Metabolic
Food
Fats

Fats are a source of essential fatty acids, and we need good fats in our diets to help us absorb the fat-soluble vitamins like A, D, E and K. Understanding which fats are healthy to consume is vital to maintaining a healthy diet. We should eat fats in their natural forms, and eliminate or reduce those that cause inflammation and disease. There is a video at the bottom of this page showing how these unhealthy oils are made, once watched, you may decide to eliminate them from your diet.

Fats / Lipids

Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. Lipids are the polymers of fatty acids that have a long, non-polar hydrocarbon chain with a small polar region containing oxygen. A fat's chemical and physical properties change depending on the arrangement of molecules. For example, the trans fatty acid elaidic acid and naturally occurring oleic acid have the same chemical formula (C9H17C9H17O2), but they have different chemical and physical properties. Oleic acid has a melting point of 13.4 °C, whereas elaidic acid has a much higher melting point of 45 °C. Oleic acid is liquid at room temperature because cis molecules are loosely packed, whereas elaidic acid is solid at room temperature because trans molecules are tightly packed.

Most natural fats and oils contain only cis double bonds, in which the carbon moieties lie on the same side. (Fig. 1) Oleic Acid (Fig 1.) Chemical structure of Oleic acid (C9H17C9H17O2), an unsaturated cis fat. In the cis configuration the carbon chain extends from the same side of the double bond making the molecule bend.

Trans fatty acids, the carbon moieties on the two sides of a double bond point in opposite directions. Elaidic Acid (Fig 2.) Chemical structure of Elaidic acid (C9H17C9H17O2), an isomer of oleic acid, but an unsaturated trans fat. In the trans configuration the carbon chain extends from opposite sides of the double bond making a straighter molecule.

Fatty acids are carboxylic acids with aliphatic chains, which can be either saturated or unsaturated. Examples of unsaturated fatty acids are palmitoleic acid, oleic acid, myristoleic acid, linoleic acid, and arachidonic acid. In unsaturated fatty acids, the carbon atoms that are missing a hydrogen atom are joined by double bonds, rather than single bonds, so that each carbon atom participates in four bonds. If the hydrogen atoms are on the same side of the double bonds of the carbon chain then it is said to be in "cis" configuration. If the hydrogen atoms are on the opposite side of the double bonds of the carbon chain, then it is said to be in "trans" configuration.

Cis fatty acids vs trans fatty acids:

"Trans fatty acids are not essential and provide no known benefit to human health" 1

An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.

unsaturated fats

Cis fatty acids has both hydrogen atoms located on the same side, while trans fatty acid has two hydrogen atoms on opposite sides. Cis-unsaturated fats contain double bonds, with hydrogens on the same side of the double bond which causes the carbon chain to bend. Cis fatty acids and trans fatty acids are metabolized differently. 2

Double bonds in the fatty acids of vegetable oils subjected to the high temperatures during refining, especially the deodorisation process, and during frying can undergo geometrical isomerization from the cis to trans configuration. 3 When heated (cooked), some unsaturated fats change from their normal geometry to trans fats. The rate of isomerization is also accelerated by free radicals. 4

Types of Fat

All fat and oil sources are mixtures of fatty acids. Fatty acids can be classified based on their length, saturation vs unsaturation, even vs odd carbon content, and linear vs branched structure.

  1. Omega 3 and Omega 6 fatty acids. Vegetable oils, like avocado oil contain ALA, anti-inflammatory compounds. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which comes from marine life, like fish, is anti-inflammatory.
  2. Mono-unsaturated fatty acids, olive oils. PPRA alpha. olive oil is cis-fatty acid ... good
  3. Poly-unsaturated fatty acids are good
  4. Saturated fatty acids, animal fats, which are niether pro-inflammatory nor anti-inflammatory. Even chain fatty acids and odd chain fatty acids (milk) phospholipid tail are anti-inflammatory.
  5. Medium-chain fatty acids (MCFAs) are fatty acids with aliphatic tails of 6 to 12(8) carbons, which can form medium-chain triglycerides, found mainly in coconut oil.
  6. Trans fat, also called trans-unsaturated fatty acids, or trans fatty acids, is a type of unsaturated fat that occurs in foods - although we lack the enzyme to effectively break the trans double bonds.
  7. Short-chain fatty acids (SCFAs) are organic acids produced by intestinal microbial fermentation of mainly undigested dietary carbohydrates, specifically resistant starches and dietary fiber, but also in a minor part by dietary and endogenous proteins.

Healthy oils that were mechanical extracted, like EVOO Olive oil, coconut, and palm oils are able to retain much of their natural essence and chemical structure. Olive oil contains about 70-80% oleic acid, a monounsaturated fatty acid with the cis configuration, but the cis fatty acids can become trans fatty acids if olive oil is heated past its smoking point of 310 degrees. Labels describing heatless methods for extracting oil, such as “cold-pressed” or “expeller-pressed,” or highlighting a lack of processing, are meant to convey an abundance of healthy bioactive molecules.

Dietary Fat

Fat is a major source of fuel energy for the body and aids in the absorption of fat-soluble vitamins and carotenoids. Small amounts of trans fats occurs in meat and dairy products; these beneficial, naturally occurring trans fats include conjugated linoleic acid (CLA) and vaccenic acid, whereas the industrially produced trans fats do not produce these fatty acids. 5

Fats provide long-lasting energy and help us feel full and satisfied after eating. This can aid in weight management. Fat is the macronutrient that has the longest duration for your body to break down and digest, compared to protein and carbohydrate. Omega-3 fatty acids found in foods like fatty fish have anti-inflammatory properties that can help reduce joint pain and other inflammation. Fatty foods are avocados, nuts, fatty fish, eggs, cheese, dark chocolate, full-fat yogurt and dairy, and olive oil.

Triglycerides

Triglycerides, which are contained in fat cells, can be broken down, then used to provide energy for the body’s metabolic processes, including growth. Triglycerides are produced in the intestine and liver from smaller fats called fatty acids. Some types of fatty acids are made by the body, but others must be obtained from food. To circulate in blood, cholesterol and triglycerides are packaged with proteins and other substances to form particles called lipoproteins. Steroids such as sterol are another major class of lipids.

Triglycerides help transport and store energy. Excess calories, especially from carbohydrates and sugars, are converted into triglycerides and stored in fat cells for later use. Maintaining healthy triglyceride and triglyceride levels through diet, exercise, and medication if necessary is important for cardiovascular health.

Cholesterol

Cholesterol is an essential component of cell membranes, of brain and nerve cells, and of bile, which helps the body absorb fats and fat-soluble vitamins. The body uses cholesterol to make vitamin D and various hormones, such as estrogen, testosterone, and cortisol. The body can produce all the cholesterol that it needs, but it also obtains cholesterol from food.

Cholesterol is transported through the bloodstream attached to lipoproteins; the cholesterol carried by LDL is called LDL-C, while the cholesterol carried by HDL is called HDL-C. Each type of lipoprotein has a different purpose and is broken down and excreted in a slightly different way. Chylomicrons, High-density lipoproteins (HDL), Low-density lipoproteins (LDL), and Very low density lipoproteins (VLDL) are main types of lipoproteins.

Dr. Robert Lustig is a neuroendocrinologist and Professor of Pediatric Endocrinology. This Youtube video discusses how there various oils are metabolized.

Truth about Fats

This video shows how commercial seed oils are made. Corn and soybeans are widely grown and used as important food and feed sources, but they are not botanically classified as vegetables.

How It's Made - Canola Oil

Digestion

When we consume dietary fats (primarily triglycerides), they are broken down in the small intestine by enzymes called lipases. The resulting fatty acids and monoglycerides are then absorbed by the intestinal cells. Once absorbed, these fatty acids are repackaged into lipoproteins called chylomicrons. These chylomicrons enter the bloodstream through the lymphatic system and transport the fats to various tissues.

Excess fats are stored in adipose tissue (body fat) in the form of triglycerides. This serves as an energy reserve for the body. When the body needs energy, hormones like glucagon and adrenaline stimulate the breakdown of stored triglycerides in adipose tissue through a process called lipolysis. This releases fatty acids into the bloodstream.

Energy

To maintain physical activity the body must constantly replenish both creatine phosphate (CP) and adenosine triphosphate (ATP). This is achieved through various energy systems:

  1. Anaerobic glycolysis: Breaks down glucose without oxygen to produce ATP rapidly, but also generates lactic acid as a byproduct.
  2. Aerobic respiration: Uses oxygen to break down glucose, fats, and sometimes proteins to produce ATP more efficiently, but at a slower rate.
  3. Beta-oxidation: Breaks down fatty acids to produce ATP, particularly during prolonged, low-intensity activities.

Fat is the body's most concentrated source of energy, providing more than twice as much potential energy as carbohydrate or protein (9 calories per gram versus 4 calories each per gram). During exercise, stored fat in the body (in the form of triglycerides in adipose or fat tissue) is broken down into fatty acids. These fatty acids are transported through the blood to muscles for fuel. This process occurs relatively slowly as compared with the mobilization of carbohydrate for fuel. Fat is also stored within muscle fibers, where it can be more easily accessed during exercise. Unlike your glycogen stores, which are limited, body fat is a virtually unlimited source of energy for athletes. Even those who are lean and mean have enough fat stored in muscle fibers and fat cells to supply up to 100,000 calories—enough for over 100 hours of marathon running! [^6]

Good Fat Facts

Olive oil has many unique nutritional properties that has a high monounsaturated fat (MUFA) content which helps to lower your "bad" LDL cholesterol. It also contains more than 30 types of phenolic compounds, which are antioxidants that protect your cells from harmful free radical molecules. Polyphenols also have prebiotic activity, which encourages growth of beneficial bacteria in your gut microbiome.

Footnotes

  1. Food and nutrition board, institute of medicine of the national academies (2005).. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients) (opens in a new tab)

  2. Advances in Nutrition Mechanisms of Action of trans Fatty Acids (opens in a new tab)

  3. The American Oil Chemists' Society Metabolism of Trans Polyunsaturated Fatty Acids Formed during Frying (opens in a new tab)

  4. Lipid Geometrical Isomerism From Chemistry to Biology and Diagnostics (opens in a new tab)

  5. Effects of Ruminant trans Fatty Acids on Cardiovascular Disease and Cancer A Comprehensive Review of Epidemiological, Clinical, and Mechanistic Studies (opens in a new tab) [6^]: Human Kinetics: The Body's Fuel Sources (opens in a new tab)