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Too much versus too little FAT

The name lipids comes from the Greek, in which “lipos” means fat. Lipids are basic components of the human diet; a completely fat-free diet is not possible, since many vegetables also contain a little fat. The human body can make saturated fatty acids and oleic acid (monounsaturated) itself, but not the essential polyunsaturated fatty acids linoleic acid and alpha-linolenic acid – these have to come from food.

The role of lipids in the body is first and foremost to provide energy, but they also play an important role in maintaining and regulating body temperature, in improving the taste of food, in protecting against cold, in the formation of the brain and the nerve fibres, in the absorption of fat-soluble vitamins and in regulating mental states and behaviour.

Sources of lipids can be natural (animal, plant), hydrogenated (with hydrogen added) or synthetic.

According to their chemical properties, lipids are divided into:

  • Cholesterol
  • Saturated fatty acids
  • Unsaturated fatty acids
  • Milk fat
  • Hydrogenated fats
  • Synthetic fats

CHOLESTEROL, a word that tends to have a negative connotation, is in fact a vital fat. It is produced mainly by the liver, carried through the blood to the tissues and forms combinations of low density (LDL – “bad” cholesterol) or high density (HDL – “good” cholesterol).

  • LDL – “bad” cholesterol leaves the liver and, in excess, is deposited in the blood vessels, which increases the risk of arteriosclerosis. For this reason it is recommended that its value be kept as low as possible.
  • HDL – “good” cholesterol carries cholesterol not used by the cells back to the liver, where it is broken down and excreted.

If the ratio between the two is not optimal, the risk of the body becoming ill increases.

The role of cholesterol is nevertheless very important in:

  • The production of bile, which is indispensable for digesting dietary fats;
  • The transport of hormones;
  • The absorption of vitamins A, D, EK and calcium;
  • Immunity;
  • The functioning of the nervous system;
  • The growth process of the child (a lack of cholesterol slows down the growth process).

SATURATED FATTY ACIDS are fats that are solid at room temperature: lard, butter, cream. They raise “bad” cholesterol, can cause inflammation in the artery walls and occur in larger amounts in animal products.

Unsaturated fatty acids are divided into two groups:

  • Monounsaturated ones, healthier than saturated ones, have a liquid consistency at normal temperatures but solidify at low temperatures and occur in: olive oil, soya beans, maize, grape seeds, hazelnuts, almonds, pistachios, walnuts, but also in fish, pork and chicken fat.
  • Polyunsaturated, or essential, ones keep their liquid consistency even at low temperatures and are obtained from: sunflowers, linseed, fish, safflower. They in turn are divided into:
  • Omega-3 fats – found in vegetable oils from soya beans, flax and nuts, in plant products (e.g. cereals, seeds, pulses, dark green leafy vegetables, nuts, figs) or in seafood, lean meat and fish (the oily ones: mackerel, salmon, sardines and herring contain more Omega-3 fatty acids than lean ones.
  • Omega-6 fats – in higher concentrations in nuts, seeds and vegetable oils.

A low intake of polyunsaturated fatty acids can lead to disorders of immunity, eyesight and intelligence as well as to dermatitis, reduce fertility and weaken the functions of the myocardium.

Milk fat favours the absorption of vitamin D and other fat-soluble vitamins, and its concentration can reach 98 % (butter).

HYDROGENATED FATS are solid at room temperature and are obtained from vegetable oils to which hydrogen has been added. During the hydrogenation process, some of the natural unsaturated fatty acids are turned into unnatural isomers, known as trans fatty acids, which the body does not recognise and which disturb digestion. Hardened fats are in turn used to obtain margarine or other fats that are preferred in the food industry for softening dough. These fats occur naturally in small amounts and in some meat and dairy products.

Eating large amounts of these hardened fats disturbs the metabolism and harms the cardiovascular system. Because of their low cost they are widely used in the food industry, and adding them makes foods creamier and crisper, keeps them looking fresh for longer and reduces the greasy feel.

SYNTHETIC FATS are used by many fast-food restaurants because they are much cheaper. They are not recognised by the body and disturb the absorption of fat-soluble vitamins, which is controversial from a nutritional point of view. Olestra, a synthetic fat, has no taste, smell or colour and can be enriched with any kind of fat-soluble vitamins or flavourings.