Omega-3 fatty acids
Omega-3s are used in the production of highly unsaturated fatty acids and series 3 eicosanoids. These substances have favorable effects on the composition of cell membranes as well as on many biochemical processes in the body: the regulation of blood pressure, vessel elasticity, immune and anti-inflammatory reactions, and blood platelet aggregation.
Among the omega-3s, only alpha-linolenic acid (ALA) is qualified as “essential”. This is because other omega-3 fatty acids can be synthesized by the body from ALA. It is particularly present in linseed and hemp oil and seeds, as well as in canola (rapeseed) and soybean oil.
Eicosapentaenoic acid (EPA). The human body can synthesize it from alpha-linolenic acid, although the conversion rate is very low.
Therefore, it is important to consume foods rich in EPA, particularly certain fatty fish. Populations that consume large quantities of fish (the Inuit of Greenland and the Japanese, for example) are significantly less affected by cardiovascular disease.
In addition, EPA is transformed into eicosanoids of series 3, substances that contribute to the protection of the arteries and the heart and which have recognized the anti-inflammatory and anti-allergic effects.
Docosahexaenoic acid (DHA). DHA is also present in marine products, more particularly in certain oily fish. It plays a fundamental role in the development of the brain and retina as well as in the formation and motility of spermatozoa.
See our fact sheet on fish oil for a comprehensive overview of the extensive scientific research that EPA and DHA have been the subject of.
Our omega-3 needs
Omega -3s and their properties are the subjects of much research every year, which leads to rapid evolution and frequent updates in nutritional recommendations on them. Here is a brief status report.
Several countries, as well as the World Health Organization, have issued recommendations regarding omega-3 intake, which can be summarized as follows1 :
- ALA: 0.8 g to 1.1 g/day
- EPA + DHA: from 0.3 g to 0.5 g/day
In 2004, a committee bringing together international experts set the ideal ALA intake at 0.7% of daily kilocalories or 1.5 g per day for a diet providing 2,000 kilocalories. These experts also recommend a minimum intake of 500 mg per day of EPA/DHA for the maintenance of good cardiovascular health.
In North America, the adequate intake of ALA is, for the moment, set at 1.1 g per day for women, and 1.6 g for men, or about 0.5% of the intake. energy. No intake is fixed for EPA /ADH. These recommendations are criticized by some experts, who consider them insufficient to reduce coronary heart disease in North America.
| To get 1.3 g of plant-based omega-3 (ALA) |
| ½ tsp. (2 ml) flaxseed oil |
| 2 tbsp. (10 ml) crushed flax seeds. |
| 2 tbsp. chia seeds* |
| 1 C. 2 tbsp (15 ml) canola oil |
| ¼ cup (60 mL) walnuts |
| 1½ tsp. 2 tbsp (22 ml) soybean oil |
| 13g hemp seeds |
| To obtain 1.3 g of omega-3 of marine origin (EPA + DHA) |
| 50g Atlantic mackerel |
| 65 g farmed Atlantic salmon |
| 80g canned pink or red salmon |
| 80g Atlantic or Pacific herring |
| 130 g canned white or albacore tuna |
| 130 g canned sardines |
Sources: USDA National Nutrient Database for Standard Reference.
*Extenso
Note. In recent years, omega-3 eggs have been commercially available. They are laid by hens whose feed is enriched with flaxseed, which, compared to ordinary eggs, increases their omega-3 content tenfold: an enriched egg meets 25% to 35% of daily omega-3 needs. 3.
As a food supplement, the benefits of omega-3
Essential fatty acids are so named because the body cannot synthesize them on its own. They must be found in food, supplements, or dietary supplements.
Typically omega-3 and omega-6 allow the proper functioning of the cardiovascular, cerebral, inflammatory, hormonal, etc. systems. Also, each of its families of fatty acids has properties, for example, omega-3s are good allies for reducing the level of triglycerides in the blood.
Omega-3 needs (more precisely alpha-linolenic acid) are between 0.8 and 1.1 g/day. With regard to omega-6, their intake should be equivalent to 2% of the number of kilocalories ingested per day.
Research
Likely effectiveness
Hypertriglyceridemia. Cod liver oil – an oil rich in omega-3 – reduces triglyceride levels by 20 to 50% in patients with hypertriglyceridemia, according to several clinical studies. Additionally, Krill oil (1-3 g/day for 3 months) may reduce total cholesterol and LDL cholesterol, as well as triglycerides in patients with hyperlipidemia.
Possible efficiency
Albuminuria and hypertension. Consumption of cod liver oil may reduce albuminuria in diabetic patients with neuropathy, as well as blood pressure in patients with mild hypertension.
Uncertain effectiveness
Arrhythmia and depression. Some preliminary data suggest that cod liver oil decreases symptoms related to ventricular arrhythmia as well as depressive symptoms, compared to those who do not consume it.
Arthritis, premenstrual syndrome. According to preliminary clinical studies, an extract of krill oil high in omega-3 (300 mg/day for one month; Neptune Technologies & Bioresources, Inc) reduces certain arthritis-related symptoms (pain, stiffness) and premenstrual syndrome. Further studies are needed to validate these results on krill oil. Krill oil also contains omega-9s but low amounts of omega-6s.
Probably ineffective
Hypercholesterolemia and pain. Cod liver oil does not appear to reduce hypercholesterolemia (high levels of total cholesterol and LDL cholesterol) in individuals with familial hypercholesterolemia. In addition, it does not reduce pain or inflammation when combined with a nonsteroidal anti-inflammatory drug (NSAID), compared to a single treatment with an NSAID.
Omega-6 fatty acids
The body uses omega-6 to make highly unsaturated fatty acids and series 1 and 2 eicosanoids.
These substances play an important role in the proper functioning of the nervous, cardiovascular, and immune systems, as well as in allergic and inflammatory reactions and the healing of wounds. Consumed in excess, omega-6 fatty acids can counteract the beneficial effects (especially cardiovascular).
An excess of omega-6 can also cause pain and inflammatory diseases such as asthma or arthritis.
Among the omega-6s, only linoleic acid (LA) is qualified as “essential”. This is because other omega-6 fats can be made by the body from LA. Unlike alpha-linolenic acid, linoleic acid is abundantly present in modern food: corn, sunflower, soybean, safflower, grapeseed oils, etc.
Gamma-linolenic acid (GLA). The body synthesizes GLA from LA, but several obstacles can hinder this conversion: excessive consumption of cholesterol and “bad fats” (trans, saturated, etc.), alcohol, aging, and diabetes, for example. You can also consume products that are direct sources of GLA: borage oil (24% GLA), evening primrose (8% GLA), blackcurrant (18% GLA), and spirulina.
Dihomo-gamma-linolenic acid (DGLA). It is a derivative of AGL. The only known food source is breast milk. DGLA converts to series 1 eicosanoids which help protect the arteries and heart, boost immunity, and exhibit anti-inflammatory effects.
This table, taken from the book Santé la Gaspésie (p. 16), is reproduced with the kind permission of the authors.
Research
Omega-6s are used to reduce the risk of coronary heart disease and cancer, as well as to fight hyperlipidemia (high levels of LDL cholesterol and total cholesterol).
Uncertain effectiveness
Attention deficit disorder with or without hyperactivity (ADHD). Taking a combination of omega-3 and omega-6 may reduce ADHD symptoms, especially in children who also have neurodevelopmental disorders.
Disorder of the acquisition of coordination. Some symptoms related to coordination disorder (eg reading, spelling a word, etc.) can be reduced in the presence of a combination of omega-3 and omega-6, according to a preliminary clinical study.
Meibomian gland dysfunction. A preliminary clinical study reports that a 6-month treatment with a combination of linoleic acid (28.5 mg) and gamma-linolenic acid (15 mg) decreases lens opacity caused by meibomian gland obstruction, in combination with standard hygiene treatment.
Probably ineffective
Multiple sclerosis and mental development. Taking omega-6 (in the form of arachidonic acid or linoleic acid) has no effect on a baby’s mental development 40 or slowing the progression of multiple sclerosis.
Omega-3: marine or vegetable source?
Experts disagree on the rate of conversion of plant-based ALA to EPA and DHA. According to some researchers, this rate varies from 5% to 10% 12-14 in the case of EPA and from 2% to 5% in the case of ADH. According to other experts, who question their colleagues’ method of calculation, these conversion rates are less than 1%.
Although it is therefore much easier to obtain EPA and DHA from fish and fish oils, experts still recommend varying the sources by regularly consuming fish, but also fish oils and fish oils. seeds rich in ALA.
Image Credit: Image by ededchechine on Freepik
