Fatty acids

What are fatty acids?

Fatty acids, which belong to the lipids, are aliphatic monocarboxylic acids and depending on their double bonds it is decided whether it is an omega 3 or an omega 6 fatty acid. In addition, fatty acids are components of fats and oils and can have an influence on our health, for better or for worse. This then depends on whether good or bad fats are consumed.

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids

A saturated fatty acid is a fatty acid that does not have a double bond between C atoms. These fatty acids are particularly abundant in meat and dairy products such as whole milk, cheese, butter and cream. They are also found a lot in baked goods such as pizza or cakes. So when we talk about "bad" fatty acids, we are referring primarily to animal fats. They are bad because, when consumed in excess, they increase the risk of arteriosclerosis and contribute to an increase in LDL cholesterol, which is dangerous to health.

Unsaturated fatty acids

Unsaturated fatty acids have at least one C=C double bond, the polyunsaturated fatty acids have two or more bonds between the carbon atoms and the chain. Some of the unsaturated fatty acids are essential for the body, as they cannot be synthesized by the body in the conventional way. Unsaturated fatty acids are found, for example, in olive oil, rapeseed oil, avocados and in nuts.

Why do I need fatty acids as an athlete?

Fatty acids perform two elementary tasks for us: They enable the utilization of fat-soluble vitamins and help build hormones. Fatty acids help to ensure that vitamins A, D, E and K can be absorbed by the body. The "good" fats serve, among other things, to build up the brain, the conductivity of the nerves, the cell structure and the production of the body's own messenger substances.

Omega 3 fatty acids in particular are essential for the human body, as they have many positive effects. These include positive effects on metabolism and athletic performance. Sports can be performed longer and the regeneration time is reduced, moreover, omega 3 supports fat burning and muscle building. In addition, the omega 3 fatty acid is said to have a wound-healing effect, so it supports the healing process of micro-injuries, which occur, for example, during muscle soreness.

Compared to other nutrients, fats contain the greatest energy density (1g fat = 9 kcal, 1g glucose/protein: 4 kcal) and are therefore an important energy supplier for sporting activities. However, they have the disadvantage that they burn more oxygen during their combustion and require twice as much time as aerobic glucose breakdown. However, this does not affect low to moderate intensity exercise, where sufficient oxygen is available. At rest, the proportion of energy provided by fats and carbohydrates is 50% each.

Aerobic endurance training improves the ability to burn fat (fatty acid transport, b -oxidation), so that well-trained endurance athletes can use fat not only as a second, but under certain conditions even as an equivalent energy source. For this reason, in endurance trained muscle fibers -an approximately two and a half larger amount of trigycerides (fats) is found than in non-endurance trained muscle fibers. During predominantly aerobic endurance activities, fatty acids can be increasingly used for energy production and thus conserve glycogen stores - e.g. for the final sprint.

Competitive athletes in particular are anxious to eat a low-fat diet, since too much fat in the diet has a performance-reducing effect (especially for endurance performance). The reason for this is likely to be the disruption of carbohydrate metabolism at various levels. In addition, a high fat content in the diet means that correspondingly fewer carbohydrates and proteins can be absorbed. It has been observed that a lower body weight indirectly means an improvement in maximal endurance capacity. This is because the lower the body weight, the higher the maximum relative oxygen uptake capacity per kg body weight - without additional training. Therefore, by increasing lean body mass, one can increase the possible intensity (e.g. speed) of endurance performance.

In a normal balanced diet, however, it is not exactly easy to eat a low-fat diet, since only about one-third of the fats are ingested as "visible fats" (vegetable oils, butter or margarine as spreadable fat, visible fat in meat or sausage). The vast majority are hidden fats, some of which are not perceived directly, e.g. the fat in bakery products, pastries (e.g. pasta), dairy products (especially the very fatty cheeses) and in sweets (chocolate has 30% fat). It is not easy and requires a strong will to eat only low-fat food in the long run. This is because aromas, flavors and fragrances are bound to fat and only develop their effect with it. Without fat, food no longer smells or tastes particularly intense.

How should I dose my intake of fatty acids?

Nutrition experts advise strength athletes to cover up to 35% of their calorie requirements with fat, while endurance athletes are advised to consume 20-25%. However, the exact dosage depends on age, physical condition and activity. In addition, requirements and supply are determined by the ratio of omega 3 to omega 6 fatty acids. According to the nutrition report of the German Nutrition Society (DGE), an optimal omega-3 to omega-6 ratio should be a maximum of 1:5.

The importance of fats for the body

With an energy density of 38.1 kJ/g (= 9.1 kcal/g), fat is the most important energy supplier. Like carbohydrates, fats consist of the elementary building blocks carbon (C), hydrogen (H) and oxygen (O); unlike proteins, they have no nitrogen (N) content. Dietary fats are primarily triglycerides and cholesterol. Triglycerides, also called neutral fats, make up the majority of all dietary fats and consist of glycerol, a trivalent alcohol, and fatty acids, with three fatty acids attached to each molecule of glycerol by esterification.

They are the storage fat that replenishes the depots in the body and can also be seen in vegetable oil or on cuts of meat. Each of these fats is characterized by a different fatty acid composition. Fatty acids are organic acids (hydrocarbon compounds) that can be divided into short-chain and long-chain fatty acids based on the length of the carbon chain. The longer the fatty acid chains in a fat, the more difficult it is to digest or melt. On the other hand, the number of double bonds in the fatty acid chain is used to distinguish between saturated fatty acids, which have no double bond (e.g. stearic acid, palmitic acid), and monounsaturated or polyunsaturated fatty acids with one (e.g. oleic acid) or more (e.g. linoleic acid) double bonds.

As the number of double bonds increases, the reactivity of the substance increases because not all of the binding possibilities are used. This is also the reason why fats with a large proportion of reactive unsaturated fatty acids spoil more quickly. For the human body, the following applies: The inert saturated fatty acids mostly go directly into the depots, while the more reactive unsaturated ones are preferentially used in the organic building processes.

Some of the unsaturated fatty acids, such as linoleic acid and linolenic acid, cannot be synthesized by the human organism itself, so they have to be supplied with food; these are then referred to as essential fatty acids. The body is able to synthesize the most important unsaturated fatty acid of all from these two: the quadruply unsaturated arachidonic acid. It is a component of almost all cell membranes and is also the starting substance for a number of important mediators with a variety of effects, including on the blood and circulation, and as a mediator of certain hormone effects ("second messenger").

Origin of fats

Fats in our food are of various origins:

Animal origin

Meat and meat products, eggs and dairy products such as butter, cheese, milk and cream, are the main sources of animal fats in Europe.

Vegetable origin

Fat can be found in plant seeds (for example, rapeseed, sunflower, corn), in fruits (for example, olives, avocado) and in nuts (for example, peanuts, almonds). The oil is obtained by washing and grinding the seeds, fruits or nuts. During heating, the oil can be separated by an extraction process. It is then refined to remove unwanted flavors, odors, colors and impurities. Some oils, such as extra virgin olive oil, walnut oil, and grapeseed oil, are pressed directly from the seed or fruit without any further refining process.

The main supply for the European oil market comes from:

• Annual oil crops grown, for example, canola, sunflower, soybean, corn and peanuts.
• Tree fruits such as olive, palm, cocoa and coconut.

Fats can occur naturally in foods such as fatty meats, oily fish, egg yolks, cheese, and full- and semi-skimmed milk, or can be added during food preparation. This can be done at home or already by the food manufacturer, for example in the production of cakes, cookies, pastries, savory snacks, meat products or mayonnaise. Oils and fats may be clearly evident in foods (for example, baking and salad oils, butter, other spreads, cream, and the visible fat on meat) or mixed with other components and thus less apparent to consumers. About 70 percent of the average fat intake is fed by so-called "hidden" fats. Knowing about fats and reading food labels can make an important contribution to a healthy and balanced diet.

Fat structure

To understand the role of fats in our health and in food production, one should know the chemistry of fats. More than 90 percent of the fats in food and in the body are triglycerides. Cholesterol, waxes and phospholipids share the remaining ten percent.

Triglycerides

All triglycerides have a fork-like structure of glycerol and three fatty acids.

Fatty acids

Fatty acids vary in the length of their carbon chain (from 4 to 22 building blocks) and in the number of their double bonds. For example, butyric acid (C4:0), palmitic acid (C16:0) and arachidic acid (C20:0) contain 4, 16 and 20 carbon atoms in their chains, respectively. Most fatty acids in our diet and body contain 16 to 18 carbon atoms (see Appendix: List of Most Common Fatty Acids). Fatty acids are classified according to the number of double bonds they contain. Saturated fats contain none, monounsaturated fats contain one, and polyunsaturated fats contain two or more double bonds.

Omega-6 and omega-3 fatty acids

Polyunsaturated fatty acids are further classified into two families depending on the position of the first double bond:

• Omega-6 (or n-6) fatty acids have the first double bond at the sixth carbon atom along the fatty acid chain and are derived mainly from linoleic acid.
• Omega-3 (or n-3) fatty acids have the first double bond at the third carbon atom along the fatty acid chain and are derived mainly from alpha-linolenic acid.

In addition to their actual name, fatty acids are often represented by a shortened numerical name based on the number of carbon atoms, the number of double bonds, and the associated omega class. For example, linoleic acid is abbreviated by C18:2 n-6. This indicates that linoleic acid has 18 carbon atoms and two double bonds and belongs to the n-6 or omega-6 family. Alpha-linolenic acid is abbreviated by C18:3 n-3: it has 18 carbon atoms, 3 double bonds and belongs to the n-3 or omega-3 family.

Essential fatty acids

The essential fatty acids linoleic acid (omega-6 fatty acid) and alpha-linolenic acid (omega-3 fatty acid) cannot be produced by the body and must therefore be ingested with food. They are important for growth, development and health. Even though the body cannot manufacture these two fatty acids - it can convert them into longer chain versions. These longer chain versions are the building blocks of eicosanoids, the precursors of some hormones (for example, prostaglandins).

These hormone-like substances play a major role in building cell membranes as well as in blood clotting, wound healing and inflammation. Although the body is able to convert alpha-linolenic acid to the long chain version EPA (eicosapentaenylic acid) and to a lesser extent to DHA (docosahexaenylic acid), this conversion appears to be limited. For this reason, we also need direct sources of these long-chain omega-3 fats in our diet. The richest source of these fatty acids is oily fish.

Cis and trans fatty acids

Unsaturated fatty acids can also be subdivided as "cis" (kinked form) or "trans" (straight form) depending on their molecular structure. Most unsaturated fatty acids in the diet exist in the cis form. In the meat and milk of ruminants (e.g. beef, sheep) and in products containing industrially modified oils that have undergone a hardening process - partial hydrogenation - a certain proportion of the unsaturated fatty acids exist in the trans form.

Function in the body

Due to their high energy density, dietary fats are the number one source of energy: fats provide more than twice the amount of energy as carbohydrates or proteins. However, the immediate energy requirement is usually covered by carbohydrates, since fat burning, so-called lipolysis, is more costly for the organism despite the higher energy gain. Any excess of energy, which is supplied by food, the body stores in depots, so the not burned fats are stored by the body as depot and as building fat. This form of energy storage saves a lot of weight and space. For example, if a bird had stored its energy in carbohydrates instead of depot fat, it would not be able to take off from the ground.

During prolonged periods of hunger and deficiency, the body draws on its energy reserves, the depot fats. Depending on external circumstances, these are replenished accordingly in "good times" in order to be prepared for bad times. During physical exertion, energy from carbohydrates is used up first, followed by energy from the fat depots, although this only occurs after about 30 minutes of continuous physical exertion. Fat burning is activated primarily during lighter endurance exertion, because the more intense the sporting activity, the greater the energy cover provided by the carbohydrates, which can be utilized more quickly.

For all those who want to get rid of annoying fat reserves through exercise, the following applies: Exercise for at least half an hour at moderate load without interruption, and only then do you get rid of the fat! In addition to their role as energy suppliers, dietary fats also ensure that the fat-soluble vitamins A, D, E and K can be absorbed in the organism. Adding butter to carrot vegetables, for example, therefore serves not only to develop the flavor, but also to improve the absorption of the vitamin A contained in the carrots. This also indicates another important property of fats. Most aroma and flavor substances are lipophilic, i.e. fat-soluble; cheese or other dairy products with a high fat content therefore taste better. Anyone who has ever undergone a strict low-fat diet knows that when the fat disappears, so does much of the flavor.

Overview of the occurrence and function of fats in the human organism:

• In white adipose tissue: depot or storage fat as well as "hunger-resistant" building fat
• In brown adipose tissue: thermoregulation
• Mechanical protection of organs e.g. kidney fat
• Skin protection against external influences
• Vehicle for the absorption of fat-soluble vitamins (A, D, E, K, provitamin carotene) as well as aroma and flavor substances
• Source of fatty acids, some of them essential, which are needed for the structure of cells or cell membranes and for various metabolic processes. They control the absorption (uptake) of fats from the intestine, regulate fat metabolism and help to lower elevated cholesterol levels.

Fats and health

Coronary heart disease

Coronary heart disease is the most common cause of death among men and women in Europe (WHO Health Report, 2002). There are many risk factors associated with the development of coronary disease. These include: high blood pressure, smoking, lack of exercise, obesity, diabetes, hereditary predisposition, and elevated blood lipid levels (cholesterol levels, LDL cholesterol, triglycerides). There is a link between diet and some of these factors, especially blood lipid levels.

Effects of diet on blood lipid levels

Cholesterol

For most people, cholesterol-containing foods, for example eggs, shellfish and liver, have little effect on blood cholesterol levels. But there are some people who react strongly to cholesterol in their diet. These people need to limit their cholesterol intake.

What is cholesterol?

Cholesterol is a fat-like substance that occurs naturally in all animal tissues, including the human body. A certain amount of cholesterol is needed by the body to build cell membranes, form sex hormones and bile acid. Bile acid helps the body absorb and digest fats. Too much cholesterol or triglycerides in the blood can cause heart and blood vessel disease. Over three-quarters of the cholesterol in the blood is produced by the body, with the rest coming from food. Cholesterol is transported in the blood in the form of lipoproteins: Low density lipoproteins (LDL - low density lipoprotein) and high density lipoproteins (HDL - high density lipoprotein).

A high concentration of LDL cholesterol is a risk factor for coronary heart disease, consequently it is sometimes called "harmful cholesterol". HDL cholesterol is associated with cholesterol breakdown, and high concentrations are beneficial. Consequently, it is often called "beneficial cholesterol.'' The higher the HDL level, the lower the risk of heart disease. Therefore, it makes sense to eat foods that help reduce LDL levels and maintain or increase HDL levels. Physical activity also increases HDL levels.

Saturated fats

The amount of saturated fat in the diet has a far greater effect on blood cholesterol levels than the amount of cholesterol-containing foods. There is evidence that saturated fat has the greatest effect on total blood cholesterol and LDL cholesterol levels. But there are differences in cholesterol-raising effects among fatty acids. In general, the effects of fatty acids with intermediate chain lengths (for example, lauric C12:0, myristin C14:0, and palmitic C16:0) are greater than those with longer chains.

Monounsaturated fats

There are many reports on how good it is to eat as little fat as possible. However, recent recommendations are that moderate fat intake, with an appropriate fat composition, is a better way to control blood lipid levels and prevent long-term health problems, because consuming normal amounts of fat maintains HDL cholesterol, the "beneficial cholesterol. This also protects against an increase in blood triglycerides, which can occur when large amounts of carbohydrate are included in the diet to replace fat (diets with little or no fat are usually high in carbohydrates). Increased amounts of monounsaturated fatty acids in the diet can lower LDL cholesterol, although this effect is largely related to the displacement of saturated fat in the diet.

Polyunsaturated fats

The long-chain omega-3 fatty acids found in fish are known for their protection against heart disease. In countries like Japan, where people eat a lot of fatty fish, heart disease has a correspondingly lower incidence. Regular consumption of fish results in both a reduction in blood triglyceride levels and a lower blood clotting potential. The long-chain fatty acids in fish do not appear to have a favorable effect on blood cholesterol; they are rather neutral in this respect.

Omega-6 polyunsaturated fatty acids have strong LDL cholesterol reducing properties that help protect against heart disease. However, very large amounts of omega-6 polyunsaturated fatty acids can cause a reduction in good HDL cholesterol levels. For this reason, and because of concerns about possible harmful effects on LDL oxidation, excessive amounts of polyunsaturated fatty acids are better not consumed.

trans fatty acids

There are concerns about high intakes of trans fatty acids in particular. Trans fatty acids are metabolized similarly to saturated fats. But there are still doubts as to whether their effect on heart health is comparable. Trans fatty acids not only raise LDL cholesterol in the same way as saturated fats, but they also lower levels of good HDL cholesterol. Trans fatty acids are found in some dairy products and in some partially hydrogenated fats used in bakery products such as cookies, cakes and pastries.

Diet, along with physical activity, plays a key role in regulating blood lipid levels. To prevent cardiovascular disease, it is recommended that the diet should include moderate fat consumption and a balance between saturated and unsaturated fats. At least 1 to 2 fish meals per week are important to maintain healthy levels of long-chain omega-3 fatty acids.

Misuse

Excessive intake, especially of fats with a high proportion of saturated fatty acids, leads to obesity due to increased depot formation, which can have a wide range of health consequences: Damage due to mechanical overload in the musculoskeletal system, reduced physical performance, local eczema and infections in the skin folds, psychological problems as well as libido and potency disorders and an increased risk of a variety of diseases such as diabetes, high blood pressure, coronary heart disease and heart attack, stroke, gout, gallstone disease and other gallbladder diseases.

Overall, fat consumption in Western industrialized countries is too high, and consumption of high-fat foods should therefore be reduced in general, with attention also being paid to hidden fats. A deficiency of fats, which can occur, for example, as a result of long-term virtually fat-free diets or fat-free artificial diets, is dangerous primarily because of the lack of essential fatty acids. The consequences are skin changes such as excessive keratinization (hyperkeratosis) and hair loss (alopecia) as well as a deficiency of blood platelets (thrombocytopenia) with increased bleeding tendency and growth disorders.

References

1. Conference Report (2000). Dietary cholesterol as a cardiac risk factor: myth or reality? Nutrition Bulletin, 25: 365-367.
2. De Lorgeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N. (1999). Mediterranean diet, traditional risk factors and the rate of cardiovascular complications after myocardial infarction; final report of the Lyon Diet Heart Study. Circulation ,99:779-785.
3. Department of Health. Report on Health & Social Subjects N°46 (1994). Nutritional Aspects of Cardiovascular Disease. HMSO, London.
4. Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (2001). Executive summary of the 3rd report of the National Cholesterol Education Program (NCEP). Journal of the American Medical Association, 285:2486-2497.
5. Hooper L. (2001). Dietetic guidelines: diet in secondary prevention of cardiovascular disease. Journal of Human Nutrition and Dietetics, 14:297-305.
6. Kelly C. (2001). Flair-Flow 4: Synthesis report on dietary fat and cardiovascular disease for health professionals. British Nutrition Foundation.
7. Roche, HM. (2000). Low-fat diets, triglycerides and coronary heart disease risk. Nutrition Bulletin , 25:49-53.
8. US Department of Agriculture/US Department of Health and Human Services (2000). Dietary guidelines for Americans, 5th edition. US Department of Agriculture Center for Nutrition Policy and Promotion, Washington, DC.
9. Kris-Etherton PM, Harris WS, Appel LJ (2002). Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation 106:2747-57.
10. FAO/WHO (1994). Fats and oils in human nutrition. Rome, Food and Agriculture Organization.
11. Hu FB, Mason JE, et al, (2001). "Types of dietary fat and risk of coronary heart disease: a critical review." Journal of the American College of Nutrition, 20:5-19.
12. Katan MB (2000). "Trans fatty acids and plasma lipoproteins." Nutrition Reviews, 58:188-191.
13. Key TJ, Allen NE, et al (2002). "The effect of diet on risk of cancer". Lancet, 360:861-868.
14. Bowman BA and Russell RM. (2001). Present knowledge in nutrition, 8th edition. International Life Sciences Institute. ILSI Press, Washington DC.
15. Truswell AS. (1995). Dietary fat: some aspects of nutrition and health and product development. ILSI Europe Concise Monograph Series. ILSI Press, Washington DC.
16. Mensink GBM, Thamm M, Haas K. (1999). Nutrition in Germany 1998. public health 61, special issue 2 S200-S206.
17. Hulshof KFAM, Brussaard JH, Kruizinga AG, Telman J, Löwik MRH. (2003). Socio-economic status, dietary intake and 10 y trends: the Dutch National Food Consumption Survey. European Journal of Clinical Nutrition 57, 128-137.
18. Étude INCA 1999 pour la France. Enquête Individuelle et Nationale sur les Consommations Alimentaires. TEC & DOC Editions 14 rue de Provigny 94236 CACHAN CEDEX FRANCE.
19. Henderson L, Gregory J, Irving K, Swan G. 2003. The National Diet and Nutrition Survey: adults aged 19-64 years. Volume 2: Energy, protein carbohydrate, fat and alcohol intake. TSO (London).