All foods with a high content of fats (intended as a nutrient) are included in the dietary group of fats. The first subdivision is between "oils" and "solid fats". The oils remain liquid at room temperature: most vegetable fats are oils. Solid fats are the ones that remain solid at room temperature and are almost all animal in origin (butter). Only a few vegetable fats, the tropical oils, are solid fats, or they become so after an industrial process called hydrogenation (such as margarine).
All fats have a very high calorie content (9 Kcal per gram, i.e., 45 calories per 1 single teaspoon of oil) and this is one of the reasons to limit their intake.
The most used fats are:
The foods in this group are the principle source of fats of the diet and contain saturated and unsaturated fats, in varying proportions, depending on whether of plant or animal origin. Some are also a good sources of vitamin E (sunflower seed and almond oils).
Solid fats are those with a greater content of saturated fat and can also contain trans fats. Trans fats make up approximately 20% of all animal fats, while in vegetable fats they are present only in the hydrogenated fats, like in margarine. The hydrogenation process converts the unsaturated fats in vegetable oils into hydrogenated fats, whose properties are similar to those of saturated fats and are also rich in trans fats. Hydrogenated fats are used in baked foods (crackers, cookies, etc.), because they hold up well to cooking at high temperatures, due to their high smoke point. Trans fats should be consumed as little as possible, so it is important to avoid foods that contain them.
All animal fats supply our body with harmful saturated fat and cholesterol. A diet high in saturated fats, trans fats and cholesterol increases the LDL-cholesterol ( "bad cholesterol") levels in the blood, which is a major risk factor for atherosclerosis and consequently for coronary heart disease and stroke.
The non-tropical vegetable oils, however, are rich in unsaturated fats, among which are monounsaturated and polyunsaturated fats, and contain limited amounts of saturated fat and zero cholesterol, like all plant foods. They are rich in essential fatty acids of the family omega-6 and some are also a good source of omega-3 fatty acids .
The oil richest in omega-3 fatty acids is flaxseed oil, produced by cold pressing of flaxseed. It is sensitive to light and heat and must therefore follow the “cold chain”: during transportation and sale in the store (if it is not refrigerated, it should not be bought because it has already lost its content of omega-3), and in the home, it should always be kept in the refrigerator with the cap closed. The intake of omega-3, from flax oil or freshly ground flaxseeds or walnuts, may be useful for the prevention of vascular diseases related to atherosclerosis.
For cooking, extra-virgin olive oil is always preferred (to be preferred, however, even when used raw), for its better ratio between the various types of fatty acids.
It 's always recommended to limit fat intake to avoid excess calories. Observing the recommended fat portions in VegPlate also helps limit the intake of saturated and trans fats. Protective fats are already present in the diet through the consumption of other foods such as legumes, nuts and oil seeds and linseed oil.
For any type of diet, the consumption of non-tropical vegetable fats (always in small amounts) reduces the risk of chronic diseases and allows the intake of essential nutrients to ensure the body's functions.
Conversely, diets high in animal fats, tropical fats (coconut palm) and hydrogenated vegetable oils, are high in saturated fat, trans fats and cholesterol (the latter only present in animal fats) and increase the risk of vascular disease. For this, the foods that contain these types of fats should be eliminated or at least kept to a minimum.
Vegetable oils (non-tropical) are rich in mono-and polyunsaturated fats, that do not increase bad cholesterol in the blood and are a source of vitamin E (sunflower and almond oil). Scientific evidence shows that the consumption of these fats is protective against vascular diseases, some cancers and is positive for bone health in the elderly. In fact the international dietary guidelines recommend the intake of vegetable oils and to limit animal fats.
Some polyunsaturated fatty acids, those of the omega-6 and omega-3 family, are essential, as they can be introduced only with diet, and cannot be produced by our bodies. Omega-6 fatty acids are even too abundantly present in a plant-based diet, while omega-3 can be obtained from flaxseed oil (in the form of ALA, alpha-linolenic acid).
Only use vegetable fats to drastically decrease the intake of saturated fats and cholesterol, present in all animal fats.
Limiting fat intake in general, because of the high calorie supply (45 calories per teaspoon), and in particular of margarine, mayonnaise and other sauces (use these products only occasionally, not habitually).
Avoid products with tropical oils (coconut, palm, palm hearts) or hydrogenated vegetable fats or not better specified "vegetable fats" because they contain a lot of saturated and trans fats. They are often found in packaged baked goods and spreadable creams.