Fatty acids are an essential part of the human diet. These acids naturally occur in some foods and are also available as dietary supplement products. In the body, fatty acids are stored primarily in adipose tissue and to a lesser extent in muscle. This article will discuss the basics of fatty acids, their advantages, and disadvantages, where they are stored in the body, and how they affect health conditions.
Fatty acids are molecules formed by joining together a chain of carbon atoms with hydrogen molecules. They play an essential role in the body. They help build cell membranes (the coating outside of cells), is used as a source of energy, and produce hormones. The key is to get the right kind of fatty acids and the correct ratio.
Fatty acids are one of the four major types of macromolecules, forming the bulk of lipids. They are composed of carbon, hydrogen, and oxygen. This hydrocarbon tail is sometimes referred to as the omega-end because it is the last carbon atom before the oxygen atom in the molecule.
History
Fatty acids were first discovered in human body tissues in the early 1800s. In 1823, chemists Michel Chevreul and Antoine Bussy isolated margaric acid from beef tallow. Margaric acid was found to have a similar melting point and solubility as stearic acid. However, unlike stearic acid, margaric acid could be digested by yeast. This discovery concluded that margaric acid was different from stearic acid and established that fatty acids were not simply solids that melted at varying temperatures.
In 1838, Theodore Nicolas Gobley named palmitin, olein, and stearin their respective positions on saponified palm oil. The terms "palmitin," "olein," and "stearin" are still used today as synonyms for palmitic, oleic, and stearic acids, respectively.
These four fatty acids were discovered by discovering several other saturated (e.g., myristic, lauric) and unsaturated (e.g., linoleic) fatty acids in animal fats and oils during the 1800s.
Production
The production of fatty acids in the body is called lipogenesis. It occurs in the adipose tissue, liver, mammary glands, and lactating breast. This process occurs through a series of biochemical reactions, resulting in the synthesis of palmitic acid from acetyl-CoA.[2]
In plants, it is formed from acetate derived from photosynthesis. However, it is synthesized from carbohydrates or proteins in a complex process in animals.
Steps involved in fat synthesis
1. Glucose from diet enters the cell via GLUT4 transporter. It is then converted to pyruvate via the glycolysis pathway.
2. Pyruvate is converted to oxaloacetate by pyruvate carboxylase enzyme.
3. Oxaloacetate combines with acetyl CoA to form citric acid or citrate via the citric acid cycle.
4. Citrate exists in mitochondria and enters the cytoplasm, where it is reconverted to oxaloacetate by ATP citrate lyase enzyme.
5. Malonyl CoA is formed by the acetyl CoA carboxylase enzyme in the presence of biotin and ATP.
6. Malonyl CoA catalyzes the condensation of acetyl-CoA with malonyl-CoA.
7. The chain elongation is carried out by chain elongating enzymes in the presence of NADPH and oxygen.
8. In the endoplasmic reticulum, the saturated fatty acids are esterified to glycerol 3-phosphate by glycerol 3-phosphate acyltransferase to form a triglyceride molecule.
Application
Fatty Acids in Food
Fatty acids are the backbone of all the fat in foods. They play a crucial role in regulating gene expression, proper development and functioning of cell membranes, transportation of lipids in the blood, and synthesis of steroid hormones.
Fatty acids are a major structural component of the human body. They are essential for the proper functioning of the cells and influence the skin's appearance, among many other functions. The human body produces some fatty acids (such as oleic acid) while others have to be eaten.
There are plenty of fatty acids that may be obtained even from vegetables and grains. However, only a few foods contain essential fatty acids (e.g., meat, fish, eggs, dairy products, and vegetables).
Fatty Acids for Skin
Fatty acids are used as a food source for the skin. There are primary essential fatty acids that humans need for healthy skin. They are linoleic acid, omega-6 fatty acid, alpha-linolenic acid, or omega-3 fatty acid.
Linoleic acid is found in many vegetable oils, such as safflower oil, sunflower oil, grape seed oil, and corn oil. In addition, alpha-linolenic acid is found in fish and some plant oils, such as flaxseed oil and canola oil.
Linoleic acid is converted to the compound gamma-linolenic acid in the human body. Gamma-linolenic acid is found in evening primrose oil and borage seed oil. The compound arachidonic acid is converted from linoleic acid in the body. It is a component of eggs, meat, and fish oils.
The American Dietetic Association says that omega-6 fatty acids may help treat atopic dermatitis -- a type of eczema -- and rheumatoid arthritis, diabetic neuropathy, and premenstrual syndrome. However, not all studies have shown positive results for these conditions.
Omega-3 fatty acids may help decrease inflammation in certain skin conditions -- including psoriasis -- according to the University of Maryland Medical Center. For this reason, people with psoriasis may want to increase their omega-3 intake. Omega-3s are found in fish, seafood, nuts, seeds, and oils. In addition, some types of fish, such as salmon and tuna, also contain vitamin D, beneficial for psoriasis.
Some studies have found that fish oil supplements can reduce symptoms of rheumatoid arthritis, which often affects the same joints as psoriatic arthritis.
Industrial uses of fatty acid
Fatty acids are used in many industrial applications. The following uses apply to tall oil fatty acids, typically 38-60% linoleic and 20-45% oleic acid.
• Metalworking fluids: Emulsifier, foaming agent, rust preventative, and lubricant.
• Lubricants: As a lubricant and rust preventative.
• Asphalt additives: As an emulsifier, wetting agent, and stabilizer.
• Agricultural uses: As a feedstock for organic fertilizers and animal feeds.
• Surfactants: In detergents, soaps, and fabric softeners.
• Cosmetics: Lipstick, nail polish remover, eye shadow, mascara, and blushers.
Classifications
Classifications of fatty acids by bonds
The classification of fatty acids refers to the degree of saturation of the heavy acid chain. Categories are based on one or more double bonds, with different classifications for cis and trans isomers. The cis isomer is the product and favored reactant in biological systems.
Saturated fats contain only single bonds, and the chain has no kinks. Unsaturated fats have double bonds and may be cis or trans-isomers. Saturated fats are relatively straight, while unsaturated fats are bent.
Saturated fatty acids
Saturated fatty acids contain only single bonds (saturated with hydrogen atoms) and have the general formula CH₃(CH₂)nCOOH. Therefore, they are solid at room temperature. Because they have no double bonds, they have the maximum hydrogen atoms possible, so they are saturated with hydrogen. Saturated fatty acids occur in animal products and tropical oils such as coconut oil.
Examples of saturated fatty acids include:
• Butyric acid (4 carbons)
• Caproic acid (6 carbons)
• Caprylic acid (8 carbons)
• Capric acid (10 carbons)
• Lauric acid (12 carbons)
• Myristic acid (14 carbons)
• Palmitic acid (16 carbons)
• Stearic acid (18 carbons)
Unsaturated fatty acids
Unsaturated fats may be classified into monounsaturated or polyunsaturated. There are several variations in the number of double bonds that are used to classify fatty acids; these include the followings:
Monounsaturated fatty acids
Monounsaturated fatty acids contain one double bond in the carbon chain and have the general formula CH₃(CH=CH[CH₂])nCOOH. They remain liquid even at low temperatures because of their kinked structure due to one double bond in their system. These are found in olive oil and peanut oil.
Examples of monounsaturated fatty acids include the followings:
Palmitoleic acid: it is found in macadamia nuts and sea buckthorn oil.
Oleic acid (omega 9) – found in olive oil and hazelnuts
Polyunsaturated fatty acids
Polyunsaturated fatty acids contain double bonds in the carbon chain and have the general formula CH₃(CH=CH[CH₂])nCOOH. They have two or more two double bonds between carbon atoms. They appear as liquid oils at room temperature because they have multiple double bonds, which cause them to twist and bend rather than form a solid mass (like saturated fats). Polyunsaturated fatty acids are found in sunflower oil, corn oil, safflower oil, and nuts and seeds. These fatty acids, including linoleic acid and alpha-linolenic acid, are essential. They cannot be produced by the body and must be obtained daily through diet.
Trans-fatty acids are polyunsaturated fat where at least one pair of carbon atoms in a methylene group is on opposite sides of the double bond (cis vs. trans).
Examples of polyunsaturated fatty acids include the followings:
Linoleic acid (omega 6) – found in hemp, pumpkin, grapeseed and sunflower seeds, walnuts, and borage oil
Gamma-linolenic acid (omega 6) – found in hemp, borage, and black currant seed oils
Alpha-linolenic acid (omega 3) – found in flaxseed, hemp seed, chia seeds, walnuts, and soybeans.
Health Benefits
Omega-3 fatty acids
Omega-3 fatty acids are polyunsaturated fats commonly found in fish, shellfish, and plant sources. They are essential fatty acids, defined as compounds that humans cannot synthesize and must be obtained from food. Instead, omega-3 fatty acids are converted into compounds called eicosanoids, which have many roles, including anti-inflammatory processes, control of blood clotting, and cell signaling.
There has been much research investigating the effect of omega-3 fatty acids on human health. These substances have been shown to protect humans from chronic conditions such as heart disease and cancer. In addition, Omega-3s provide a rich source of anti-inflammatory compounds and have been highly valued for their contributions to overall health and wellness.
The two omega-3 fatty acids essential for human metabolism are alpha-linolenic acid (ALA) and eicosapentaenoic acid (EPA).
Health benefits of omega-3
• Omega-3 fatty acids are anti-inflammatory, reducing the risk of heart attacks, strokes, and arthritis. It's even been suggested that omega-3s may help reduce the symptoms of depression and inhibit the growth of cancerous tumors, such as breast and colon cancers.
• Omega-3s may help prevent heart disease by lowering overall blood cholesterol levels, decreasing triglycerides (another type of fat found in the blood), reducing blood pressure, and preventing irregular heartbeat.
• Omega 3 fatty acids play a significant role in the skin. They treat psoriasis, eczema, and other allergies and ailments.
• Also, they help reduce swelling eliminate itchiness, redness, and flakiness from the skin. Omega 3 is also a natural moisturizer found in olive oil, fish oil, sardines, and other sources.
• Omega-3 fatty acids can also promote healthier pregnancy outcomes and lower the risk of dementia and Alzheimer's disease.
However, too many omega-3 fatty acids may result in inevitable consequences despite all these benefits. Here are a few disadvantages of these essential fats.
The disadvantages of omega-3 fatty acids are that they can slow down the blood clotting process, resulting in excessive bleeding during injury or surgery. This usage can also be problematic during childbirth.
Contrary to popular belief, omega-3 fatty acids are not a magic elixir or a panacea for all ills. When taking omega-3 fatty acids as a nutritional source, one must factor in the weather's heat as it can affect how fresh the product is and will be less beneficial.
Omega-6 fatty acids
Omega-6 is also a group of polyunsaturated fatty acids. These fatty acids are essential because they cannot be produced within the body, and they must obtain through diet. This group includes vital constituents such as linoleic acid (LA), gamma-linolenic acid (GLA), and arachidonic acid (AA). Although omega-6 fatty acids are crucial, there is a debate over whether omega-6 fatty acids are beneficial for health or potentially harmful to heart health.
Omega-6 fatty acids benefits include:
• Skin health: Omega-6 fatty acids can improve skin health, including helping to prevent skin cancer. They may also help reduce acne, psoriasis, and inflammation.
• Heart health: Omega-6 fatty acids can help reduce the chance of heart disease, including heart attacks and stroke.
• Immune system support: Omega-6 fatty acids may help support a healthy immune system. This may be due to their anti-inflammatory effects.
• Brain health: Omega-6s play an essential role in brain function and development. Although more research is needed, they may help slow age-related mental decline as you get older.
Notwithstanding, omega-6 has some disadvantages. One common drawback is that omega-6 fatty acids can promote inflammation when consumed in large amounts. This is bad because inflammation can lead to life-threatening diseases like cancer, heart disease, and diabetes. Also, omega-6 fatty acids can increase the risk of obesity by promoting fat storage. Omega-6 fatty acids are also linked to insulin resistance. Insulin resistance means that the body's cells don't respond to insulin appropriately. This condition is a precursor to type two diabetes.
It's essential to maintain a balanced diet that contains various nutrients, including adequate amounts of omega-3 and omega-6 fatty acids. An excellent way to do this is by eating lots of fruits and vegetables and avoiding foods high in saturated fats and trans fats as much as possible.
Classification by Length
The length of their hydrocarbon chain also classifies fatty acids. These classifications include:
Volatile fatty acids
Fatty acids with carbon chains that are less than six carbons long are referred to as volatile fatty acids (VFAs). These include acetic acid, propionic acid, isobutyric acid, butyric acid, valeric acid, and caproic acid.
Short-chain fatty acids
Fatty acids with carbon chains that are six to 12 carbons long are referred to as short-chain fatty acids (SCFAs). These include hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid.
Medium-chain fatty acids
Fatty acids with carbon chains that are 13 to 21 carbons long are referred to as medium-chain fatty acids (MCFAs). These include tridecanoic acid, pentadecanoic acid, and heptadecanoic acid.
Long-chain fatty acids
Fatty acids with carbon chains that are 22 or more carbons long are referred to as long-chain fatty acids (LCFAs). These include myristoleic acid, palmitoleic acid, arachidonic acid, stearidonic acid, and arachidonic alpha.
Summary
The most common form of fatty acids is triglycerides. When the fatty acids are in glycerol form, they are called glucosides. Before being ingested by humans, fatty acids are often attached to a deactivation end product, produced by the liver and sold in pharmacies as drugs. This results in inactive acylglycerols. Fatty acids have many essential roles with plants and animals, including their use in biosynthesis to produce phospholipids for cell membranes, steroids, prostaglandins, leukotrienes, dolichols, and others. In addition, they can act as signaling molecules because they possess a hydrophobic region that allows them to travel through the cell membrane. The importance of this function is underscored by eukaryotic cells that cannot use fatty acids due to the lack of necessary enzymes.
Timeline
