Omega-3 or Omega-6: which is better?
Now that such a large number of supplements based on omega-3 fatty acids have appeared, the question inevitably arises: maybe we should simply switch our diet to omega-3 fatty acids, and we will get rid of atherosclerosis forever, be healthy and eternally young?
Then why were many generations of Ukrainians, whose diet mainly consisted of products containing omega-6 polyunsaturated fatty acids, distinguished by good health, vigor, and activity?
So, what is actually better: the omega-6 fatty acids we are used to, found in meat, lard (salo), and sunflower oil, or omega-3, which we mainly get from fish oil and deep-sea fatty fish from cold waters – salmon, trout, eel, mackerel, etc.?
You can read about how omega-3 differs from omega-6 in chemical structure here… As for the main representatives and their action:
– the main omega-6 fatty acids familiar to us are arachidonic 20:4 and linoleic 18:2, common in pork lard, meat (arachidonic), and sunflower, pumpkin, and corn oils (linoleic):arachidonic CH3–(CH2)4–(CH=CH–CH2)4–(CH2)2–COOH 20:4 ω–6
linoleic CH3–(CH2)4–(CH=CH–CH2)2–(CH2)6–COOH 18:2 ω–6
– the main omega-3 fatty acids are eicosapentaenoic (EPA) 20:5, docosahexaenoic (DHA) 22:6, as well as alpha-linolenic acid (18:3). Long-chain fatty acids of the omega-3 family (EPA, DHA) are produced by algae and plankton; alpha-linolenic acid is found in linseed (flax) oil. Deep-sea fish from cold waters (salmon, trout, mackerel, herring, sardine, tuna) feed on plankton, and the fish oil obtained from them is the main source of omega-3 family fatty acids for humans:
eicosapentaenoic CH3–CH2–(CH=CH–CH2)5–(CH2)2–COOH 20:5 ω–3
docosahexaenoic CH3–CH2–(CH=CH–CH2)6–CH2–COOH 22:6 ω–3
alpha-linolenic CH3–CH2–(CH=CH–CH2)3–(CH2)6–COOH 18:3 ω–3
The amount and type of polyunsaturated fatty acids in food affects the structure of cell membranes.
Since fatty acids of the omega-6 family dominate in the diet of residents of non-coastal regions, arachidonic acid (which belongs to this group) prevails in the structure of their cell membranes.
In peoples who consume a lot of deep-sea fish and seafood, on the contrary, there is a greater incorporation of polyunsaturated fatty acids of the omega-3 family (EPA and DHA) into cell membranes, leading to a decrease in the content of omega-6 fatty acids.
When omega-3 fatty acids are consumed, they partially replace omega-6 fatty acids in the membranes of almost all cells: erythrocytes, granulocytes, platelets, endothelial cells, monocytes, and lymphocytes. In addition, with the active intake of omega-3 fatty acids into the body, the composition of fatty acids changes in various organs towards an increase in omega-3: in the lung parenchyma, brain tissue, liver, spleen, intestinal mucosa, and muscles. The “omega-3 / omega-6 fatty acid” ratio in the membranes of the listed cells and organs shifts towards an increase in omega-3.
In terms of chemical structure, arachidonic acid (20:4, omega-6) and eicosapentaenoic acid (20:5, omega-3) are very similar, and the main difference lies in the presence of one additional double bond in the latter. Therefore, both of these fatty acids compete in membranes for the same enzyme systems that convert them into lipid mediators – eicosanoids (paracrine hormones – substances formed in almost all cells of the body and acting near the site of secretion), which differ significantly in structure and, especially, in metabolic activity.
This competition at the enzymatic level (cyclooxygenase-lipoxygenase) manifests itself in a change in the composition of the formed eicosanoids – prostaglandins (PG), thromboxanes (Tx), and leukotrienes (LT).
When a cell is activated by a stimulus that changes the geometric orientation of phospholipids in membranes and activates phospholipase A2, arachidonic acid (or its competitors that are part of cell membranes – EPA, DHA) is released from phospholipids, followed by metabolism via the cyclooxygenase or lipoxygenase pathway (in normally functioning cells, products of free radical lipid oxidation can serve as such a stimulus).
The cyclooxygenase pathway leads to the formation of prostaglandins and thromboxanes, while the lipoxygenase pathway of metabolism leads to the formation of leukotrienes.
Arachidonic acid (omega-6) is metabolized by the enzyme cyclooxygenase with the formation of 2 series of prostaglandins and thromboxanes (PG E2, PG I2, Tx A2) and by the enzyme 5-lipoxygenase – 4 series of leukotrienes (LT B4, C4, D4, E4).
Eicosapentaenoic acid (omega-3) is metabolized by the same enzymes with the formation of 3 series of prostaglandins and thromboxanes (PG E3, PG I3, Tx A3), and 5 series of leukotrienes (LT B5, C5, D5, E5).
With an increased intake of omega-3 fatty acids from food:
– the production of prostaglandin E2 (PG E2) metabolites decreases;
– the formation of leukotriene LT B4 – an inducer of inflammation, chemotaxis, and leukocyte adhesion – decreases;
– the level of prostaglandin I3 (PG I3) increases, which, in the absence of a decrease in prostaglandin I2 (PG I2), leads to an increase in the concentration of total prostaglandin. PG I2 and PG I3 are active vasodilating agents and suppress platelet aggregation;
– the concentration of leukotriene LT B5 – a weak anti-inflammatory agent and chemotaxis factor – increases;
– the level of thromboxane Tx A2 – a powerful vasoconstrictor and activator of platelet aggregation – decreases;
– the concentration of thromboxane Tx A3 in plasma – a weak vasoconstrictor and inducer of platelet aggregation – increases.
For a healthy organism, the most important thing is to maintain high muscle tone, preserve the integrity of blood vessels, and prevent bleeding from minor household injuries.
Therefore, under these circumstances, the synthesis of metabolites with broncho- and vasoconstrictive properties, as well as inducers of blood cell aggregation, is necessary, whereas products with anti-inflammatory properties are required in relatively small amounts in the total volume of synthesized substances. Such requirements are met by metabolites of omega-6 acid – arachidonic acid, which is the main component of the phospholipid bilayer of cell membranes in residents of non-coastal areas.
In disease conditions, substances with antispasmodic, anti-inflammatory, and platelet aggregation-inhibiting properties – metabolites of omega-3 eicosapentaenoic acid – are more beneficial to humans.
The results of epidemiological surveys of the population of coastal areas of Greenland, Japan, the Netherlands, and a number of other countries have established a high concentration of eicosapentaenoic and docosahexaenoic fatty acids in the blood plasma of residents of these regions with a low content of linoleic and arachidonic acids.
It is this fact that explains the extremely low level of cardiovascular diseases (atherosclerosis, ischemic heart disease, hypertension) in residents of coastal areas.
It would seem: here is the solution in the fight against heart and vascular diseases! Exclude sources of omega-6 fatty acids (the meat, lard, and sunflower oil we are used to) from food and switch to omega-3 (fish, seafood, flaxseed oil).
And what will happen?
The slightest cut and the smallest wound will bleed for a long time, huge hematomas will form under the skin instead of small bruises from bumps, and a simple fall on ice can lead to a fatal outcome as a result of incessant bleeding. We can add to this hypotension, lethargy, fatigue, and weak muscle tone.
It is as a result of excessive consumption of omega-3 fatty acids that Eskimos have been noted to have increased bleeding, frequent development of hemarthrosis in response to the slightest trauma, and hypotension.
Therefore, for a healthy person, it is necessary to observe a rational ratio of omega-3 and omega-6 acids in food – 1:4–6, respectively.
However, the indicated ratio is optimal for healthy people and may vary depending on the diseases a person has and their stage.
Thus, studies by American (Simopoulos, 2002, 2006, 2008) and Japanese (Hagi et al., 2010; Takeuchi et al., 2008) scientists showed that in the secondary prevention of cardiovascular diseases, a concentration of omega-3 and omega-6 fatty acids in the diet in a ratio of 1:4 led to a 70% reduction in total mortality. A ratio of 1:5 had a beneficial effect on asthma patients, while a ratio of 1:10 led to adverse consequences. A ratio of 1:2.5 showed a decrease in rectal cell proliferation in patients with colorectal cancer, while a ratio of 1:4 with the same amount of omega-3 fatty acids did not have the proper effect. A similar ratio of 1:2–3 suppressed inflammation in patients with rheumatoid arthritis.
According to the literature, increasing the concentration of omega-3 fatty acids in the body leads to an improvement in the condition of patients with various mental disorders, including stress, anxiety, cognitive impairment, mood disorders, and schizophrenia.
However, if the dose exceeds 4 g per day, along with increased vascular bleeding and hypotension, the appearance of negative mental effects is also possible – increased anxiety, restlessness, irritability, tearfulness, and depressive disorders.
German specialists (Rupp et al., 2008) consider the optimal dose of omega-3 fatty acids to be 1 g per day, and as a preventive measure for ischemic heart disease, they recommend eating fatty fish dishes at least twice a week, which will amount to an average of about 2 g per week of the sum of omega-3 polyunsaturated fatty acids (EPA + DHA).
Thus, any diseases are multigenic and multifactorial by nature. Therefore, it is obvious that therapeutic doses of omega-3 fatty acids in unhealthy people should depend on the nature of the existing disease and its severity.
At the same time, it should be remembered that exceeding the dose of omega-3 fatty acids – 4 g per day – can lead to highly undesirable side effects listed above: vascular bleeding, hypotension, weakening of muscle tone, appearance of mental effects – increased anxiety, restlessness, irritability, tearfulness, and depressive disorders.
So, let us recall Paracelsus once again: “All things are poison and nothing is without poison; only the dose makes a thing not a poison”…
Content of omega-3 fatty acids in fish and marine products
References
Havrysyuk V.K. The use of omega-3 polyunsaturated fatty acids in medicine // Ukr. pulmonol. journ. – 2001. – No. 3. – P. 5–10.
Havrysyuk V.K., Yachnyk A.I., Leshchenko S.I., Morozova N.A., Dziublyk Y.A. Prospects for the use of omega-3 polyunsaturated fatty acids in medicine // Pharm. bulletin. – 1999. – No. 3. – P. 39–41.
Kazymyroko V.K., Maltsov V.I. The function of unsaturated fatty acids in the body // Health of Ukraine. – 2004. – No. 10 (95). – P.36–37.
Kazymyroko V.K., Maltsov V.I., Butylin V.Yu., Horobets N.I. Free radical oxidation and antioxidant therapy. – Kyiv: Morion, 2004. – 160 p.
Perova N.V. Prevention of cardiovascular diseases: sources of increasing human consumption of omega-3 polyunsaturated fatty acids // Handbook for outpatient physicians. – 2007. – Vol.4, No. 6. – P.17-20.
Pyzh M.V., Graciansky N.A., Dobrovolsky A.B. The effect of a diet enriched with omega-3 polyunsaturated fatty acids on the indicators of the fibrinolytic system of blood in patients at the early stages of ischemic heart disease // Cardiology. – 1993. – No. 6. – P. 21–25.
Burghardt P.R., Kemmerer E.S., Buck B.J., Osetek A.J., Yan C., Koch L.G., Britton S.L., Evans S.J. Dietary n–3:n–6 fatty acid ratios differentially influence hormonal signature in a rodent model of metabolic syndrome relative to healthy controls // Nutr. Metab. (Lond). – 2010. – No. 7. – P.53.
Clandinin M.T., Jumpsen J., Suh M. Relationship between fatty acid accretion, membrane composition, and biologic functions // J. Pediatr. – 1994. – Vol.125, No. 5, Pt 2. – P.25–32.
Fontani G., Corradeschi F., Felici A., Alfatti F., Migliorini S., Lodi L. Cognitive and physiological effects of Omega-3 polyunsaturated fatty acid supplementation in healthy subjects // Eur. J. Clin. Invest. – 2005. – Vol.35, No. 11. – P.691-699.
Grоnn M., Gоrbitz C., Christensen E., Levorsen A., Ose L., Hagve T.A., Christophersen B.O. Dietary n–6 fatty acids inhibit the incorporation of dietary n–3 fatty acids in thrombocyte and serum phospholipids in humans: a controlled dietetic study // Scand. J. Clin. Lab. Invest. – 1991. – Vol.51, No. 3. – P.255–263.
Hagi A., Nakayama M., Shinzaki W., Haji S., Ohyanagi H. Effects of the omega–6:omega–3 fatty acid ratio of fat emulsions on the fatty acid composition in cell membranes and the anti–inflammatory action // JPEN J. Parenter. Enteral. Nutr. – 2010. – Vol.34, No. 3. – P.263–270.
Haug A., Olesen I., Christophersen O.A. Individual variation and intraclass correlation in arachidonic acid and eicosapentaenoic acid in chicken muscle // Lipids Health Dis. – 2010. – No. 9. – P.37.
Perica M.M., Delas I. Essential fatty acids and psychiatric disorders // Nutr. Clin. Pract. – 2011. – Vol.26, No. 4. – P.409-425.
Rupp H., Wagner D., Rupp T., Schulte L.M., Maisch B. Risk stratification by the “EPA+DHA level” and the “EPA/AA ratio” focus on anti-inflammatory and antiarrhythmogenic effects of long-chain omega-3 fatty acids // Herz. – 2004. – Vol.29, No. 7. – P.673-685.
Simopoulos A.P. The importance of the ratio of omega–6/omega–3 essential fatty acids // Biomed. Pharmacother. – 2002. – Vol.56, No. 8. – P.365–379.
Simopoulos A.P. Evolutionary aspects of diet, the omega–6/omega–3 ratio and genetic variation: nutritional implications for chronic diseases // Biomed. Pharmacother. – 2006. – Vol.60, No. 9. – P.502–507.
Simopoulos A.P. The importance of the omega–6/omega–3 fatty acid ratio in cardiovascular disease and other chronic diseases // Exp. Biol. Med. (Maywood). – 2008. – Vol.233, No. 6. – P.674–688.
Song C., Li X., Leonard B.E., Horrobin D.F. Effects of dietary n-3 or n-6 fatty acids on interleukin-1beta-induced anxiety, stress, and inflammatory responses in rats // J. Lipid. Res. – 2003. – Vol.44, No. 10. – P.1984-1991.
Takeuchi H., Kojima K., Sekine S., Murano Y., Aoyama T. Effect of dietary n–6/n–3 ratio on liver n–6/n–3 ratio and peroxisomal beta–oxidation activity in rats // J. Oleo Sci. – 2008. – Vol.57, No. 12. – P.649–657.
Thomson A.B., Keelan M., Lam T., Rajotte R.V., Garg M.L., Clandinin M.T. Fish oil modifies effect of high cholesterol diet on intestinal absorption in diabetic rats // Diabetes Res. – 1993. – Vol.22, No. 4. – P.171–183.