Trans fats are UNDESIDERED lipid molecules because they are recognized as harmful. They are naturally present in some foods (especially milk, derivatives and some meats), but in concentrations absolutely reduced compared to those of industrial products containing hydrogenated fats.
Hydrogenated fats and hydrogenation
Without going into the subject (which has already been extensively discussed in the various articles), let's give an understandable meaning to the term "hydrogenated fat": it is an unsaturated lipid (with one or more double bonds, therefore initially of liquid consistency ) artificially saturated (breaking the double bonds by adding the missing hydrogens, therefore transformed into a solid ) through a chemical-physical process called hydrogenation; this artifact is carried out at the request of the food industries which, based on the needs of the various preparations (brioches, bread sticks, etc.) choose the specific consistency of hydrogenated fat (there are different levels of hydrogenation).
NB . There are many hydrogenated fats and they differ from each other for different characteristics: starting fatty acids, saturation level (one, two or more hydrogenated double bonds), concentration of trans fatty acids (obtained involuntarily by hydrogenation), etc.
Trans fatty acids
In organic chemistry a fatty acid is defined trans when, from the "geometric" point of view, the hydrogen (H) normally bound to a carbon (C) is placed in a specularly opposite direction to the cis form. Apparently the molecule does not change, except for a small detail, well, this very trifle makes a trans fat a potentially harmful element.
Foods rich in trans fats
Trans fatty acids are present mainly in hydrogenated fats, therefore in foods that contain margarines or in those fried in semi-hydrogenated oils / fats; but not only! Even the simple excessive thermal exposure favors the cis / trans mutation, as happens for example during excessive frying and / or exceeding the smoke point; furthermore, following peroxidation and rancidity (due to bacteria, light, oxygen, high temperatures etc.) a further increase in these unwanted molecules can be observed.
However, there are also many natural foods that in themselves contain trans fatty acids ; this is the case of dairy products and meat obtained from the slaughter of some animals. This phenomenon is linked to the gastrointestinal physiology of ruminants that, during the digestive process, undergo bacterial fermentation of the digestive content; during this process, microorganisms cause the conversion of some cis fatty acids into trans fatty acids then absorbed in the intestine, secreted in milk and / or accumulated in meat. Let me be clear, we are talking about concentrations ranging from 1/7 to 1/30 of those referred to margarines, therefore (in my opinion) scarcely relevant, even if noteworthy.
Foods that contain the greatest amount of trans fatty acids are:
Margarines, brioches, sweet snacks, pretzels, frozen french fries, krafen, butter, bouillon cubes, soup preparations, fast-food foods, frozen fish in breadcrumbs, bag-corn popcorn, aged cheeses, etc.
Side effects
Eating predominantly, or even only frequently, foods rich in trans fats is harmful to health; they have been linked by several scientific studies to: 1. Alterations of lipid metabolism 2. Cytological alterations related to the structure of cell membranes of neurons (cells of the nervous system):
- Foods rich in trans fats worsen the transport of fats in the blood by lipoproteins; they cause a reduction in cholesterol transporters from the periphery to the liver (HDL) and increase cholesterol carriers from the liver to the periphery (LDL). In the long term, this undesired mechanism can determine the accumulation of oxidized LDL inside the vascular walls and subsequently (also thanks to the inflammatory processes) the formation of atherosclerotic plaques with an increased risk of mortality (atherosclerosis).
- Foods rich in trans fats worsen cellular efficiency and functionality; they are inserted in the liquid mosaic of the cellular membranes causing a relative "stiffening" with consequent limitation of the energy production, absorption and communication potential with the other cells.
Definitely:
"a diet characterized by foods rich in trans fats correlates with the increased risk of:
- Hypercholesterolemia (... and diabetes)
- Atherosclerosis
... and also negatively affects the integrity of the central nervous system; the brain of a subject that frequently feeds on trans fats ages faster, is more prone to degenerative diseases such as senile dementia and reacts badly to depressive disorders ".
NB . Trans fats compete with essential fatty acids in the constitution of cell membranes, therefore, even a significant intake of omega 3 and omega 6 can be nullified by an overall incorrect diet.
Important : from 13/12/2014 the expression "totally or partially hydrogenated", depending on the case, must appear on the label if the oils or fats present in the food have been hydrogenated.
It is also mandatory to specify the specific plant origin of the oils that make up the mixture of vegetable fats (eg palm oil, coconut oil, etc.)
Bibliography:
- Manual of oils and fats - P. Capella, E. Fedeli, G. Bonaga, G. Lerker - New techniques - 12.3
- Manual of clinical nutrition - R. Mattei - Maedi-Care - pag 37-38
