Linoleic acid is an essential fatty acid that humans must obtain from their diet because their bodies do not produce it. It is an 18-carbon-long, unsaturated, omega-6 fatty acid. Also known as LA, linoleic acid is found in a number of vegetable oils, including sunflower, safflower, and corn oils. As an unsaturated fatty acid, it is a much healthier dietary component than the saturated fatty acids found in meat or dairy products.
Essential fatty acids are a necessary component of the diet, because humans cannot synthesize them. Humans must obtain linoleic acid from food, despite the tendency to try and avoid anything that contains fat. There are health benefits derived from consuming both monounsaturated and polyunsaturated fats.
Fats are necessary for the intake and transport of fat-soluble vitamins, such as vitamin D. It is particularly important that children and babies have adequate fats in their diets to insure proper brain and eyesight development. There is some evidence that having extra linoleic acid in the diet of infants with cystic fibrosis can help improve their health.
The metabolism of linoleic acid, and its role in health, is somewhat complex. It is a precursor to arachidonic acid, which can be turned into many biologically-active molecules. This acid is metabolized to prostaglandins, which are among a number of other molecules known as eicosanoids.
Prostaglandins are chemicals that have an array of effects on the body. They are present in every cell, and are required for the body’s proper maintenance. There are many types of prostaglandins, however, and some can also have negative health effects. For instance, they can lead to inflammation, causing pain in such diseases as arthritis.
Omega-3 fatty acids are polyunsaturated fatty acids, and have a different number of double bonds than the omega-6 fatty acids, like linoleic acid. Humans primarily obtain omega-3 fatty acids in their diet from seafood. For this reason, many Western diets include much lower amounts of omega-3 than omega-6 fatty acids.
Fatty acids of the omega-3 class produce different types of eicosanoids than do omega-6 fatty acids. The omega-6 varieties are much more likely to cause inflammation than those produced from the omega-3s. A diet too rich in omega-6 fatty acids is thought to have negative health effects, such as contributing to inflammatory diseases like rheumatoid arthritis.
Many studies recommend that people lower the dietary ratio of omega-6 to omega-3 fatty acids, to reduce the chance of illness. It is still healthier to eat omega-6 fatty acids, however, than to eat saturated and trans-fat fatty acids. The evidence for a link between large amounts of dietary saturated and trans-fats and cardiovascular disease is quite strong.