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This time, we will talk about fats and fatty acids, which are essential for carbohydrate restriction.
Some people say that it's okay to eat a lot of any type of fat when restricting carbohydrates, but it's important to choose the type carefully.
However, there are many similar terms, such as the difference between saturated and unsaturated fatty acids, long-chain and short-chain fatty acids, trans fatty acids, essential fatty acids, omega-3, omega-6, omega-9, linolenic acid, linoleic acid, oleic acid, etc. It can be confusing.
In addition to the fact that they are difficult to understand and handle because they are high molecular weight, I think what makes them confusing is that each food contains multiple of these fatty acids, and there is not a one-to-one correspondence between the names of the fatty acids and the names of foods.
First, let's explain the difference between saturated and unsaturated fatty acids.
What is the difference between saturated and unsaturated?
Lipids is a general term that includes fats and oils, fatty acids, glycerin, cholesterol, etc.
Fatty acids are the main components of lipids , and so-called oils are made up of three fatty acids bound to glycerin.
Among organic compounds composed of carbon (C), hydrogen (H), and oxygen (O), carboxylic acids that have a carboxyl group at one end are called fatty acids, and fatty acids that have double bonds between carbon atoms are called unsaturated fatty acids .
Fatty acids with one double bond are called monounsaturated fatty acids, and those with two or more double bonds are called polyunsaturated fatty acids.
Fatty acids that have no double bonds are called saturated fatty acids. Next, we will explain saturated fatty acids in detail.
What are the characteristics of saturated fatty acids?
The changing perception of lipids on the cover of TIME
Saturated fatty acids are basically solid fats that do not melt at body temperature. They are often animal-based fats such as beef fat and butter.
For a long time, saturated fatty acids have been considered to be unhealthy oils that cause arteriosclerosis, but this image has completely changed over the past 10 years.
As shown on the cover of TIME, saturated fatty acids are chemically stable and resistant to oxidation, as is clear from the way they are bonded, and they are now said to be an oil that should be actively consumed.
Saturated fatty acids are classified by the number of carbon atoms into short-chain fatty acids (seven or fewer carbon atoms), medium-chain fatty acids (eight to 11 carbon atoms), and long-chain fatty acids (12 or more carbon atoms). Let's start by looking at short-chain fatty acids.
What are the characteristics of short-chain fatty acids?
Milk contains small amounts of short-chain fatty acids
The only foods that contain short-chain fatty acids are dairy products (and they only make up a small proportion of the diet), and most of these are produced in the large intestine when intestinal bacteria break down ingested dietary fiber.
Short-chain fatty acids include acetic acid, butyric acid, propionic acid, and hexanoic acid. Butyric acid is used as energy for colonic epithelial cells, while acetic acid and propionic acid are used for metabolism in the liver and muscles.
Other roles of short-chain fatty acids include the biological regulation function, prevention and treatment of cancer, obesity, diabetes, and immune diseases, as well as preventing the entry of harmful substances near the mucous membrane of the intestinal tract, keeping the intestinal tract slightly acidic, and suppressing the action of enzymes produced by bad bacteria.
Because it plays such an important role in maintaining a healthy intestinal environment, it is attracting attention from the perspective of improving the intestinal environment.
In order to produce short-chain fatty acids in the large intestine, it is recommended to take dietary fiber, oligosaccharides, and probiotic supplements; you cannot expect much benefit from simply consuming a lot of short-chain fatty acids orally.
Next, let's look at medium-chain fatty acids.
What are the characteristics of medium-chain fatty acids?
Coconut oil is rich in medium-chain fatty acids
Medium-chain fatty acids are also found in breast milk. They are shorter than long-chain fatty acids and are slightly water-soluble. Therefore, they enter the liver directly from the small intestine via the portal vein and are broken down there.
Medium-chain fatty acids absorbed in the intestinal tract are sent to the liver along with the blood, where ketone bodies are synthesized and sent to the entire body along with the blood to be used as an energy source for the TCA cycle, including the brain.
On the other hand, long-chain fatty acids are digested and absorbed in the small intestine, then transported through lymphatic vessels and veins to adipose tissue, muscles, and the liver, where they are broken down and stored as needed, so it takes time for them to be used as energy.
A major feature of medium-chain fatty acids is that they are broken down about four times faster than long-chain fatty acids, and can be converted into energy in a short period of time. Fatty acids classified as medium-chain fatty acids include unfamiliar fatty acids such as myristic acid and lauric acid.
In food, it is mainly found in coconut oil and palm oil. For those who don't like the smell of coconut, there is no need to worry as various companies are selling products called MCT oil.
MCT oil also became famous when Nagatomo took it three to four hours before a match to use ketone bodies as an energy source.
There are also many reports that medium-chain fatty acids are effective in preventing and improving Alzheimer's disease. In the brain of Alzheimer's disease, insulin is ineffective and the brain's energy source, glucose, cannot be absorbed properly, which causes memory loss and other problems to progress.
The logic is that when you take in medium-chain fatty acids, your brain's nerve cells can use ketone bodies as an energy source, which improves memory and cognitive function. It is also known that medium-chain fatty acids increase the number of mitochondria in muscles and strengthen the power of muscle synthesis.
These are fatty acids that everyone from babies to the elderly should actively consume. Next, let's look at long-chain fatty acids.
What are long-chain fatty acids?
Beef fat is rich in long-chain fatty acids
These are fatty acids found in large amounts in beef and pork oils, and stearic acid and palmitic acid are typical long-chain fatty acids.
Although consuming too much can raise your cholesterol levels, cholesterol itself is not bad.
Cholesterol has long been blamed for being a factor in arteriosclerosis, but it is becoming clear that arteriosclerosis occurs simply when cholesterol accumulates in the blood vessels that have become inflamed due to high blood sugar levels, and that the actual cause is the inflammation of the blood vessels caused by high blood sugar.
If we compare the inflammation caused by hyperglycemia to a fire, cholesterol is the "firefighters" that come to put out the fire, but the firefighters end up blocking blood vessels, making them the bad guys.
If cholesterol levels remain too high for a long period of time, even slight inflammation can make you more susceptible to arteriosclerosis, so it is desirable to keep LDL cholesterol below 190 mg/dl, which is the standard in Europe and the United States.
Cholesterol is also an important nutrient essential for life, as it is a raw material for cell membranes and bile acids, as well as vitamin D, anti-stress hormones, and sex hormones.
Cholesterol levels depend largely on one's constitution, and it has been found that cholesterol ingested through food does not have much effect on cholesterol levels in the body, so it can be said that there is no problem as long as you do not eat too much pork or beef fat.
Summary of saturated fatty acids
So far, we have been talking about saturated fatty acids. Saturated fatty acids are stable and do not oxidize easily. They are classified into three types based on the length of the molecule (number of carbon atoms). Short-chain fatty acids are a matter of intestinal bacteria, so try your best with probiotics. Take in medium-chain fatty acids actively. Don't be nervous about long-chain fatty acids, there is no problem if you take them in moderation. That is the summary. Now, let's move on to talking about unsaturated fatty acids.What are the characteristics of unsaturated fatty acids?
As explained above, among organic compounds composed of carbon (C), hydrogen (H), and oxygen (O), unsaturated fatty acids with one double bond between carbon atoms are called monounsaturated fatty acids, and unsaturated fatty acids with two or more are called polyunsaturated fatty acids. However, they can be further classified into several types depending on which carbon atom, counting from the terminal carbon, contains the first double bond .
The symbol used is the Greek letter "ω = omega." Fatty acids whose first double bond is in the third position from the terminal carbon (omega carbon) are called "omega-3 fatty acids," those whose first double bond is in the sixth position are called "omega-6 fatty acids," and those whose first double bond is in the ninth position are called "omega-9 fatty acids."
The three omega fatty acids mentioned above are well known, but there are also omega-5 and omega-7 fatty acids.
Fatty acids are classified as omega-0 depending on where the double bond begins, and the names of fatty acids are determined by the number of double bonds they have, so it may seem a little complicated, but the difference between saturated and unsaturated should now be easy to understand.
Before talking about unsaturated fatty acids, let us first explain what trans fatty acids are, for which the WHO has set an intake limit.
Unsaturated fatty acids with the same chemical formula can have cis and trans forms.
Difference between cis and trans types Many of you may have heard of cis and trans types in high school chemistry, but trans refers to substances that have the same chemical formula but different three-dimensional shapes. Specifically, cis means "on the same side," and in the case of fatty acids, it means that the hydrogen atoms are on the same side of the carbon double bond. Trans means "across the sky," and in the case of fatty acids, it means that the hydrogen atoms are on opposite sides of the carbon double bond. Most unsaturated fatty acids found in nature are cis types . Trans fatty acids are not found in nature very often, and are produced by microorganisms in the stomachs of ruminant animals such as cows. As a result, small amounts of trans fatty acids are naturally found in milk and dairy products, but margarine is entirely made up of trans fatty acids . It is known that excessive intake of trans fatty acids increases LDL (bad) cholesterol but lowers HDL (good) cholesterol. For this reason, the World Health Organization (WHO) has warned that people should limit their intake of trans fatty acids to less than 1% of their total daily energy intake. Next, we will explain unsaturated fatty acids in order of decreasing omega number.
What are omega-3 fatty acids?
Omega-3 is an essential fatty acid that cannot be synthesized in the body and must be consumed through food or supplements. Fatty acids are named according to the number of double bonds, depending on where the double bond begins.
| Classification by double bond position | Is intake necessary? | Number of double bonds | Names of famous fatty acids | Foods that contain a lot of |
| Omega-3 fatty acids | Required | 6 | DHA | Fish oil |
| Five | EPA | |||
| 3 | α-Linolenic acid | Linseed oil, perilla oil |
Omega-6 fatty acids
Corn oil is rich in omega-6 fatty acids. It cannot be synthesized in the body, so it must be consumed through food. However, since vegetable oils are omega-6, there is no shortage of them, and if there is too much omega-6 compared to omega-3, prostaglandins that cause inflammation are produced, so it is better not to consume too much . The appropriate ratio of omega-3 to omega-6 is considered to be up to 1:4, and consuming more than that makes you more susceptible to inflammation.
| Classification by double bond position | Is intake necessary? | Number of double bonds | Names of famous fatty acids | Foods that contain a lot of |
| Omega-6 fatty acids | Required | Four | Arachidonic acid | It is also synthesized in meat, fish, eggs, and the body. |
| 3 | γ-Linolenic acid | Porage oil, evening primrose oil | ||
| 2 | Linoleic acid | Soybean oil, corn oil |
Omega-9 fatty acids
Olive oil rich in omega-9 fatty acids Monounsaturated fatty acids can be called omega-9 fatty acids. There are oleic acid, eicosenoic acid, elaidic acid, mead acid, erucic acid, and nervonic acid, but the most representative fatty acid is oleic acid, which is found in large amounts in foods such as olive oil , almond oil, rapeseed oil, and sunflower oil.
| Classification by double bond position | Is intake necessary? | Number of double bonds | Names of famous fatty acids | Foods that contain a lot of |
| Omega-9 fatty acids | Not required | 1 | oleic acid | Olive oil |
