Lipids
Macronutrient.
Provide 9 Kcalories per gram; it is an energy-yielding nutrient
Functions are stored energy (adipose tissue), organ protection,
temperature regulator, insulation such as myelin that covers nerve cells, lipid
membrane around cells, and emulsifiers to keep fats dispersed in body fluids.
Lipids are made of organic molecules carbon, hydrogen, and oxygen.
Fats consist of glycerol fatty acids joind by an ester bond.
- A. Triglycerides - composed of three fatty acids and one glycerol molecule.
- B. Saturated fatty acid - fatty acid with carbon chains fully saturated with hydrogen.
- C. Monounsaturated fatty acid - fatty acid that has a carbon chain with one unsaturated double bond.
- D. Polyunsaturated fatty acid - fatty acid that has two or more double bonds on the carbon chain.
Essential fatty acids part of the polyunsaturated fatty acids
- E. Linoleic acid an essential polyunsaturated fatty acid, its first double bond is at the 6th carbon and this is why it can be called Omega 6.
- F. Linolenic acid an essential polyunsaturated fatty acid, its first double bond is at the 3rd carbon and this is why it can be called Omega 3, and is the main member of the omega-3 family.
- G. Eicosapentaenoic acid (EPA) , may be derived inefficiently from linolenic acid and is the main fatty acid found in fish, also called omega 3.
- H. Docosahexaenoic acid (DHE), is an omega 3 fatty acid, is synthesized in body from alph-linolenic acid, and is present in fish. DHA is present in retina and brain.
Nonessential
- I. Sterols serve a vital function in the body, are produced by the body, and are not essential nutrients. This structure of a lipid is cholesterol which is a waxy substance that doesn't look like a triglyceride. It doesn't have a glycerol backbone or fatty acids, but because it is impermeable in water, it is a lipid.
- J. CIS- Trans Fatty acids hydrogenation makes monounsaturated and polyunsaturated fatty acids go from a state of their original form that is cis to a trans form. Addition of hydrogen ions will cause vegetable oil to harden. Additionally, they may stimulate cholesterol synthesis, and are potentially carcinogenic.
Absorption process of triglycerides. This is the fat that your body deals with most of the time.
They are absorbed with the transport of chylomicrons into the lymphatic system
which in turn will pour into the blood stream at the thoracic duct. Once it
enters the blood stream the chylomicrons take the triglycerides into the cells.
The triglycerides that are on the outer part of the chylomicrons are broken
down by lipoprotein lipase. Lipoprotein lipase can be found on the walls of
capillaries. It is this enzyme that will break it into fatty acids and
monoglycerides. The fatty acids are taken by the body's cells while the
monoglycerides are taken to the liver to be processed.
More Info on Lipids:
- 1. Lipids are structural components found in every cell of the human body. That is, they form the lipid bilayer found in individual cells. They also serve as the myelin sheath found in neurons.
- 2. Lipids provide us with energy. Most of that energy is in the form of triacylglycerols.
- 3. Both lipids and lipid derivatives serve as vitamins and hormones.
- 4. Lipophilic bile acids aid in lipid solubility.
Recommendations for Fat Intake: Although there are different types of fat the effect on
health and disease, the basic message is simple: leave out the bad fats and
replace them with good fats. Try to limit saturated fats in your diet, and try
to eliminate trans fats from partially hydrogenated oils.Replace saturated and
trans fats with polyunsaturated and monounsaturated fats. As of January 1,
2006, trans fat must be listed on food labels. More and more
"trans-fat" free products are becoming available. Keep in mind,
though, that according to the FDA, a product claiming to have zero trans fat
can actually contain up to a half gram. You may still want to scan the ingredient
list for "partially hydrogenated vegetable oil" and "vegetable
shortening," and look for an alternative product without those words.
