Lipids (fats)

A triglyceride is a molecule of glycerol, to which three molecules of fatty acids are attached. This is the main form of lipids in living organisms and in our food, and also the main form of storage of energy in our organism. To use fats as fuel for charging ATP, our liver splits molecules of triglyceride into three molecules of fatty acids and a molecule of glycerol. By the way, though glycerol is a part of fat molecules, it does not belong to lipids, it belongs to the group of alcohols. Fatty acids can be burned as such, or the liver can use them to make ketone bodies, which are the best fuel for mitochondria.

Fatty acids differ by the number of atoms in the chain. Their number can be even or odd. Natural fats contain mostly fatty acids with an even number of atoms of carbon, but there are also those with the odd number. Some of the fatty acids are absolutely necessary for us (essential fatty acids), some can harm our health, or even be poisonous.

Examples of acids with odd numbers of atoms of carbon. The shortest fatty acid has just one atom of carbon, and this is an odd number. This fatty acid is called formic acid, which is used by ants as poison, and it is poisonous for us in a substantial amount. The acid with 15 atoms of carbon (pentadecanoic acid, aka pentadecylic acid, C15) is present in fats of cow milk and butter (about 1% of all milk fats). It is important for membranes of our cells.

Examples of acids with the even number of atoms of carbon: acetic acid (the one that is in vinegar) he's the shortest with the even number of atom of carbon – it has two such atoms (C2), Acetic acid can cause harm in a considerable concentration (over 2 to 3%), and even chemical burns of the mucus membrane at a concentration of over 10% and even of skin at even higher concentration, because it's an acid. But in concentration of up to 0.5% it is certainly not harmful, it gives a pleasant flavor to some of our meals and has some useful influence on us, even though the mechanism of this influence has not been studied.  Palmitic acid (C16) and stearic acid (C18) are rather common in natural fats and belong to long-chain acids.  Caprylic acid (C8) and capric acid (C10) belong to medium-chain fatty acids and make a considerable part of coconut oil, and also are found in fats of goat milk. The above picture shows a molecule of caprylic acid (from the Latin word "capra" – goat); it is also known as the octanoic acid.

Such acids are called unsaturated because they are "not completely saturated" with hydrogen. They can be made saturated by creation of certain conditions – a certain temperature, a certain pressure and chemicals that are ready to lend atoms of hydrogen with molecules of fatty acids. People invented a way how to do this and obtained margarine – an artificial fat that is composed mainly of artificially saturated fatty acids, which initially were unsaturated. This invention, probably, has saved a lot of people from death from starvation, but it also caused a certain damage to the health of many people, not as much by the fact that, in margarine, saturated fats are made artificially, as by the fact that not all unsaturated fats became saturated, but, in the process of saturation, certain undesirable transformations occurred to them.  

Unsaturated fatty acids can be monounsaturated (with one double bond in the chain of atoms of carbon), or polyunsaturated(with two or more double bonds in one chain). MUFA – monounsaturated fatty acid; PUFA – polyunsaturated fatty acid. 

Trans fats have been known since 1903, but they began to be talked about as a health hazard only around the late 1970s. These talks encountered a substantial resistance, therefore, for a long time the use of trans fats in food industry continued. Only in 2018, in the USA, addition of such fats to food products was pronounced to be "not recommended", rather than prohibited. But this restriction is only about addition, rather than formation of trans fats in the process of making food. Far from  all countries recommend not to add trans fats.

Normal fatty acids (cis fats) can become trans fats as a result of influence of high temperature and some other factors. For instance, in saturation of unsaturated fats with hydrogen (which is done for making margarine), a part of unsaturated fats becomes saturated, and a (small) part becomes trans fats. Also, it is believed that frying food with the use of vegetable oils may cause formation of trans fats, especially when the same portion of oil is used for frying several times (like in deep fat frying). And even extraction of seed oils by heating ground seeds and pressing them is suspected in formation of a small amount of trans fats.

The matter is that we are not adapted to normally metabolize trans fats. It was noticed that their regular consumption in a substantial amount causes a considerable increase of lipoproteins of low and very low density (there will be more about lipoproteins further). It is believed that such lipoproteins (especially of low and very low density) are related to cardiovascular disorders. Even though "not everything is unambiguous" with low-density lipoproteins, it looks that very-low-density lipoproteins, in certain conditions, can be a factor of elevated risk, especially when they are oxidized, which decreases their volume and substantially increases their density. 

It is also believed that trans fats, in certain conditions, can be carcinogenic.

Once again: Nobody recommends you anything and does not call you to anything. That trans fats are not a natural food for us is an irrefutable fact. The rest of what is written here about trans fats, as of 2024, is not finally established. Make your own conclusions.

Probably, everyone has heard about health benefits of omega-3. Some, probably, have heard that omega-6 is not particularly healthy. And there also omega-7 and omega-9. Certainly, everyone remembers that omega is the last letter of the Greek alphabet. But here we speak about fats, not about the alphabet. What does this Greek letter have to do with them?

The ending of a fatty acid, that is, the last atom of carbon with three hydrogen atoms attached to it is called "omega". And this last atom is numbered as 1. Omega-3 is an unsaturated fatty acid, which has a double bond between the third and the fourth atoms of carbon, counting from the ending of the molecule. Omega-6 is also an unsaturated fatty acid between the sixth and the seventh atoms of carbon (counted from the ending). The same applies to the rest of omegas.

If a fatty acid is polyunsaturated, that is, has more than one double bond in the chain of carbon atoms, its omega number is determined by the first double bond from the ending. Omega-3 and omega-6 are usually polyunsaturated, while omega-7 and omega-9 are monounsaturated.

Each "omega" plays its own role. We need all these omegas, but in different amounts and different proportions. Violation of these proportions can cause health problems. This is especially the case with omega-3 and omega-6. It is believed that a too small fraction of omega-3, in comparison with omega-6, in our food leads to a cronic inflamation and cronic elevation of cortisol level, which, in turn, provokes insulin resistance and disrupts automatic regulation of absorption, accumulation and expenditure of energy, that is, disbalances metabolism. 

In our food, there is usually enough of omega-6 acids. Practically all fats are a mix of triglycerides, a part of which have saturated fatty acids, and the other part, unsaturated fatty acids, mostly, omega-6. So, if we do not exclude fats from our food completely, we get a sufficient amount of omega-6.

The situation is more complicated with omega-3. Generally, there are smaller quantities of these fatty acids in our food. Besides, there are three different omega-3s, which we need all, namely, ALA, EPA and DHA – these are abbreviated chemical names of these acids. Usually, these abbreviations are shown on the package of food supplements generally titled "Omega-3". 

ALA is present in some of the plants and their fats, such as olive oil, flax seeds and oil out of them, sezame seeds and oil from them, nuts, etc. But it is practically absent in the oils most widely used in culinary – sunflower, palm and rape seed oils. But we need it. This does not mean that we need to completely exclude omega-6 and eat only what contains ALA, but it makes sense to ensure that there is more ALA in our food. 

When we consume enough ALA, many of us can use it to make EPA and DHA. But we are not very good at it, and some people cannot do this at all. Besides, ALA is not always available in sufficient quantities. So, it is desirable to ensure that our food should contain EPA and DHA. EPA is present in many kinds of marine and oceanic algae. And fish oil contains both EPA and DHA. So, consumption of marine or oceanic oily fish (or fish oil, or food supplements made out of it) will provide us EPA and DHA omega-3 fatty acids.

All these omegas are valuable for us not as sources of energy. They are necessary for the structural built of our cells, and they participate in complicated biochemical processes. And only their excess quantities can be burned in mitochondria for charging ATP. But saturated fats are a better fuel than unsaturated.

This is written not for selling you olive oil or "Omega-3" food supplements. Do not buy, if you think that you are fooled and that all this is just an advertisement. Seek for additional information and make your own conclusions.

A few decades ago, cholesterol was accused of killing many people. Ih has not been exculpated even as of 2024, even though many specialists doubt that it was well-grounded or refute it completely as ungrounded.

Cholesterol is a substance belonging to the group of lipids. It is present practically in all animals. It is absolutely necessary for life of animals, including people. In its name, "chole" come from the Latin word meaning "bile". Yes, without cholesterol, there can be no bile, and without bile, we cannot digest food. Cholesterol is also a base for production of certain hormones, including cortisol, sexual hormones – female (estrogen, progestin) and male (testosterone), and many others.

Also, cholesterol is included in all living cells of our body, including cellular membranes. Without it, cells cannot funciton. Many cells produce it, and nervous cells, which cannot produce it, receive it from other cells through blood.

Also, cholesterol may come with food, especially with saturated fats (predominantly, of animal origin, but there are also saturated fats of vegetable origin). If we consume such fats, there can be up to 30% of cholesterol in our organism that comes from food, and the remaining 70% or more are produced by the organism. If we get on a diet that does not have cholesterol at all, then 100% of the cholesterol we need will be produced in our organism.

Cholesterol is very important in recovery of the organism after a trauma. This recovery requires production of a large number of new cells, and this requires "building materials", including cholesterol. 

Why was cholesterol accused of murder? Because in people, who had myocardial infarction, elevated level of cholesterol was found. Also, a lot of cholesterol was found in "cholesterol plaques", which form in blood vessels (arteries) and slow down blood flow up until its compete blocking, when the plaques grow bigger.  So, it was concluded that elevated cholesterol is the main cause of cardiovascular diseases.

Some medical doctors and scientists, who have studied cholesterol for long time, come to a conclusion that such accusations are groundless. Imagine, they say, you walk or drive along a street and see a traffic accident. And near that place, you see a car of the traffic police. Then you see one more traffic accident, and the traffic police near it. Then again, and again. And there are always the traffic police near it, and in more serious cases, there is an ambulance, and sometimes even a fire truck. And you make a conclusion: the cause of traffic accidents is police cars. Logical, is it not? Or, maybe, not entirely logical?

Here is what these doctors and scientists explain. Myocardial infarction is a serious trauma. The organism is trying to minimize its consequences and provides everything that is needed for recovering, including cholesterol, and this is why it is high in people with infarction.  Cholesterol plaques begin not from cholesterol, but as microtraumas on the inner surface of blood vessels, caused by other causes, in particular, by very low density lipoproteins, which became oxidized as a result of metabolic disorders and became considerably smaller (this, substantially increased their density). And the organism reacts to  these microtraumas by increasing cholesterol, but it cannot correct metabolism on its own. And so traumatization of the walls of the vessels continues, and so does accumulation of cholesterol in the traumatized blood vessels. 

Besides, it was found out that people with a lower body mass index (BMI) have a higher level of cholesterol than people with a higher BMI, even if they get the same food. In people with the third stage of obesity (BMI 40 or more), cholesterol is much lower than in lean people (BMI 20). Who of these people has a higher risk of cardiovascular problems and death of the myocardial infarction? According to the logic of the claim that "cholesterol kills", the risk for the lean people is much higher than for the obese, and this is the lean who must die more frequently because of cardiovascular problems. Does it not contradict to what we usually observe?

Despite these logical contradictions, a large number of doctors still recommend limiting or excluding animal fats from food (because they contain cholesterol). And when they detect an elevated level of cholesterol in the blood of their patients, they prescribe very expensive medications for lowering it. Yes, these medications effectively lower the level of cholesterol, but they cause unpleasant side effects. But do they avert cardiovascular problems? There are two answers to this question. Some specialists say: "Yes". Others say: "No, they almost do not", and quote results of long-term studies of lethality caused by cardiovascular diseases among those who took such medications and who did not. Тhese studies show a very insignificant difference; that is, one can assume that these medications do not prolong life and do not reduce probability of death of a cardiovascular disease. They only reduce the level of cholesterol in the blood, just as it is said in their description.

This is a group of substances composed of two fatty acids, a molecule of glycerol and a phosphate group. Phospholipid molecules have a hydrophilic "head" and a hydrophobic "tail", owing to which they can form stable emulsions in substances, which do not normally mix (for instance, water and oil). In living organisms, phospholipids are present in cells, especially, in the cell membranes, and ensure their elasticity. Phospholipids are necessary for our health, and we obtain them from food. Especially rich with phospholipids are liver, yolks, sunflower seeds and soy beans.

Phospholipids are used in the food industry for making stable emulsions, for instance, in making mayonnaise and chocolate. They are also produced as a food supplement.

Phospholipids are also known as lecithin.

Lipoproteins do not belong to lipids, though they are lipids attached to a molecule of a special protein. Most lipids (except some of the fatty acids) do not dissolve in water and do not mix with it. Besides, they show a tendency to gather in large globules that form out of small globules that merge when they are suspended in water.  Eventually, water and fats completely separate and form a layer of fats over a layer of water.

To transport lipids by blood to the cells requiring them, our organism attaches them to those special protein molecules. Such a combined particle can freely travel through the blood vessels without merging with other such particles.

There are high-density lipoproteins (HDL), low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL). We need them all, but, for the normal health, it is important that certain proportions between them are maintained at least approximately.

Different kinds of lipoproteins transport different lipids, but all of them also transport cholesterol. Therefore, sometimes they are called cholesterol, which is a simplification. According to this simplification, it is thought that HDL is "good" cholesterol, while LDL and VLDL are "bad" cholesterol, even though cholesterol is the same in all of them, when they transport it. Recent studies show that the situation is more complicated, that LDL and VLDL as such are not "bad". Moreover, there are indications that vascular problems emerge not because of the lipoproteins as such, but because some of them become damaged (oxidized VLDL), and they become damaged much more frequently in people with metabolic disorders. 

We will not comment this, we will only remember that LDLs and VLDLs existed in human organisms long before the beginning of the "epidemic" of cardiovascular diseases (at that time, people did not even have an idea of their existence). Only when this "epidemic" reached a threatening scope, cholesterol and lipoproteins were accused of it.

Studies continue, as well as discussions of specialists on this matter. And this is not surprising, because the object of these studies is too complicated, which makes it difficult to distinguish the influence of some factors from the influence of other factors, because, among other things, a change of one of the factors changes many others.