Chap 3 J Pistack

MS/ED

Lipids – the true name for fats of all kinds

Lipids include true fats, oils, and the related lipoids and sterols

Dietary fats are found in both plant and animal products

Lipids are insoluble in water and are greasy to the touch

Animal fats consist of a larger content of saturated fat, tend to have a higher melting point, and are solid at room temperature

Plant derived fats have more unsaturated fat than animal fats, are normally in the form of oils, and have a lower melting point

Comprise elements carbon, hydrogen, and oxygen

The basic structural unit of a true fat is one molecule of glycerol attached to one, two, or three fatty acids

A fatty acid is composed of a chain of carbon atoms with hydrogen and a few oxygen atoms attached

Monoglycerides - one fatty acid attached to glycerol

Diglycerides – two fatty acids attached to glycerol

Triglycerides – three fatty acids attached to glycerol

Fatty acid carbon chains vary in length from 2 to 24 carbon atoms

The length of the chain determines how the body transports and processes the fatty acid Short <6 Medium 8-12 Long 13-24

The length of the chain has dietary implications

Saturated, trans-fat, unsaturated, monounsaturated, and polyunsaturated are names indicating the degree of hydrogen atom saturation of the carbon chain of a fatty acid

A saturated fatty acid is filled with as many hydrogen atoms as the carbon atoms can bond with – thus, it is saturated

In an unsaturated fatty acid the carbon atoms are joined together by one or more double bonds, not holding its maximum number of hydrogen atoms and is therefore unsaturated

Double bonds between two carbon atoms when there are two few hydrogen atoms to fill all the spaces

A monounsaturated fatty acid has only one carbon to carbon double bond

A polyunsaturated fatty acid has more than one carbon to carbon double bond

Solid at room temperature Animal or tropical oil origin Become rancid slowly – because of their

chemical stability Products made with this fat have a longer

shelf life All of the carbons are attached to hydrogen

with no double bonds

Liquid at room temperature Plant origins Become rancid quickly Have a double carbon bond (one or

more hydrogen atoms could be added to the fatty acid chain)

A double bond on a fatty acid causes the chain to bend or change shape

Has a health benefit

The addition of hydrogen to fat of vegetable origin

If enough hydrogen is added to only break some of the double bonds the fat is considered partially hydrogenated

If all double bonds are broken with added hydrogen the fat is completely hydrogenated

Made from unsaturated fats by commercially adding hydrogen at double-bond sites

Causes an unnatural bend in the fatty acid chain

Has a health detriment

Fats serve as a fuel source as well as a vehicle for fat-soluble vitamins –A, D,E, and K

Due to the chemical composition of fats they are a more concentrated energy source than carbohydrates

Gram for gram, fats furnish twice as many calories as carbohydrates

Seven major functions of fats in the body

1 - Supply fuel to most tissues 2 - Serves as an energy reserve 3 - Insulate the body 4 – Support and protect vital organs

Act as a pad to absorb mechanical shock Protected organs include eyes and kidneys

5 - Lubricate body tissues Oils manufactured by the body supply glands like

the sebaceous glands, to secrete the oils to the skin to control water loss

6 - Form an integral part of cell membranes

Plays a role in drug, nutrient, and metabolite transport

Provides barrier against water soluble substances

7 -Carrier for fat-soluble vitamins

Not a true fat but belongs to a group called sterols

Cholesterol is a component of many foods we eat

Our bodies make about 1000 mg a day

Present only in animal foods

A component of bile salts that aid digestion

Essential component of cell membranes Found in the brain, nerve tissue, and blood Precursor for steroid hormone production Necessary for the production of

Cortisone Adrenaline Estrogen Testosterone

Dietary fat plays a key role in health Some fat in the diet is necessary for

optimal health Adds satiety and palatability (flavor) Good fats are found in nuts, avocado,

canola, olive, and peanut oil Polyunsaturated fats are the form of

omega 3 and omega 6