Tartalomjegyzék
Tartalomjegyzék
Originally posted 2017 / Updated December 2022
While most Americans eat way too much of the omega-6 oils found in meats and most vegetable oils, they suffer a relative deficiency of the omega-3 oils — a situation that is associated with an increased risk for heart disease and about 60 other conditions, including various forms of cancer, arthritis, stroke, high blood pressure, skin diseases, and diabetes.1
Particularly important to good health are the longer-chain omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fish, especially cold-water fish such as salmon, mackerel, herring, and halibut. Although the body can convert alpha-linolenic acid, a short-chain omega-3 fatty acid, from flaxseeds and flaxseed oil, chia seeds, and walnuts, it is much more efficient to get them from fish oil or marine algae supplements concentrated for EPA+DHA. Furthermore, there is evidence that many people have a difficult time converting alpha-linolenic acid to the longer-chain omega-3s like EPA and DHA.2
The main omega-3 fatty acid in the vegetarian diet is alpha-linolenic acid (ALA), which is derived from foods such as flaxseeds and flax oil, chia and walnuts. While some ALA is converted to EPA, it is a rather inefficient conversion, and supplementation with ALA from flaxseed oil has little effect on raising DHA levels. Not surprisingly, several studies have demonstrated that vegetarians and vegans have much lower blood levels of DHA and EPA when compared to those who eat fish or take fish oil supplements.2
Based upon a considerable body of evidence, the health benefits of EPA+DHA appear when the concentration within red blood cells achieves a value greater than 8%. Levels under 4% are considered high risk for over 60 different health conditions. Previous studies have shown that vegans, vegetarians, and omnivores who do not eat fish or take fish oil supplements, are typically below 4% EPA+DHA in their blood.1
Several studies have shown that vegetarians and vegans have much lower blood levels of EPA and DHA compared to those who eat fish. There are now marine algae sources that provide these valuable omega-3 fatty acids. Based upon an analysis of the fatty acid profiles in vegetarians and vegans, it seems essential that they supplement with these marine algae sources.2
One study was conducted to better define the level of these omega-3 fatty acids in vegans and to determine the effects of a vegan omega-3 supplement on blood measurements from marine algae providing 254 mg EPA+DHA a day for four months.3
A total of 165 vegans participated in the study for blood measurement. A subset of 46 subjects with a baseline omega-3 index of <4% were given a vegetarian omega-3 supplement for four months and then retested. The average level of EPA+DHA in the blood of the 165 vegans was 3.7%, with roughly 2 out of 3 vegans having levels below 4% and 1 out of 3 even lower at less than 3%. These results clearly show that a substantial number of vegan subjects have low omega-3 status.
In the subset that received the marine microalgae-derived EPA+DHA supplement, blood levels increased from 3.1% to 4.8%. These results indicate that there was a very good response to the relatively low dose of EPA+DHA, given higher dosages are required to achieve the target of 8% in these individuals. The likely dosage is at least 1,000 mg EPA+DHA daily when using a marine algae source of EPA+DHA.
One of the biggest reasons why long-chain omega-3 fatty acids are important has to do with the function of these fatty substances in cellular membranes. All cells have both an exterior cell membrane as well as internal cell membranes that surround important cellular compartments such as the mitochondria – the energy-producing compartments in our cells.
A diet that is deficient in omega-3 fatty acids, particularly EPA and DHA, results in altered cell membranes. And without a healthy membrane, cells lose their ability to hold water, vital nutrients, and electrolytes. They also lose their ability to communicate with other cells and be controlled by regulating hormones. They simply do not function properly and are also more easily damaged.
Altered cell membrane function is a critical factor in the development of virtually every chronic disease, especially cancer, diabetes, arthritis, and heart disease. Not surprisingly, long-chain omega-3 fatty acids have shown tremendous protective effects against all of these diseases. Long-chain omega-3 fatty acids, but not alpha-linolenic acid, are also transformed into regulatory compounds known as eicosanoids, resolvins, protectins, and endocannabinoids. Through their effects on these regulatory compounds, long-chain omega-3 fatty acids can mediate many physiological processes making them useful in re-establishing proper cellular function making them useful in improving overall health.
Through balancing eicosanoid (prostaglandins and related compounds) metabolism, long-chain omega-3 fatty acids can positively influence inflammation, pain, and swelling and play a key role in maintaining blood pressure and heart function. Omega-3 fatty acids are also critical to proper brain function and positive mood.
What all of the research indicates is that higher blood levels of the long-chain omega-3 fatty acids, but not linolenic acid, are associated with greater health, happiness, and longevity. Regarding reducing all cause mortality, pooled analysis from 17 studies examining the associations between blood omega-3 fatty acid levels and risk for all-cause mortality found the risk for death from all causes was significantly lower (by 15-18%) in the highest vs the lowest group for circulating long-chain omega-3 fatty acids. Similar relationships were seen for death from cardiovascular disease, cancer and other causes. No associations were seen with alpha-linolenic acid levels. These findings suggest that higher circulating levels of long-chain omega-3 fatty acids are associated with a lower risk of premature death.4
The human brain is a vat of fat. The type of fat that is regularly consumed in the diet plays a major role in the composition of the fat in the brain and how well your brain functions. A diet composed mostly of saturated fat, animal fatty acids, cholesterol, and omega-6 fatty acids produces cell membranes that are much less fluid than those of people who eat optimum levels of omega-3 fatty acids. DHA is particularly important for determining the necessary fluidity at the synapses between brain cells that transmit signals from one cell to the next.5
The long-chain omega-3 fats also function in the manufacture of neurotransmitters and the binding of neurotransmitters to produce effective transmission of the brain cell signal. Omega-3 fatty acids also influence the activity of key enzymes that break down the key neurotransmitters that influence mood like serotonin, epinephrine, dopamine, and norepinephrine.5,6
How this relates in real life is that higher intakes of long-chain omega-3 fatty acids are associated with better mood and mental function scores.6-9 EPA+DHA daily may help reduce the risk of developing Alzheimer’s or dementia by nearly 40%. In other words, out of ten people who develop Alzheimer’s disease that does not eat or supplement with EPA+DHA supplementation, four people would not have developed the condition if they would have consumed higher intakes of omega-3 fatty acids.
Dr. Daniel Amen and his colleagues have shown through advanced brain imaging that long-chain omega-3 fatty acid supplementation can improve blood flow to key areas of the brain involved in memory and cognition.10
Adding to the scientific support of the benefits of long-chain omega-3 fatty acids on brain health are over thirty clinical trials showing that EPA+DHA produces considerable benefits in improving mood and reducing feelings of stress.8,9
The benefits of long-chain omega-3 fatty acid supplementation for cardiovascular health have been demonstrated in more than 300 clinical trials. These fatty acids exert a myriad of beneficial effects, including improving blood cholesterol and triglyceride levels, improving the function of the lining of blood vessels and flexibility of blood vessels, improving blood and oxygen supply to the heart, and producing a mild effect in lowering blood pressure.12
The long-chain omega-3 fatty acids also protect against excessive adhesiveness or “stickiness” of platelets. While saturated fats and oxidized cholesterol increase platelet aggregation, EPA and DHA and the monounsaturated fats from olive oil, nuts, and seeds have the opposite effect. The beneficial effects of fish oils on platelet aggregation may be one of the key reasons why higher levels of EPA and DHA in the diet and blood are associated with a reduced risk of stroke or heart attack.
As stated above, an omega-3 index of greater than 8% is associated with the greatest protection against heart disease, Taking a total combined 1000 mg of EPA and DHA daily is required to achieve or surpass the 8% target of the omega-3 index.
Fish oil supplementation significantly reduces various blood markers indicative of inflammation.15-17 The most consistent finding related to the mechanisms of action is a reduction in the production of inflammatory mediators known as cytokines produced by white blood cells. And the most consistent marker reduced is C-reactive protein, a common blood test used as an independent risk factor for heart disease and general systemic inflammation. Numerous clinical studies have validated the health benefits of various conditions associated with inflammation, including those involving joint health.18,19
Various forms of fish oil and marine algae products in the marketplace provide sufficient concentrations of long-chain omega-3 fatty acids. The first criterion in selecting quality fish oil is purity. The product should be a highly concentrated form of long-chain omega-3 fatty acids free from lipid peroxides, heavy metals, environmental contaminants, and other harmful compounds. These “pharmaceutical grade” fish oil products are preferred and generally contain at least 60% EPA+DHA content. Whether the form is a triglyceride or ethyl-ester does not really matter as both forms have shown very similar absorption and clinical effects. As it relates to krill oil, wild salmon oil, and other marine lipids, the key is supplying the recommended levels of EPA+DHA associated with health benefits, i.e., generally 1,000 mg combined of EPA+DHA.
In regard to marine algae sources of long-chain omega-3 fatty acids, it is essential to point out that many products provide only DHA and not EPA. This is not as ideal as those that provide both EPA and DHA in equal concentrations. Again, to gain health benefits, ideally, the daily intake should be 1,000 mg combined of EPA+DHA.
Numerous studies indicate that fish consumption offers significant health promotion and protection against many chronic diseases, primarily as a result of the fish being a source of long-chain omega-3 fatty acids. However, nearly all fish contain trace amounts of mercury. In most cases, the mercury content in fish is of little concern because the level is so low, but if you are eating a lot of fish, it could pose a problem. Two to four servings per week is a good goal, but going above that may be counterproductive. The fish most likely to have the lowest level of methylmercury are salmon, cod, mackerel, cold-water tuna, farm-raised catfish, and herring. Swordfish, shark, and other large predatory fish usually contain the highest levels of mercury.
The bottom line is that taking a high-quality fish oil or marine algae concentrate source of long-chain omega-3 fatty acids provides the assurance that you are meeting your requirements for these valuable fatty acids without the mercury, PCBs, dioxins, and other contaminants often found in fish.
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