Fat

There are three types of fatty acids in fat: saturated, monounsaturated, and polyunsaturated. It is their ratio that determines the nutritional value.
Animal fats are high in saturated fatty acids. They increase cholesterol levels in the blood, thus promoting the development of atherosclerosis, heart and vascular diseases, and cancer. Consuming abundant saturated fatty acids can be a cause of lung, colon, rectal, breast, and prostate cancer. An exception is made only for one type of animal fats – fish oils, such as mackerel, herring, salmon, and trout. It is recommended to eat them as often as possible because of the polyunsaturated omega-3 fatty acids they contain.
The nutritional value of oil is determined by the ratio of fatty acids it contains and the amount of fat-soluble vitamins. In vegetable oil, unsaturated fatty acids, namely oleic, linoleic, and alpha-linolenic acids, make up a significant portion of all fatty acids. Omega-6 and omega-3 PUFAs are particularly important. There are opinions that a lack of omega-6 derivatives can be one of the risk factors associated with cancer. Omega-3 PUFAs reduce platelet aggregation, as well as the risk of thrombus formation, affect the electrical activity of the heart muscle, suppress the occurrence of arrhythmias. They reduce triglyceride concentration in the blood, as well as the incidence of ischemic heart disease.
The World Health Organization (WHO) recommends that the ratio of omega-6 to omega-3 PUFAs in food should be 1:1–5:1. In recent decades, a distorted trend in this recommendation has emerged: more and more oil rich in omega-6 is consumed, and too little omega-3 PUFAs. For example, sunflower oil. The ratio between these acids in various food products ranges from 10:1–20:1. An excessive amount of omega-6 reduces LDL cholesterol and increases HDL cholesterol. Metabolites produced from omega-6 fatty acids cause vasoconstriction and platelet aggregation.
More than saturated trans isomeric acids, formed during the hydrogenation, i.e., hardening of vegetable oils, increase the risk of dyslipidemia, type II diabetes, and the entry of carcinogens into cells.
The quality of vegetable oil is determined by its chemical composition, method of extraction, refining technology, and the natural physiologically active substances preserved during it. It is recommended to consume at least 2–3 tablespoons of unheated oil per day with various dishes or salads.

Source | Dietary Treatment in General Practice | Dietitian Doctor Jūratė Dobrovolskienė