What precisely are omega-6 fatty acids?
Omega-6 fatty acids form a category of polyunsaturated fatty acids. These fatty acids are made up of a carbon chain with a carboxylic group (-COOH) at one end and a methyl group (-CH3) at the other. The length of this chain and the type of bonds between the carbon atoms determine whether the fatty acid is saturated or unsaturated. Saturated fatty acids possess solely single bonds, while unsaturated fatty acids also contain double bonds. In the structure of omega-6 fatty acids, the first double bond is located at the sixth carbon atom, counted from the methyl group, which is designated as omega. Among omega-6 fatty acids, linoleic acid (LA) and arachidonic acid (AA) are distinguished. The former is supplied through diet, while the latter is also synthesized from linoleic acid during metabolic processes in the body.
Omega-6 fatty acids - origins
Sources of omega-6 fatty acids include corn oil, soybean oil, sunflower oil, egg yolk, sunflowers, pumpkin seeds, nuts, and others. The content of arachidonic acid and linoleic acid in selected food products are presented in the following tables, based on data from the USDA Food Composition Databases. Table 1. Linoleic acid (LA) in selected food products Source: USDA Food Composition Databases Table 2. Arachidonic acid (AA) in selected food products Source: USDA Food Composition Databases.
Omega-6 Fatty Acids – Their Distinctive Traits
Omega-6 fatty acids are polyunsaturated fatty acids that play an indispensable role in the construction and functionality of body cell membranes. These fatty acids impact the permeability of membranes, ion transport, calcium ion binding, and the concentration of prostaglandins. Adequate saturation of cell membranes with omega-6 fatty acids allows for an increase in their fluidity, which ensures proper cell function, including heart and nervous system. Moreover, omega-6 fatty acids are indispensable building blocks for cell membranes in the nervous system, which is of paramount importance for correct brain development and functioning, especially in children and adolescents.
Influence of omega-6 fatty acids on weight reduction
Omega-6 fatty acids have a significant impact on weight gain. During the metabolic process, arachidonic acid produces metabolites that activate specific receptors, increasing hunger, stimulating the production of fat cells, and increasing the level of triglycerides. This was confirmed by the study of Ruzicka J. et al. in rats. Rodents that consumed large amounts of omega-6 fatty acids had a significantly higher body mass than those fed omega-3 fatty acids. Wang L. et al. conducted a study on women of normal body weight, investigating the relationship between the content of omega-3 and omega-6 fatty acids in the phospholipid membranes of red blood cells and the relationship between these contents and weight gain. The 10-year study found that a high content of omega-6 fatty acids is correlated with weight gain and the accumulation of fat tissue.
CLA-containing linoleic acid for body weight reduction
CLA (conjugated linoleic acid) is a trans-fatty acid isomer belonging to the family of omega-6 fatty acids. Its natural sources include milk and its derivatives, such as ruminant milk, as well as meat, such as beef, pork, and lamb. The effects of CLA on the body vary depending on the places in the chain where the configuration occurred. Its most active form is CLA with a cis-9, trans-11, trans-10, cis-12 linolenic acid configuration. In natural CLA products, the cis-9, trans-11 configuration is present in 90% of cases. CLA-containing linoleic acid has a range of positive properties, including: – it inhibits the processes of fat tissue accumulation (in contrast to other omega-6 fatty acids); – has anti-inflammatory properties; – exhibits anticancer properties; – increases the body's resistance; – has a positive effect in cases of hypertension and diabetes.
Unsaturated omega-6 and omega-3 fatty acids
Crucial unsaturated omega-6 and omega-3 fatty acids should constitute approximately one third of the body's daily fat requirement. Both these groups of fatty acids are metabolized by the same enzymes in the body, but have opposing physiological effects. Omega-3 fatty acids display anti-inflammatory properties, while omega-6 fatty acids are pro-inflammatory. Therefore, proper consumption in the correct ratio is key to maintaining balance in the body. Research has shown that a diet with an adequate ratio of omega-6 to omega-3 has a preventive effect on the development of cardiovascular diseases and reduces the number of deaths caused by these diseases. Furthermore, a high level of omega-6 fatty acids in relation to omega-3 can contribute to the development of insulin resistance by increasing insulin resistance in cells. Optimal ratios of omega-6 to omega-3 range from 3:1 to 5:1.
Do Omega-6 Fatty Acids Truly Cause Harm?
In our body, omega-6 fatty acids undergo various enzymatic transformations. As previously mentioned, linoleic acid gives rise to arachidonic acid (AA), from which inflammatory mediators such as prostaglandins, thromboxanes, fatty hydroxides, lipoxins, and leukotrienes originate. Furthermore, they exhibit a prothrombotic effect and increase blood viscosity.
Impact of excessive intake of omega-6 fatty acids
In recent years, there has been an increase in the consumption of omega-6 fatty acids compared to omega-3 fatty acids. In the past, humans used to consume meat from wild animals and wild plants. At present, these fatty acids are very frequently consumed at a ratio of 20:1 or even higher. Excessive consumption of omega-6 fatty acids is a relatively new problem that has emerged in the last 100 to 150 years. This is due to the change in the Omega-3 content of foods. Currently, the food that people consume comes from breeding and plantations. Fish and farmed meat contain more omega-6 fatty acids and less omega-3 fatty acids compared to their wild counterparts. The ratio of omega-6 to omega-3 fatty acids in a free-range egg is 1:3, while it is 19:1 in an egg from intensive farming. High consumption of omega-6 fatty acids can lead to an increased risk of atherosclerosis, obesity, and diabetes. A high content of arachidonic acid in fat tissue is associated with a higher BMI index in children. Additionally, large amounts of omega-6 fatty acids in women during the perinatal period may increase the risk of obesity in children. Although omega-6 fatty acids have a pro-inflammatory and prothrombotic effect, some scientific studies disprove a negative influence of excessive consumption of these acids on the increase of inflammation markers in the body.