Friday, May 22, 2009

The Truth About Fats and Lipids

Fats, like carbohydrates, are composed of carbon, hydrogen and oxygen.  Fat contains more carbon and hydrogen and less oxygen than carbs, making it a more concentrated form of fuel yielding 2.25 times as much energy per gram as carbs.  

As they relate to nutrition, a fat that is in a liquid state at room temperature is called an oil. Fats are generally insoluble in water but soluble in organic solvents as ether and chloroform.

There are 3 essential fatty acids:
1. Linoleic acid - Omega 6 (vegetable oils)
2. Linolenic acid - Omega 3 (flax seeds, cold water fish)
3. Arachidonic acid - Omega 9 (animal fat sources, our bodies produce their own)

Lipids refer to fats and other compounds which resemble fat. There are 3 classifications of lipids:
1. Simple lipids are esters of glycerol and fatty acids (monoglycerides, diglycerides and triglycerides).
2. Compound lipids are combinations of simple lipids with nonlipid substances (phospholipids, glycolipids and lipoproteins).
3. Derived lipids are substances produced during the breakdown of simple and compound lipids, such as cholesterol, which is an essential component of brain and nerve tissue, all cell membranes increase flexibility and stability, can be converted into hormones, bile and Vitamin D, digestion, steriod hormones and Ergosterol (used in the metabolism of Vitamin A.  The body produces about 1000ml of cholesterol per day and adjusts this amount downward if a person has a high intake of dietary cholesterol.

Classifications by degree of saturation of fat:
1. Unsaturated 
• have carbon atoms for hydrogen atom bonding, which is critical to helping the body remove gydrogen ions which accumulate as a result of metabolism.  Too much hydrogen in the body results in acidosis and enzyme deactivation.
• are usually liquid at room temperature.
• are divided into monounsaturated and polyunsaturated fatty acids; monounsaturated fatty acids can only bind one hydrogen atom while polyunsaturated fatty acids can gind to two or more gydrogen atoms, ie., Linolenic acid (Omega 3).
• plant fats are predominantly unsaturated
• cell membranes composed of UFA are more flexible, divide more efficiently and promote a quicker exchange of nutrients and wastes.

2. Saturated
• have all carbon atoms bound to hydrogen atoms
• are solid at room temperature
• found in animal fat
• considered to dangerous type of fat and assoicated with artherosclerosis and high levels of cholesterol.

Note:  Generally, unsaturated fats are found in vegetables and saturated fats are found in animal fat;  however, there are always exceptions such as coconut oil, which is mostly saturated and fish oil, or poultry witch is mostly unsaturated.

Function of Fats
• Fat protects the spleen, pancreas, bladder and liver, and are protected from injury by making the abdomen a fat depository.  
•Fat accounts for almost half of the make up of the abdominal cavity.  Fat provides warmth and guards against the loss of excessive heat.
• Fat give us energy.  Gram for gram, fat gives us twice as many calories and the same amount of carbs or proteins.  Fat must be present to convert carbs or protein to energy.  Dairy acid is necessary in the diet.
• Fat is needed for absorbtion and digestion of oil soluble nutrients.  Vitamins A, D, E and K are absorbed in fatty acids.  Fats are needed for calcium absorbtion.
• Fat is the major ingredient in the insulation of nerve fibers since the myelin sheaths which protect and insulate the nerve are made of fat.
• Some fats are essential because the body cannot make linoleic, linolenic and arachidonic acids on its own.
• Cell membranes are composed of fat and therefore require fat to reproduce.
• Fatty acids are related to hormones in the body.  Sufficient hormones are present when the adrenal, pituitary and pancreas glands are operating properly.  The fatty (adipose) tissue of the body produces fatty acids, and their utilization is triggered by the hormone, insulin, which depresses their release while adrenaline, ACTH, glucagon and growth hormones cause an increase in their release.
• Prostaglandins are lipids associated with various embranes in the body ad act as hormone-like substances.
• Fat is fuel.  Carbs simply do no supply as much energy per gram as fat.  Protein is only a secondary source of energy since it takes extra energy for the body to convert protein into fuel. Fat supplies the most efficient energy to the body.
• Fats are used in the production of many crucial body substances. Hemoglobin, the pigment that enables red bloods cells to carry oxygen to all parts of the body, is a lipid and a type of fatty acid.

Digestion of Fat
• Fats remain in the stomach up to 3 1/2 hours after ingestion.
• Bile salts emulsify and reduce fats into smaller particles.
• Lipase in pancreatic secretions hydrolyzes triglycerides into fatty acids and glycerol.


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