Lipid, carbohydrate, and protein are macronutrients. Fatty acids are the components of so-called fat or oil, which belong to lipid. You might be confused with a variety of names, though, there is not so much need in practice to distinguish them. The word "fat" may assume a negative impression because of the association with obesity. To be sure, taking too much fat leads you to obesity and then to lifestyle related diseases. But, in fear of fats, largely restricting them also has an adverse effect on your health. Fatty acids are an indispensable nutrient to the human body, and taking a moderate amount of fat is one of the key factors in being healthy.
Fatty acid is preserved in the adipose tissue for energy reserve after ingested into the body. In addition, it has some crucial functions such as constituting the cell membranes, the brain, and some kinds of hormones in the human body. Although some types of fatty acids are produced in the body when necessary, it is desirable for humans to take them in moderation from a variety of foods. Fatty acids classified into four as shown below would be helpful in practical use.
Such as palmitic acid and stearic acid belong to saturated fatty acid. This fatty acid is often seen in the animal fats. Butter contains around 70% of its total fat as saturated fatty acid. While lard and tallow consist of saturated fat and oleic acid each 40 to 50 percent. As for plants, coconut oil and palm oil in the tropics have saturated fat in them. Generally, saturated fats are higher in melting points, in contrast to unsaturated fats that have lower ones. Therefore, oils or fats mentioned above are usually semi-solid at room temperature.
Oleic acid, a representative of this group, is widely found in both plants and animals. Olive oil and rapeseed oil consist largely of oleic acid. There are vegetables that are genetically modified to have a high proportion of oleic acid instead of linoleic acid. Safflower oil and Sunflower oil are being commercialized as high-oleic vegetable oils. These oils are said to have been developed after the study results that linoleic acid is easier to spoil than oleic acid and that taking too much linoleic acid has a negative effect on human health.
Mammals including humans need to take in this fatty acid from food because they are unable to produce this fat within their bodies, which is why omega-6 fatty acid is called an essential fatty acid. However, we can eat this unconsciously through meal, as omega-6 fatty acid is present in a variety of plants. Therefore, we barely lack this essential fatty acid unless we have extremely unbalanced diets. Rather, we are prone to have excessive amounts of omega-6 fatty acid where and when foods abound. Taking too much omega-6 offsets the benefit of omega-3 fatty acid mentioned next. The vast majority of omega-6 fatty acid is linoleic acid. Such as soybean oil and corn oil contain high proportion of linoleic acids. Meanwhile, cows, sheep, and other ruminants have a conjugated linoleic acid (CLA) in their bodies. This CLA has proved to have an anticancer effect.
Omega-3 fatty acid is another essential fatty acid. Alpha-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) belong to this group. Omega-3 fatty acid is relatively scarce in nature compared to other fatty acids, and so we need less amount of omega-3 than omega-6. Omega-3 fatty acid might be recognized as medicine rather than oil because it has some beneficial effect on humans: lowering the heart disease risk, improving intelligence, and alleviating mental disorder, etc. However, only a limited range of organisms contains omega-3 fatty acid, which can easily lead us to lack this fatty acid if we have unbalanced diets. Therefore, we need to secure some sauces of omega-3 fatty acid. The most recommendable candidate is marine food, especially oily fish such as mackerel, sardine, and saury. We can also take in omega-3 fatty acid from flaxseed oil and perilla oil.