282 OLIVE OILS AND HEALTH In conclusion, there is considerable evidence suggesting that this type of fat has a positive effect on health, although findings are sometimes inconsistent. Furthermore, it is often difficult to determine whether these benefits are due specifically to this nutrient or to the overall dietary pattern and associated lifestyle, which are frequently linked. Olive oils are very rich in monounsaturated fatty acids, but when included in the diet, they are often part of broader dietary patterns that involve high consumption of vegetables, fruits, legumes, nuts, fish, and low-fat dairy products, along with moderate red wine intake. As a result, the observed health benefits of these lipids cannot be attributed solely to their monounsaturated fatty acid content. In Unit “B” of this book, the effects of olive oils (which are high in monounsaturated fatty acids) on different life stages and physical activity are discussed; Unit “C” addresses their impact on various diseases; and Unit “D” examines their role within the Mediterranean diet and general lifestyle context. - oleic acid; oleic Oleic acid is a monounsaturated omega-9 fatty acid with 18 carbon atoms (18:1 ϖ-9) and a single cis double bond at the ninth carbon. It is the main representative of monounsaturated fatty acids. Its salts and esters are known as oleates. oleic acid (C18H34O2) (C18:1 cis ω-9) 9 oleic acid O OH Oleic acid is not an essential fatty acid, as previously mentioned. It can be synthesised by the body from stearic acid (C18:0 -saturated-) through the action of an enzyme that introduces a double bond at the 9-10 position of the hydrocarbon chain. This mainly results in oleic acid, but also in palmitoleic acid. Oleic acid is also obtained from the diet, primarily from plant-based foods, and to a lesser extent from animal sources such as meat and dairy products. Most vegetable oils are rich in this fatty acid, especially olive oil (63-80% of total fatty acids, depending on the variety) and rapeseed (canola) oil (56-70%). It is also found in olives, avocados and nuts. When vegetable oils are fully hydrogenated, oleic acid is converted into its saturated form, stearic acid. However, if the hydrogenation is only partial, trans fatty acids may be formed. The trans isomer of oleic acid that appears in this process is known as elaidic acid. Oleic acid plays an essential role in maintaining the structure of cell membranes, among other functions. It is the most abundant fatty acid in most mammalian cells, accounting for around 40% of total fatty acids. Its intake has been associated with potential benefits for cardiovascular health and cancer, but the scientific evidence remains inconsistent and sometimes contradictory. It is also important to consider that this fatty acid is not consumed in isolation, but as part of a broader dietary pattern and lifestyle. These combined factors may have a greater impact on health outcomes than any single dietary component on its own. H H H H H H H H H H H H H H H H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ,,.o Hc-c-c-c-c-c-c-c-c=c-c-c-c-c-c-c-c-c 3 I I 1 1 1 1 1 1 1 1 1 1 1 1 'oH HHHHHHH HHHHHHH
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