nutrition

Monounsaturated fats

Chemical Structure

Monounsaturated fatty acids are molecules formed by a long carbon chain, which begins with a carboxylic group (COOH), ends with a methyl group (CH3) and has a series of carbon atoms in the central part, each of which is coupled to two hydrogen atoms; an exception to what has been described is a single pair that - by binding a single hydrogen atom per unit of carbon - is held together by a double bond (see figure). Unlike monounsaturated fatty acids, the carbonaceous chain of polyunsaturates has at least two double bonds, while that of saturated fatty acids does not.

In each monounsaturated fatty acid there is a molecular "folding" at the double bond. For this reason the triglycerides that contain them cannot "pack themselves up" sufficiently to form a solid structure; consequently, a food rich in monounsaturated fats is liquid at room temperature, it is more fluid than those in which saturated fats prevail, but it has a higher melting point than foods rich in polyunsaturated fats (which solidify at lower temperatures).

In nature, the most common monounsaturated fats are:

  • palmitoleic acid (C16: 1ω7);
  • oleic acid (C18: 1ω9);
  • erucic acid (C22: 1ω13).

If we take the palmitoleic monounsaturated acid as an example, the acronym C16: 1ω7 indicates the presence of 16 carbon atoms, with a double bond between the seventh and eighth starting from the methyl end (terminal).

Health properties and effects

Oleic acid is undoubtedly the most important and known monounsaturated fatty acid, capable of conferring peculiarities interested in the foods that are rich in it. The high stability - which translates into a high resistance to heat and oxidation - improves the shelf life of these foods, preserves them from rancidity and makes them particularly suitable for frying. Therefore the constant genetic improvement of the cultivation of oil plants aims, in many cases, to increase their content in oleic acid. A particularly rich food of this precious nutrient is olive oil, which contains it in percentages varying from 59 to 80%. Excellent concentrations of oleic acid are also recorded in almonds, hazelnuts, peanuts, pistachios and their respective oils.

When compared to a diet rich in saturated fatty acids, a diet rich in oleic acid favors the maintenance of normal blood fluidity and reduces the amount of cholesterol associated with low-density lipoproteins (LDL or bad cholesterol), while it has no major effect on the level of triglycerides and cholesterol associated with high density lipoproteins (which tends to increase). This does not mean that the more olive oil is consumed and the more it is earned in health (indeed ...), but simply that it should be preferred to animal lipids, contained in butter, lard and lard, and to the hydrogenated ones of margarines.

Erucic acid, unlike oleic acid, is part of "undesirable" monounsaturated fatty acids (at least in the food and health sectors). If consumed in large quantities (the law requires that oils and margarines contain less than 5% of it) it has negative repercussions on growth, on the liver and on the heart. For this reason, thanks to the aforementioned genetic improvement of crops, today we have rape oils (renamed "canola") with a very low erucic acid content.

Palmitoleic monounsaturated fatty acid is also not a friend to human health, as it behaves exactly like an atherogenic saturated fatty acid. When compared to a diet rich in oleic acid, a diet rich in palmitoleic acid tends to increase bad LDL cholesterol and decrease good HDL. Palmitoleic acid is found in various foods and abounds particularly in Macadamia oil ( Macadamia integrifolia ) and in that of sea buckthorn ( Hippophae rhamnoides ).