balance of omega-3 and omega-6 fats in their diets, instead of the current (Western diets) 1:17. 37 Seafood risks are exaggerated because Food Agencies are “conservative” with 10 fold safety margins for uncertainty when non-linear dose responses are ignored. Natural protection mechanisms are also overlooked – For instance selenium in shellfish blocks mercury poisoning [http://www.seafoodandhealth.org/documents/MicrosoftPowerPoint-PPTRalston.pdf]. There has been a significant reduction in emissions of dioxins to the environment during the past decade and dietary intake has fallen by about 85% since 1982 and continues to fall steadily [Food Standards Agency]. Shellfish are low in both mercury and polychlorinated biphenyls (PCBs). Other benefits of eating shellfish include iodine an important factor for childhood development.

The most widely available source of EPA and DHA is cold water oily fish such as wild salmon, herring, mackerel, anchovies and sardines. The oil from these fish have a profile of around seven times as much omega-3 as omega-6. Farmed salmon, being grain fed, have a higher proportion of omega-6 than wild salmon. Other oily fish such as tuna also contain omega-3 in somewhat lesser amounts. Consumers of oily fish should be aware of the potential presence of heavy metals and fat-soluble pollutants like PCBs and dioxins which may accumulate up the food chain.[23] Some supplement manufacturers remove heavy metals and other contaminants from the oil through various means, such as molecular distillation (see above), which increases purity, potency and safety.

Even some forms of fish oil may not be optimally digestible. Of four studies that compare bioavailability of the triglyceride form of fish oil vs. the ester form, two have concluded that the natural triglyceride form is better, and the other two studies did not find a significant difference. No studies have shown the ester form to be superior although it is cheaper to manufacture.

Although fish is a dietary source of omega-3 fatty acids, fish do not synthesize them; they obtain them from the algae in their diet. For this reason, there is often a significant difference in EPA and DHA concentrations in farmed vs wild caught fish.

Flax

Flax (aka linseed) (Linum usitatissimum) and its oil are perhaps the most widely available botanical sources of omega-3. Flaxseed oil consists of ca. 55% ALA (alpha-linolenic acid). Flax, like chia, contains approximately three times as much omega-3 as omega-6.

15 grams of flaxseed oil provides ca. 8 grams of ALA, which is converted in the body to EPA and then DHA at an efficiency of (5%-10%), and (2%-5%) respectively.

Botanical sources

Here are listed the most knwon botanical sources, and their Omega-3 amount.

  • Chia: 64% Omega-3
  • Kiwi: 62% Omega-3
  • Perilla: 58% Omega-3
  • Flax: 55% Omega-3
  • Lingonberry: 49% Omega-3
  • Purslane: 35% Omega-3
  • Sea Buckthorn: 32% Omega-3
  • Hemp: 20% Omega-3

Eggs

Eggs produced by chickens fed a diet of greens and insects produce higher levels of omega-3 fatty acids than chickens fed corn or soybeans.

Available Forms

In addition to the dietary sources described, EPA and DHA can be taken in the form of fish oil capsules. Flaxseed, flaxseed oil, and fish oil should be kept refrigerated. Whole flaxseeds must be ground within 24 hours of use, otherwise the ingredients lose their activity. Flaxseeds are also available in ground form in a special mylar package so that 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.

Sources: http://www.wikipedia.com/, http://www.umm.edu/

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