The need for fats is 15-20% of the total energy needs. One gram of fat contains 9 calories.
A balanced diet should be present saturated, monounsaturated and polyunsaturated fatty acids.
Sources of animal fats are meat, fish, milk, cheese, butter.
Sources of vegetable fats – cereals, nuts, seeds, vegetable oils. Margarine, though has a vegetable origin, but the physiological effects similar to animal fat.
In a balanced diet of fats of vegetable origin should prevail (50-70% of total fat).
In fats of vegetable origin predominant polyunsaturated fatty acids in fats of animal origin – saturated.
If the diet restricts the intake of fat, then it is necessary to introduce an additional all essential fatty acids. Sources of essential fatty acids – nuts, vegetable oil, fish and fish oil.
Monounsaturated fatty acids found in olive, peanut and canola oil.
Sources of omega-6 polyunsaturated fatty acids are sunflower oil, corn oil, soybean oil, grape seed oil; sources of omega-3 fatty acids – fish oil (it is contained in cod, trout, mackerel, tuna, salmon and other fish) and vegetable oils (soybean, Hazelnut, linseed).
Greater than 20 grams per day of omega-6 fatty acid ratio or improper omega-3 and omega-6 fatty acids in the body reduces the level of high density lipoprotein and increases the risk of free radical damage by light and oxygen.
The most valuable for the body are polyunsaturated fatty acids. Some of them (linoleic and linolenic) are essential and must necessarily come from food. On their ratio depends on the structure and function of cell membranes, they form the substance-regulators of immune processes.
Useful for people polyunsaturated fatty acids have a cis form. Under the influence of temperature, direct sunlight and oxygen fatty acids can be transformed into harmful to human health trans form.
Therefore, vegetable oils are best kept in a dark tightly sealed bowl and eat without cooking. Trans form fatty acids should not exceed 5-7% of the total fatty acids. Many trans-forms found in margarine, which is explained by hydrogenation of fats in its industrial production.